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   1476050篇
  免费   27556篇
  国内免费   7107篇
电工技术   34593篇
综合类   6419篇
化学工业   270348篇
金属工艺   64655篇
机械仪表   42214篇
建筑科学   45352篇
矿业工程   11534篇
能源动力   50305篇
轻工业   107701篇
水利工程   14901篇
石油天然气   38036篇
武器工业   162篇
无线电   196698篇
一般工业技术   279674篇
冶金工业   145979篇
原子能技术   34105篇
自动化技术   168037篇
  2021年   15634篇
  2020年   11906篇
  2019年   14662篇
  2018年   16519篇
  2017年   16004篇
  2016年   21620篇
  2015年   17396篇
  2014年   28664篇
  2013年   87808篇
  2012年   34737篇
  2011年   47360篇
  2010年   42877篇
  2009年   51473篇
  2008年   44120篇
  2007年   41409篇
  2006年   43587篇
  2005年   38955篇
  2004年   40773篇
  2003年   40642篇
  2002年   39738篇
  2001年   36205篇
  2000年   34840篇
  1999年   33702篇
  1998年   39552篇
  1997年   35734篇
  1996年   33004篇
  1995年   29381篇
  1994年   27646篇
  1993年   27582篇
  1992年   25737篇
  1991年   22798篇
  1990年   23186篇
  1989年   22243篇
  1988年   20719篇
  1987年   19058篇
  1986年   18386篇
  1985年   21723篇
  1984年   22118篇
  1983年   20056篇
  1982年   19094篇
  1981年   19187篇
  1980年   17798篇
  1979年   18374篇
  1978年   17593篇
  1977年   17108篇
  1976年   17471篇
  1975年   15923篇
  1974年   15435篇
  1973年   15493篇
  1972年   12990篇
排序方式: 共有10000条查询结果,搜索用时 0 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