期刊文献+
共找到45,574篇文章
< 1 2 250 >
每页显示 20 50 100
Effect of home environment on neuropsychiatric development in preterm infants discharged from NICU at 18 months corrected age
1
作者 Yuan Tian Chuncao Zhang +4 位作者 Feng Liu Xia Hong Li Shen Jinjin Chen Haifeng Jiang 《General Psychiatry》 2025年第1期46-54,共9页
Background There have been numerous intervention studies focusing on the development of preterm infants,but there has been limited investigation into the home environment as a determinant of developmental outcomes in ... Background There have been numerous intervention studies focusing on the development of preterm infants,but there has been limited investigation into the home environment as a determinant of developmental outcomes in preterm infants.The aspects and extent to which the home environment affects the early(18 months corrected age)neuropsychological development of preterm infants are still unclear.Aims This study aimed to analyse the effect of the home environment on the neuropsychiatric development of preterm infants at 18 months corrected age after discharge from the neonatal intensive care unit(NICU).It also sought to provide a basis for promoting neuropsychiatric development among preterm infants by improving the home environment.Methods In this retrospective cross-sectional study,275 preterm infants born between January 2019 and January 2022 were followed up for systematic management after discharge from the NICU at Shanghai Children's Hospital.The Home Nurture Environment Questionnaire was used to assess the home environment of the infants and analyse its impact on the developmental quotient(evaluated by the Gesell Developmental Scale)and the rate of developmental delays at 18 months corrected age.Results A total of 41.454%of the infants were extremely preterm.The developmental quotient scores at 18 months corrected age were in the middle of the scale.The language domain had the highest rate of developmental delay(46.182%),followed by the adaptive domain(37.091%).Multiple logistic regression analyses showed that compared with infants in supportive home environments,infants with moderate/unsupportive home environments had significantly elevated risks of development delay:2.162-fold for global(odds ratio(OR)2.162,95% confidence interval(Cl)1.274 to 3.665,p=0.004),2.193-fold for fine motor(OR 2.193,95%CI 1.161 to 4.140,p=0.016),2.249-fold for language(0R 2.249,95%CI 1.336 to 3.786,p=0.002)and 2.042-fold for personal-social(OR 2.042,95%CI 1.149 to 3.628,p=0.015).Conclusions A supportive home environment is a crucial protective factor for the neuropsychological development of preterm infants.It is associated with higher developmental quotient scores and protects against neuropsychiatric delays.Incorporating evaluation and continuous improvement of the home environment into the management framework for preterm infants to promote optimal neurodevelopment is essential. 展开更多
关键词 home nurture environment questionnaire developmental quotient preterm infants home environment NICU multiple logistic regression analyses neuropsychiatric development
在线阅读 下载PDF
CO hydrogenation conversion driven by micro-environments of active sites over iron carbide catalysts
2
作者 Nan Song Xingxing Li +6 位作者 Ebtihal Abograin Wenyao Chen Junbo Cao Jing Zhang De Chen Xuezhi Duan Xinggui Zhou 《Green Energy & Environment》 2025年第2期367-373,共7页
Essentially clearing the structure-activity relationship between iron carbide catalysts involving multiple active centers to understand the reaction mechanism of CO hydrogenation conversion process is still a great ch... Essentially clearing the structure-activity relationship between iron carbide catalysts involving multiple active centers to understand the reaction mechanism of CO hydrogenation conversion process is still a great challenge.Here,two main micro-environment factors,namely electronic properties and geometrical effects were found to have an integrated effect on the mechanism of CO hydrogenation conversion,involving active sites on multiple crystal phases.The Bader charge of the surface Fe atoms on the active sites had a guiding effect on the CO activation pathway,while the spatial configuration of the active sites greatly affected the energy barriers of CO activation.Although the defective surfaces were more conducive to CO activation,the defective sites were not the only sites to dissociate CO,as CO always tended to dissociate in a wider area.This synergistic effect of the micro-environment also occurred during the CO conversion process.Surface C atoms on relatively flat configurations were more likely to form methane,while the electronic properties of the active sites could effectively describe the C-C coupling process,as well as distinguish the coupling mechanisms. 展开更多
