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   301507篇
  免费   7058篇
  国内免费   1364篇
电工技术   4966篇
综合类   770篇
化学工业   46206篇
金属工艺   9227篇
机械仪表   8508篇
建筑科学   8624篇
矿业工程   776篇
能源动力   8400篇
轻工业   34680篇
水利工程   2623篇
石油天然气   2161篇
武器工业   36篇
无线电   37344篇
一般工业技术   54321篇
冶金工业   57052篇
原子能技术   3674篇
自动化技术   30561篇
  2022年   1411篇
  2021年   2957篇
  2020年   2211篇
  2019年   2530篇
  2018年   4162篇
  2017年   4149篇
  2016年   4525篇
  2015年   3425篇
  2014年   5268篇
  2013年   15085篇
  2012年   9379篇
  2011年   12297篇
  2010年   9514篇
  2009年   10397篇
  2008年   11121篇
  2007年   10926篇
  2006年   9860篇
  2005年   8792篇
  2004年   8574篇
  2003年   8601篇
  2002年   8272篇
  2001年   8314篇
  2000年   7196篇
  1999年   7710篇
  1998年   19735篇
  1997年   13443篇
  1996年   10040篇
  1995年   7461篇
  1994年   6438篇
  1993年   6321篇
  1992年   4321篇
  1991年   4067篇
  1990年   3848篇
  1989年   3668篇
  1988年   3551篇
  1987年   2821篇
  1986年   2737篇
  1985年   3460篇
  1984年   3023篇
  1983年   2744篇
  1982年   2557篇
  1981年   2630篇
  1980年   2417篇
  1979年   2202篇
  1978年   2024篇
  1977年   2423篇
  1976年   3244篇
  1975年   1706篇
  1974年   1578篇
  1973年   1674篇
排序方式: 共有10000条查询结果,搜索用时 562 毫秒
81.
82.
83.
84.
85.
86.
87.
Water Resources Management - This paper aims to evaluate the possibility of using non-utilized hydraulic energy in urban water distribution systems. For this purpose, the viability and possible...  相似文献   
88.
For decades now, Douglas Crimp’s landmark 1980 essay ‘The Photographic Activity of Postmodernism’ has shaped our understanding of modernism’s aftermath, at least as it unfolded in North America and Western Europe. Less remembered, however, is the degree to which the procedures of disjunction, copying, appropriation, and outright theft that he highlighted were epitomised not just by contemporary photography, but by photomontage in particular. This article recovers the debates that led critics such as Crimp, Abigail Solomon-Godeau, Christopher Phillips, Benjamin Buchloh and others to turn to photomontage as one of their principal objects of concern in what became known as the postmodern critique of photography. Why was montage tasked to perform this critical function, particularly by people around the journal October who had not otherwise devoted the balance of their writing to photography’s history? The article suggests that these men and women, along with the contemporary artists they foregrounded, manifested what Mary Anne Doane has called a ‘desire for signification’, a reaction in the late 1970s against the mute theatricality of minimalist and conceptual art. Photomontage reintroduced representation to contemporary art and to the canon of art history. But unlike the reemerging illusionism in painting that also manifested this desire, montage guarded against an uncomplicated realism by highlighting and critiquing operations of representation in a manner that painting no longer could.  相似文献   
89.
In the quest for new antibacterial agents, a series of novel long- and medium-chain mono- and disubstituted β-lactones was developed. Their activity against three pathogenic mycobacteria—M. abscessus, M. marinum, and M. tuberculosis—was assessed by the resazurin microtiter assay (REMA). Among the 16 β-lactones synthesized, only 3-hexadecyloxetan-2-one (VM005) exhibited promising activity against M. abscessus, whereas most of the β-lactones showed interesting activities against M. marinum, similar to that of the classical antibiotic, isoniazid. Regarding M. tuberculosis, six compounds were found to be active against this mycobacterium, with β-lactone VM008 [trans-(Z)-3-(hexadec-7-en-1-yl)-4-propyloxetan-2-one] being the best growth inhibitor. The promising antibacterial activities of the best compounds in this series suggest that these molecules may serve as leads for the development of much more efficient antimycobacterial agents.  相似文献   
90.
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