期刊文献+
共找到191篇文章
< 1 2 10 >
每页显示 20 50 100
Gender differences in the burden of near vision loss in China:An analysis based on GBD 2021 data
1
作者 LIU Yu ZHU Liping +4 位作者 LIN Yanhui WANG Yanbing XIONG Kun LI Xuhong YAN Wenguang 《中南大学学报(医学版)》 北大核心 2025年第6期1030-1041,共12页
Objective:Near vision loss(NVL)is one of the leading causes of visual impairment worldwide,exerting a profound impact on individual quality of life and socio-economic development.This study aims to analyze the burden ... Objective:Near vision loss(NVL)is one of the leading causes of visual impairment worldwide,exerting a profound impact on individual quality of life and socio-economic development.This study aims to analyze the burden of NVL in China by sex and age groups from 1990 to 2021 and to project trends over the next 15 years.Methods:Using data from the Global Burden of Disease(GBD)2021 database,we conducted descriptive analyses of NVL prevalence in China,calculated age-standardized prevalence rates(ASPR)and age-standardized disability-adjusted life years rates(ASDR)to compare burden differences between sexes and age groups,and applied an autoregressive integrated moving average(ARIMA)model to predict NVL trends for the next 15 years.The model selection was based on best-fit criteria to ensure reliable projections.Results:From 1990 to 2021,China’s ASPR of NVL rose from 10096.24/100000 to 15624.54/100000,and ASDR increased from 101.75/100000 to 158.75/100000.In 2021,ASPR(16551.70/100000)and ASDR(167.69/100000)were higher among females than males(14686.21/100000 and 149.76/100000,respectively).China ranked highest globally in both NVL cases and disability-adjusted life years(DALYs),with female burden significantly exceeding male burden.Projections indicated this trend and sex gap will persist until 2036.Compared with 1990,the prevalence cases and DALYs increased by 239.20%and 238.82%,respectively in 2021,with the highest burden among females and the 55−59 age group.The ARIMA model predicted continued increases in prevalence and DALYs by 2036,with females maintaining a higher burden than males.Conclusion:This study reveals a marked increase in the NVL burden in China and predicts continued growth in the coming years.Public health policies should prioritize NVL prevention and control,with special attention to women and middle-aged populations to mitigate long-term societal and health impacts. 展开更多
关键词 China near vision loss Global Burden of Disease database autoregressive integrated moving average model gender differences
在线阅读 下载PDF
Cultural Differences and Language Teaching
2
作者 高延玲 《陕西师范大学学报(哲学社会科学版)》 CSSCI 北大核心 2002年第S3期160-165,共6页
Mistakes occur here and there when Chinese learners of English apply the foreign language in practice. This paper analyzes some common mistakes derived from cultural differences and tries to illustrate that language, ... Mistakes occur here and there when Chinese learners of English apply the foreign language in practice. This paper analyzes some common mistakes derived from cultural differences and tries to illustrate that language, as a part of culture should be taught and learnt as an integral part of learning about the target culture so that learners can gain a full understanding and good command of the foreign language. 展开更多
关键词 LANGUAGE CULTURE CULTURAL differences LANGUAGE teaching
在线阅读 下载PDF
On Cultural Differences between English and Chinese --From the Aspect of Seven Types of Meaning
3
作者 刘海萍 《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312-314,共3页
This paper analyzes cultural differences of English and Chinese in terms of Seven Types of Meaning . It proceeds from the theory of Leech’s Seven Types of meaning , then comparatively illustrates with analysis of eac... This paper analyzes cultural differences of English and Chinese in terms of Seven Types of Meaning . It proceeds from the theory of Leech’s Seven Types of meaning , then comparatively illustrates with analysis of each type of meaning and cultural differences. And concludes with the cause of cultural differences and problems of it in cross-cultural communication with the hope that Chinese student could avoid Chinglish in learning and both Chinese and foreigners could avoid cultural shock when communicating with each other. 展开更多