关键词 MICRO-environment CO hydrogenation conversion Electronic property Local environment Synergistic effect
在线阅读 下载PDF
Advancements in Passive Wireless Sensing Systems in Monitoring Harsh Environment and Healthcare Applications
3
作者 Wei Yue Yunjian Guo +9 位作者 Jong‐Chul Lee Enkhzaya Ganbold Jia-Kang Wu Yang Li Cong Wang Hyun Soo Kim Young-Kee Shin Jun-Ge Liang Eun-Seong Kim Nam-Young Kim 《Nano-Micro Letters》 2025年第5期145-192,共48页
Recent advancements in passive wireless sensor technology have significantly extended the application scope of sensing,particularly in challenging environments for monitoring industry and healthcare applications.These... Recent advancements in passive wireless sensor technology have significantly extended the application scope of sensing,particularly in challenging environments for monitoring industry and healthcare applications.These systems are equipped with battery-free operation,wireless connectivity,and are designed to be both miniaturized and lightweight.Such features enable the safe,real-time monitoring of industrial environments and support high-precision physiological measurements in confined internal body spaces and on wearable epidermal devices.Despite the exploration into diverse application environments,the development of a systematic and comprehensive research framework for system architecture remains elusive,which hampers further optimization of these systems.This review,therefore,begins with an examination of application scenarios,progresses to evaluate current system architectures,and discusses the function of each component—specifically,the passive sensor module,the wireless communication model,and the readout module—within the context of key implementations in target sensing systems.Furthermore,we present case studies that demonstrate the feasibility of proposed classified components for sensing scenarios,derived from this systematic approach.By outlining a research trajectory for the application of passive wireless systems in sensing technologies,this paper aims to establish a foundation for more advanced,user-friendly applications. 展开更多
关键词 Wireless sensing Passive detection Harsh environment Biomedical monitoring Flexible sensors
在线阅读 下载PDF
Obtaining Electromagnetic Properties of Multi-Type Media in Realistic Environments:State-of-the-Art and Prospects
4
作者 Guo Lantu Guan Ke +5 位作者 Liu Ting He Danping Zhang Haixia Zhu Qiuming Lu Jun Zhang Minggao 《China Communications》 2025年第1期25-40,共16页
To meet the requirements of electromagnetic(EM)theory and applied physics,this study presents an overview of the state-of-the-art research on obtaining the EM properties of media and points out potential solutions tha... To meet the requirements of electromagnetic(EM)theory and applied physics,this study presents an overview of the state-of-the-art research on obtaining the EM properties of media and points out potential solutions that can break through the bottlenecks of current methods.Firstly,based on the survey of three mainstream approaches for acquiring EM properties of media,we identify the difficulties when implementing them in realistic environments.With a focus on addressing these problems and challenges,we propose a novel paradigm for obtaining the EM properties of multi-type media in realistic environments.Particularly,within this paradigm,we describe the implementation approach of the key technology,namely“multipath extraction using heterogeneous wave propagation data in multi-spectrum cases”.Finally,the latest measurement and simulation results show that the EM properties of multi-type media in realistic environments can be precisely and efficiently acquired by the methodology proposed in this study. 展开更多
关键词 electromagnetic properties of media multi-type media parameter inversion ray tracing realistic environment
在线阅读 下载PDF
Effects of thinning on the understory light environment of different stands and the photosynthetic performance and growth of the reforestation species Phoebe bournei 被引量:2
5
作者 Shicheng Su Nianqing Jin Xiaoli Wei 《Journal of Forestry Research》 SCIE EI CAS CSCD 2024年第1期12-28,共17页
