期刊文献+
共找到374篇文章
< 1 2 19 >
每页显示 20 50 100
Expression of transcription factors in polycystic ovary syndrome
1
作者 ZHANG Qi ZHU Shujuan JIANG Bin 《中南大学学报(医学版)》 北大核心 2025年第3期447-456,共10页
Objective:Polycystic ovary syndrome(PCOS)is a common endocrine disorder that affects women’s health.This study aims to investigate gene and transcription factor(TF)expression differences between PCOS patients and hea... Objective:Polycystic ovary syndrome(PCOS)is a common endocrine disorder that affects women’s health.This study aims to investigate gene and transcription factor(TF)expression differences between PCOS patients and healthy individuals using bioinformatics approaches,and to verify the function of key transcription factors,with the goal of providing new insights into the pathogenesis of PCOS.Methods:Differentially expressed genes(DEGs)and differentially expressed transcription factors(DETFs)between PCOS patients and controls were identified from the RNA sequencing dataset GSE168404 using bioinformatics methods.Functional enrichment analysis was performed using Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)databases.The expression and function of core transcription factors were further validated in ovarian tissues of PCOS model mice and control mice using Western blotting and reverse transcription quantitative polymerase chain reaction(RTqPCR).Results:A total of 332 DEGs were identified between PCOS patients and controls,including 259 upregulated and 73 downregulated genes in the PCOS group.19 DETFs were further screened,of which 16 were upregulated and 3 were downregulated in PCOS.The upregulated DETFs(including TFCP2L1,DACH1,ESR2,AFF3,SMAD9,ZNF331,HOPX,ATOH8,HIF3α,DPF3,HOXC4,HES1,ID1,JDP2,SOX4,and ID3)were primarily associated with lipid metabolism,development,and cell adhesion.Protein and mRNA expression analysis in PCOS model mice revealed significantly decreased levels of hypoxia-inducible factor(HIF)1αand HIF2α,and significantly increased expression of HIF3αcompared to control mice(all P<0.001).Conclusion:Significant differences in gene and TF expression exist between PCOS patients and healthy individuals.HIF-3αmay play a crucial role in PCOS and could serve as a novel biomarker for diagnosis and a potential therapeutic target. 展开更多
关键词 polycystic ovary syndrome transcription factor hypoxia-inducible factors regulatory networks BIOINFORMATICS
在线阅读 下载PDF
Study on the phytoplankton community structure and its driving factors in Furong Creek during spring and autumn under the influence of cascade weirs
2
作者 REN Jiangshan YU Jun +2 位作者 LI Jingjuan LYU Jianzhang WANG Xiaogang 《水利水电技术(中英文)》 北大核心 2025年第3期171-185,共15页
[Objective]The construction of weirs changes the hydraulic characteristics of rivers and affects the structure of phytoplankton communities and the health of aquatic ecosystems in the river.This study aims to explore ... [Objective]The construction of weirs changes the hydraulic characteristics of rivers and affects the structure of phytoplankton communities and the health of aquatic ecosystems in the river.This study aims to explore the nonlinear response relationship between phytoplankton community structure and its driving factors in spring and autumn in Furong Creek under the construction of cascade weirs.[Methods]The structure of phytoplankton communities and related environmental factors were investigated in Furong Creek from 2023 to 2024.This study focused on the analysis of the changes of nutrient concentrations and biomass of phytoplankton in autumn and spring within the same dry season in Furong Creek.Redundancy analysis was used to identify the key factors influencing the structure of phytoplankton communities.The MIKE 11 model was employed to simulate the hydrodynamic changes in the river.Combined with total nitrogen and permanganate index,a GAM model of phytoplankton diversity index and hydrodynamic factors was developed,and the change of phytoplankton diversity after the optimized layout of the cascade weirs was fitted.[Results]The result showed that the annual average value of Shannon-Wiener diversity index of phytoplankton in Furong Creek was 2.79,which was in a state of mild pollution.A total of 239 species from 95 genera in 8 phyla were identified.Among the phytoplankton,Chlorophyta was the dominant group throughout the year in Furong Creek,followed by Bacillariophyta and Cyanophyta.The cell abundance of phytoplankton ranged from 3.11 to 20.64 mg/L and from 0.23 to 6.31 mg/L in spring and autumn,which indicated a clear seasonal succession of phytoplankton community structure.Compared with autumn,the relative abundance of Cyanophyta significantly decreased in spring across the whole river section,while Chrysophyta and Dinophyta showed significant increase at some monitoring sites,leading to water bloom phenomenon and a noticeable decline in the diversity of phytoplankton.The dominant species in the water bodies throughout the year were Cyclotella catenata,Chlorella vulgaris,Scenedesmus bijuga,Scenedesmus quadricauda,Chroomonas acuta,Cryptomonas ovata,and Cryptomonas erosa.Redundancy analysis(RDA)showed that hydrodynamic factors(v,h)and water environmental factors(TN,COD_(Mn))were the main influencing factors of phytoplankton community structure.