关键词 cultural differences Chinese English seven types of meaning
在线阅读 下载PDF
Differences Between Male andFemale Sex in Speech Behaviour
4
作者 赵清丽 《陕西师范大学学报(哲学社会科学版)》 CSSCI 北大核心 2002年第S3期193-196,共4页
This paper describes male-female differences in speech behavior from the following aspects: their different attitudes towards public speaking and private speaking; their different attitudes towards public details and ... This paper describes male-female differences in speech behavior from the following aspects: their different attitudes towards public speaking and private speaking; their different attitudes towards public details and private details; their different purposes towards troubles; their different attitudes towards asking information. Then this paper presents explanations for male-female differences in speech behavior from social point of view and anthropological point of view. 展开更多
关键词 male-female DIFFERENCE SPEECH behavior
在线阅读 下载PDF
Identity and Differences Between Chinese and Western Cultural Philosophy
5
作者 Chen Jiafu Wang Weili 《学术界》 CSSCI 北大核心 2018年第11期262-272,共11页
Cultural philosophy refers to the study of cultural principles with philosophical viewpoints and methods to form a theoretical system of cultural views and cultural activities.It mainly discusses the history and devel... Cultural philosophy refers to the study of cultural principles with philosophical viewpoints and methods to form a theoretical system of cultural views and cultural activities.It mainly discusses the history and development of culture,the motive force and conditions of culture,the role of tradition in social history,the comparison of various cultures,and the conflict and blending of cultures.This paper attempts to explore an effective way to integrate the two modes of thinking of Chinese and Western cultural philosophy through a comparative analysis of the differences and identity between Chinese and Western cultural philosophy.The study of cultural identity and differences between China and Western countries has a certain practical significance for cross-cultural communication in China. 展开更多
关键词 CULTURAL PHILOSOPHY differences IDENTITY
在线阅读 下载PDF
An Analysis of the Cultural Differences Between China and the West from the Perspective of Mode of Thinking
6
作者 Zhang Yan Yu Bin 《学术界》 CSSCI 北大核心 2018年第7期257-267,共11页
People with various cultural backgrounds and habits have different modes of thinking,making it difficult to communicate between different cultures. Based on culture,thinking and their relationship,this paper analyzes ... People with various cultural backgrounds and habits have different modes of thinking,making it difficult to communicate between different cultures. Based on culture,thinking and their relationship,this paper analyzes the differences between Chinese and the Western cultures to find the solutions to the problem of how to use the differences to establish international mind and global vision to achieve"cultural confidence". 展开更多
关键词 cultural differences modes of thinking intercultural communication
在线阅读 下载PDF
Genetic Differences of Mitten Crabs Based on RFLP Analysis on Mitochondrial Cytochrome Oxidase Subunit I(COI) Gene
7
作者 HU Pengfei WANG Qian +1 位作者 DAI Wei WANG Xiaomei 《Journal of Northeast Agricultural University(English Edition)》 CAS 2008年第1期51-57,共7页
The genetic differences of 15 mitten crab populations from 6 river systems in China's Mainland and 1 population from Russia were studied based on RFLP analysis of mitochondrial cytochrome oxidase subunit I (CO I... The genetic differences of 15 mitten crab populations from 6 river systems in China's Mainland and 1 population from Russia were studied based on RFLP analysis of mitochondrial cytochrome oxidase subunit I (CO I). The results showed that Tas I-RFLP pattern could be used as a genetic marker to distinguish Eriocheir hepuensis from Eriocheir sinensis, Eriocheirjaponica and Eriocheir leptognathus; genetic distances among 13 populations of Eriocheir sinensis range from 0 to 0.015, indicating that they were different geographic strains; the subspecies status of Eriocheir sinensis and Eriocheir hepuensis (population from Nanliujiang) were considered owning to their genetic distances of 0.02-0.044, indicating that genetic divergence between them was low; Eriocheir leptognathus (population from Nanpaihe, Tianjin) was the most distant taxon with genetic distances value of 0.147-0.195, which could be defined as genetic distances between species in genus Eriocheir. 展开更多