Light levels determine regeneration in stands and a key concern is how to regulate the light environment of different stand types to the requirements of the understory.In this study,we selected three stands typical in... Light levels determine regeneration in stands and a key concern is how to regulate the light environment of different stand types to the requirements of the understory.In this study,we selected three stands typical in south China(a Cryptomeria japonica plantation,a Quercus acutissima plantation,and a mixed stand of both)and three thinning intensities to determine the best understory light environ-ment for 3-year-old Phoebe bournei seedlings.The canopy structure,understory light environment,and photosynthe-sis and growth indicators were assessed following thin-ning.Thinning improved canopy structure and understory light availability of each stand;species composition was the reason for differences in the understory light environ-ment.Under the same thinning intensity,the mixed stand had the greatest light radiation and most balanced spectral composition.P.bournei photosynthesis and growth were closely related to the light environment;all three stands required heavy thinning to create an effective and sustained understory light environment.In a suitable understory light environment,the efficiency of light interception,absorption,and use by seedlings was enhanced,resulting in a higher carbon assimilation the main limiting factor was stomatal conductance.As a shade-avoidance signal,red/far-red radia-tion is a critical factor driving changes in photosynthesis and growth of P.bournei seedlings,and a reduction increased light absorption and use capacity and height:diameter ratios.The growth advantage transformed from diameter to height,enabling seedlings to access more light.Our findings suggest that the regeneration of shade-tolerant species such as P.bournei could be enhanced if a targeted approach to thinning based on stand type was adopted. 展开更多
关键词 THINNING Understory light environment Phoebe bournei Photosynthetic performance Growth performance
在线阅读 下载PDF
Regulating the coordination microenvironment of atomic bismuth sites in nitrogen-rich carbon nanosheets as anode for superior potassium-ion batteries 被引量:1
6
作者 Yiye Tan Haoxiang Lin +2 位作者 Zhisong Chen Li Niu Hongyan Li 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2024年第12期365-374,共10页
Carbon-based materials are recognized as anodes fulling of promise for potassium ion batteries(PIBs)due to advantages of affordable cost and high conductivity.However,they still face challenges including structural un... Carbon-based materials are recognized as anodes fulling of promise for potassium ion batteries(PIBs)due to advantages of affordable cost and high conductivity.However,they still face challenges including structural unstability and slow kinetics.It is difficult to achieve efficient potassium storage with unmodified carbonaceous anode.Herein,atomic bismuth(Bi)sites with different atom coordinations anchored on carbon nanosheets(CNSs)have been synthesized through a template method.The properties of prepared multi-doping carbon anodes Bi-N_(3)S_(1)/CNSs,Bi-N_(3)P_(1)/CNSs and Bi-N_(4)/CNSs were probed in PIBs.The configuration Bi-N_(3)S_(1) with stronger charge asymmetry exhibits superior potassium storage performance compared to Bi-N_(3)P_(1) and Bi-N_(4) configurations.The Bi-N_(3)S_(1)/CNSs display a rate capacity of 129.2 mAh g^(-1)even at 10 A g^(-1)and an impressive cyclability characterized by over 5000 cycles at 5 A g^(-1),on account of its optimal coordination environment with more active Bi centers and K^(+)adsorption sites.Notably,assembled potassium-ion full cell Mg-KVO//Bi-N_(3)S_(1)/CNSs also shows an outstanding cycling stability,enduring 3000 cycles at 2 A g^(-1).Therefore,it can be demonstrated that regulating the electronic structure of metallic centre M-N_(4) via changing the type of ligating atom is a feasible strategy for modifying carbon anodes,on the base of co-doping metal and non-metal. 展开更多
关键词 Potassium ion batteries Carbon anodes CO-DOPING Coordination environment Atomic Bi-N_(3)S_(1)sites
在线阅读 下载PDF
Synthesis and nitrogen content regulation of diamond in a high-pressure hydrogen-rich environment
7
作者 黄国锋 陈良超 房超 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第6期541-546,共6页
