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   514731篇
  免费   9653篇
  国内免费   2551篇
电工技术   9899篇
技术理论   5篇
综合类   1347篇
化学工业   79679篇
金属工艺   19852篇
机械仪表   14930篇
建筑科学   12955篇
矿业工程   2530篇
能源动力   12717篇
轻工业   48767篇
水利工程   5154篇
石油天然气   8647篇
武器工业   265篇
无线电   59057篇
一般工业技术   98376篇
冶金工业   99269篇
原子能技术   9868篇
自动化技术   43618篇
  2021年   5127篇
  2020年   3794篇
  2019年   4647篇
  2018年   7645篇
  2017年   7581篇
  2016年   8151篇
  2015年   5877篇
  2014年   9276篇
  2013年   24298篇
  2012年   15013篇
  2011年   19311篇
  2010年   15635篇
  2009年   16909篇
  2008年   18032篇
  2007年   17936篇
  2006年   15599篇
  2005年   13625篇
  2004年   12662篇
  2003年   12473篇
  2002年   11977篇
  2001年   12296篇
  2000年   11406篇
  1999年   11941篇
  1998年   30213篇
  1997年   21443篇
  1996年   16180篇
  1995年   12018篇
  1994年   10843篇
  1993年   10757篇
  1992年   7741篇
  1991年   7445篇
  1990年   7316篇
  1989年   7088篇
  1988年   6806篇
  1987年   5815篇
  1986年   5731篇
  1985年   6358篇
  1984年   6016篇
  1983年   5653篇
  1982年   5141篇
  1981年   5264篇
  1980年   4963篇
  1979年   4910篇
  1978年   4618篇
  1977年   5416篇
  1976年   7415篇
  1975年   3996篇
  1974年   3815篇
  1973年   3809篇
  1972年   3249篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
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   
72.
A hybrid sorbent material for removal of hydrogen sulfide from air was developed. The material is based on activated carbon and iron compounds obtained from waste iron(II) sulfate(VI) heptahydrate. The iron salt is deposited on the carbonaceous support and subjected to oxidation (Fe2+ to Fe3+) using atmospheric oxygen under alkaline conditions. An effect of H2O2 addition to the process on the composition of the resultant material was also examined. X-ray diffraction (XRD) analyses confirmed easy conversion of waste FeSO4·7H2O to iron oxides Fe3O4 and FeOOH. The activated carbon supporting iron oxides revealed a higher efficiency in H2S elimination from air compared to the commercial activated carbon, without any modification.  相似文献   
73.
At the hydroelectric unit No. 11 of the Nizhnekamsk hydroelectric power plant, the filling wedges of a rotor were investigated by ultrasound in the free st  相似文献   
74.
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   
75.
Urbano  Cristóbal  Ardanuy  Jordi 《Scientometrics》2020,124(1):575-602
Scientometrics - The interdisciplinary nature of library and information science (LIS) research has been highlighted for some time now. The term “interdisciplinary” is used primarily in...  相似文献   
76.
Russian Journal of Non-Ferrous Metals - Rolling bearing rings comprise a large reserve for expanding powder metallurgy production. This reserve is being incompletely implemented. The hot forging of...  相似文献   
77.
Metallurgical and Materials Transactions B - The process of obtaining titanium tetrachloride (TiCl4) from the quartz-leucoxene concentrate (QLC) from the Yaregskoe oil-titanium field was studied....  相似文献   
78.
Hassan  Lovelu  Khan  K. A. 《Microsystem Technologies》2020,26(3):1031-1041

The efficiency of any electric cell or battery is very important. To keep it in mind it has been studied the columbic efficiency, voltaic efficiency and energy efficiency of a PKL (Pathor Kuchi Leaf) Quasi Voltaic Cell or Modified Voltaic Cell. It was found that the columbic efficiency data illustrated that this efficiency was lower comparing to other efficiencies may be the absence of salt bridge or separator between the electrodes. Because, our designed and fabricated PKL cell does not have any salt bridge. So that the internal resistance is lower than the traditional voltaic cell and as a result more current was found. The voltage and current changes with time and I–V characteristics for PKL unit cell, module, panel and array have also been studied. It is shown that the voltaic and energy efficiency have been studied. However, the highest efficiency was obtained for 40% PKL sap with 5% secondary salt in 55% aqueous solution, which implies that the concentration of PKL juice can play an important role regarding efficiency. It was also found that the average energy efficiency was 97.43% and it was also found that the average voltaic efficiency was 57.29%. Finally, morphological study FESEM (Field Emission Scanning Electron Microscopy) has also been performed. It is seen that the results confirmed that Zn was deposited on the Cu surface during the electro deposition process in PKL solution. Using AAS, it has been measured the concentration of [Cu2+] as a reactant ion and the concentration of [Zn2+] as a product ion those have been tabulated and graphically discussed. The variation of pH has also been studied with time and which was also tabulated and graphically discussed.

  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