关键词 mitten crab genetic differences mitochondrial CO I gene RFLP
在线阅读 下载PDF
Genes Expressing Differences in Upland Cotton Fiber Development Between 12 DPA and 16 DPA
8
作者 LU Cai-rui1,YU Shu-xun1,WANG Wu1,2(1.Cotton Research Institute,Chinese Academy of Agricultural Sciences Key Laboratory of Cotton Genetic Improvement,Ministry of Agriculture,Anyang,Henan 455000,China 2.Plant and Environmental Sciences Department,New Mexico State University,Las Cruces,NM 88003 USA) 《棉花学报》 CSCD 北大核心 2008年第S1期70-,共1页
Cotton is the major dominant natural fiber crop on the earth.Although some current cotton genetics and breeding programs had made great progresses in cotton lint yield increases and disease resistance(tolerance),fiber... Cotton is the major dominant natural fiber crop on the earth.Although some current cotton genetics and breeding programs had made great progresses in cotton lint yield increases and disease resistance(tolerance),fiber quality has little improvement.Global understanding genes expression 展开更多
关键词 Genes Expressing differences in Upland Cotton Fiber Development Between 12 DPA and 16 DPA
在线阅读 下载PDF
Estimating extreme temperature differences in steel box girder using long-term measurement data 被引量:5
9
作者 丁幼亮 王高新 《Journal of Central South University》 SCIE EI CAS 2013年第9期2537-2545,共9页
The extreme temperature differences in fiat steel box girder of a cable-stayed bridge were studied.Firstly,by using the long-term measurement data collected by the structural health monitoring system installed on the ... The extreme temperature differences in fiat steel box girder of a cable-stayed bridge were studied.Firstly,by using the long-term measurement data collected by the structural health monitoring system installed on the Runyang Cable-stayed Bridge,the daily variations as well as seasonal ones of measured temperature differences in the box girder cross-section area were summarized.The probability distribution models of temperature differences were further established and the extreme temperature differences were estimated with a return period of 100 years.Finally,the temperature difference models in cross-section area were proposed for bridge thermal design.The results show that horizontal temperature differences in top plate and vertical temperature differences between top plate and bottom plate are considerable.All the positive and negative temperature differences can be described by the weighted sum of two Weibull distributions.The maximum positive and negative horizontal temperature differences in top plate are 10.30 ℃ and -13.80 ℃,respectively.And the maximum positive and negative vertical temperature differences between top plate and bottom plate are 17.30 ℃ and-3.70 ℃,respectively.For bridge thermal design,there are two vertical temperature difference models between top plate and bottom plate,and six horizontal temperature difference models in top plate. 展开更多
关键词 structural health monitoring cable-stayed bridge steel box girder temperature difference extreme value analysis
在线阅读 下载PDF
Measurement of Grain Production Efficiency in Main Grain-producing Areas and Analysis of Inter-provincial Differences--A Study Based on Super-SBM Model and Malmquist Index
10
作者 Qi Heng Su Jing-yan 《Journal of Northeast Agricultural University(English Edition)》 CAS 2022年第2期86-96,共11页
