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   853351篇
  免费   12554篇
  国内免费   2530篇
电工技术   15818篇
综合类   826篇
化学工业   127090篇
金属工艺   35239篇
机械仪表   27679篇
建筑科学   19741篇
矿业工程   4377篇
能源动力   23581篇
轻工业   66299篇
水利工程   8935篇
石油天然气   15010篇
武器工业   48篇
无线电   98418篇
一般工业技术   170343篇
冶金工业   159965篇
原子能技术   16814篇
自动化技术   78252篇
  2022年   5044篇
  2021年   8265篇
  2020年   6261篇
  2019年   7744篇
  2018年   17129篇
  2017年   17058篇
  2016年   15714篇
  2015年   9115篇
  2014年   14473篇
  2013年   39076篇
  2012年   23857篇
  2011年   35231篇
  2010年   28748篇
  2009年   31152篇
  2008年   31458篇
  2007年   32304篇
  2006年   24103篇
  2005年   23729篇
  2004年   21857篇
  2003年   21552篇
  2002年   19830篇
  2001年   19401篇
  2000年   18177篇
  1999年   19144篇
  1998年   49146篇
  1997年   34448篇
  1996年   26440篇
  1995年   19792篇
  1994年   17244篇
  1993年   17057篇
  1992年   12290篇
  1991年   11496篇
  1990年   11368篇
  1989年   10932篇
  1988年   10114篇
  1987年   9090篇
  1986年   8877篇
  1985年   9881篇
  1984年   9134篇
  1983年   8180篇
  1982年   7616篇
  1981年   7733篇
  1980年   7262篇
  1979年   7091篇
  1978年   6894篇
  1977年   8172篇
  1976年   10714篇
  1975年   5943篇
  1974年   5558篇
  1973年   5724篇
排序方式: 共有10000条查询结果,搜索用时 31 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.
Investigation on the miniaturized parallel multichannel-based devices packed with glass beads to improve the mass exchange execution is the critical focal point of the current study. One of the essential parameters to specify the miniaturized devices' flow distribution is the residence time distribution (RTD). In the present context, the RTDs of a liquid tracer were investigated for the air-water multiphase flows (concurrent) across the multichannel-based miniaturized devices (comprising of 11 similar dimensional parallel channels). The devices were variable in height and packed with glass beads. The conductivity estimations generated the RTD curves and were addressed by the axial dispersion model (ADM). The fluid-flow rates differed within the range of 5–23 ml min−1. The axial dispersion coefficients and the rate of the specific energy dispersion were investigated. The effects of pressure difference and geometry on the hydrodynamic attributes and mixing properties were well-illustrated, and the new correlations were suggested.  相似文献   
3.
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.
9.
10.
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   
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