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   547446篇
  免费   7955篇
  国内免费   1521篇
电工技术   9564篇
综合类   422篇
化学工业   83975篇
金属工艺   23503篇
机械仪表   17655篇
建筑科学   11488篇
矿业工程   3712篇
能源动力   13954篇
轻工业   38992篇
水利工程   6489篇
石油天然气   13955篇
武器工业   31篇
无线电   59929篇
一般工业技术   113953篇
冶金工业   100871篇
原子能技术   13619篇
自动化技术   44810篇
  2021年   5402篇
  2020年   4221篇
  2019年   5333篇
  2018年   9342篇
  2017年   9354篇
  2016年   9989篇
  2015年   6208篇
  2014年   9978篇
  2013年   26472篇
  2012年   15699篇
  2011年   20225篇
  2010年   16272篇
  2009年   18097篇
  2008年   18426篇
  2007年   18059篇
  2006年   15875篇
  2005年   14209篇
  2004年   13528篇
  2003年   13321篇
  2002年   12631篇
  2001年   12508篇
  2000年   11776篇
  1999年   12109篇
  1998年   30961篇
  1997年   21639篇
  1996年   16440篇
  1995年   12158篇
  1994年   10671篇
  1993年   10821篇
  1992年   7808篇
  1991年   7556篇
  1990年   7507篇
  1989年   7116篇
  1988年   6835篇
  1987年   6146篇
  1986年   6050篇
  1985年   6634篇
  1984年   6106篇
  1983年   5641篇
  1982年   5225篇
  1981年   5490篇
  1980年   5086篇
  1979年   5089篇
  1978年   5235篇
  1977年   5778篇
  1976年   7732篇
  1975年   4554篇
  1974年   4428篇
  1973年   4532篇
  1972年   3941篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
1.
2.
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   
3.
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   
4.
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   
5.
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   
6.
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.
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   
10.
Combustion, Explosion, and Shock Waves - Results of a numerical study of mixing, ignition, and combustion of a cold hydrogen jet propagating along the lower wall of a channel parallel to a...  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