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   84591篇
  免费   1042篇
  国内免费   410篇
电工技术   781篇
综合类   2316篇
化学工业   11789篇
金属工艺   4823篇
机械仪表   3028篇
建筑科学   2168篇
矿业工程   562篇
能源动力   1154篇
轻工业   3616篇
水利工程   1279篇
石油天然气   343篇
无线电   9335篇
一般工业技术   16489篇
冶金工业   2714篇
原子能技术   259篇
自动化技术   25387篇
  2023年   16篇
  2022年   31篇
  2021年   34篇
  2020年   26篇
  2019年   35篇
  2018年   14470篇
  2017年   13395篇
  2016年   9991篇
  2015年   629篇
  2014年   263篇
  2013年   288篇
  2012年   3173篇
  2011年   9440篇
  2010年   8313篇
  2009年   5576篇
  2008年   6816篇
  2007年   7811篇
  2006年   164篇
  2005年   1238篇
  2004年   1144篇
  2003年   1191篇
  2002年   560篇
  2001年   110篇
  2000年   196篇
  1999年   70篇
  1998年   88篇
  1997年   47篇
  1996年   69篇
  1995年   21篇
  1994年   29篇
  1993年   27篇
  1992年   19篇
  1991年   37篇
  1990年   14篇
  1988年   17篇
  1969年   24篇
  1968年   44篇
  1967年   34篇
  1966年   43篇
  1965年   44篇
  1963年   29篇
  1962年   22篇
  1961年   18篇
  1960年   30篇
  1959年   35篇
  1958年   38篇
  1957年   36篇
  1956年   34篇
  1955年   64篇
  1954年   70篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
In the recent sub-20 nm technology node, the process variability issues have become a major problem for scaling of MOS devices. We present a design for a strained Si/SiGe FinFET on an insulator using a 3D TCAD simulator. The impact of metal gate work function variability (WFV) on electrical parameters is studied. Such impact of WFV for different mole fractions (x) of the SiGe layer in a strained SOI-FinFET with varying grain size is presented. The results show that as the mole fraction is increased, the variability in threshold voltage (σVT) and off current (σIoff) is decreased; while, the variability of on-current (σIon) is increased. A notable observation is the distribution of electrical parameters approaches a normal distribution for smaller grain sizes.  相似文献   
2.
Mobile software applications have to cope with a particular environment that involves small size, limited resources, high autonomy requirements, competitive business models and many other challenges. To provide development guidelines that respond to these needs, several practices have been introduced; however, it is not clear how these guidelines may contribute to solve the issues present in the mobile domain. Furthermore, the rapid evolution of the mobile ecosystem challenges many of the premises upon which the proposed practices were designed. In this paper, we present a survey of the literature on software assurance practices for mobile applications, with the objective of describing them and assessing their contribution and success. We identified, organized and reviewed a body of research that spans in three levels: software development processes, software product assurance practices, and software implementation practices. By carrying out this literature survey, we reviewed the different approaches that researchers on Software Engineering have provided to address the needs that raise in the mobile software development arena. Moreover, we review the evolution of these practices, identifying how the constant changes and modernization of the mobile execution environment has impacted the methods proposed in the literature. Finally, we introduced discussion on the application of these practices in a real productive setting, opening an area for further research that may determine if practitioners have followed the proposed assurance paradigms.  相似文献   
3.
Ghosh  Puja  Bhowmick  Brinda 《SILICON》2020,12(5):1137-1144

This paper addresses reliability issues associated with temperature of Ferroelectric Dopant Segregated Schottky Barrier Tunnel Field Effect Transistor (Fe DS-SBTFET). The simulated results are compared with Dopant Segregated Schottky Barrier TFET (DS-SBTFET). This is achieved by varying the operating temperature from 300 to 500 K. DC parameters such as ION/IOFF ratio, drain current characteristics and subthreshold swing (SS) for a range of temperature have been highlighted. Moreover, the influence of temperature on various RF figure of merits such as gate capacitance (CGG), intrinsic delay, cutoff frequency (fT) etc. have been investigated. The device linearity has been analyzed by considering the effect of temperature variation on linearity parameters like gm2, gm3, 1-dB compression point, VIP2, VIP3 and IIP3. The device characteristics get upgraded by the increase in cut-off frequency and reduction in intrinsic delay at elevated temperature.

  相似文献   
4.
This paper presents an integrated passive damping approach in hybrid metal-CFRP parts for structural applications. In this concept a viscoelastic material is embedded in the joint zone of the hybrid component. To examine the connection strength single-lap-joint specimens were produced and tested and the influence of the used material combinations, different surface structures, and different process parameters i.e. the moment of cross-linking were evaluated. Afterwards, the metal-CFRP hybrids were tested in quasi-static tests to assess their connection strength and failure behaviour. Dynamic cyclic tensile tests with step-wise increased loading conditions were performed to determine the specimens damping behaviour and to estimate their fatigue performance. Finally, these results are compared to a state of the art metal-CFRP hybrid with rivets connecting both materials.  相似文献   
5.
In this paper, we consider the classical finite mixture model, which is an effective tool for modeling lifetime distributions for random samples from heterogeneous populations. We discuss new results on stochastic comparison for two finite mixtures when each of them is drawn from one of the following semiparametric families, i.e., proportional hazards, accelerated lifetime and proportional reversed hazards.  相似文献   
6.
7.
8.
Variations of Incomplete Open Cubes is the major project by the twentieth-century conceptual artist Sol LeWitt. In this paper we interpret the enumerative component of the project as embeddings of graphs. This formulation permits use of an algorithm to check the completeness of the list of the structures produced by the artist. Our conclusion is that the artist found the correct number of structures (that is, 122), but that his list contains a mistake in the presentation of a pair of incomplete cubes, a discovery that appears not to have been noted before.  相似文献   
9.
10.
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