首页 | 官方网站   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   436397篇
  免费   5682篇
  国内免费   1616篇
工业技术   443695篇
  2022年   4096篇
  2021年   6447篇
  2020年   4915篇
  2019年   6136篇
  2018年   7283篇
  2017年   7018篇
  2016年   7186篇
  2015年   4581篇
  2014年   7423篇
  2013年   20601篇
  2012年   11841篇
  2011年   16634篇
  2010年   13247篇
  2009年   14937篇
  2008年   14628篇
  2007年   14409篇
  2006年   13111篇
  2005年   11920篇
  2004年   12230篇
  2003年   11998篇
  2002年   11454篇
  2001年   11023篇
  2000年   10061篇
  1999年   10259篇
  1998年   25021篇
  1997年   17299篇
  1996年   13220篇
  1995年   9787篇
  1994年   8769篇
  1993年   8660篇
  1992年   6339篇
  1991年   5878篇
  1990年   5887篇
  1989年   5593篇
  1988年   5293篇
  1987年   4599篇
  1986年   4567篇
  1985年   5036篇
  1984年   4561篇
  1983年   4192篇
  1982年   3826篇
  1981年   3854篇
  1980年   3516篇
  1979年   3412篇
  1978年   3491篇
  1977年   3940篇
  1976年   4994篇
  1975年   3028篇
  1974年   2779篇
  1973年   2800篇
排序方式: 共有10000条查询结果,搜索用时 375 毫秒
1.
Multimedia Tools and Applications - Remote Sensing categorical signature classification has gained significant implications on spatial resolution image analysis due to differences in the...  相似文献   
2.
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   
3.
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   
4.
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.
Virtual Reality - It is generally accepted that natural environments reduce stress and improve mood. Since access to natural environments is sometimes limited, virtual natural environments,...  相似文献   
10.
Multimedia Tools and Applications - Mammograms are the images used by radiologists to diagnose breast cancer. Breast cancer is one of the most common cancers in women. The early detection of breast...  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-23

京公网安备 11010802026262号