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   275920篇
  免费   4897篇
  国内免费   1443篇
电工技术   6057篇
技术理论   2篇
综合类   1431篇
化学工业   40077篇
金属工艺   11075篇
机械仪表   9504篇
建筑科学   7476篇
矿业工程   1622篇
能源动力   6814篇
轻工业   23912篇
水利工程   2825篇
石油天然气   4852篇
武器工业   158篇
无线电   36571篇
一般工业技术   52119篇
冶金工业   47283篇
原子能技术   5698篇
自动化技术   24784篇
  2021年   2570篇
  2020年   1977篇
  2019年   2478篇
  2018年   3919篇
  2017年   4034篇
  2016年   4148篇
  2015年   2927篇
  2014年   4824篇
  2013年   12190篇
  2012年   7528篇
  2011年   9850篇
  2010年   7858篇
  2009年   8807篇
  2008年   9554篇
  2007年   9481篇
  2006年   8721篇
  2005年   7908篇
  2004年   7469篇
  2003年   7268篇
  2002年   6922篇
  2001年   6988篇
  2000年   6607篇
  1999年   6772篇
  1998年   14595篇
  1997年   10607篇
  1996年   8452篇
  1995年   6691篇
  1994年   5962篇
  1993年   5735篇
  1992年   4675篇
  1991年   4298篇
  1990年   4116篇
  1989年   3843篇
  1988年   3672篇
  1987年   3198篇
  1986年   3082篇
  1985年   3624篇
  1984年   3389篇
  1983年   3036篇
  1982年   2857篇
  1981年   2956篇
  1980年   2768篇
  1979年   2650篇
  1978年   2499篇
  1977年   2945篇
  1976年   3554篇
  1975年   2316篇
  1974年   2312篇
  1973年   2318篇
  1972年   1849篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
61.
Lund  Brady D.  Maurya  Sanjay Kumar 《Scientometrics》2020,125(3):2491-2504
Scientometrics - This study investigates a potential relationship between highly-cited scholarly papers and the number of citations received by other papers with which they share a journal issue....  相似文献   
62.
Morozov  Yu. D.  Pemov  I. F.  Matrosov  M. Yu.  Zin’ko  B. F. 《Metallurgist》2020,63(9-10):933-950
Metallurgist - We consider domestic and foreign standards for rolled metals used in bridge building. Domestic standards contain elevated requirements to the reliability of rolled metals in terms of...  相似文献   
63.
Russian Journal of Non-Ferrous Metals - This article is devoted to the influence of sodium lignosulfonate (SL), anionic surfactants (sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate...  相似文献   
64.
65.
66.
An alternative Equivalent Electrical Circuit for Proton Exchange Membrane Fuel Cells is modelled in this study. Both I–V characteristics and H2 consumptions corresponding to generated power under load and no-load conditions are investigated. For this purpose, H2 consumptions and I–V characteristics of three different sized PEMFCs are tested. There is a very good harmony between the model results and measured values (relative error %0.7, %6.4 and %2.5 for FC-A, FC-B and FC-C respectively). In the proposed model current passes only on parallel resistance and not on serial resistance at no-load condition. Thus, a FC with higher parallel resistance should be preferred. Another key output of this study is that based on the proposed model, performance comparison of FCs can be performed with the parameters defined in this work. Proposals made in this study can easily be used for performance analysis of FCs under for both steady state and transient analysis.  相似文献   
67.
The mammalian cell cycle is important in controlling normal cell proliferation and the development of various diseases. Cell cycle checkpoints are well regulated by both activators and inhibitors to avoid cell growth disorder and cancerogenesis. Cyclin dependent kinase 20 (CDK20) and p21Cip1/Waf1 are widely recognized as key regulators of cell cycle checkpoints controlling cell proliferation/growth and involving in developing multiple cancers. Emerging evidence demonstrates that these two cell cycle regulators also play an essential role in promoting cell survival independent of the cell cycle, particularly in those cells with a limited capability of proliferation, such as cardiomyocytes. These findings bring new insights into understanding cytoprotection in these tissues. Here, we summarize the new progress of the studies on these two molecules in regulating cell cycle/growth, and their new roles in cell survival by inhibiting various cell death mechanisms. We also outline their potential implications in cancerogenesis and protection in heart diseases. This information renews the knowledge in molecular natures and cellular functions of these regulators, leading to a better understanding of the pathogenesis of the associated diseases and the discovery of new therapeutic strategies.  相似文献   
68.
Powder Metallurgy and Metal Ceramics - The theoretical strength of LaB6 and MeB2 borides and a eutectic LaB6–TiB2 system is calculated with quasiharmonic approximation for uniaxial strain in...  相似文献   
69.
70.
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