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   1587644篇
  免费   27997篇
  国内免费   6985篇
电工技术   34525篇
综合类   6524篇
化学工业   273263篇
金属工艺   65168篇
机械仪表   44706篇
建筑科学   48379篇
矿业工程   11489篇
能源动力   50421篇
轻工业   125788篇
水利工程   16083篇
石油天然气   37570篇
武器工业   136篇
无线电   198162篇
一般工业技术   299039篇
冶金工业   203238篇
原子能技术   33997篇
自动化技术   174138篇
  2021年   15595篇
  2019年   14730篇
  2018年   16119篇
  2017年   15363篇
  2016年   21764篇
  2015年   17530篇
  2014年   28934篇
  2013年   88238篇
  2012年   37909篇
  2011年   51223篇
  2010年   43541篇
  2009年   51441篇
  2008年   47540篇
  2007年   45114篇
  2006年   46997篇
  2005年   41464篇
  2004年   43800篇
  2003年   43528篇
  2002年   42402篇
  2001年   39676篇
  2000年   37738篇
  1999年   37308篇
  1998年   56931篇
  1997年   46636篇
  1996年   40430篇
  1995年   33937篇
  1994年   31539篇
  1993年   31041篇
  1992年   27166篇
  1991年   24441篇
  1990年   24607篇
  1989年   23702篇
  1988年   22274篇
  1987年   20377篇
  1986年   19946篇
  1985年   23340篇
  1984年   23067篇
  1983年   20999篇
  1982年   19710篇
  1981年   19841篇
  1980年   18476篇
  1979年   19052篇
  1978年   18179篇
  1977年   18853篇
  1976年   21415篇
  1975年   16321篇
  1974年   15851篇
  1973年   15924篇
  1972年   13414篇
  1971年   11994篇
排序方式: 共有10000条查询结果,搜索用时 703 毫秒
221.
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   
222.
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   
223.
224.
225.
226.
227.
228.
229.
230.
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