The regulating nitrogen content of diamond in a hydrogen-rich high-temperature and high-pressure(HPHT) growth environment was systematically investigated in this work by developing three growth systems,namely, "F... The regulating nitrogen content of diamond in a hydrogen-rich high-temperature and high-pressure(HPHT) growth environment was systematically investigated in this work by developing three growth systems,namely, "FeNi+Ti", "FeNi+G_(3)N_(6)H_(6)",and "FeNi+Ti+C_(3)N_(6)H_(6)".Optical microscopy,infrared spectroscopy,and photoluminescence(PL)spectroscopy measurements were conducted to analyze the spectroscopic characteristics of diamonds grown in these three systems.From our analysis,it was demonstrated that the presence of hydrogen in the sp^(3) hybrid C-H does not directly affect the color of the diamond and facilitates the increase of the nitrogen-vacancy(NV) center concentration in a highnitrogen-content diamond.In addition,titanium plays an important role in nitrogen removal,while its impact on hydrogen doping within the diamond lattice is insignificant.Most importantly,by regulating the ratio of nitrogen impurities that coexist in the nitrogen and hydrogen HPHT environment,the production of hydrogenous Ⅱa-type diamond,hydrogenous Ib-type diamond,and hydrogenous high-nitrogen-type diamonds was achieved with a nitrogen content of less than 1 ppm to 1600 ppm. 展开更多
关键词 DIAMOND HPHT superhard material hydrogen-rich environment
在线阅读 下载PDF
Predict the evolution of mechanical property of Al-Li alloys in a marine environment
8
作者 Wei Li Lin Xiang +6 位作者 Guang Wu Hongli Si Jinyan Chen Yiming Jin Yan Su Jianquan Tao Chunyang Huang 《Defence Technology(防务技术)》 SCIE EI CAS CSCD 2024年第1期557-566,共10页
The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of Marine equipment and materials.This study it is to develop a Machine learni... The ocean is one of the essential fields of national defense in the future,and more and more attention is paid to the lightweight research of Marine equipment and materials.This study it is to develop a Machine learning(ML)-based prediction method to study the evolution of the mechanical properties of Al-Li alloys in the marine environment.We obtained the mechanical properties of Al-Li alloy samples under uniaxial tensile deformation at different exposure times through Marine exposure experiments.We obtained the strain evolution by digital image correlation(DIC).The strain field images are voxelized using 2D-Convolutional Neural Networks(CNN)autoencoders as input data for Long Short-Term Memory(LSTM)neural networks.Then,the output data of LSTM neural networks combined with corrosion features were input into the Back Propagation(BP)neural network to predict the mechanical properties of Al-Li alloys.The main conclusions are as follows:1.The variation law of mechanical properties of2297-T8 in the Marine atmosphere is revealed.With the increase in outdoor exposure test time,the tensile elastic model of 2297-T8 changes slowly,within 10%,and the tensile yield stress changes significantly,with a maximum attenuation of 23.6%.2.The prediction model can predict the strain evolution and mechanical response simultaneously with an error of less than 5%.3.This study shows that a CNN/LSTM system based on machine learning can be built to capture the corrosion characteristics of Marine exposure experiments.The results show that the relationship between corrosion characteristics and mechanical response can be predicted without considering the microstructure evolution of metal materials. 展开更多
关键词 Marine environment Al-Li alloy Machine learning CORROSION
在线阅读 下载PDF
Biological origin and depositional environment of crude oils in the Qiongdongnan Basin: Insights from molecular biomarkers and whole oil carbon isotope
9
作者 Zi-Ming Zhang Du-Jie Hou +4 位作者 Xiong Cheng Da-Ye Chen Gang Liang Xia-Ze Yan Wei-He Chen 《Petroleum Science》 SCIE EI CAS CSCD 2024年第5期3029-3046,共18页
Molecular biomarker and whole oil carbon isotope(δ^(13)C_(oil)) analyses were conducted on eleven typical crude oils from the Qiongdongnan Basin to investigate their biological sources and depositional environments. ... Molecular biomarker and whole oil carbon isotope(δ^(13)C_(oil)) analyses were conducted on eleven typical crude oils from the Qiongdongnan Basin to investigate their biological sources and depositional environments. Saturated hydrocarbon biomarkers in most samples are characterized by angiosperm-derived compounds, with aromatic compounds dominated by the naphthalene, phenanthrene, biphenyl, and fluorene series. The related source rocks of these oils were mainly deposited under oxic condition, but a subanoxic-suboxic and enclosed water column condition in the Central Depression during Oligocene.The identification of simonellite and related compounds in the aromatic fractions provides reliable evidence for the input of coniferous gymnosperms. Cadalene may also have a potential association