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   1665216篇
  免费   26801篇
  国内免费   7164篇
电工技术   35588篇
综合类   6564篇
化学工业   280475篇
金属工艺   67236篇
机械仪表   48624篇
建筑科学   49552篇
矿业工程   12026篇
能源动力   50652篇
轻工业   131210篇
水利工程   16958篇
石油天然气   38548篇
武器工业   162篇
无线电   202129篇
一般工业技术   310225篇
冶金工业   236840篇
原子能技术   34837篇
自动化技术   177555篇
  2021年   15755篇
  2020年   12131篇
  2019年   14896篇
  2018年   20219篇
  2017年   20002篇
  2016年   23700篇
  2015年   17878篇
  2014年   28990篇
  2013年   88612篇
  2012年   40028篇
  2011年   56312篇
  2010年   47436篇
  2009年   54791篇
  2008年   51421篇
  2007年   49654篇
  2006年   48184篇
  2005年   44316篇
  2004年   45232篇
  2003年   44788篇
  2002年   43191篇
  2001年   40264篇
  2000年   38218篇
  1999年   38519篇
  1998年   67632篇
  1997年   53078篇
  1996年   44278篇
  1995年   36056篇
  1994年   33027篇
  1993年   32923篇
  1992年   27472篇
  1991年   24788篇
  1990年   25018篇
  1989年   24121篇
  1988年   22660篇
  1987年   20802篇
  1986年   20192篇
  1985年   23510篇
  1984年   22982篇
  1983年   20950篇
  1982年   19790篇
  1981年   19974篇
  1980年   18623篇
  1979年   18940篇
  1978年   18222篇
  1977年   19099篇
  1976年   21845篇
  1975年   16335篇
  1974年   15748篇
  1973年   15900篇
  1972年   13352篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
Russian Journal of Non-Ferrous Metals - Rolling bearing rings comprise a large reserve for expanding powder metallurgy production. This reserve is being incompletely implemented. The hot forging of...  相似文献   
32.
Journal of Communications Technology and Electronics - Abstract—The two-dimensional diffraction problem of a plane polarized TM-wave on two identical solid silver nanocylinders is considered....  相似文献   
33.
Wireless Personal Communications - The rapid development of Information and Communication Technology and the growing number of devices connected to the Internet make the Internet of Things (IoT) as...  相似文献   
34.
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   
35.
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   
36.
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   
37.
38.
39.
40.
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