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   601628篇
  免费   9947篇
  国内免费   1769篇
电工技术   10604篇
综合类   477篇
化学工业   93098篇
金属工艺   25817篇
机械仪表   22423篇
建筑科学   14763篇
矿业工程   2976篇
能源动力   15445篇
轻工业   52919篇
水利工程   6031篇
石油天然气   9984篇
武器工业   23篇
无线电   71694篇
一般工业技术   120269篇
冶金工业   98696篇
原子能技术   11538篇
自动化技术   56587篇
  2021年   5065篇
  2020年   3807篇
  2019年   4477篇
  2018年   14270篇
  2017年   14788篇
  2016年   11928篇
  2015年   5980篇
  2014年   9357篇
  2013年   25039篇
  2012年   17600篇
  2011年   27873篇
  2010年   23093篇
  2009年   23986篇
  2008年   24204篇
  2007年   25166篇
  2006年   16480篇
  2005年   17996篇
  2004年   15791篇
  2003年   15193篇
  2002年   13895篇
  2001年   13361篇
  2000年   12370篇
  1999年   12735篇
  1998年   29704篇
  1997年   21168篇
  1996年   16475篇
  1995年   12447篇
  1994年   10994篇
  1993年   10786篇
  1992年   8058篇
  1991年   7771篇
  1990年   7433篇
  1989年   7320篇
  1988年   7106篇
  1987年   5893篇
  1986年   5773篇
  1985年   6924篇
  1984年   6409篇
  1983年   5807篇
  1982年   5432篇
  1981年   5591篇
  1980年   5302篇
  1979年   5111篇
  1978年   5040篇
  1977年   5796篇
  1976年   7415篇
  1975年   4496篇
  1974年   4285篇
  1973年   4325篇
  1972年   3627篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
52.
Theoretical Foundations of Chemical Engineering - New research results, as well as those published earlier by the authors, on the synthesis of azo compounds based on nitroanilines obtained by the...  相似文献   
53.
Polymer Bulletin - In this study, we synthesized a new ion-imprinted polymer (IIP) based on introduction of amidoxime groups in acrylonitrile, complexation with Cd2+ ions and polymerization with...  相似文献   
54.
The price of cobalt has increased by some 450% in the past two years, mainly due to increasing demand for lithium–ion batteries. With an official 2017 production of 64 kt, the Democratic Republic of Congo produces more than half of the world’s cobalt. African Copperbelt operations have traditionally focused on copper production; however, it has now become imperative to also consider cobalt recovery from these ores. A plethora of processing routes is possible. Most hydrometallurgical flowsheets recover cobalt from the raffinate of the low-grade copper solvent-extraction circuit. Downstream purification processes include sequential precipitation with a variety of reagents, solvent extraction, and ion exchange. Product choices include hydroxide, carbonate, sulfate, and metal cathode. This study assesses technical and economic advantages and limitations of various approaches to the hydrometallurgical processing of cobalt in an African context.  相似文献   
55.
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   
56.
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   
57.
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   
58.
Multimedia Systems - The preferences of Web information purchasers are changing. Cost-effectiveness (i.e., an emphasis on performance with respect to price) is becoming less regarded than...  相似文献   
59.
Photonic Network Communications - Optical packet switching is a prominent technology proposing not only a reduction in the energy consumption by the elimination of numerous...  相似文献   
60.
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