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   972305篇
  免费   13946篇
  国内免费   3524篇
电工技术   18700篇
技术理论   5篇
综合类   1817篇
化学工业   149569篇
金属工艺   38762篇
机械仪表   30525篇
建筑科学   22827篇
矿业工程   6354篇
能源动力   25696篇
轻工业   78686篇
水利工程   11020篇
石油天然气   20575篇
武器工业   285篇
无线电   107952篇
一般工业技术   192826篇
冶金工业   178731篇
原子能技术   21358篇
自动化技术   84087篇
  2021年   9094篇
  2020年   6760篇
  2019年   8458篇
  2018年   14171篇
  2017年   14200篇
  2016年   15085篇
  2015年   10273篇
  2014年   16700篇
  2013年   45781篇
  2012年   26764篇
  2011年   36367篇
  2010年   29145篇
  2009年   32366篇
  2008年   33228篇
  2007年   33096篇
  2006年   29102篇
  2005年   25995篇
  2004年   24373篇
  2003年   23903篇
  2002年   22940篇
  2001年   22589篇
  2000年   21416篇
  1999年   21778篇
  1998年   52838篇
  1997年   37622篇
  1996年   29236篇
  1995年   22013篇
  1994年   19847篇
  1993年   19547篇
  1992年   14627篇
  1991年   13886篇
  1990年   13780篇
  1989年   13430篇
  1988年   12645篇
  1987年   11402篇
  1986年   11067篇
  1985年   12630篇
  1984年   11600篇
  1983年   10794篇
  1982年   9818篇
  1981年   10103篇
  1980年   9359篇
  1979年   9557篇
  1978年   9267篇
  1977年   10443篇
  1976年   13429篇
  1975年   8266篇
  1974年   7902篇
  1973年   7985篇
  1972年   6696篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
3.
Grachev  A. I. 《Semiconductors》2022,56(2):67-70
Semiconductors - In this work, we discuss for the first time the principle of rotation in the constant electric field of a conducting particle with participation of the Lorentz force, which ensures...  相似文献   
4.
Journal of Communications Technology and Electronics - A quantitative comparison of the spectral characteristics of the human visual system and matrix photodetectors is carried out. Criteria for a...  相似文献   
5.
Koroteev  A. S. 《Atomic Energy》2021,130(4):202-208
Atomic Energy - The history and direction of further development of space nuclear energetics are examined. The functional diagram and principle of operation of a promising, powerful,...  相似文献   
6.
Xiao  Zhu  Chen  Yanxun  Jiang  Hongbo  Hu  Zhenzhen  Lui  John C. S.  Min  Geyong  Dustdar  Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of...  相似文献   
7.
8.
Garzan oil field is located at the south east of Turkey. It is a mature oil field and the reservoir is fractured carbonate reservoir. After producing about 1% original oil in place (OOIP) reservoir pressure started to decline. Waterflooding was started in order to support reservoir pressure and also to enhance oil production in 1960. Waterflooding improved the oil recovery but after years of flooding water breakthrough at the production wells was observed. This increased the water/oil ratio at the production wells. In order to enhance oil recovery again different techniques were investigated. Chemical enhanced oil recovery (EOR) methods are gaining attention all over the world for oil recovery. Surfactant injection is an effective way for interfacial tension (IFT) reduction and wettability reversal. In this study, 31 different types of chemicals were studied to specify the effects on oil production. This paper presents solubility of surfactants in brine, IFT and contact angle measurements, imbibition tests, and lastly core flooding experiments. Most of the chemicals were incompatible with Garzan formation water, which has high divalent ion concentration. In this case, the usage of 2-propanol as co-surfactant yielded successful results for stability of the selected chemical solutions. The results of the wettability test indicated that both tested cationic and anionic surfactants altered the wettability of the carbonate rock from oil-wet to intermediate-wet. The maximum oil recovery by imbibition test was reached when core was exposed 1-ethly ionic liquid after imbibition in formation water. Also, after core flooding test, it is concluded that considerable amount of oil can be recovered from Garzan reservoir by waterflooding alone if adverse effects of natural fractures could be eliminated.  相似文献   
9.
Journal of Computer and Systems Sciences International - It is shown that the Lyapunov theorem on the distribution properties of the sum of random variables with different distribution densities...  相似文献   
10.
Refractories and Industrial Ceramics - The paper introduces a promising technology for utilizing a traditional scheme for implementing a flow-through micro-arc oxidation method to restore localized...  相似文献   
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