China's food security mainly depends on the core areas of food production.Under the dual constraints of resource scarcity and environmental degradation,improving the grain production efficiency of the main grain-p... China's food security mainly depends on the core areas of food production.Under the dual constraints of resource scarcity and environmental degradation,improving the grain production efficiency of the main grain-producing areas has become the fundamental way to strengthen the grain production capacity and improve the national food security capability,and to improve the efficiency of grain production in major grain-producing areas requires empirical support.This paper used the Super SBM model and the Malmquist index to measure the grain production efficiency of the main grain-producing areas from 2001 to 2020 from both static and dynamic perspectives,and compared the differences in grain production efficiency among different soil types and different provinces(autonomous regions)in the main grain-producing areas.The results showed that from 2001 to 2020,the grain production in the main grain-producing areas was in a relatively ineffective state,and the differences in grain production efficiency among different soil types and different provinces(autonomous regions)in the main grain-producing areas were obvious.The order of grain production efficiency in different soil types was black soil region>red-yellow soil region>paddy soil region>fluvo-aquic soil region,and the order of grain production efficiency of the provinces(autonomous regions)in the main grain-producing areas was Jilin>Heilongjiang>Inner Mongolia>Jiangxi>Hunan>Sichuan>Hubei>Jiangsu>Liaoning>Henan>Anhui>Shandong>Hebei.From 2001 to 2020,the total factor productivity of grain in the main grain-producing areas increased,but due to the trade-off between the technological progress and the growth of technical efficiency,the increase in the total factor productivity of grain in the main grain-producing areas was small,and the growth mainly came from the increase of input factors in this period.The total factor productivity of grain in Hebei,Heilongjiang,Liaoning,Jilin,Inner Mongolia,Shandong,Jiangsu,Henan and Anhui increased,but the increase was small,while the total factor productivity of grain in Jiangxi,Sichuan,Hunan and Hubei provinces declined. 展开更多
关键词 main grain-producing area grain production efficiency inter-provincial difference
在线阅读 下载PDF
Acute Inflammatory Pain Induces Sex-different Brain Alpha Activity in Anesthetized Rats Through Optically Pumped Magnetometer Magnetoencephalography
11
作者 MIAO Meng-Meng REN Yu-Xuan +5 位作者 WU Wen-Wei ZHANG Yu PAN Chen LIN Xiang-Hong LIN Hui-Dan CHEN Xiao-Wei 《生物化学与生物物理进展》 北大核心 2025年第1期244-257,共14页
Objective Magnetoencephalography(MEG),a non-invasive neuroimaging technique,meticulously captures the magnetic fields emanating from brain electrical activity.Compared with MEG based on superconducting quantum interfe... Objective Magnetoencephalography(MEG),a non-invasive neuroimaging technique,meticulously captures the magnetic fields emanating from brain electrical activity.Compared with MEG based on superconducting quantum interference devices(SQUID),MEG based on optically pump magnetometer(OPM)has the advantages of higher sensitivity,better spatial resolution and lower cost.However,most of the current studies are clinical studies,and there is a lack of animal studies on MEG based on OPM technology.Pain,a multifaceted sensory and emotional phenomenon,induces intricate alterations in brain activity,exhibiting notable sex differences.Despite clinical revelations of pain-related neuronal activity through MEG,specific properties remain elusive,and comprehensive laboratory studies on pain-associated brain activity alterations are lacking.The aim of this study was to investigate the effects of inflammatory pain(induced by Complete Freund’s Adjuvant(CFA))on brain activity in a rat model using the MEG technique,to analysis changes in brain activity during pain perception,and to explore sex differences in pain-related MEG signaling.Methods This study utilized adult male and female Sprague-Dawley rats.Inflammatory pain was induced via intraplantar injection of CFA(100μl,50%in saline)in the left hind paw,with control groups receiving saline.Pain behavior was assessed using von Frey filaments at baseline and 1 h post-injection.For MEG recording,anesthetized rats had an OPM positioned