[Conclusion]The result show that the nutrient concentration,phytoplankton biomass,and density in Furong Creek in spring are significantly higher than in autumn.The GAM model,constructed by combining hydrodynamic and environmental factors,can effectively reflect the nonlinear relationship between phytoplankton diversity index and its driving factors.In spring,with an increase in nutrient concentration,the habitat conditions of low flow speed and high water depths formed by overflow weirs will lead to a decrease in the Shannon-Wiener index of phytoplankton and an intensified risk of eutrophication.However,a reasonable layout scheme of cascade weirs will improve the diversity of phytoplankton and reduce the risk of eutrophication in the river.The findings of this study can help deepen the understanding of the ecological and environmental effects of cascade weir construction in the river. 展开更多
关键词 cascade weirs MIKE 11 model redundancy analysis GAM model influencing factors
在线阅读 下载PDF
Influencing factors analysis of hard limestone reformation and strength weakening under acidic effect
3
作者 HOU Ming-xiao HUANG Bing-xiang +2 位作者 ZHAO Xing-long JIAO Xue-jie ZHENG Chen-yang 《Journal of Central South University》 SCIE EI CAS CSCD 2024年第7期2446-2466,共21页
Roof disaster has always been an important factor restricting coal mine safety production.Acidic effect can reform the rock mass structure to weaken the macroscopic strength characteristics,which is an effective way t... Roof disaster has always been an important factor restricting coal mine safety production.Acidic effect can reform the rock mass structure to weaken the macroscopic strength characteristics,which is an effective way to control the hard limestone roof.In this study,the effects of various factors on the reaction characteristics and mechanical properties of limestone were analyzed.The results show that the acid with stronger hydrogen production capacity after ionization(pK_(a)<0)has more prominent damage to the mineral grains of limestone.When pKa increases from−8.00 to 15.70,uniaxial compressive strength and elastic modulus of limestone increase by 117.22%and 75.98%.The influence of acid concentration is manifested in the dissolution behavior of mineral crystals,the crystal defects caused by large-scale acid action will lead to the deterioration of limestone strength,and the strength after 15%concentration reformation can be reduced by 59.42%.The effect of acidification time on limestone has stages and is the most obvious in the initial metathesis reaction stage(within 60 min).The key to the strength damage of acidified limestone is the participation of hydrogen ions in the reaction system.Based on the analytic hierarchy process method,the influence weights of acid type,acid concentration and acidification time on strength are 24.30%,59.54% and 16.16%,respectively.The research results provide theoretical support for the acidification control of hard limestone roofs in coal mines. 展开更多
关键词 hard roof acidic effect structural reformation strength weakening influencing factors
在线阅读 下载PDF
A Prognostic Model Based on Colony Stimulating Factors-related Genes in Triple-negative Breast Cancer
4
作者 GUO Yu-Xuan WANG Zhi-Yu +7 位作者 XIAO Pei-Yao ZHENG Chan-Juan FU Shu-Jun HE Guang-Chun LONG Jun WANG Jie DENG Xi-Yun WANG Yi-An 《生物化学与生物物理进展》 SCIE CAS CSCD 北大核心 2024年第10期2741-2756,共16页
Objective Triple-negative breast cancer(TNBC)is the breast cancer subtype with the worst prognosis,and lacks effective therapeutic targets.Colony stimulating factors(CSFs)are cytokines that can regulate the production... Objective Triple-negative breast cancer(TNBC)is the breast cancer subtype with the worst prognosis,and lacks effective therapeutic targets.Colony stimulating factors(CSFs)are cytokines that can regulate the production of blood cells and stimulate the growth and development of immune cells,playing an important role in the malignant progression of TNBC.This article aims to construct a novel prognostic model based on the expression of colony stimulating factors-related genes(CRGs),and analyze the sensitivity of TNBC patients to immunotherapy and drug therapy.Methods We downloaded CRGs from public databases and screened for differentially expressed CRGs between normal and TNBC tissues in the TCGA-BRCA database.Through LASSO Cox regression analysis,we constructed a prognostic model and