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   607402篇
  免费   7286篇
  国内免费   1034篇
电工技术   11216篇
综合类   531篇
化学工业   93604篇
金属工艺   27805篇
机械仪表   21050篇
建筑科学   13397篇
矿业工程   4638篇
能源动力   14980篇
轻工业   46341篇
水利工程   7563篇
石油天然气   15373篇
武器工业   39篇
无线电   64341篇
一般工业技术   127664篇
冶金工业   98607篇
原子能技术   15004篇
自动化技术   53569篇
  2021年   5573篇
  2020年   4088篇
  2019年   5350篇
  2018年   13945篇
  2017年   14251篇
  2016年   12760篇
  2015年   6352篇
  2014年   10426篇
  2013年   26354篇
  2012年   17396篇
  2011年   25895篇
  2010年   21571篇
  2009年   22617篇
  2008年   23047篇
  2007年   24032篇
  2006年   16333篇
  2005年   16728篇
  2004年   15271篇
  2003年   14848篇
  2002年   13730篇
  2001年   12909篇
  2000年   12452篇
  1999年   12026篇
  1998年   27656篇
  1997年   20043篇
  1996年   15644篇
  1995年   12022篇
  1994年   10888篇
  1993年   10633篇
  1992年   8344篇
  1991年   8040篇
  1990年   7937篇
  1989年   7673篇
  1988年   7394篇
  1987年   6658篇
  1986年   6459篇
  1985年   7328篇
  1984年   6641篇
  1983年   6360篇
  1982年   5717篇
  1981年   5845篇
  1980年   5586篇
  1979年   5689篇
  1978年   5634篇
  1977年   6149篇
  1976年   7654篇
  1975年   5070篇
  1974年   4867篇
  1973年   4943篇
  1972年   4256篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
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.
Gelatin is one of the most important multifunctional biopolymers and is widely used as an essential ingredient in food, pharmaceutical, and cosmetics. Porcine gelatin is regarded as the leading source of gelatin globally then followed by bovine gelatin. Porcine sources are favored over other sources since they are less expensive. However, porcine gelatin is religiously prohibited to be consumed by Muslims and the Jewish community. It is predicted that the global demand for gelatin will increase significantly in the future. Therefore, a sustainable source of gelatin with efficient production and free of disease transmission must be developed. The highest quality of Bovidae-based gelatin (BG) was acquired through alkaline pretreatment, which displayed excellent physicochemical and rheological properties. The utilization of mammalian- and plant-based enzyme significantly increased the gelatin yield. The emulsifying and foaming properties of BG also showed good stability when incorporated into food and pharmaceutical products. Manipulation of extraction conditions has enabled the development of custom-made gelatin with desired properties. This review highlighted the various modifications of extraction and processing methods to improve the physicochemical and functional properties of Bovidae-based gelatin. An in-depth analysis of the crucial stage of collagen breakdown is also discussed, which involved acid, alkaline, and enzyme pretreatment, respectively. In addition, the unique characteristics and primary qualities of BG including protein content, amphoteric property, gel strength, emulsifying and viscosity properties, and foaming ability were presented. Finally, the applications and prospects of BG as the preferred gelatin source globally were outlined.  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.
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   
8.
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   
9.
Multimedia Tools and Applications - The three-dimensional models of brain tumors serve as diagnostic assistance for physicians, surgeons, and radiologists. The proposed system establishes an...  相似文献   
10.
Journal of Chemical Ecology - Biocontrol agents such as parasitic wasps use long-range volatiles and host-associated cues from lower trophic levels to find their hosts. However, this chemical...  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