on their head within a magnetic shield,undergoing two 15-minute sessions:a 5-minute baseline followed by a 10-minute mechanical stimulation phase.Data analysis included artifact removal and time-frequency analysis of spontaneous brain activity using accumulated spectrograms,generating spectrograms focused on the 4-30 Hz frequency range.Results MEG recordings in anesthetized rats during resting states and hind paw mechanical stimulation were compared,before and after saline/CFA injections.Mechanical stimulation elevated alpha activity in both male and female rats pre-and post-saline/CFA injections.Saline/CFA injections augmented average power in both sexes compared to pre-injection states.Remarkably,female rats exhibited higher average spectral power 1 h after CFA injection than after saline injection during resting states.Furthermore,despite comparable pain thresholds measured by classical pain behavioral tests post-CFA treatment,female rats displayed higher average power than males in the resting state after CFA injection.Conclusion These results imply an enhanced perception of inflammatory pain in female rats compared to their male counterparts.Our study exhibits sex differences in alpha activities following CFA injection,highlighting heightened brain alpha activity in female rats during acute inflammatory pain in the resting state.Our study provides a method for OPM-based MEG recordings to be used to study brain activity in anaesthetized animals.In addition,the findings of this study contribute to a deeper understanding of pain-related neural activity and pain sex differences. 展开更多
关键词 MAGNETOENCEPHALOGRAPHY PAIN sex differences alpha activity INFLAMMATION
在线阅读 下载PDF
基于DEMATEL和TOPSIS的低空安防系统方案多属性评价方法 被引量:1
12
作者 施玮 吴坚 《科学技术与工程》 北大核心 2025年第14期6109-6117,共9页
针对低空经济发展涉及的安全管理问题,在总结低空经济相关技术路线原理及落地方案的运行经验,分析低空安防普适性的4个建设方案:雷达与通感一体技术融合方案、广播式自动相关监视技术方案、远程识别技术方案和基于TDOA(time difference ... 针对低空经济发展涉及的安全管理问题,在总结低空经济相关技术路线原理及落地方案的运行经验,分析低空安防普适性的4个建设方案:雷达与通感一体技术融合方案、广播式自动相关监视技术方案、远程识别技术方案和基于TDOA(time difference of arrival)无线电技术的多源融合方案的基础上,构建无人飞行器探测技术评价指标体系,并建立了一种基于决策试验评估实验室(decision-making trial and evaluation laboratory, DEMATEL)和优劣解距离法(technique for order preference by similarity to an ideal solution, TOPSIS)的多属性评价方法。结果发现,以TDOA为基础的多源融合方案是构建城市低空安防体系的有效路径和普适性方案。研究表明,低空安防体系的建设是一个系统性工程,需要政府、企业和社会各方的共同努力,在技术、数据、运营等多个层面进行整合,以适应未来低空经济的发展需求。 展开更多
关键词 低空经济 低空安防系统 多属性评价方法 TDOA(time difference of arrival)技术 无人机管控
在线阅读 下载PDF
Analysis of the effect of vibration on the homogeneity of the kinematic mechanism of an angular mirror translational interferometer
13
作者 XU Xue-Rong PENG Yi-Tian +1 位作者 GU Ming-Jian JIANG Teng-teng 《红外与毫米波学报》 北大核心 2025年第3期425-430,共6页
The effect of external vibration on the velocity uniformity of the moving mechanism of the angular mir⁃ror translational Fourier transform interferometer(hereinafter referred to as interferometer)can be quantitatively... The effect of external vibration on the velocity uniformity of the moving mechanism of the angular mir⁃ror translational Fourier transform interferometer(hereinafter referred to as interferometer)can be quantitatively analysed by the interferometer optical range difference velocity stability.The article proposes a more comprehen⁃sive method of analysing the optical range difference velocity uniformity for the reliability of the interferometer ki⁃nematic mechanism under the influence of on-orbit microvibration in the process of space spectroscopy detection.The method incorporates the structural response of the interferometer caused by external excitation into the stabili⁃ty analysis as one of the influencing factors,so as to reflect the reliability of the interferometer in orbit more realis⁃tically,and judge the microvibration criticality that the interferometer can withstand more accurately.At the same time,an optical surface model of the interferometer is established to further theoretically characterise the effect of microvibration on the homogeneity of the interferometric mechanism.The method discussed in the article pro⁃vides a way of thinking for the judgement of the reliability of the mechanism movement under the external excita⁃tion perturbation as well as the research on the optimisation of the mechanism control. 展开更多