stratified TNBC patients into high-risk and low-risk groups based on the colony stimulating factors-related genes risk score(CRRS).We further analyzed the correlation between CRRS and patient prognosis,clinical features,tumor microenvironment(TME)in both high-risk and low-risk groups,and evaluated the relationship between CRRS and sensitivity to immunotherapy and drug therapy.Results We identified 842 differentially expressed CRGs in breast cancer tissues of TNBC patients and selected 13 CRGs for constructing the prognostic model.Kaplan-Meier survival curves,time-dependent receiver operating characteristic curves,and other analyses confirmed that TNBC patients with high CRRS had shorter overall survival,and the predictive ability of CRRS prognostic model was further validated using the GEO dataset.Nomogram combining clinical features confirmed that CRRS was an independent factor for the prognosis of TNBC patients.Moreover,patients in the high-risk group had lower levels of immune infiltration in the TME and were sensitive to chemotherapeutic drugs such as 5-fluorouracil,ipatasertib,and paclitaxel.Conclusion We have developed a CRRS-based prognostic model composed of 13 differentially expressed CRGs,which may serve as a useful tool for predicting the prognosis of TNBC patients and guiding clinical treatment.Moreover,the key genes within this model may represent potential molecular targets for future therapies of TNBC. 展开更多
关键词 triple-negative breast cancer colony stimulating factors prognostic model tumor microenvironment drug sensitivity
在线阅读 下载PDF
Roles of NAC transcription factors in cotton
5
作者 XU Yuewei ZHAO Yunlei +3 位作者 CHEN Wei SANG Xiaohui ZHAO Pei WANG Hongmei 《Journal of Cotton Research》 CAS 2024年第3期289-301,共13页
Climate deterioration,water shortages,and abiotic stress are the main threats worldwide that seriously affect cotton growth,yield,and fiber quality.Therefore,research on improving cotton yield and tolerance to biotic ... Climate deterioration,water shortages,and abiotic stress are the main threats worldwide that seriously affect cotton growth,yield,and fiber quality.Therefore,research on improving cotton yield and tolerance to biotic and abiotic stresses is of great importance.The NAC proteins are crucial and plant-specific transcription factors(TFs)that are involved in cotton growth,development,and stress responses.The comprehensive utilization of cotton NAC TFs in the improvement of cotton varieties through novel biotechnological methods is feasible.Based on cotton genomic data,genome-wide identification and analyses have revealed potential functions of cotton NAC genes.Here,we comprehensively summarize the recent progress in understanding cotton NAC TFs roles in regulating responses to drought,salt,and Verticillium wilt-related stresses,as well as leaf senescence and the development of fibers,xylem,and glands.The detailed regulatory network of NAC proteins in cotton is also elucidated.Cotton NAC TFs directly bind to the promoters of genes associated with ABA biosynthesis and secondary cell-wall formation,participate in several biological processes by interacting with related proteins,and regulate the expression of downstream genes.Studies have shown that the overexpression of NAC TF genes in cotton and other model plants improve their drought or salt tolerance.This review elucidates the latest findings on the functions and regulation of cotton NAC proteins,broadens our understanding of cotton NAC TFs,and lays a fundamental foundation for further molecular breeding research in cotton. 展开更多
关键词 COTTON NAC transcription factor STRESS Regulatory network
在线阅读 下载PDF
Directly searching method for slip plane and its influential factors based on critical state of slope 被引量:30
6
作者 林杭 曹平 +2 位作者 宫凤强 李江腾 桂易林 《Journal of Central South University》 SCIE EI CAS 2009年第1期131-135,共5页
In order to determine the slip plane of slope directly by the calculation results of strength reduction method, and analyze the influential factors of slope stability, a numerical model was established in plane strain... In order to determine the slip plane of slope directly by the calculation results of strength reduction method, and analyze the influential factors of slope stability, a numerical model was established in plane strain mode by FLAC3D for homogeneous soil slope, whose parameters were reduced until the slope reached the critical state. Then FISH program was used to get the location data of slip plane from displacement contour lines. Furthermore, the method to determine multiple slip planes was also proposed by setting different heights of elastic areas. The influential factors for the stability were analyzed, including cohesion, internal friction angle, and tensile strength. The calculation results show that with the increase of cohesion, failure mode of slope changes from shallow slipping to the deep slipping, while inclination of slip plane becomes slower and slipping volume becomes larger; with the increase of friction angle, failure mode of slope changes from deep slipping to shallow slipping, while slip plane becomes steeper and upper border of slip plane comes closer to the vertex of slope; the safety factor increases little and slip plane goes far away from vertex of slope with the increase of tensile strength. 展开更多
