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   567538篇
  免费   7092篇
  国内免费   995篇
电工技术   10576篇
综合类   468篇
化学工业   89915篇
金属工艺   23393篇
机械仪表   18536篇
建筑科学   12563篇
矿业工程   4311篇
能源动力   14495篇
轻工业   45909篇
水利工程   6941篇
石油天然气   14964篇
武器工业   39篇
无线电   60554篇
一般工业技术   116520篇
冶金工业   96148篇
原子能技术   14734篇
自动化技术   45559篇
  2021年   5500篇
  2019年   5281篇
  2018年   9230篇
  2017年   9422篇
  2016年   9850篇
  2015年   6044篇
  2014年   10273篇
  2013年   26193篇
  2012年   15821篇
  2011年   21157篇
  2010年   17034篇
  2009年   18871篇
  2008年   19152篇
  2007年   18824篇
  2006年   16347篇
  2005年   14807篇
  2004年   14085篇
  2003年   13747篇
  2002年   13304篇
  2001年   12901篇
  2000年   12374篇
  1999年   12066篇
  1998年   27855篇
  1997年   20192篇
  1996年   15729篇
  1995年   12074篇
  1994年   10926篇
  1993年   10679篇
  1992年   8371篇
  1991年   8135篇
  1990年   8024篇
  1989年   7787篇
  1988年   7502篇
  1987年   6770篇
  1986年   6551篇
  1985年   7419篇
  1984年   6735篇
  1983年   6459篇
  1982年   5802篇
  1981年   5926篇
  1980年   5655篇
  1979年   5753篇
  1978年   5676篇
  1977年   6190篇
  1976年   7709篇
  1975年   5115篇
  1974年   4908篇
  1973年   4982篇
  1972年   4286篇
  1971年   4042篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
211.
Journal of Communications Technology and Electronics - Approximate formulas for calculating the coefficient of reflection from an artificial magnetic conductor (AMC) based on a capacitive lattice...  相似文献   
212.
An effective practical approach that allows not only a significant reduction in the scope of practical experiments in the course of studying suspension separation processes in hydrocyclones, but also makes it possible to assess the intensity of random components of the processes and define the interrelation between such components and hydrodynamics of flows in a hydrocyclone is presented. Within the frames of the developed probabilistic‐statistical model of suspension separation in hydrocyclones on the basis of statistical self‐similarity properties, a relationship was found between determined and random components of the processes. This allowed transitioning from three‐parameter probability density functions for suspension particles in hydrocyclones to two‐parameter functions; thus significantly improving the efficiency of practical application of the developed model.  相似文献   
213.
Power Technology and Engineering - The monitoring of hydraulic structures as high-risk facilities is discussed. Monitoring should ensure the reliability and functioning of a hydraulic structure...  相似文献   
214.
Theoretical Foundations of Chemical Engineering - A choline chloride–sulfosalicylic acid deep eutectic solvent (DES) is proposed for dissolving the oxides Co(II), Cu(II), Zn(II), Fe(III),...  相似文献   
215.
Atomic Energy - The results of calculations and experimental determination of the neutronics characteristics of the IRT-T research reactor are presented. The IRT-T reactor is a pool reactor with...  相似文献   
216.
Protection of Metals and Physical Chemistry of Surfaces - In this work, a universal sorbent has been obtained that works according to the mechanisms of chemisorption and adsorption by impregnating...  相似文献   
217.
Journal of Communications Technology and Electronics - Microstrip band-pass filters (BPFs) containing quarter-wavelength resonators and a Π-shaped half-wavelength resonator placed next to each...  相似文献   
218.
Spontaneous mutations in the EEF1A2 gene cause epilepsy and severe neurological disabilities in children. The crystal structure of eEF1A2 protein purified from rabbit skeletal muscle reveals a post-translationally modified dimer that provides information about the sites of interaction with numerous binding partners, including itself, and maps these mutations onto the dimer and tetramer interfaces. The spatial locations of the side chain carboxylates of Glu301 and Glu374, to which phosphatidylethanolamine is uniquely attached via an amide bond, define the anchoring points of eEF1A2 to cellular membranes and interorganellar membrane contact sites. Additional bioinformatic and molecular modeling results provide novel structural insight into the demonstrated binding of eEF1A2 to SH3 domains, the common MAPK docking groove, filamentous actin, and phosphatidylinositol-4 kinase IIIβ. In this new light, the role of eEF1A2 as an ancient, multifaceted, and articulated G protein at the crossroads of autophagy, oncogenesis and viral replication appears very distant from the “canonical” one of delivering aminoacyl-tRNAs to the ribosome that has dominated the scene and much of the thinking for many decades.  相似文献   
219.
Wireless Personal Communications - The majority of security systems for wireless sensor networks are based on symmetric encryption. The main open issue for these approaches concerns the...  相似文献   
220.
The ‐centroid problem or leader–follower problem is generalized considering different customer choice rules where a customer may use facilities belonging to different firms, if the difference in travel distance (or time) is small enough. Assuming essential goods, some particular customer choice rules are analyzed. Linear programming formulations for the generalized ‐medianoid and ‐centroid problems are presented and an exact solution approach is applied. Some computational examples are included.  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