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   331300篇
  免费   3409篇
  国内免费   974篇
电工技术   5389篇
综合类   2469篇
化学工业   47575篇
金属工艺   19373篇
机械仪表   14058篇
建筑科学   6787篇
矿业工程   3232篇
能源动力   6120篇
轻工业   16582篇
水利工程   4661篇
石油天然气   8959篇
武器工业   22篇
无线电   34381篇
一般工业技术   72916篇
冶金工业   40664篇
原子能技术   7602篇
自动化技术   44893篇
  2021年   2064篇
  2019年   2004篇
  2018年   22178篇
  2017年   21702篇
  2016年   16021篇
  2015年   3139篇
  2014年   4057篇
  2013年   8961篇
  2012年   10130篇
  2011年   21272篇
  2010年   18713篇
  2009年   16324篇
  2008年   17214篇
  2007年   19394篇
  2006年   5735篇
  2005年   8866篇
  2004年   7075篇
  2003年   6837篇
  2002年   5347篇
  2001年   4611篇
  2000年   4443篇
  1999年   4262篇
  1998年   10236篇
  1997年   7209篇
  1996年   5544篇
  1995年   4151篇
  1994年   3636篇
  1993年   3874篇
  1992年   3008篇
  1991年   3040篇
  1990年   2890篇
  1989年   2852篇
  1988年   2875篇
  1987年   2510篇
  1986年   2569篇
  1985年   2854篇
  1984年   2687篇
  1983年   2554篇
  1982年   2301篇
  1981年   2269篇
  1980年   2348篇
  1979年   2359篇
  1978年   2383篇
  1977年   2487篇
  1976年   2876篇
  1975年   2188篇
  1974年   2068篇
  1973年   2166篇
  1972年   1940篇
  1971年   1755篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
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   
93.
Tsyplenkov  V. V.  Shastin  V. N. 《Semiconductors》2019,53(10):1334-1339
Semiconductors - Long-wavelength acoustic phonon-assisted relaxation rates for the excited 1s(T), 2p0, 2s, 3p0, 2p±, 4p0, and 3p± states of antimony donors in a germanium crystal are...  相似文献   
94.
The data on the use of solar photovoltaic plants (PVPs) for providing a reliable and guaranteed power supply to telecommunication systems and cellular communication systems in the conditions prevalent in Uzbekistan are given. The research-based structures developed by OOO MIR SOLAR and the selection of PVP elements ensuring their reliable operation are described. The main influencing factors are discussed, and the use of effective combinations of different types of panels (from monocrystalline and polycrystalline silicon) and a specially developed controller are considered.  相似文献   
95.
This work presents simulation of microstructure evolution in the nugget zone (NZ) of a AZ31-Mg-alloy friction stir weld. The process parameters (tool geometrical characteristics, rotational speed, travel speed, applied load) have been correlated with the resulting microstructural features in the NZ of the weld (grain size and population) with the aid of the MICRESS software, which provides the ability to simulate both nucleation and grain growth during dynamic recrystallization phenomena evolving in the NZ during the weld thermal cycle. The input parameters of the developed model include the tool geometry, the welding conditions as well as the recrystallization energy, the grain boundary mobility and specific material properties. NZ microstructure obtained by simulation shows good agreement with experimental measurements for both grain population and size.  相似文献   
96.
97.
98.
99.
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   
100.
Technical Physics Letters - Specific features of monitoring the state of a flowing medium by method of nuclear magnetic resonance (NMR) are considered. An approach to studying the state of a...  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