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   1541780篇
  免费   26385篇
  国内免费   7144篇
电工技术   34819篇
综合类   6545篇
化学工业   274074篇
金属工艺   65377篇
机械仪表   44314篇
建筑科学   47003篇
矿业工程   11637篇
能源动力   50413篇
轻工业   117978篇
水利工程   15549篇
石油天然气   38068篇
武器工业   157篇
无线电   198043篇
一般工业技术   289774篇
冶金工业   176077篇
原子能技术   34304篇
自动化技术   171177篇
  2021年   15660篇
  2020年   11948篇
  2019年   14710篇
  2018年   17004篇
  2017年   16409篇
  2016年   22007篇
  2015年   17572篇
  2014年   28837篇
  2013年   88226篇
  2012年   36398篇
  2011年   49901篇
  2010年   43906篇
  2009年   52158篇
  2008年   46391篇
  2007年   43953篇
  2006年   45433篇
  2005年   40758篇
  2004年   42392篇
  2003年   42104篇
  2002年   41271篇
  2001年   37860篇
  2000年   36207篇
  1999年   35370篇
  1998年   48028篇
  1997年   41254篇
  1996年   36716篇
  1995年   31617篇
  1994年   29434篇
  1993年   29290篇
  1992年   26502篇
  1991年   23622篇
  1990年   23969篇
  1989年   23085篇
  1988年   21598篇
  1987年   19786篇
  1986年   19184篇
  1985年   22513篇
  1984年   22576篇
  1983年   20550篇
  1982年   19460篇
  1981年   19564篇
  1980年   18253篇
  1979年   18700篇
  1978年   17948篇
  1977年   18143篇
  1976年   19688篇
  1975年   16226篇
  1974年   15661篇
  1973年   15773篇
  1972年   13241篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
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   
22.
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   
23.
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   
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