with gymnosperms since it shows a strong positive correlation with simonellite. Evidence from density, nalkanes, short-chain alkylbenzenes and secondary brine inclusions indicates that the unique crude oil B13-1 may have suffered from thermal alteration. These crude oils(excluding B13-1) can be classified into four types based on the δ^(13)C_(oil)values and molecular biomarkers. Type A oil(solely S34-3) is characterized by non-angiosperm plants, with minor dinoflagellates and increasing contribution from conifer gymnosperms than others. Type B oils(L17-2, L18-1, L25-1, and L25-1W) show heavy δ^(13)C_(oil)(-24 ‰to-25 ‰) and mixed contributions from both angiosperms and marine algae, with the marine algae contribution increasing. Type C oils(L13-2 and B21-1) share similar biological sources with Type B, but the moderately δ^(13)C_(oil)(-25‰ to-26‰) and high level of terrestrial biomarkers suggesting a predominant contribution of angiosperms. Type D oils(Y13-1a, Y13-1b, and Y13-4) possess the lightestδ^(13)C_(oil)(mainly below-26‰) and are primarily derived from angiosperms, with mangrove vegetation playing an important role. Spearman correlation analysis among 14 source biomarker parameters withδ^(13)C_(oil)and geological setting of related source rocks implied that the marine algae should be responsible for the heavy δ^(13)C_(oil)in the Type B. The contribution of marine algae in the Central Depression may have been neglected in the past, as it is usually covered by remarkable angiosperm biomarkers. 展开更多
关键词 Gas chromatography-mass spectrometry Molecular biomarker Simonellite Biological source Depositional environment
在线阅读 下载PDF
Tree mycorrhizal associations determine how biodiversity,large trees,and environmental factors drive aboveground carbon stock in temperate forests
10
作者 Yue Chen Zikun Mao +2 位作者 Jonathan A.Myers Jinghua Yu Xugao Wang 《Forest Ecosystems》 SCIE CSCD 2024年第4期448-456,共9页
Biodiversity,large trees,and environmental conditions such as climate and soil have important effects on forest carbon stocks.However,recent studies in temperate forests suggest that the relative importance of these f... Biodiversity,large trees,and environmental conditions such as climate and soil have important effects on forest carbon stocks.However,recent studies in temperate forests suggest that the relative importance of these factors depends on tree mycorrhizal associations,whereby large-tree effects may be driven by ectomycorrhizal(EM)trees,diversity effects may be driven by arbuscular mycorrhizal(AM)trees,and environment effects may depend on differential climate and soil preferences of AM and EM trees.To test this hypothesis,we used forest-inventory data consisting of over 80,000 trees from 631 temperate-forest plots(30 m×30 m)across Northeast China to examine how biodiversity(species diversity and ecological uniqueness),large trees(top 1%of tree diameters),and environmental factors(climate and soil nutrients)differently regulate aboveground carbon stocks of AM trees,EM trees,and AM and EM trees combined(i.e.total aboveground carbon stock).We found that large trees had a positive effect on both AM and EM tree carbon stocks.However,biodiversity and environmental factors had opposite effects on AM vs.EM tree carbon stocks.Specifically,the two components of biodiversity had positive effects on AM tree carbon stocks,but negative effects on EM tree carbon stocks.Environmental heterogeneity(mean annual temperature and soil nutrients)also exhibited contrasting effects on AM and EM tree carbon stocks.Consequently,for the total carbon stock,the positive large-tree effect far surpasses the diversity and environment effect.This is mainly because when integrating AM and EM tree carbon stock into total carbon stock,the opposite diversity-effect(also environment-effect)on AM vs.EM tree carbon stock counteracts each other while the consistent positive large-tree effect on AM and EM tree carbon stock is amplified.In summary,this study emphasized a mycorrhizal viewpoint to better understand the determinants of overarching aboveground carbon profile across regional forests. 展开更多
关键词 BIODIVERSITY Ecological uniqueness environment heterogeneity Large trees Mycorrhizal associations Tree carbon stock
在线阅读 下载PDF
Distribution and geochemical significance of alkylbenzenes for crude oil with different depositional environments and thermal maturities
11
作者 Bing-Kun Meng Dao-Fu Song +1 位作者 Yuan Chen Sheng-Bao Shi 《Petroleum Science》 SCIE EI CAS CSCD 2024年第2期777-790,共14页
