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   4977篇
  免费   177篇
  国内免费   9篇
电工技术   49篇
综合类   1篇
化学工业   908篇
金属工艺   85篇
机械仪表   86篇
建筑科学   296篇
矿业工程   18篇
能源动力   131篇
轻工业   458篇
水利工程   43篇
石油天然气   38篇
武器工业   1篇
无线电   274篇
一般工业技术   852篇
冶金工业   980篇
原子能技术   18篇
自动化技术   925篇
  2023年   29篇
  2022年   24篇
  2021年   80篇
  2020年   73篇
  2019年   63篇
  2018年   91篇
  2017年   72篇
  2016年   122篇
  2015年   88篇
  2014年   160篇
  2013年   347篇
  2012年   241篇
  2011年   319篇
  2010年   222篇
  2009年   190篇
  2008年   254篇
  2007年   231篇
  2006年   189篇
  2005年   191篇
  2004年   138篇
  2003年   129篇
  2002年   130篇
  2001年   79篇
  2000年   70篇
  1999年   79篇
  1998年   97篇
  1997年   106篇
  1996年   72篇
  1995年   73篇
  1994年   53篇
  1993年   68篇
  1992年   76篇
  1991年   44篇
  1990年   49篇
  1989年   53篇
  1988年   49篇
  1987年   48篇
  1986年   56篇
  1985年   70篇
  1984年   57篇
  1983年   68篇
  1982年   48篇
  1981年   35篇
  1980年   45篇
  1979年   61篇
  1978年   45篇
  1977年   45篇
  1976年   37篇
  1975年   37篇
  1973年   25篇
排序方式: 共有5163条查询结果,搜索用时 15 毫秒
21.
22.
Abstract: Facility location and customer allocation problems are pervasive in industry and in the private sector. In this paper, we outline a new approach to solving these problems that avoids the need to resort to integer programming techniques. The approach exploits the mathematical structure of the problem as well as characteristics frequently found in applied location/allocation problems. Using this approach, large scale problems are readily solvable on personal computers. We illustrate the approach on a small example and provide computational results based on a real-world application of the technique. Extensions to include additional problem features are also discussed.  相似文献   
23.
24.
A neurostimulator application-specific integrated circuit (ASIC) with scalable circuitry that can stimulate 14 channels, has been developed for an epi-retinal vision prosthesis. This ASIC was designed to allow seven identical units to be connected to control up to 98 channels, with the ability to stimulate 14 electrodes simultaneously. The neurostimulator forms part of a vision prosthesis, designed to restore vision to patients who have lost their sight due to retinal diseases such as retinitis pigmentosa and macular degeneration. For charge balance, the neurostimulator was designed to stimulate with current sources and sinks operating together, and with the ability to drive a hexagonal mosaic of electrodes to reduce the electrical crosstalk that occurs when multiple bipolar stimulation sites are active simultaneously. A hexagonal mosaic of electrodes surrounds each stimulation site and has been shown to effectively isolate each site, increasing the ability to inject localized independent charge into multiple regions simultaneously.  相似文献   
25.
This study focuses on the visualization of a series of large earthquake simulations collectively called TeraShake. The simulation series aims to assess the impact of San Andreas Fault earthquake scenarios in Southern California. We discuss the role of visualization in gaining scientific insight and aiding unexpected discoveries.  相似文献   
26.
We have used the technique of antibody reshaping to producea humanized antibody specific for the a toxin of Clostridiumperfringens. The starting antibody was from a mouse hybridomafrom which variable (V) region nucleo-tide sequences were determined.The complementarity-determining regions (CDRs) from these Vregions were then inserted into human heavy and light chainV region genes with human constant region gene fragments subsequentlyadded. The insertion of CDRs alone into human frameworks didnot produce a functional reshaped antibody and modificationsto the V region framework were required. With minor frameworkmodifications, the affinity of the original murine mAb was restoredand even exceeded. Where affinity was increased, an alteredbinding profile to overlapping peptides was observed. Computermodelling of the reshaped heavy chain V regions suggested thatamino acids adjacent to CDRs can either contribute to, or distort,CDR loop conformation and must be adjusted to achieve high bindingaffinity.  相似文献   
27.
28.
The pressure-flow (P-F) relationship in intravenous catheters is shown to be represented by the predictive model P = RLF + RTF2. The pressure loss due to F, calculated from experimental data, was found to equal the expected Poiseuille laminar flow loss. Pressure loss due to F2 was found to be the sum of turbulent P losses due to entrance length flow disturbance, kinetic energy at the outflow, and minor shape change losses. Analysis of the flow capabilities of intravenous catheters can be used to evaluate suitability for specific intravenous infusion needs.  相似文献   
29.
Although it rejects self-awareness as psychological bedrock, behavior-analytic theory can be stated self-inclusively, keeping the theorist within view. Its principles of discrimination and generalization have been elaborated to include concepts and higher order conditionalities, including those of logic and of awareness. Its violating a cultural bias that is called the "fundamental attribution error" may be a primary source of controversies. Its other disagreements with mainstream psychologies hinge more on contiguous vs remote causation than on mentalism vs antimentalism, which Skinner emphasized. The nonmediational, Skinnerian theorist is a participation in the world rather than an isolated self. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
30.
Describes the history and evolution of the Department of Psychology at the Fayetteville campus of the University of Arkansas and discusses the contributions of the persons influential in the evolution. (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