关键词 SLOPE strength reduction slip plane STABILITY influential factors
在线阅读 下载PDF
Effects of fundamental factors on coupled vibration of wind-rail vehicle-bridge system for long-span cable-stayed bridge 被引量:11
7
作者 张明金 李永乐 汪斌 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第5期1264-1272,共9页
In a wind-vehicle-bridge(WVB) system,there are various interactions among wind,vehicle and bridge.The mechanism for coupling vibration of wind-vehicle-bridge systems is explored to demonstrate the effects of fundament... In a wind-vehicle-bridge(WVB) system,there are various interactions among wind,vehicle and bridge.The mechanism for coupling vibration of wind-vehicle-bridge systems is explored to demonstrate the effects of fundamental factors,such as mean wind,fluctuating wind,buffeting,rail irregularities,light rail vehicle vibration and bridge stiffness.A long cable-stayed bridge which carries light rail traffic is regarded as a numerical example.Firstly,a finite element model is built for the long cable-stayed bridge.The deck can generally be idealized as three-dimensional spine beam while cables are modeled as truss elements.Vehicles are modeled as mass-spring-damper systems.Rail irregularities and wind fluctuation are simulated in time domain by spectrum representation method.Then,aerodynamic loads on vehicle and bridge deck are measured by section model wind tunnel tests.Eight vertical and torsional flutter derivatives of bridge deck are identified by weighting ensemble least-square method.Finally,dynamic responses of the WVB system are analyzed in a series of cases.The results show that the accelerations of the vehicle are excited by the fluctuating wind and the track irregularity to a great extent.The transverse forces of wheel axles mainly depend on the track irregularity.The displacements of the bridge are predominantly determined by the mean wind and restricted by its stiffness.And the accelerations of the bridge are enlarged after adding the fluctuating wind. 展开更多
关键词 wind-vehicle-bridge system coupled vibration long-span cable-stayed bridge fundamental factors
在线阅读 下载PDF
Coupling effects of influence factors on probability of corrosion initiation time of reinforced concrete 被引量:6
8
作者 张小刚 赵衍刚 +1 位作者 邢锋 卢朝辉 《Journal of Central South University》 SCIE EI CAS 2011年第1期223-229,共7页
The coupling model of major influence factors such state affecting the chloride diffusion process in concrete is as environmental relative humidity, load-induced crack and stress discussed. The probability distributio... The coupling model of major influence factors such state affecting the chloride diffusion process in concrete is as environmental relative humidity, load-induced crack and stress discussed. The probability distributions of the critical chloride concentration Cc, the chloride diffusion coefficient D, and the surface chloride concentration Cs were determined based on the collected natural exposure data. And the estimation of probability of corrosion initiation considering the coupling effects of influence factors is presented. It is found that the relative humidity and curing time are the most effective factors affecting the probability of corrosion initiation before and after 10 years of exposure time. At the same exposure time, the influence of load-induced crack and stress state on the probability of corrosion initiation is obvious, in which the effect of crack is the most one 展开更多
关键词 reinforced concrete corrosion initiation time coupling influence model influence factors natural exposure data probability distribution
在线阅读 下载PDF
Intervention decision-making in MAV/UAV cooperative engagement based on human factors engineering 被引量:10
9
作者 ZHONG Yun YAO Peiyang +1 位作者 WAN Lujun YANG Juan 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2018年第3期530-538,共9页