A total of 45 alkylbenzenes were detected and identified in crude oils with different depositional environments and thermal maturities from the Tarim Basin,Beibuwan Basin,and Songliao Basin using comprehensive two-dim... A total of 45 alkylbenzenes were detected and identified in crude oils with different depositional environments and thermal maturities from the Tarim Basin,Beibuwan Basin,and Songliao Basin using comprehensive two-dimensional gas chromatography time-of-flight mass spectrometry(GC×GCTOFMS).By analyzing the distribution characteristics of C0-C5alkylbenzenes,it is found that the content of some alkylbenzenes varies greatly in crude oils.Based on the distribution characteristics of 1,2,4,5-tetramethylbenzene(Te MB)and 1,2,3,4-Te MB,the ratio of 1,2,4,5-Te MB to 1,2,3,4-Te MB is proposed to indicate the organic matter origin and depositional environment of ancient sediments.Oil samples originated mainly from lower hydrobiont,algae,bacteria and source rocks deposited under reducing/anoxic conditions have low 1,2,4,5-/1,2,3,4-Te MB values(less than 0.6),while oil samples originated mainly from terrestrial higher plants and source rocks deposited under oxic/sub-oxic conditions have higher 1,2,4,5-/1,2,3,4-Te MB values(greater than 1.0).The significant difference of 1,2,4,5-/1,2,3,4-Te MB values is controlled by 1,2,4,5-Te MB content.1,2,4,5-Te MB content in oils derived from source rocks deposited in oxidized sedimentary environment(greater than 1.0 mg/g whole oil)is higher than that in oils from source rocks deposited in reduced sedimentary environment(less than 1.0 mg/g whole oil).1,2,4,5-/1,2,3,4-Te MB ratio might not or slightly be affected by evaporative fractionation,biodegradation and thermal maturity.1,2,4,5-/1,2,3,4-Te MB ratio and 1,2,4,5-Te MB content can be used as supplementary parameter for the identification of sedimentary environment and organic matter input.It should be noted that compared to the identification of organic matter sources,the 1,2,4,5-/1,2,3,4-Te MB parameter is more effective in identifying sedimentary environments. 展开更多
关键词 1 2 4 5-Tetramethylbenzene GC×GC-TOFMS Organic matter origin Depositional environment
在线阅读 下载PDF
Protected simultaneous quantum remote state preparation scheme by weak and reversal measurements in noisy environments
12
作者 Mandal Manoj Kumar Choudhury Binayak S. Samanta Soumen 《Chinese Physics B》 SCIE EI CAS CSCD 2024年第2期169-177,共9页
We discuss a quantum remote state preparation protocol by which two parties, Alice and Candy, prepare a single-qubit and a two-qubit state, respectively, at the site of the receiver Bob. The single-qubit state is know... We discuss a quantum remote state preparation protocol by which two parties, Alice and Candy, prepare a single-qubit and a two-qubit state, respectively, at the site of the receiver Bob. The single-qubit state is known to Alice while the two-qubit state which is a non-maximally entangled Bell state is known to Candy. The three parties are connected through a single entangled state which acts as a quantum channel. We first describe the protocol in the ideal case when the entangled channel under use is in a pure state. After that, we consider the effect of amplitude damping(AD) noise on the quantum channel and describe the protocol executed through the noisy channel. The decrement of the fidelity is shown to occur with the increment in the noise parameter. This is shown by numerical computation in specific examples of the states to be created. Finally, we show that it is possible to maintain the label of fidelity to some extent and hence to decrease the effect of noise by the application of weak and reversal measurements. We also present a scheme for the generation of the five-qubit entangled resource which we require as a quantum channel. The generation scheme is run on the IBMQ platform. 展开更多
关键词 multi-qubit entangled channel quantum remote state preparation noisy environments weak and reversal measurements
在线阅读 下载PDF
Influences of different alkaline and acidic diagenetic environments on diagenetic evolution and reservoir quality of alkaline lake shales
13
作者 LI Changzhi GUO Pei +2 位作者 XU Jinghong ZHONG Kai WEN Huaguo 《Petroleum Exploration and Development》 SCIE 2024年第1期97-113,共17页
