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   1472059篇
  免费   27236篇
  国内免费   6936篇
电工技术   34264篇
综合类   6503篇
化学工业   265565篇
金属工艺   63758篇
机械仪表   41973篇
建筑科学   45333篇
矿业工程   11413篇
能源动力   50178篇
轻工业   108871篇
水利工程   14765篇
石油天然气   37504篇
武器工业   186篇
无线电   195727篇
一般工业技术   280102篇
冶金工业   148044篇
原子能技术   33885篇
自动化技术   168160篇
  2021年   15373篇
  2020年   11791篇
  2019年   14543篇
  2018年   15344篇
  2017年   14678篇
  2016年   21031篇
  2015年   17264篇
  2014年   28619篇
  2013年   87604篇
  2012年   34686篇
  2011年   46759篇
  2010年   41886篇
  2009年   50378篇
  2008年   43802篇
  2007年   40800篇
  2006年   44162篇
  2005年   38717篇
  2004年   40970篇
  2003年   40961篇
  2002年   40069篇
  2001年   36828篇
  2000年   35343篇
  1999年   34120篇
  1998年   40042篇
  1997年   36251篇
  1996年   33435篇
  1995年   29683篇
  1994年   27975篇
  1993年   27821篇
  1992年   26069篇
  1991年   23098篇
  1990年   23407篇
  1989年   22415篇
  1988年   20954篇
  1987年   19301篇
  1986年   18683篇
  1985年   21991篇
  1984年   22282篇
  1983年   20243篇
  1982年   19200篇
  1981年   19269篇
  1980年   17849篇
  1979年   18482篇
  1978年   17454篇
  1977年   16932篇
  1976年   17480篇
  1975年   15738篇
  1974年   15337篇
  1973年   15393篇
  1972年   12914篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
211.
Wireless Personal Communications - The orthogonal frequency division multiplexing (OFDM) is the most encouraging multi-carrier modulation system chosen for the high data rates but the objective is...  相似文献   
212.
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   
213.
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   
214.
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   
215.
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   
216.
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   
217.
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   
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