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   386186篇
  免费   23995篇
  国内免费   12244篇
电工技术   17208篇
技术理论   31篇
综合类   20074篇
化学工业   63863篇
金属工艺   22458篇
机械仪表   22601篇
建筑科学   26067篇
矿业工程   10539篇
能源动力   9671篇
轻工业   21390篇
水利工程   6266篇
石油天然气   21273篇
武器工业   2335篇
无线电   42615篇
一般工业技术   52464篇
冶金工业   18835篇
原子能技术   3263篇
自动化技术   61472篇
  2024年   1299篇
  2023年   5055篇
  2022年   8577篇
  2021年   12403篇
  2020年   9234篇
  2019年   7856篇
  2018年   21761篇
  2017年   21936篇
  2016年   17751篇
  2015年   12525篇
  2014年   14969篇
  2013年   17828篇
  2012年   21939篇
  2011年   29580篇
  2010年   25653篇
  2009年   22186篇
  2008年   22840篇
  2007年   23324篇
  2006年   16964篇
  2005年   16084篇
  2004年   10696篇
  2003年   9610篇
  2002年   8363篇
  2001年   7033篇
  2000年   7679篇
  1999年   8987篇
  1998年   7324篇
  1997年   6174篇
  1996年   5786篇
  1995年   4753篇
  1994年   3947篇
  1993年   2758篇
  1992年   2243篇
  1991年   1696篇
  1990年   1240篇
  1989年   991篇
  1988年   810篇
  1987年   557篇
  1986年   420篇
  1985年   286篇
  1984年   200篇
  1983年   130篇
  1982年   137篇
  1981年   101篇
  1980年   78篇
  1968年   43篇
  1966年   43篇
  1965年   47篇
  1955年   63篇
  1954年   68篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
State space explosion is a key problem in the analysis of finite state systems. The sweep-line method is a state exploration method which uses a notion of progress to allow states to be deleted from memory when they are no longer required. This reduces the peak number of states that need to be stored, while still exploring the full state space. The technique shows promise but has never achieved reductions greater than about a factor of 10 in the number of states stored in memory for industrially relevant examples. This paper discusses sweep-line analysis of the connection management procedures of a new Internet standard, the Datagram Congestion Control Protocol (DCCP). As the intuitive approaches to sweep-line analysis are not effective, we introduce new variables to track progress. This creates further state explosion. However, when used with the sweep-line, the peak number of states is reduced by over two orders of magnitude compared with the original. Importantly, this allows DCCP to be analysed for larger parameter values. Somsak Vanit-Anunchai was partially supported by an Australian Research Council Discovery Grant (DP0559927) and Suranaree University of Technology. Guy Edward Gallasch was supported by an Australian Research Council Discovery Grant (DP0559927).  相似文献   
42.
This paper presents an approach of measuring in real-time the vector of finger that is pointing to an object. DSP is used in the operation processing unit in order to do the real-time processing. The steps include the extraction of flesh-colored regions from an image, the labeling of the flesh-colored regions, and the detection of two characteristic positions on the finger so that the direction that the finger is pointing at will be calculated. The entire process takes about 29 msec, which makes it possible to have the frame rate of 34 fps. With this frame rate, this measurement approach is considered real-time and promising to be merged into other application systems. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008  相似文献   
43.
44.
Domain-Driven, Actionable Knowledge Discovery   总被引:1,自引:0,他引:1  
Data mining increasingly faces complex challenges in the real-life world of business problems and needs. The gap between business expectations and R&D results in this area involves key aspects of the field, such as methodologies, targeted problems, pattern interestingness, and infrastructure support. Both researchers and practitioners are realizing the importance of domain knowledge to close this gap and develop actionable knowledge for real user needs.  相似文献   
45.
46.
47.
48.
49.
A boron-doped diamond field emitter diode with ultralow turn-on voltage and high emission current is reported. The diamond field emitter diode structure with a built-in cap was fabricated using molds and electrostatic bonding techniques. The emission current versus anode voltage of the capped diamond emitter diode with boron doping, sp2 content, and vacuum thermal electric (VTE) treatment shows a very low turn-on voltage of 2 V. A high emission current of 1 μA at an anode voltage of less than 10 V can be obtained from a single diamond tip. The turn-on voltage is significantly lower than comparable silicon field emitters  相似文献   
50.
The oxygen absorption process in highly aligned YBa2Cu3Ox samples in air and in pure oxygen was studied at several constant temperatures. The process can be expressed in two steps, a chemical reaction controlled step and a diffusion controlled step. The kinetic equations are as follows respectively:
(1 − at) ln(1 − at) + at = kDt

The activation energy was calculated using an Arrhenius equation. The technical conditions of heat treatment for oxygen absorption of highly aligned YBa2Cu3Ox crystals are discussed.  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