关键词 Fourier-interferometer optical range difference velocity stability TREMOR space spectroscopy detection
在线阅读 下载PDF
Study on Color Difference of Color Reproduction of 3D Objects
14
作者 GU Chong DENG Yi-qiang 《印刷与数字媒体技术研究》 北大核心 2025年第4期33-38,69,共7页
To investigate the applicability of four commonly used color difference formulas(CIELAB,CIE94,CMC(1:1),and CIEDE2000)in the printing field on 3D objects,as well as the impact of four standard light sources(D65,D50,A,a... To investigate the applicability of four commonly used color difference formulas(CIELAB,CIE94,CMC(1:1),and CIEDE2000)in the printing field on 3D objects,as well as the impact of four standard light sources(D65,D50,A,and TL84)on 3D color difference evaluations,50 glossy spheres with a diameter of 2cm based on the Sailner J4003D color printing device were created.These spheres were centered around the five recommended colors(gray,red,yellow,green,and blue)by CIE.Color difference was calculated according to the four formulas,and 111 pairs of experimental samples meeting the CIELAB gray scale color difference requirements(1.0-14.0)were selected.Ten observers,aged between 22 and 27 with normal color vision,were participated in this study,using the gray scale method from psychophysical experiments to conduct color difference evaluations under the four light sources,with repeated experiments for each observer.The results indicated that the overall effect of the D65 light source on 3D objects color difference was minimal.In contrast,D50 and A light sources had a significant impact within the small color difference range,while the TL84 light source influenced both large and small color difference considerably.Among the four color difference formulas,CIEDE2000 demonstrated the best predictive performance for color difference in 3D objects,followed by CMC(1:1),CIE94,and CIELAB. 展开更多
关键词 Color difference formula 3D objects Light source Gray scale Normalized residual sum of squares
在线阅读 下载PDF
A Fast Algorithm for Solving the Poisson Equations Based on the Discrete Cosine/Sine Transforms in the Finite Difference Method
15
作者 LI Congcong WANG Danxia +1 位作者 JIA Hongen ZHANG Chenhui 《应用数学》 北大核心 2025年第3期651-669,共19页
To enhance the computational efficiency of spatio-temporally discretized phase-field models,we present a high-speed solver specifically designed for the Poisson equations,a component frequently used in the numerical c... To enhance the computational efficiency of spatio-temporally discretized phase-field models,we present a high-speed solver specifically designed for the Poisson equations,a component frequently used in the numerical computation of such models.This efficient solver employs algorithms based on discrete cosine transformations(DCT)or discrete sine transformations(DST)and is not restricted by any spatio-temporal schemes.Our proposed methodology is appropriate for a variety of phase-field models and is especially efficient when combined with flow field systems.Meanwhile,this study has conducted an extensive numerical comparison and found that employing DCT and DST techniques not only yields results comparable to those obtained via the Multigrid(MG)method,a conventional approach used in the resolution of the Poisson equations,but also enhances computational efficiency by over 90%. 展开更多
关键词 Phase-field model Finite difference method Fast Poisson solver(DC-T/DST) Explicit invariant energy quadratization Unconditional energy stability
在线阅读 下载PDF
美国《保健物理》(Health Physics)杂志英文摘要(2025年128卷第6期)
16
《辐射防护》 北大核心 2025年第5期539-544,共6页
