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   199663篇
  免费   2505篇
  国内免费   612篇
电工技术   3468篇
综合类   149篇
化学工业   28978篇
金属工艺   8052篇
机械仪表   6071篇
建筑科学   4813篇
矿业工程   1304篇
能源动力   5127篇
轻工业   17119篇
水利工程   2297篇
石油天然气   4040篇
武器工业   8篇
无线电   23079篇
一般工业技术   40051篇
冶金工业   37327篇
原子能技术   5087篇
自动化技术   15810篇
  2021年   1606篇
  2019年   1570篇
  2018年   2574篇
  2017年   2645篇
  2016年   2779篇
  2015年   1794篇
  2014年   3077篇
  2013年   8946篇
  2012年   5051篇
  2011年   7024篇
  2010年   5591篇
  2009年   6352篇
  2008年   6446篇
  2007年   6516篇
  2006年   5586篇
  2005年   5233篇
  2004年   5014篇
  2003年   4894篇
  2002年   4538篇
  2001年   4660篇
  2000年   4582篇
  1999年   4733篇
  1998年   11386篇
  1997年   8125篇
  1996年   6419篇
  1995年   4681篇
  1994年   4280篇
  1993年   4077篇
  1992年   3228篇
  1991年   3080篇
  1990年   2872篇
  1989年   2952篇
  1988年   2833篇
  1987年   2399篇
  1986年   2311篇
  1985年   2716篇
  1984年   2506篇
  1983年   2348篇
  1982年   2092篇
  1981年   2204篇
  1980年   2034篇
  1979年   2124篇
  1978年   2122篇
  1977年   2369篇
  1976年   3190篇
  1975年   1835篇
  1974年   1762篇
  1973年   1773篇
  1972年   1444篇
  1971年   1341篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
ABSTRACT

Bacteriocin is a proteinaceous biomolecule produced by bacteria (both Gram-positive and Gram-negative) that exhibits antimicrobial activity against closely related species, and food-borne pathogens. It has recently gained importance and attracted the attention of several researchers looking to produce it from various substrates and bacterial strains. This ushers in a new era of food preservation where the use of bacteriocin in food products will be an alternative to chemical preservatives, and heat treatment which are understood to cause unwanted side effects, and reduce sensory and nutritional quality. However, this new market depends on the success of novel downstream separation schemes from various types of crude feedstocks which are both effective and economic. This review focuses on the downstream separation of bacteriocin from various sources using both conventional and novel techniques. Finally, recommendations for future interesting areas of research that need to be pursued are highlighted.  相似文献   
2.
Multidimensional Systems and Signal Processing - The paper is devoted to the development of the octonion Fourier transform (OFT) theory initiated in 2011 in articles by Hahn and Snopek. It is also...  相似文献   
3.
4.
5.
Fefelov  S. A.  Kazakova  L. P.  Bogoslovskiy  N. A.  Bylev  A. B.  Yakubov  A. O. 《Semiconductors》2020,54(4):450-453
Semiconductors - The current–voltage characteristics measured on Ge2Sb2Te5 thin films in the current mode are studied. The effect of multilevel recording is established when applying...  相似文献   
6.
7.

To increase the efficiency of designing systems intended for monitoring surface cracks in aluminum structures during their working life, we have analyzed a two-dimensional symmetric problem on uniaxial extension of an Al-polyimide-Cu layered structure with ideal adhesion between layers and a model crack in the aluminum base. The problem has been first solved for a sample with the crack modeled by a zero-thickness notch using the ANSYS engineering simulation program package. It is shown that this setting of the problem can lead to inadequate results as manifested, in particular, by significantly overstated mechanical stresses in aluminum in the region of crack emergence on the surface. In order to eliminate this difficulty, we propose to use the structure with a model defect in the form of a notch of nonzero thickness in the initial unstressed state of the structure. Recommendations for selecting the thickness of a notch used in the model structure are given.

  相似文献   
8.
9.
10.
Sequencing of rice genome has facilitated the understanding of rice evolution and has been utilized extensively for mining of DNA markers to facilitate marker-assisted breeding. Simple sequence repeat (SSR) markers that are tandemly repeated nucleotide sequence motifs flanked by unique sequences are presently the maker of choice in rice improvement due to their abundance, co-dominant inheritance, high levels of allelic diversity, and simple reproducible assay. The current level of genome coverage by SSR markers in rice is sufficient to employ them for genotype identification and marker-assisted selection in breeding for mapping of genes and quantitative trait loci analysis. This review provides comprehensive information on the mapping and applications of SSR markers in investigation of rice cultivars to study their genetic divergence and marker-assisted selection of important agronomic traits.  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