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   1565233篇
  免费   26476篇
  国内免费   7044篇
电工技术   34651篇
综合类   6460篇
化学工业   274569篇
金属工艺   65010篇
机械仪表   44232篇
建筑科学   47444篇
矿业工程   11561篇
能源动力   50513篇
轻工业   120153篇
水利工程   15751篇
石油天然气   37845篇
武器工业   150篇
无线电   198226篇
一般工业技术   292492篇
冶金工业   193610篇
原子能技术   34242篇
自动化技术   171844篇
  2021年   15700篇
  2020年   12047篇
  2019年   14819篇
  2018年   17311篇
  2017年   16611篇
  2016年   22168篇
  2015年   17620篇
  2014年   28881篇
  2013年   88277篇
  2012年   37190篇
  2011年   50787篇
  2010年   44046篇
  2009年   51935篇
  2008年   47010篇
  2007年   44370篇
  2006年   45937篇
  2005年   40923篇
  2004年   42822篇
  2003年   42567篇
  2002年   41392篇
  2001年   38531篇
  2000年   36749篇
  1999年   36398篇
  1998年   54891篇
  1997年   45180篇
  1996年   39082篇
  1995年   32885篇
  1994年   30519篇
  1993年   30471篇
  1992年   26688篇
  1991年   23782篇
  1990年   24076篇
  1989年   23166篇
  1988年   21658篇
  1987年   19929篇
  1986年   19240篇
  1985年   22549篇
  1984年   22516篇
  1983年   20460篇
  1982年   19444篇
  1981年   19614篇
  1980年   18210篇
  1979年   18622篇
  1978年   17911篇
  1977年   18085篇
  1976年   19718篇
  1975年   16073篇
  1974年   15548篇
  1973年   15662篇
  1972年   13122篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Journal of Materials Science -  相似文献   
2.
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   
3.
4.
5.
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   
6.
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   
7.
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   
8.
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   
9.
Theoretical Foundations of Chemical Engineering - On the basis of the classic concepts of the theory of solid-phase combustion, for the first time, a model with a detailed scheme of chemical...  相似文献   
10.
Multimedia Tools and Applications - Recently, many concepts in technology has been changed. According to the digital transformation trends, Internet of Things (IoT) represents an interested...  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