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   1479233篇
  免费   25830篇
  国内免费   7009篇
电工技术   34017篇
综合类   6366篇
化学工业   269188篇
金属工艺   63512篇
机械仪表   41207篇
建筑科学   45951篇
矿业工程   11303篇
能源动力   50132篇
轻工业   110764篇
水利工程   14988篇
石油天然气   37250篇
武器工业   130篇
无线电   195060篇
一般工业技术   279259篇
冶金工业   151416篇
原子能技术   33731篇
自动化技术   167798篇
  2021年   15501篇
  2020年   11796篇
  2019年   14601篇
  2018年   14457篇
  2017年   13663篇
  2016年   20754篇
  2015年   17196篇
  2014年   28596篇
  2013年   87563篇
  2012年   34771篇
  2011年   46450篇
  2010年   41390篇
  2009年   49914篇
  2008年   43644篇
  2007年   40649篇
  2006年   44439篇
  2005年   38715篇
  2004年   41095篇
  2003年   41048篇
  2002年   40147篇
  2001年   37100篇
  2000年   35505篇
  1999年   34377篇
  1998年   42162篇
  1997年   37333篇
  1996年   33942篇
  1995年   29913篇
  1994年   28151篇
  1993年   27977篇
  1992年   25906篇
  1991年   22966篇
  1990年   23291篇
  1989年   22305篇
  1988年   20896篇
  1987年   19139篇
  1986年   18519篇
  1985年   21891篇
  1984年   22232篇
  1983年   20230篇
  1982年   19209篇
  1981年   19283篇
  1980年   17860篇
  1979年   18477篇
  1978年   17662篇
  1977年   17165篇
  1976年   17587篇
  1975年   15950篇
  1974年   15470篇
  1973年   15566篇
  1972年   13010篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
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   
32.
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   
33.
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   
34.
Photonic Network Communications - Optical packet switching is a prominent technology proposing not only a reduction in the energy consumption by the elimination of numerous...  相似文献   
35.
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   
36.
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