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   341786篇
  免费   5193篇
  国内免费   1504篇
电工技术   6059篇
综合类   436篇
化学工业   53832篇
金属工艺   14851篇
机械仪表   10217篇
建筑科学   8127篇
矿业工程   2068篇
能源动力   8251篇
轻工业   30475篇
水利工程   3635篇
石油天然气   8218篇
武器工业   26篇
无线电   35844篇
一般工业技术   69132篇
冶金工业   62549篇
原子能技术   8194篇
自动化技术   26569篇
  2021年   2851篇
  2019年   2587篇
  2018年   4881篇
  2017年   4737篇
  2016年   5142篇
  2015年   3514篇
  2014年   5583篇
  2013年   15274篇
  2012年   8944篇
  2011年   11740篇
  2010年   9617篇
  2009年   10886篇
  2008年   11151篇
  2007年   11098篇
  2006年   9581篇
  2005年   8744篇
  2004年   8135篇
  2003年   7751篇
  2002年   7751篇
  2001年   7649篇
  2000年   7163篇
  1999年   7359篇
  1998年   18100篇
  1997年   13365篇
  1996年   10416篇
  1995年   7768篇
  1994年   6886篇
  1993年   6780篇
  1992年   5091篇
  1991年   5021篇
  1990年   4798篇
  1989年   4800篇
  1988年   4650篇
  1987年   4026篇
  1986年   4002篇
  1985年   4610篇
  1984年   4347篇
  1983年   3972篇
  1982年   3745篇
  1981年   3922篇
  1980年   3829篇
  1979年   3713篇
  1978年   3733篇
  1977年   4426篇
  1976年   5889篇
  1975年   3442篇
  1974年   3277篇
  1973年   3314篇
  1972年   2874篇
  1971年   2677篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The bromodomain and extra terminal (BET) family of bromodomain-containing proteins (BCPs) have been the subject of extensive research over the past decade, resulting in a plethora of high-quality chemical probes for their tandem bromodomains. In turn, these chemical probes have helped reveal the profound biological role of the BET bromodomains and their role in disease, ultimately leading to a number of molecules in active clinical development. However, the BET subfamily represents just 8/61 of the known human bromodomains, and attention has now expanded to the biological role of the remaining 53 non-BET bromodomains. Rapid growth of this research area has been accompanied by a greater understanding of the requirements for an effective bromodomain chemical probe and has led to a number of new non-BET bromodomain chemical probes being developed. Advances since December 2015 are discussed, highlighting the strengths/caveats of each molecule, and the value they add toward validating the non-BET bromodomains as tractable therapeutic targets.  相似文献   
42.
Seed processing technologies are essential for seed safety and functionality through protection of physicochemical quality, pathogen inactivation, aflatoxin detoxification and alleviation of mutagenicity. Design of a pilot-scale unit of pulsed electric fields (PEF) to treat sesame seeds with respect to quality parameters, Aspergillus parasiticus inactivation and aflatoxin reduction as well as alleviation of aflatoxin mutagenicity were prompted in this study. PEF energy ranged from 0.97 to 17.28 J achieved maximum reductions of peroxide value and acidity number of 67.4 and 85.7%, respectively, and did not change color L*, a*, b* and hue values. A 60% reduction of A. parasiticus counts occurred at the maximum PEF energy. Aflatoxins G1, G2, B1, and B2 contents decreased by 94.7, 92.7, 86.9, and 98.7%, respectively. Except for the samples treated by 2.16 J with 100 μg/plate and by 6.80 J with 10 μg/plate, PEF treatment provided elimination of aflatoxin mutagenity. It is concluded that PEF treatment can be used to treat sesame seeds with preservation of physicochemical properties, inactivation of A. parasiticus and decomposition of aflatoxins with reduced mutagenicity.  相似文献   
43.
Theoretical Foundations of Chemical Engineering - The extraction of nitric and oxalic acids by neutral compounds TBP, DBBP, and TBPO have been studied. The optimal conditions of their separation...  相似文献   
44.

Surface integrity characterization of manufactured component is very important as it significantly affects the in-service performance of the component. Till now, surface integrity was evaluated using conventional measurement technique like microhardness tester, X-ray diffraction, optical microscopy and surface roughness tester. But, this technique being laboratory based cannot be used for in-service monitoring of the surface integrity. The present study focuses on the characterization of surface integrity upon electric discharge machined sample using non-destructive magnetic Barkhausen noise technique. Electric discharge machining was performed in die-sinking mode on die steel using copper–tungsten electrode (negative polarity). Experiment was performed by selecting different levels of peak current, gap voltage and pulse on time. Surface integrity characteristics like microhardness change, residual stress, microstructural alteration and surface roughness were analysed using microhardness tester, X-ray diffraction, optical microscopy and surface roughness tester, respectively, and were then correlated with magnetic parameter like root mean square value and peak value obtained from Barkhausen noise signal. The results show a good correlation between magnetic parameter (RMS and Peak value) of Barkhausen noise with the microhardness and surface roughness of the machined sample.

  相似文献   
45.
46.
47.
48.
49.
50.
Wu  Li  Li  Jing  Fu  Caixia  Kühn  Bernd  Wang  Xiaolin 《Magma (New York, N.Y.)》2019,32(4):501-509
Magnetic Resonance Materials in Physics, Biology and Medicine - To investigate the value of using diffusion-weighted imaging (DWI) and intravoxel incoherent motion DWI (IVIM-DWI) to assess the...  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