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   307788篇
  免费   6818篇
  国内免费   1180篇
电工技术   4845篇
综合类   456篇
化学工业   47325篇
金属工艺   9264篇
机械仪表   8388篇
建筑科学   8694篇
矿业工程   681篇
能源动力   8729篇
轻工业   36037篇
水利工程   2606篇
石油天然气   2133篇
武器工业   15篇
无线电   37086篇
一般工业技术   55204篇
冶金工业   59158篇
原子能技术   3714篇
自动化技术   31451篇
  2022年   1757篇
  2021年   3172篇
  2020年   2395篇
  2019年   2763篇
  2018年   4366篇
  2017年   4451篇
  2016年   4761篇
  2015年   3564篇
  2014年   5524篇
  2013年   15443篇
  2012年   9728篇
  2011年   12800篇
  2010年   9857篇
  2009年   10705篇
  2008年   11310篇
  2007年   11019篇
  2006年   9879篇
  2005年   8984篇
  2004年   8709篇
  2003年   8463篇
  2002年   7877篇
  2001年   7931篇
  2000年   7116篇
  1999年   7680篇
  1998年   20213篇
  1997年   13799篇
  1996年   10244篇
  1995年   7598篇
  1994年   6574篇
  1993年   6474篇
  1992年   4351篇
  1991年   4177篇
  1990年   3933篇
  1989年   3715篇
  1988年   3612篇
  1987年   2865篇
  1986年   2784篇
  1985年   3478篇
  1984年   3053篇
  1983年   2746篇
  1982年   2584篇
  1981年   2642篇
  1980年   2433篇
  1979年   2225篇
  1978年   2045篇
  1977年   2457篇
  1976年   3272篇
  1975年   1726篇
  1974年   1584篇
  1973年   1668篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Alcohol-free beer with isotonic properties is getting more popular and its production can be carried out by different production strategies; however, interrupted fermentation is still a challenge. Therefore, the objective of this study was to develop a low-alcohol isotonic beer (<0.5% v/v) by interrupted fermentation. Moreover, the major objective is to compare the developed product to commercial beverages (sports drinks, ‘Pilsen' regular beer, alcohol-free beers and low-alcohol isotonic beer). The beverages were evaluated based on pH, alcohol content (% v/v), total titratable acidity (mEq L−1), osmolality (mOsmol kg−1), bitterness International Bitterness Units, colour European Brewery Convention, total phenolic compounds (mg L−1 gallic acid), reducing and total sugars (%) and Na and K contents (mg L−1). The developed low-alcohol isotonic beer presented characteristics similar to sports drinks, with the advantage of being richer in phenolic compounds and suitable osmolality. Despite salts were added in its formulation, the grades attributed to all beers employed in the sensory evaluation, as well as the purchase intention did not present significant differences.  相似文献   
2.
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   
3.
4.
5.
6.
Here we report some recent biophysical issues on the preparation of solute-filled lipid vesicles and their relevance to the construction of “synthetic cells.” First, we introduce the “semi-synthetic minimal cells” as the liposome-based cell-like systems, which contain a minimal number of biomolecules required to display simple and complex biological functions. Next, we focus on recent aspects related to the construction of synthetic cells. Emphasis is given to the interplay between the methods of synthetic cell preparation and the physics of solute encapsulation. We briefly introduce the notion of structural and compositional “diversity” in synthetic cell populations.  相似文献   
7.
8.
9.
10.
A contact layer element for large deformations   总被引:1,自引:0,他引:1  
  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