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   1460918篇
  免费   25611篇
  国内免费   6905篇
电工技术   34806篇
综合类   6332篇
化学工业   270798篇
金属工艺   65270篇
机械仪表   42931篇
建筑科学   44823篇
矿业工程   11641篇
能源动力   50170篇
轻工业   104222篇
水利工程   14611篇
石油天然气   38190篇
武器工业   138篇
无线电   196945篇
一般工业技术   279577篇
冶金工业   130648篇
原子能技术   34306篇
自动化技术   168026篇
  2021年   15469篇
  2020年   11743篇
  2019年   14508篇
  2018年   17434篇
  2017年   17078篇
  2016年   21884篇
  2015年   17377篇
  2014年   28565篇
  2013年   87793篇
  2012年   34456篇
  2011年   47754篇
  2010年   43689篇
  2009年   52471篇
  2008年   44351篇
  2007年   41854篇
  2006年   43034篇
  2005年   38905篇
  2004年   40625篇
  2003年   40348篇
  2002年   39420篇
  2001年   35569篇
  2000年   34365篇
  1999年   32850篇
  1998年   33750篇
  1997年   32614篇
  1996年   30939篇
  1995年   28067篇
  1994年   26735篇
  1993年   26620篇
  1992年   25564篇
  1991年   22529篇
  1990年   22976篇
  1989年   22074篇
  1988年   20489篇
  1987年   18897篇
  1986年   18206篇
  1985年   21537篇
  1984年   22007篇
  1983年   19946篇
  1982年   19023篇
  1981年   19102篇
  1980年   17673篇
  1979年   18267篇
  1978年   17523篇
  1977年   16845篇
  1976年   16942篇
  1975年   15850篇
  1974年   15393篇
  1973年   15457篇
  1972年   12940篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
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   
22.
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   
23.
24.
25.
26.
27.
28.
29.
30.
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