Thin section and argon-ion polishing scanning electron microscope observations were used to analyze the sedimentary and diagenetic environments and main diagenesis of the Permian Fengcheng Formation shales in differen... Thin section and argon-ion polishing scanning electron microscope observations were used to analyze the sedimentary and diagenetic environments and main diagenesis of the Permian Fengcheng Formation shales in different depositional zones of Mahu Sag in the Junggar Basin,and to reconstruct their differential diagenetic evolutional processes.The diagenetic environment of shales in the lake-central zone kept alkaline,which mainly underwent the early stage(Ro<0.5%)dominated by the authigenesis of Na-carbonates and K-feldspar and the late stage(Ro>0.5%)dominated by the replacement of Na-carbonates by reedmergnerite.The shales from the marginal zone underwent a transition from weak alkaline to acidic diagenetic environments,with the early stage dominated by the authigenesis of Mg-bearing clay and silica and the late stage dominated by the dissolution of feldspar and carbonate minerals.The shales from the transitional zone also underwent a transition from an early alkaline diagenetic environment,evidenced by the formation of dolomite and zeolite,to a late acidic diagenetic environment,represented by the reedmergnerite replacement and silicification of feldspar and carbonate minerals.The differences in formation of authigenic minerals during early diagenetic stage determine the fracability of shales.The differences in dissolution of minerals during late diagenetic stage control the content of free shale oil.Dolomitic shale in the transitional zone and siltstone in the marginal zone have relatively high content of free shale oil and strong fracability,and are favorable“sweet spots”for shale oil exploitation and development. 展开更多
关键词 shale diagenesis alkaline environment authigenic minerals dissolution Permian Fengcheng Formation Mahu Sag Junggar Basin
在线阅读 下载PDF
Ecosystem health: ecological sustainability target of strategic environment assessment 被引量:1
14
作者 陈昆玉 《Journal of Forestry Research》 SCIE CAS CSCD 2003年第2期146-150,共5页
Strategic environment assessment (SEA) and ecosystem health are two new ideas on environmental management. On the basis of reviewing some relevant literature, this paper made discussions on the ecological sustainabili... Strategic environment assessment (SEA) and ecosystem health are two new ideas on environmental management. On the basis of reviewing some relevant literature, this paper made discussions on the ecological sustainability target of SEA, the content of ecosystem health as well as the interrelations between SEA and ecosystem health. For a good SEA, its ecological sustainability principles should be provided with distinct content and a general assessment system. A framework for ecosystem health assessment was established according to the content of ecosystem health, and combined into SEA as SEA抯 ecological sustainability target, we can effectively guide decision-makers to make suitable indigenous means and local solutions. , The basic principles and procedure of SEA for ecosystem health are also discussed in the paper. 展开更多
关键词 environment impact assessment Strategic environmental assessment Ecosystem health
在线阅读 下载PDF
SPEECH ENHANCEMENT METHOD FOR LPC AUTOREGRESSIVE MODEL AND SYSTEM IMPLEMENTATION OF COMMAND WORD RECOGNITION USED IN NOISY ENVIRONMENT
15
作者 王承发 吕成国 +1 位作者 孙立新 李俊庆 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 1998年第2期113-120,共8页
At present, almost all the systems and products for speech recognition are working in quiet environment and their performances are degraded or even can′t work when they are operated in high noisy environment. In this... At present, almost all the systems and products for speech recognition are working in quiet environment and their performances are degraded or even can′t work when they are operated in high noisy environment. In this paper, after analyzing the features of speech and noise, a speech enhancement method for LPC autoregressive model for command words recognition used in noisy environment is proposed, and an experimental system is realized. In different background noisy environments, we conduct experiments about SNR, basic accuracy, noise resistant ability and system environment adaptability with different microphones. The experimental results show that the system has good recognition performance in high noisy environments. The system can resist many kinds of noises and meet the needs of application areas on the whole such as military, traffic, marketplace and factory etc. 展开更多
关键词 speech recognition noisy environment Wiener filter
在线阅读 下载PDF
Stress verification of a TLP under extreme wave environment
16
作者 闫发锁 张大刚 +1 位作者 孙丽萍 戴仰山 《Journal of Marine Science and Application》 2009年第2期132-136,共5页