Aiming at the intervention decision-making problem in manned/unmanned aerial vehicle(MAV/UAV) cooperative engagement, this paper carries out a research on allocation strategy of emergency discretion based on human f... Aiming at the intervention decision-making problem in manned/unmanned aerial vehicle(MAV/UAV) cooperative engagement, this paper carries out a research on allocation strategy of emergency discretion based on human factors engineering(HFE).Firstly, based on the brief review of research status of HFE, it gives structural description to emergency in the process of cooperative engagement and analyzes intervention of commanders. After that,constraint conditions of intervention decision-making of commanders based on HFE(IDMCBHFE) are given, and the mathematical model, which takes the overall efficiency value of handling emergencies as the objective function, is established. Then, through combining K-best and variable neighborhood search(VNS) algorithm, a K-best optimization variable neighborhood search mixed algorithm(KBOVNSMA) is designed to solve the model. Finally,through three groups of simulation experiments, effectiveness and superiority of the proposed algorithm are verified. 展开更多
关键词 manned/unmanned aerial vehicle(MAV/UAV) intervention decision-making human factors engineering structural description K-best algorithm variable neighborhood search algorithm
在线阅读 下载PDF
Estimation of SO_2 emission factors from copper smelting industry in Yunnan Province,China 被引量:3
10
作者 张艳 唐晓龙 +1 位作者 易红宏 马洁云 《Journal of Central South University》 SCIE EI CAS 2013年第3期742-748,共7页
Copper smelting is a significant source of SO2 emission. It is important to quantify SO2 emissions from combustion sources for regulatory and control purposes in relation to air quality. The characteristics of SO2 emi... Copper smelting is a significant source of SO2 emission. It is important to quantify SO2 emissions from combustion sources for regulatory and control purposes in relation to air quality. The characteristics of SO2 emissions from copper smelting industry in Yurman Province, China, were examined. Analysis based on the present situation, material balance and measuring method were used to confirm SO2 emission factors of copper smelting industry. Results show that SO2 emission factors for Isa system, side blown-continuous converting system (SB-CC), blast furnace-continuous converting systems (B-CC) and blast furnace-converter blowing (B-C) are 11.69-18.64, 62.44--101.4, 19.43-37.88 and 45.48-81.03 kg/t(blister copper), respectively. The comprehensive emission factor based on all smelting plants is found to be in the range of 23-39.99 kg-SO2/t(blister copper) for Yunnan Province, China. The results are compared with those for discharge coefficients of industrial pollutants in the First National General Survey of Pollution Sources and the emission factor of the total amount of major pollutants. It is observed that there are some differences among emission factors. 展开更多
关键词 copper smelting industry SO2 emission factors material balance measuring method
在线阅读 下载PDF
New weighting factors assignment of evidence theorybased one vidence distance 被引量:3
11
作者 ChenLiangzhou ShiWenkang DuFeng 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2005年第2期273-278,共6页
Evidence theory has been widely used in the information fusion for its effectiveness of the uncertainty reasoning. However, the classical DS evidence theory involves counter-intuitive behaviors when the high conflict ... Evidence theory has been widely used in the information fusion for its effectiveness of the uncertainty reasoning. However, the classical DS evidence theory involves counter-intuitive behaviors when the high conflict information exists. Based on the analysis of some modified methods, Assigning the weighting factors according to the intrinsic characteristics of the existing evidence sources is proposed, which is determined on the evidence distance theory. From the numerical examples, the proposed method provides a reasonable result with good convergence efficiency. In addition, the new rule retrieves to the Yager's formula when all the evidence sources contradict to each other completely. 展开更多
关键词 evidence theory rule of combination weighting factors evidence distance.
在线阅读 下载PDF
Degradation of chlorothalonil by ultrasonic irradiation:Kinetics and impact factors 被引量:2
12
作者 郭洪光 高乃云 +2 位作者 黎雷 金玄雄 陈喆 《Journal of Central South University》 SCIE EI CAS 2011年第4期1068-1073,共6页
Factors on degradation of chlorothalonil(CLT) in water by high frequency ultrasonic irradiation were investigated.The effects of initial concentration of chlorothalonil,dosages of tertiary butyl alcohol,humic acid and... Factors on degradation of chlorothalonil(CLT) in water by high frequency ultrasonic irradiation were investigated.The effects of initial concentration of chlorothalonil,dosages of tertiary butyl alcohol,humic acid and initial pH value on degradation of chlorothalonil,as well as the reaction mechanism were studied.The results reveal that chlorothalonil could be effectively degradated by ultrasonic irradiation.The reaction constant value kapp decreased from 0.014 1 to 0.010 2 min-1 with the initial concentration increasing from 50 to 400 μg/L during 180 min irradiation.Tertiary butyl alcohol had negative effect on chlorothalonil degradation,while lower concentration of humic acid promoted the sonolysis,and kapp declined with the further concentration increasing.The kapp varied little when the pH value ranged from 3.10 to 10.28.It may be concluded that mechanical and pyrolysis process played main roles on the degradation of chlorothalonil in ultrasonic irradiation rather than ·OH attack.The electrical energy per order(EEo) values for sonolysis degradation of CLT were also calculated to evaluate the cost of the process. 展开更多
