首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   9074篇
  免费   434篇
  国内免费   19篇
电工技术   111篇
综合类   19篇
化学工业   1786篇
金属工艺   234篇
机械仪表   363篇
建筑科学   248篇
矿业工程   29篇
能源动力   393篇
轻工业   926篇
水利工程   50篇
石油天然气   14篇
武器工业   1篇
无线电   1309篇
一般工业技术   1680篇
冶金工业   959篇
原子能技术   66篇
自动化技术   1339篇
  2024年   15篇
  2023年   100篇
  2022年   142篇
  2021年   253篇
  2020年   216篇
  2019年   197篇
  2018年   250篇
  2017年   258篇
  2016年   289篇
  2015年   256篇
  2014年   379篇
  2013年   609篇
  2012年   558篇
  2011年   624篇
  2010年   498篇
  2009年   488篇
  2008年   530篇
  2007年   438篇
  2006年   340篇
  2005年   304篇
  2004年   271篇
  2003年   259篇
  2002年   219篇
  2001年   152篇
  2000年   159篇
  1999年   158篇
  1998年   366篇
  1997年   228篇
  1996年   184篇
  1995年   120篇
  1994年   92篇
  1993年   98篇
  1992年   54篇
  1991年   43篇
  1990年   35篇
  1989年   41篇
  1988年   37篇
  1987年   37篇
  1986年   19篇
  1985年   31篇
  1984年   20篇
  1983年   22篇
  1982年   10篇
  1981年   17篇
  1980年   16篇
  1979年   8篇
  1978年   14篇
  1977年   16篇
  1976年   17篇
  1972年   7篇
排序方式: 共有9527条查询结果,搜索用时 15 毫秒
991.
Accurate knowledge of the thermal properties of building components is necessary to implement adequate energy saving strategies in buildings. Outdoor experiments using test cells are very useful tools for realistic estimation of these properties. This paper describes the analyses performed, and the procedure followed in identifying and solving some problems found when building components are tested for UA and gA in a test cell under warm and moderate weather conditions. A window component was tested in a PASLINK test cell at the CIEMAT’s ‘Plataforma Solar de Almería (PSA-CIEMAT)’ in Tabernas (Almería, Spain) and several data sets recorded under quite different weather and test conditions were analysed. First the problems identified when applying the usual test and linear analysis procedures are described. Then hypotheses about the cause of these problems are formulated. Afterwards, strategies followed for testing these hypotheses are described. Once the cause of the problems had been identified, they were fine tuned to find a model for accurate UA and gA estimation. This study demonstrated that nonlinear models, in which long wave radiation is considered as nonlinear effect, yield remarkably better performance than the commonly used linear models, for estimating the component UA and gA values.  相似文献   
992.
In this report, we describe simple thermal oxidation of niobium for the fabrication of niobium oxides, emphasizing that niobium oxide nanowires can be prepared upon the concentration of oxygen in the environment. For example, dense Nb2O5 nanowires on thin oxide film are produced if the annealing is performed in a restricted concentration of oxygen (herein, 3 Torr vacuum). If most of the oxygen is removed in the environment, the nanowires are sparely formed. The nanowires consist of a superlattice monoclinic Nb2O5 with a growth direction of [0 0 1].  相似文献   
993.
Neural-inspired branch predictors achieve very low branch misprediction rates. However, previously proposed implementations have a variety of characteristics that make them challenging to implement in future high-performance processors. In particular, the path-based neural predictor (PBNP) and the piecewise-linear (PWL) predictor require deep pipelining and additional area to support checkpointing for misprediction recovery. The complexity of the PBNP predictor stems from the fact that the path history length, which determines the number of tables and pipeline stages, is equal to the history length, which is typically very long for high accuracy. We propose to decouple the path-history length from the outcome-history length through a new technique called modulo-path history. By allowing a shorter path history, we can implement the PBNP and PWL predictors with significantly fewer tables and pipeline stages while still exploiting a traditional long branch outcome history.  相似文献   
994.
ABSTRACT:  Over the course of 2 days, top researchers in the fields of bacterial spore biology and computational biology discussed approaches to determine the cause of spore germination heterogeneity. Biological and mathematical data gaps were identified, and experimental approaches and computational strategies for modeling spore germination were presented and evaluated. As a result of these interactions, future research directions were defined, the outcome of which should result in a robust model to help define the molecular mechanism(s) of spore germination. Mechanistic understanding of germination will be instrumental for developing novel sterilization, treatment, and decontamination strategies to mitigate threats posed by spores.  相似文献   
995.
