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   479158篇
  免费   5308篇
  国内免费   2705篇
电工技术   9880篇
技术理论   5篇
综合类   1529篇
化学工业   73232篇
金属工艺   20356篇
机械仪表   13950篇
建筑科学   12366篇
矿业工程   2162篇
能源动力   11281篇
轻工业   46297篇
水利工程   4659篇
石油天然气   7184篇
武器工业   285篇
无线电   55176篇
一般工业技术   88058篇
冶金工业   93543篇
原子能技术   8859篇
自动化技术   38349篇
  2021年   4043篇
  2020年   2977篇
  2019年   3730篇
  2018年   5404篇
  2017年   5320篇
  2016年   5979篇
  2015年   4520篇
  2014年   7256篇
  2013年   20873篇
  2012年   12239篇
  2011年   16707篇
  2010年   13480篇
  2009年   14678篇
  2008年   15845篇
  2007年   16072篇
  2006年   14419篇
  2005年   12926篇
  2004年   11937篇
  2003年   11630篇
  2002年   11600篇
  2001年   11778篇
  2000年   10932篇
  1999年   11554篇
  1998年   28024篇
  1997年   20037篇
  1996年   15404篇
  1995年   11556篇
  1994年   10363篇
  1993年   10155篇
  1992年   7519篇
  1991年   7284篇
  1990年   6986篇
  1989年   6884篇
  1988年   6597篇
  1987年   5646篇
  1986年   5606篇
  1985年   6483篇
  1984年   6042篇
  1983年   5524篇
  1982年   5011篇
  1981年   5189篇
  1980年   4856篇
  1979年   4866篇
  1978年   4743篇
  1977年   5429篇
  1976年   7554篇
  1975年   4121篇
  1974年   3906篇
  1973年   3880篇
  1972年   3300篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
A novel monitoring method for plasma-charging damage is proposed. This method performs a quick and accurate evaluation using antenna PMOSFET. It was found that not only hot-carrier (HC) lifetime but transistor parameters such as initial gate current and substrate current were changed according to the degree of plasma-charging damage. However, the present work suggests that monitoring the shift of drain current after a few seconds of HC stress is a more accurate method to indicate plasma-charging damage. The monitoring method using the present test structure is demonstrated to be useful for realizing highly reliable devices  相似文献   
52.
The three-dimensional structure of glutathione S-transferase from Arabidopsis thaliana has been solved at 2.2 A resolution (Reinemer et al., 1996). The enzyme forms a dimer of two identical subunits. The structure shows a new G-site architecture and a novel and unique dimer interface. Each monomer of the protein forms a separate G-site. Therefore, the requirements on the dimer interface are reduced. As a consequence, the interactions between the monomers are weaker and residues at the dimer interface are more variable. Thus, the dimer interface looses its relevance for a classification of plant glutathione S-transferases and the formation of heterodimers becomes even more difficult to predict.  相似文献   
53.
The physical widths of reference features incorporated into electrical linewidth test structures patterned in films of monocrystalline silicon have been determined from Kelvin voltage measurements. The films in which the test structures are patterned are electrically insulated from the bulk-silicon substrate by a layer of silicon dioxide provided by SIMOX (Separation by the IMplantation of OXygen) processing. The motivation is to facilitate the development of linewidth reference materials for critical-dimension (CD) metrology-instrument calibration. The selection of the (110) orientation of the starting silicon and the orientation of the structures' features relative to the crystal lattice enable a lattice-plane-selective etch to generate reference-feature properties of rectangular cross section and atomically planar sidewalls. These properties are highly desirable for CD applications in which feature widths are certified with nanometer-level uncertainty for use by a diverse range of CD instruments. End applications include the development and calibration of new generations of CD instruments directed at controlling processes for manufacturing devices having sub-quarter-micrometer features  相似文献   
54.
A new commercially available diode model is described. This unified model is capable of simulating the widest range of diode technologies of any presently available. The emphasis of this paper is on describing the model's extensive features and flexibility in the different domains of operation and is of particular interest in power applications  相似文献   
55.
Uses a Markov process to model a real-time expert system architecture characterized by message passing and event-driven scheduling. The model is applied to the performance evaluation of rule grouping for real-time expert systems running on this architecture. An optimizing algorithm based on Kernighan-Lin heuristic graph partitioning for the real-time architecture is developed and a demonstration system based on the model and algorithm has been developed and tested on a portion of the advanced GPS receiver (AGR) and manned manoeuvring unit (MMU) knowledge bases  相似文献   
56.
57.
58.
59.
This research was supported under project No. 6.02.02/128-93 as part of the state scientific-technical program on future information technologies and systems by the Ukrainian State Committee, of Science and Technology.  相似文献   
60.
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