关键词 ultrasonic irradiation CHLOROTHALONIL KINETICS impact factors
在线阅读 下载PDF
Factors affecting phenol adsorption on clay-solidified grouting curtain 被引量:1
13
作者 陈永贵 叶为民 张可能 《Journal of Central South University》 SCIE EI CAS 2011年第3期854-858,共5页
Batch experiments were conducted to study the adsorption of phenol on clay-solidified grouting curtain (CSGC) and the effects of contact time,pH and adsorbent concentration on the adsorption were investigated.Under th... Batch experiments were conducted to study the adsorption of phenol on clay-solidified grouting curtain (CSGC) and the effects of contact time,pH and adsorbent concentration on the adsorption were investigated.Under the experimental conditions used,2 d was adequate to determine the equilibrium of phenol adsorption onto CSGC.The amount of phenol adsorbed by CSGC from an initial concentration of 100mg/L was found to be 8.4mg/g.The adsorption process includes particle diffusion and liquid film diffusion,and the latter is the predominating step of the adsorption process.The adsorption ability of CSGC decreased with pH but it increased non-linearly with the CSGC concentration.The optimized concentration for CSGC was found to be 20g/L for the adsorption of 100mg/L phenol. 展开更多
关键词 clay-solidified grouting curtain ADSORPTION PHENOL effective factors
在线阅读 下载PDF
Protective role of FoxO transcription factors against oxidative stress-induced chondrocyte dysfunction:a new therapeutic target for osteoarthritis 被引量:1
14
作者 Ri-kang WANG 《中国药理学与毒理学杂志》 CAS CSCD 北大核心 2017年第10期975-975,共1页
Chondrocyte dysfunction has been demonstrated to be a major inducer of osteoarthritis(OA).The pathological mechanism of chondrocyte dysfunction is definitely multifactoral,but oxidative stressis regarded as one of the... Chondrocyte dysfunction has been demonstrated to be a major inducer of osteoarthritis(OA).The pathological mechanism of chondrocyte dysfunction is definitely multifactoral,but oxidative stressis regarded as one of the leading causes of apoptosis,autophagy,senescence,and mitochondrial dysfunctionin chondrocytes.Strategies for arresting oxidative stress-induced chondrocyte dysfunction have been considered as potential therapeutic targets for OA.Recently,fork head box O(Fox O)transcription factors have been determined to play a protective role in chondrocytes through the regulation of autophagy and defense against oxidative stress;they also regulate growth,maturation,and matrix synthesis.To explore Fox O′s potential role in the treatment of OA,we first discussed the recent advances in the field of oxidative stress-induced chondrocyte dysfunction and then emphasized the protective role of fox otranscription factors as a potential molecular target for the treatment of OA.Understanding the function of fox otranscription factors will be important in designing next-generation therapies to prevent or reverse the development of OA. 展开更多
关键词 fox otranscription factors oxidative stress chondrocyte dysfunction OSTEOARTHRITIS
在线阅读 下载PDF
Effect of key factors on cold orbital forging of a spur bevel gear 被引量:1
15
作者 庄武豪 董丽颖 《Journal of Central South University》 SCIE EI CAS CSCD 2016年第2期277-285,共9页
Cold orbital forging is an advanced spur bevel gear forming technology. Generally, the spur bevel gear in the cold orbital forging process is formed by two steps: the preforming step and the final step. Due to the gre... Cold orbital forging is an advanced spur bevel gear forming technology. Generally, the spur bevel gear in the cold orbital forging process is formed by two steps: the preforming step and the final step. Due to the great importance of the final step to gear forming and its complication with interactive factors, this work aims at examining the influence of key factors on the final step in cold orbital forging of a spur bevel gear. Using the finite element(FE) method and control variate method, the influence rules of four key factors, rotation velocity of the upper tool, n, feeding velocity of the lower tool, v, tilted angle of the upper tool, γ, friction factor between the tools and the billet, m, on the geometry and the deformation inhomogeneity of the cold orbital forged gear are thoroughly clarified. The research results show that the flash becomes more homogeneous with increasing v, increasing m, decreasing n or decreasing γ. And the deformation of the gear becomes more homogeneous with increasing v, decreasing n or decreasing γ. Finally, a corresponding experiment is conducted, which verifies the accuracy of FE simulation conclusions. 展开更多