The scheme and procedure for thermal fatigue estimation of a thermally stratified branch line were developed. One-way FSI (fluid and structure interaction) scheme was applied to evaluate the thermal stratification piping. Thermal flow analysis, stress analysis and fatigue estimation were performed in serial order. Finally, detailed monitoring locations and mitigation scheme for the integrity maintenance of piping were recommended. All wall mesh and transient temperature distribution data obtained from the CFD (computational fluid dynamics) analysis were directly imported into the input data of stress analysis model without any calculation for heat transfer coefficients. Cumulated usage factors for fatigue effect review with nodes were calculated. A modified method that combines ASME Section III, NB-3600 with NB-3200 was used because the previous method cannot consider the thermal stratification stress intensity. As the results of evaluation, the SCS (shutdown cooling system) line, branch piping of the RCS (reactor coolant system) line, shows that the CUF (cumulative usage factor) value exceeds 1.0, ASME Code limit, in case thermal stratification load is included. The HPSI (high pressure safety injection) line, re-branch piping, shows that temperature difference between top and bottom of piping exceeds the criterion temperature, 28°C, and that the CUF value exceeds 1.0. Therefore, these branch pipings require a detailed review, monitoring or analysis. In particular, it is recommended that the HPSI piping should be shifted backward to decrease the influence of turbulent penetration intensity from the RCS piping. This paper was recommended for publication in revised form by Associate Editor Jae Young Lee Kwang-Chu Kim received his B.S., M.S. and Ph.D degrees from department of mechanical engineering, Kyunghee University in 1993, 1995 and 2000, respectively. He has worked for Korea Power Engineering Company since 1995 and he is now a senior researcher. Dr. Kim’s research area includes CFD analysis, flow control, plant design and simulator. Jong-Han Lim received his B.S. degree from department of mechanical engineering, Chosun University in 1981, M.S. and Ph.D degrees from department of mechanical engineering, Kyunghee University in 1986 and 1992, respectively. He worked for Hyundai Motors Company during 1986-95. He is now a professor in department of mechanical & automotive engineering, Kyungwon University. Dr. Lim’s research interests are in the area of thermal flow, internal combustion and liquid atomization. Jun-Kyu Yoon received his B.S. degree from department of mechanical engineering, Chosun University in 1981, M.S. degree from department of mechanical engineering, Kyunghee University in 1987 and Ph.D degree from department of mechanical engineering, Myongji University in 2001. He worked for Hyundai Motors Company and Asia Motors Company during 1985–96. He is now a professor in department of mechanical & automotive engineering, Kyungwon University. Dr. Yoon’s research interests are in the area of flow control, heat transfer, liquid atomization, spray and combustion.  相似文献   
996.
The Elman Recurrent Neural Network was employed for the prediction of in-vitro dissolution profiles of matrix controlled release theophylline pellet preparation, leading to the potential use of an intelligent learning system in the development of pharmaceutical products with desired drug release characteristics. A total of six different formulations containing various matrix ratios of substance to control the release rate of theophylline were used for experimentation. By using the leave-one-out cross-validation approach, the dissolution profiles of all the matrix ratios were consumed for training, except for one set that was taken as a reference profile, with which the network predicted profiles were compared. Performance of the network was assessed using the similarity factor, f 2 , a criterion for dissolution profile comparison recommended by the United States Food and Drug Administration. Simulation results indicated that the Elman network was capable of predicting dissolution profiles that were similar to the reference profiles with an error of less than 8%. In addition, the Bootstrap method was used to estimate the confidence intervals of the f 2 values. The results revealed the potential of a neural-network-based intelligent system in solving non-linear time-series prediction problems in pharmaceutical product development.  相似文献   
997.
998.
A global, tridimensional, and comprehensive model for the drug problem is presented. On a flat matrix with five components (growing, production, processing, traffic/distribution, and consumption) and seven dimensions (individual, family, restricted group, neighborhood, city/region, national, and international), six different perspectives are employed (psychobiological, social/political, economics, legal, historical/cultural, and geographical). Each psychoactive substance may be analyzed separately.  相似文献   
999.
Quadrature mirror filters have been used extensively in subband coding of speech signals. The authors introduce a novel efficient approach for the design of equiripple quadrature mirror filters. The new approach is more efficient than the previously proposed design method in terms of computer time and memory requirement  相似文献   
1000.
Reports analyses of outcome measures obtained from patients, therapists, and clinical observers in the Penn Psychotherapy Project, a 5-yr study of factors that predict outcome in outpatient psychotherapy. The data from the "method factors" study by D. S. Cartwright et al (see record 1963-06833-001) were also reanalyzed. Results in both studies were very similar. Substantial agreement was found among viewpoints about broadly defined treatment outcomes, although distinct viewpoints did clearly exist. Contrary to a common opinion, consensus measures of psychotherapy outcome could be meaningfully defined. Relationships among posttreatment ratings of benefits from therapy and measures of adjustment obtained before and after treatment were explored. A strong relationship was found between the residual gain score and ratings of benefits, suggesting that posttreatment ratings of outcome take account of the fact that the amount of change to be expected depends on the initial level of functioning. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号