Stress response of a tension leg platform (TLP) in extreme environments was investigated in this paper. A location on one of the gussets was selected as the object point, where directional stresses were numerically ... Stress response of a tension leg platform (TLP) in extreme environments was investigated in this paper. A location on one of the gussets was selected as the object point, where directional stresses were numerically simulated and also experimentally verified by a strain gage. Environmental loading and the platform's structural strength were analyzed in accordance with industrial standards, utilizing linear wave theory and the finite element method (FEM). The fast Fourier transform technique was used to calculate the stress response amplitude operators (RAO) from the records of measurements. A comparison was performed between the stress RAO of the numerical simulation and that of the actual measurements. The results indicated that the stress RAO of the numerical simulation fitted well with measured data at specified wave headings with different periods. 展开更多
关键词 TLP stress RAO extreme environment numerical simulation monitoring measurement
在线阅读 下载PDF
The Use of Virtual Learning Environment in Chinese Higher Education 被引量:1
17
作者 谢苑苑 《海外英语》 2014年第14期103-104,共2页
The paper analyzes the current condition of the use of virtual learning environment(VLE) in Zhejiang University of Chinese Medicine. It is indicated that students show a positive attitude toward this technology, but t... The paper analyzes the current condition of the use of virtual learning environment(VLE) in Zhejiang University of Chinese Medicine. It is indicated that students show a positive attitude toward this technology, but the use of it fails to meet students' perception. In light of this, recommendations are made with a view to enhance the use of VLE. 展开更多
关键词 VIRTUAL LEARNING environment CHINESE STUDENTS HIGH
在线阅读 下载PDF
Creating an English Environment to Foster the Students' Ability in Communicating
18
作者 崔月霞 《海外英语》 2011年第12X期183-185,共3页
English is becoming more and more important in communicating as the further development of the reform and opening up. We English teacher should try our best to create and arrange a kind of language environment accordi... English is becoming more and more important in communicating as the further development of the reform and opening up. We English teacher should try our best to create and arrange a kind of language environment according to our students' practical life in order to improve and enhance their interest in English studying, to encourage them to practice English during their daily life and to cultivate their ability to communicate in English. 展开更多
关键词 AN English environment the students’ ABILITY COMMUNICATING
在线阅读 下载PDF
Current Situation and Future Development of“Affordance”in College English Learning Environment in Information Age
19
作者 邹艳 王可心 《海外英语》 2019年第16期266-268,共3页
With the increasing development of economy and society,the 21st century will surely become an era of rapid development of information technology.Based on the macro and micro levels of education in China,this paper int... With the increasing development of economy and society,the 21st century will surely become an era of rapid development of information technology.Based on the macro and micro levels of education in China,this paper introduces the"affordance theory"to analyze and discuss the current situation of College English learning environment in China,and puts forward new goals and principles to promote the future development of College English learning environment in order to better promote its effective transformation. 展开更多
关键词 COLLEGE ENGLISH Learning environment AFFORDANCE EFFECTIVENESS
在线阅读 下载PDF
On Improving the Classroom Environment of English Learning in College
20
作者 杨元元 《海外英语》 2013年第5X期67-68,共2页
This paper, firstly, acknowledges the importance of classroom environment and the problems existing in the college English classroom. And then, it offers some ways of improving the classroom environment which is very ... This paper, firstly, acknowledges the importance of classroom environment and the problems existing in the college English classroom. And then, it offers some ways of improving the classroom environment which is very critical to evaluate educational programs and curriculum and provides guidance to teachers who are eager to boost their classroom teaching. 展开更多
关键词 CLASSROOM learning environment TEACHER-CENTERED LE
在线阅读 下载PDF
上一页 1 2 250 下一页 到第
使用帮助 返回顶部