Evaluation of Gamma Index Analysis for Detecting Errors in Patient-specific Quality Assurance in Intensity Modulated Radiotherapy Taylan Tugrul1(1.Department of Radiation Oncology,Medicine Faculty of Van Yüzü... Evaluation of Gamma Index Analysis for Detecting Errors in Patient-specific Quality Assurance in Intensity Modulated Radiotherapy Taylan Tugrul1(1.Department of Radiation Oncology,Medicine Faculty of Van YüzüncüYıl University,Van,Turkey)Abstract:Quality assurance practices performed before treatment are believed to identify various potential errors.In this study,2-dimensional(2D)dosimetric results were analyzed by making some intentional mistakes in six different treatment plans.In this way,the detectability of errors was investigated.In all segments of all treatment plans,one of the multileaf collimators was kept fixed at different positions on the central axis.In addition to multileaf collimators error,gantry error was also examined in the study.The dose distribution results obtained by Treatment Planning System(TPS)were compared with those obtained by the 2D array device,both as local calculation and global calculation methods,using the gamma analysis method.When the results are examined in the case where the Multi-leaf collimators(MLC)is fixed at the 1 cm position. 展开更多
关键词 making some intentional mistakes six different treatment plansin multileaf collimators patient specific quality assurance gantry error intensity modulated radiotherapy assurance practices gamma index analysis
在线阅读 下载PDF
Mechanical response and impact tendency index correction of gangue-coal combined structure
17
作者 WEN Zhi-jie XU Chang-long +2 位作者 GONG Feng-qiang ZUO Yu-jun SONG Zhen-qi 《Journal of Central South University》 2025年第6期2288-2306,共19页
To investigate the mechanical response during failure and the impact tendency characteristics of gangue-coal combined structure,uniaxial compression tests were conducted on nine groups of combined structures,each with... To investigate the mechanical response during failure and the impact tendency characteristics of gangue-coal combined structure,uniaxial compression tests were conducted on nine groups of combined structures,each with varying gangue thicknesses and positions.The response patterns of compressive strength,elastic modulus,pre-peak accumulated energy,elastic energy index,and impact energy index were systematically analyzed.Furthermore,a new index for evaluating the impact tendency of gangue-containing coal was proposed,and its effectiveness was verified.The findings are as follows:(1)As the gangue thickness increases,both the compressive strength and the pre-peak energy of the combined structure decrease,whereas the elastic modulus increases accordingly.When the gangue is located in the lower middle position,the combined structure exhibits the lowest compressive strength and elastic modulus but the highest pre peak energy.(2)As the gangue shifts toward the middle position of the combined structure,the failure mode gradually transitions from comple te“crushing”failure to an incomplete“point-type”failure.As gangue thickness further increases,the failure region evolves from overall failure to localized failure,with the degree of failure shifting from complete to incomplete.The K_(crc)value corresponding to“crushing”complete failure is higher and has a stronger impact tendency compared to“point-type”incomplete failure.(3)The proposed comprehensive impact instability evaluation index K_(crc)for the gangue-coal combined structure has shown a significant positive correlation with compressive strength(R_(c))and impact energy index(K_(E)),further verifyi ng its rationality in comprehensively assessing the impact tendency of gangue-containing coal bodies.Applying this index to the evaluation of gangue-containing coal seams provides a more accurate reflection of their impact tendency compared with the residual energy index,which has a wide range of potential applications and practical significance. 展开更多
关键词 gangue-coal combined structure mechanical response peak elastic energy density difference impact tendency comprehensive impact instability index
在线阅读 下载PDF
不同症状类型苜蓿病毒病AMV病原检测及其寄主范围测定 被引量:4
18
作者 周建玲 梁巧兰 +5 位作者 魏列新 周其宇 田龙 陈应娥 王存颖 张国印 《草业学报》 CSCD 北大核心 2024年第1期126-137,共12页
为明确采自田间不同症状类型苜蓿病毒病病样中苜蓿花叶病毒(alfalfa mosaic virus,AMV)的带毒情况、症状表现与叶绿素含量的相关性及AMV的寄主范围,本试验通过田间调查采样、症状归类、丙酮乙醇混合液法和双抗体夹心酶联免疫吸附测定(DA... 为明确采自田间不同症状类型苜蓿病毒病病样中苜蓿花叶病毒(alfalfa mosaic virus,AMV)的带毒情况、症状表现与叶绿素含量的相关性及AMV的寄主范围,本试验通过田间调查采样、症状归类、丙酮乙醇混合液法和双抗体夹心酶联免疫吸附测定(DAS-ELISA)法对不同病样的叶绿素和AMV含量进行测定和检测,并对提纯至不同症状类型病样中AMV对9科32种植物的致病性进行测定。结果表明田间苜蓿病毒病病样有轻花叶、重花叶、叶片边缘褪绿黄化型和叶片畸形皱缩花叶矮化型4种症状类型,均带有AMV,且叶绿素含量、AMV含量与症状表现之间具有正相关性,症状表现最严重的叶片畸形皱缩花叶矮化型病样的叶绿素a、b、总叶绿素含量均比对照低58.00%以上,类胡萝卜素含量比对照高134.06%,AMV含量最高,为252.96 pg·mL^(-1);寄主范围测定表明AMV可侵染7科27种植物,对西葫芦致病性最强,症状表现为局部枯斑,30 d时AMV浓度为316.19 pg·mL^(-1)。 展开更多
