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   1456401篇
  免费   27329篇
  国内免费   7008篇
电工技术   34393篇
综合类   6368篇
化学工业   267534篇
金属工艺   64196篇
机械仪表   41424篇
建筑科学   44881篇
矿业工程   11476篇
能源动力   50207篇
轻工业   105635篇
水利工程   14639篇
石油天然气   37865篇
武器工业   143篇
无线电   195850篇
一般工业技术   276555篇
冶金工业   138666篇
原子能技术   33994篇
自动化技术   166912篇
  2021年   15509篇
  2020年   11821篇
  2019年   14584篇
  2018年   15862篇
  2017年   15299篇
  2016年   21210篇
  2015年   17284篇
  2014年   28573篇
  2013年   87630篇
  2012年   34130篇
  2011年   46316篇
  2010年   42206篇
  2009年   50917篇
  2008年   43311篇
  2007年   40495篇
  2006年   43256篇
  2005年   38408篇
  2004年   40377篇
  2003年   40344篇
  2002年   39465篇
  2001年   35879篇
  2000年   34574篇
  1999年   33336篇
  1998年   37269篇
  1997年   34408篇
  1996年   32125篇
  1995年   28803篇
  1994年   27221篇
  1993年   27191篇
  1992年   25632篇
  1991年   22635篇
  1990年   23035篇
  1989年   22111篇
  1988年   20574篇
  1987年   18953篇
  1986年   18254篇
  1985年   21605篇
  1984年   22036篇
  1983年   19988篇
  1982年   19043篇
  1981年   19142篇
  1980年   17727篇
  1979年   18313篇
  1978年   17552篇
  1977年   16934篇
  1976年   17131篇
  1975年   15888篇
  1974年   15406篇
  1973年   15470篇
  1972年   12957篇
排序方式: 共有10000条查询结果,搜索用时 687 毫秒
211.
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   
212.
The use of field robots can greatly decrease the amount of time, effort, and associated risk compared to if human workers were to carryout certain tasks such as disaster response. However, transportability and reliability remain two main issues for most current robot systems. To address the issue of transportability, we have developed a lightweight modularizable platform named AeroArm. To address the issue of reliability, we utilize a multimodal sensing approach, combining the use of multiple sensors and sensor types, and the use of different detection algorithms, as well as active continuous closed‐loop feedback to accurately estimate the state of the robot with respect to the environment. We used Challenge 2 of the 2017 Mohammed Bin Zayed International Robotics Competition as an example outdoor manipulation task, demonstrating the capabilities of our robot system and approach in achieving reliable performance in the fields, and ranked fifth place internationally in the competition.  相似文献   
213.
214.
215.
216.
217.
218.
219.
220.
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