关键词 cold orbital forging FE modeling key factors spur bevel gears
在线阅读 下载PDF
Family-relatedFactorsThatInfluenceChildren’sAcademicAchievementsinSchool
16
作者 何献忠 《陕西师范大学学报(哲学社会科学版)》 CSSCI 北大核心 2002年第S1期323-328,共6页
This essay studies various family-related factors that influence a child’s academic achievement in school in P.R. China. The factors are illustrated under three categories: the family’s social class and education, e... This essay studies various family-related factors that influence a child’s academic achievement in school in P.R. China. The factors are illustrated under three categories: the family’s social class and education, early home environment and family material condition. The author discusses the relevant factors by way of relating the knowledge of social environment to his own experiences as a student and then teacher in China. The essay closes with a discussion directing the public’s attention to the concern about home-related factors influencing a child’s academic achievements in school. 展开更多
关键词 family related factors childrens academic achievements home environment material condition
在线阅读 下载PDF
New Methods of Determining the Mixed Mode Stress Intensity Factors for V-Shaped Notch
17
作者 Lin Zhong-qin Yu Haiyan Chen Guanlong Li Shu-hui 《上海交通大学学报》 EI CAS CSCD 北大核心 2004年第z2期188-193,共6页
In this paper, on the basis of the stress field given by D.H.Chen, three new photoelastic methods are developed for determining the stress intensity factors K1 and K2 of V-shaped notch. Some photoelastic experiments a... In this paper, on the basis of the stress field given by D.H.Chen, three new photoelastic methods are developed for determining the stress intensity factors K1 and K2 of V-shaped notch. Some photoelastic experiments are performed on a skew -symmetric 45° notch. Measurements of the coordinates components of r,θand fringe order N are made for progressively smaller fringes and used in the proposed methods to solve K1 and K2.Plots of apparent K vs. r/l are made and extrapolated to the notch tip to yield the true values of K1 and K2.The results obtained by the three methods are very close to each other. When the notch problem is simplified as a crack problem, the corresponding equation is identical to the one proposed by D.G. Smith, which shows that the proposed methods are applicable for both notch and crack problems. 展开更多
关键词 photoelastic stress INTENSITY factors ISOCHROMATIC FRINGE V-SHAPED NOTCH
在线阅读 下载PDF
Controlling Factors Affecting Pressure Differential Development of the Upper Paleozoic Gas Reservoir in the Sulige and Yulin Area of the Ordos Basin
18
作者 Hao Xu~1,Junfeng Zhang~2,Chengzao Jia~3,Dazhen Tang~1,Ming Li~3,Wenzhong Zhang~1 1.Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Accumulation Mechanism,Ministry of Education,China University of Geosciences(Beijing),Beijing 100083,China. 2.PetroChina Exploration and Production Company,Beijing 100724,China 3.Research Institute of Petroleum Exploration & Development,Beijing 100083,China 《地学前缘》 EI CAS CSCD 北大核心 2009年第S1期126-127,共2页
The origin and distribution of Upper Paleozoic reservoirs pressure in mid-northem Ordos Basin has attracted widespread attention in recent years.The reservoir pressure of Sulige area shows characteristics of basically... The origin and distribution of Upper Paleozoic reservoirs pressure in mid-northem Ordos Basin has attracted widespread attention in recent years.The reservoir pressure of Sulige area shows characteristics of basically subnormal pressure,and the reservoir pressure of Yulin area shows characteristics of basically normal hydrostatic pressure.In the sense of structural location, 展开更多
关键词 ORDOS BASIN SULIGE area Yulin area formation PRESSURE controlling factors
在线阅读 下载PDF
Using Multiple Risk Factors and Generalized Linear Mixed Models with 5-Fold Cross-Validation Strategy for Optimal Carotid Plaque Progression Prediction
19
作者 Qingyu Wang Dalin Tang +5 位作者 Liang Wang Gador Canton Zheyang Wu Thomas SHatsukami Kristen L Billiar Chun Yuan 《医用生物力学》 EI CAS CSCD 北大核心 2019年第A01期74-75,共2页
