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   186542篇
  免费   14211篇
  国内免费   7786篇
电工技术   10566篇
技术理论   9篇
综合类   10801篇
化学工业   29111篇
金属工艺   11626篇
机械仪表   11417篇
建筑科学   11162篇
矿业工程   4652篇
能源动力   4070篇
轻工业   11837篇
水利工程   3883篇
石油天然气   10265篇
武器工业   1334篇
无线电   19597篇
一般工业技术   28456篇
冶金工业   11858篇
原子能技术   5178篇
自动化技术   22717篇
  2024年   848篇
  2023年   2676篇
  2022年   5432篇
  2021年   7208篇
  2020年   5365篇
  2019年   4525篇
  2018年   5653篇
  2017年   6188篇
  2016年   5676篇
  2015年   6477篇
  2014年   8396篇
  2013年   10227篇
  2012年   11179篇
  2011年   11951篇
  2010年   10351篇
  2009年   10046篇
  2008年   10007篇
  2007年   9491篇
  2006年   8772篇
  2005年   7428篇
  2004年   5681篇
  2003年   5267篇
  2002年   5265篇
  2001年   4751篇
  2000年   4106篇
  1999年   3428篇
  1998年   2656篇
  1997年   2228篇
  1996年   1995篇
  1995年   1744篇
  1994年   1469篇
  1993年   1252篇
  1992年   1226篇
  1991年   1083篇
  1990年   1101篇
  1989年   1019篇
  1988年   897篇
  1987年   844篇
  1986年   764篇
  1985年   717篇
  1984年   701篇
  1981年   670篇
  1979年   739篇
  1978年   777篇
  1977年   739篇
  1976年   755篇
  1975年   713篇
  1974年   719篇
  1973年   723篇
  1972年   705篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
51.
The kinetics of glycidyl methacrylate block polymerization to high conversion was experimentally investigated with variations of the photoinitiator concentration, temperature, and power of UV illumination. The kinetic curves of this polymerization process contain three characterized sections of coordinates of “conversion–time,” namely: The first one is practically linear to a conversion of ≈0.5, the second represents, by itself, the autoacceleration process, and the third presents the autodecelation process. An additional peculiarity of such a polymerization process is poor reproduction of the kinetic measurements. This reproduction does not correspond to instrumental error. Derivation of a kinetic model for block linear polymerization was done. This model is, quantitatively, in good agreement with all the data of the experimental material. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 3556–3569, 2002  相似文献   
52.
The effect of turbulizing asperities positioned on one of the walls of a plane channel on the intensity of exchange processes near a smooth wall with injection of different working media is studied experimentally. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 3, pp. 404–408, 1997.  相似文献   
53.
54.
Scientific-Technical Center “Atomtekhénergo.” Leningrad Nuclear Power Plant. N. V. Sultanov Institute of Nuclear Reactors, Russian Scientific Center “Kurchatovskii institut.” Translated from Atomnaya énergiya, Vol. 76, No. 6, pp. 470–473, June, 1994.  相似文献   
55.
56.
57.
Analytical solution of a system of nonlinear measuring equations of a 12-pole microwave reflectometer was obtained. Criteria for selecting a true solution in the general case were developed and the analysis was conducted for a number of particular cases that may generate practical interest.  相似文献   
58.
The formation specifics of the structure and phase composition of densely sintered ceramics based on a low-melting argillaceous material from Belarus together with a combined flux and a grog additive are investigated. The correlation between the physicochemical properties, structure, phase composition, and the time-temperature firing schedules of the developed materials are investigated. Electron probe microanalysis makes it possible to monitor variations in the chemical composition at various local sites and compare it with the estimated composition of the mixture. The optimum regimes for the heat treatment of articles are determined. __________ Translated from Steklo i Keramika, No. 6, pp. 32 – 36, June, 2005.  相似文献   
59.
We present an automatic algorithm to segment all the local and global asymmetric units of a three-dimensional density map of icosahedral viruses. This approach is readily applicable to the structural analysis of a broad range of virus structures that are reconstructed using cryo-electron microscopy (cryo-EM) technique. Our algorithm includes three major steps operating on the three dimensional density map: the detection of critical points of the volumetric density function, the detection of global and local symmetry axes, and, finally, the boundary segmentation of all the asymmetric units. We demonstrate the efficacy of our algorithm and report our results on several experimental volumetric datasets, consisting of both reconstructed cryo-EM molecular density maps taken from the European Bioinformatics Institute archive, as well our own synthetically generated (blurred) maps calculated from X-ray resolution molecular structural data taken from the Protein Data Bank.  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