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   264365篇
  免费   3398篇
  国内免费   1098篇
电工技术   4865篇
技术理论   1篇
综合类   970篇
化学工业   42505篇
金属工艺   16142篇
机械仪表   10924篇
建筑科学   5218篇
矿业工程   4044篇
能源动力   4347篇
轻工业   11249篇
水利工程   4418篇
石油天然气   13554篇
武器工业   134篇
无线电   21825篇
一般工业技术   64853篇
冶金工业   33755篇
原子能技术   11301篇
自动化技术   18756篇
  2021年   3685篇
  2020年   2802篇
  2019年   3199篇
  2018年   5943篇
  2017年   6318篇
  2016年   6572篇
  2015年   3737篇
  2014年   6219篇
  2013年   11084篇
  2012年   8414篇
  2011年   10118篇
  2010年   8281篇
  2009年   9049篇
  2008年   9051篇
  2007年   8648篇
  2006年   7075篇
  2005年   6139篇
  2004年   5882篇
  2003年   5639篇
  2002年   5450篇
  2001年   5252篇
  2000年   5178篇
  1999年   4491篇
  1998年   7604篇
  1997年   6161篇
  1996年   4651篇
  1995年   3806篇
  1994年   3546篇
  1993年   3740篇
  1992年   3265篇
  1991年   3393篇
  1990年   3528篇
  1989年   3403篇
  1988年   3294篇
  1987年   3288篇
  1986年   3176篇
  1985年   3339篇
  1984年   3276篇
  1983年   3163篇
  1982年   3011篇
  1981年   3081篇
  1980年   3090篇
  1979年   3271篇
  1978年   3503篇
  1977年   3484篇
  1976年   3942篇
  1975年   3219篇
  1974年   3293篇
  1973年   3344篇
  1972年   2991篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
Puzanov  A. S.  Obolenskiy  S. V.  Kozlov  V. A. 《Semiconductors》2020,54(8):946-950
Semiconductors - On the basis of the Monte Carlo algorithm, a method for calculating the energy spectrum of hot nonequilibrium electrons and holes in the track of a primary recoil atom after being...  相似文献   
72.
73.
74.
Programming and Computer Software - Image segmentation using a hierarchical sequence of piecewise constant approximations that minimally differ from the original image in terms of the total squared...  相似文献   
75.
76.
77.
Connexin- and pannexin (Panx)-formed hemichannels (HCs) and gap junctions (GJs) operate an interaction with the extracellular matrix and GJ intercellular communication (GJIC), and on account of this they are involved in cancer onset and progression towards invasiveness and metastatization. When we deal with cancer, it is not correct to omit the immune system, as well as neglecting its role in resisting or succumbing to formation and progression of incipient neoplasia until the formation of micrometastasis, nevertheless what really occurs in the tumor microenvironment (TME), which are the main players and which are the tumor or body allies, is still unclear. The goal of this article is to discuss how the pivotal players act, which can enhance or contrast cancer progression during two important process: “Activating Invasion and Metastasis” and the “Avoiding Immune Destruction”, with a particular emphasis on the interplay among GJIC, Panx-HCs, and the purinergic system in the TME without disregarding the inflammasome and cytokines thereof derived. In particular, the complex and contrasting roles of Panx1/P2X7R signalosome in tumor facilitation and/or inhibition is discussed in regard to the early/late phases of the carcinogenesis. Finally, considering this complex interplay in the TME between cancer cells, stromal cells, immune cells, and focusing on their means of communication, we should be capable of revealing harmful messages that help the cancer growth and transform them in body allies, thus designing novel therapeutic strategies to fight cancer in a personalized manner.  相似文献   
78.
Interaction of molybdenyl(VI) bis(acetylacetonate) with polyphenylsiloxane in xylene and under mechanochemical activation conditions has been investigated. The interaction in solution proceeds with splitting of the siloxane bond and formation of polymolybdenum(VI) phenylsiloxane with different silicon/metal ratios. The fractions with the silicon/metal ratio < 2 are characterized with high degree of crystallinity and low solubility, whereas those with the ratio > 2 are amorphous. The interaction of the above reagents under mechanical activation conditions proceeds with the formation of soluble polymers similar to those obtained in a solution with the silicon/molybdenum ratio equal to 2.6. The crystal chemistry parameters of the fraction obtained in solution with the ratio Si/Mo equals to 1:2 have been calculated on the basis of the X-ray diffraction analysis data using the Debye–Shearer equation. It has been demonstrated that the chain cross section found using the Miller–Boyer method coincides with that calculated geometrically on the basis of literature data on bond lengths and angles. It is shown that the interaction of molybdenyl(VI) bis(acetylacetonate) with polyphenylsiloxane takes place in solution more deeply than under the conditions of mechanochemical activation and is accompanied by the process of separation siloxanes connection. This leads to the formation of a fraction with smaller ratio of substances than the initial ratio.  相似文献   
79.
80.
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