Background Cardiovascular diseases are closely linked to atherosclerotic plaque development and rupture.Plaque progression prediction is of fundamental significance to cardiovascular research and disease diagnosis,pre... Background Cardiovascular diseases are closely linked to atherosclerotic plaque development and rupture.Plaque progression prediction is of fundamental significance to cardiovascular research and disease diagnosis,prevention,and treatment.Generalized linear mixed models(GLMM)is an extension of linear model for categorical responses while considering the correlation among observations.Methods Magnetic resonance image(MRI)data of carotid atheroscleroticplaques were acquired from 20 patients with consent obtained and 3D thin-layer models were constructed to calculate plaque stress and strain for plaque progression prediction.Data for ten morphological and biomechanical risk factors included wall thickness(WT),lipid percent(LP),minimum cap thickness(MinCT),plaque area(PA),plaque burden(PB),lumen area(LA),maximum plaque wall stress(MPWS),maximum plaque wall strain(MPWSn),average plaque wall stress(APWS),and average plaque wall strain(APWSn)were extracted from all slices for analysis.Wall thickness increase(WTI),plaque burden increase(PBI)and plaque area increase(PAI) were chosen as three measures for plaque progression.Generalized linear mixed models(GLMM)with 5-fold cross-validation strategy were used to calculate prediction accuracy for each predictor and identify optimal predictor with the highest prediction accuracy defined as sum of sensitivity and specificity.All 201 MRI slices were randomly divided into 4 training subgroups and 1 verification subgroup.The training subgroups were used for model fitting,and the verification subgroup was used to estimate the model.All combinations(total1023)of 10 risk factors were feed to GLMM and the prediction accuracy of each predictor were selected from the point on the ROC(receiver operating characteristic)curve with the highest sum of specificity and sensitivity.Results LA was the best single predictor for PBI with the highest prediction accuracy(1.360 1),and the area under of the ROC curve(AUC)is0.654 0,followed by APWSn(1.336 3)with AUC=0.6342.The optimal predictor among all possible combinations for PBI was the combination of LA,PA,LP,WT,MPWS and MPWSn with prediction accuracy=1.414 6(AUC=0.715 8).LA was once again the best single predictor for PAI with the highest prediction accuracy(1.184 6)with AUC=0.606 4,followed by MPWSn(1. 183 2)with AUC=0.6084.The combination of PA,PB,WT,MPWS,MPWSn and APWSn gave the best prediction accuracy(1.302 5)for PAI,and the AUC value is 0.6657.PA was the best single predictor for WTI with highest prediction accuracy(1.288 7)with AUC=0.641 5,followed by WT(1.254 0),with AUC=0.6097.The combination of PA,PB,WT,LP,MinCT,MPWS and MPWS was the best predictor for WTI with prediction accuracy as 1.314 0,with AUC=0.6552.This indicated that PBI was a more predictable measure than WTI and PAI. The combinational predictors improved prediction accuracy by 9.95%,4.01%and 1.96%over the best single predictors for PAI,PBI and WTI(AUC values improved by9.78%,9.45%,and 2.14%),respectively.Conclusions The use of GLMM with 5-fold cross-validation strategy combining both morphological and biomechanical risk factors could potentially improve the accuracy of carotid plaque progression prediction.This study suggests that a linear combination of multiple predictors can provide potential improvement to existing plaque assessment schemes. 展开更多
关键词 Multiple Risk factors GENERALIZED Linear 5-Fold Cross-Validation STRATEGY AUC
在线阅读 下载PDF
Sources and control factors of rare earth elements in Late Permian mudstones,Southwest China
20
作者 肖明国 庄新国 +1 位作者 易炜 毛婉慧 《Journal of Central South University》 SCIE EI CAS 2012年第6期1741-1752,共12页
The material sources and control factors of rare earth elemems (REEs) for 25 borehole bulk samples from the Late Permian Longtan Formation in Mount Huaying (borehole number: ZK10-6), Sichuan Province, South China... The material sources and control factors of rare earth elemems (REEs) for 25 borehole bulk samples from the Late Permian Longtan Formation in Mount Huaying (borehole number: ZK10-6), Sichuan Province, South China, were investigated. All samples were determined by inductively coupled plasma mass spectrometry (ICP-MS). The chondrite-normalized distribution patterns of mudstone samples are uniform. All samples belong to the light rare earth element (LREE)-rich type and are enriched in LREEs relative to heavy rare earth elements (HREEs). The distribution curves of REEs in mudstone are highly similar to Mount Emei basalt and the three periods of REEs enrichment correspond to three Mount Emei basalt eruption cycles in Longtan period. The results indicate that REE patterns are not controlled by materials from the seawater or land plants. The predominant sources of REEs are from terrigenous material as indicated by negative Eu anomaly. So, the sources of REEs are controlled by terrigenous material, and the Mount Emei basalt is the predominant source of terrigenous material. Thus, transgression-regression is another control factor of REEs enrichment. 展开更多
关键词 rare earth elements (REEs) control factors material sources transgression-regression Mount Emei basalt LatePermian
在线阅读 下载PDF
上一页 1 2 19 下一页 到第
使用帮助 返回顶部