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   601047篇
  免费   7985篇
  国内免费   1164篇
电工技术   10993篇
综合类   1091篇
化学工业   93928篇
金属工艺   23845篇
机械仪表   19318篇
建筑科学   13318篇
矿业工程   4693篇
能源动力   14816篇
轻工业   47407篇
水利工程   7433篇
石油天然气   15009篇
武器工业   43篇
无线电   61855篇
一般工业技术   119097篇
冶金工业   111800篇
原子能技术   14826篇
自动化技术   50724篇
  2021年   5569篇
  2019年   5333篇
  2018年   9643篇
  2017年   10060篇
  2016年   10821篇
  2015年   6771篇
  2014年   10642篇
  2013年   26525篇
  2012年   17650篇
  2011年   23263篇
  2010年   17587篇
  2009年   19509篇
  2008年   19575篇
  2007年   19292篇
  2006年   16788篇
  2005年   17728篇
  2004年   16353篇
  2003年   15574篇
  2002年   14032篇
  2001年   13538篇
  2000年   12580篇
  1999年   12476篇
  1998年   32052篇
  1997年   22779篇
  1996年   17449篇
  1995年   13098篇
  1994年   11646篇
  1993年   11453篇
  1992年   8506篇
  1991年   8314篇
  1990年   8202篇
  1989年   7964篇
  1988年   7690篇
  1987年   6915篇
  1986年   6669篇
  1985年   7522篇
  1984年   6753篇
  1983年   6495篇
  1982年   5889篇
  1981年   6048篇
  1980年   5790篇
  1979年   5786篇
  1978年   5743篇
  1977年   6725篇
  1976年   8830篇
  1975年   5189篇
  1974年   4936篇
  1973年   5014篇
  1972年   4313篇
  1971年   4071篇
排序方式: 共有10000条查询结果,搜索用时 203 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