关键词 苜蓿 病毒病 苜蓿Detection of AMV pathogen of alfalfa virus diseases with different symptom types and its host ranges花叶病毒 寄主植物 叶绿素 致病性 症状表现
在线阅读 下载PDF
Localization in modified polar representation: hybrid measurements and closed-form solution 被引量:2
19
作者 CONG Xunchao SUN Yimao +2 位作者 YANG Yanbing ZHANG Lei CHEN Liangyin 《Journal of Systems Engineering and Electronics》 SCIE CSCD 2024年第3期575-588,共14页
Classical localization methods use Cartesian or Polar coordinates, which require a priori range information to determine whether to estimate position or to only find bearings. The modified polar representation (MPR) u... Classical localization methods use Cartesian or Polar coordinates, which require a priori range information to determine whether to estimate position or to only find bearings. The modified polar representation (MPR) unifies near-field and farfield models, alleviating the thresholding effect. Current localization methods in MPR based on the angle of arrival (AOA) and time difference of arrival (TDOA) measurements resort to semidefinite relaxation (SDR) and Gauss-Newton iteration, which are computationally complex and face the possible diverge problem. This paper formulates a pseudo linear equation between the measurements and the unknown MPR position,which leads to a closed-form solution for the hybrid TDOA-AOA localization problem, namely hybrid constrained optimization(HCO). HCO attains Cramér-Rao bound (CRB)-level accuracy for mild Gaussian noise. Compared with the existing closed-form solutions for the hybrid TDOA-AOA case, HCO provides comparable performance to the hybrid generalized trust region subproblem (HGTRS) solution and is better than the hybrid successive unconstrained minimization (HSUM) solution in large noise region. Its computational complexity is lower than that of HGTRS. Simulations validate the performance of HCO achieves the CRB that the maximum likelihood estimator (MLE) attains if the noise is small, but the MLE deviates from CRB earlier. 展开更多
关键词 LOCALIZATION modified polar representation time difference of arrival(TDOA) angle of arrival(AOA) closed-form solution
在线阅读 下载PDF
Target acquisition performance in the presence of JPEG image compression
20
作者 Boban Bondzulic Nenad Stojanovic +3 位作者 Vladimir Lukin Sergey A.Stankevich Dimitrije Bujakovic Sergii Kryvenko 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第3期30-41,共12页
This paper presents an investigation on the effect of JPEG compression on the similarity between the target image and the background,where the similarity is further used to determine the degree of clutter in the image... This paper presents an investigation on the effect of JPEG compression on the similarity between the target image and the background,where the similarity is further used to determine the degree of clutter in the image.Four new clutter metrics based on image quality assessment are introduced,among which the Haar wavelet-based perceptual similarity index,known as HaarPSI,provides the best target acquisition prediction results.It is shown that the similarity between the target and the background at the boundary between visually lossless and visually lossy compression does not change significantly compared to the case when an uncompressed image is used.In future work,through subjective tests,it is necessary to check whether this presence of compression at the threshold of just noticeable differences will affect the human target acquisition performance.Similarity values are compared with the results of subjective tests of the well-known target Search_2 database,where the degree of agreement between objective and subjective scores,measured through linear correlation,reached a value of 90%. 展开更多
关键词 JPEG compression Target acquisition performance Image quality assessment Just noticeable difference Probability of target detection Target mean searching time
在线阅读 下载PDF
上一页 1 2 10 下一页 到第
使用帮助 返回顶部