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   1560447篇
  免费   26412篇
  国内免费   7076篇
电工技术   34699篇
综合类   6413篇
化学工业   274294篇
金属工艺   65444篇
机械仪表   44679篇
建筑科学   47044篇
矿业工程   11584篇
能源动力   50499篇
轻工业   116927篇
水利工程   15900篇
石油天然气   37986篇
武器工业   132篇
无线电   198647篇
一般工业技术   293331篇
冶金工业   190143篇
原子能技术   34338篇
自动化技术   171875篇
  2021年   15718篇
  2020年   11988篇
  2019年   14764篇
  2018年   17574篇
  2017年   17055篇
  2016年   22292篇
  2015年   17604篇
  2014年   28879篇
  2013年   88183篇
  2012年   36983篇
  2011年   50754篇
  2010年   44251篇
  2009年   52386篇
  2008年   46765篇
  2007年   44407篇
  2006年   45520篇
  2005年   40850篇
  2004年   42636篇
  2003年   42391篇
  2002年   41158篇
  2001年   38191篇
  2000年   36497篇
  1999年   36190篇
  1998年   54090篇
  1997年   44389篇
  1996年   38670篇
  1995年   32614篇
  1994年   30301篇
  1993年   30223篇
  1992年   26475篇
  1991年   23717篇
  1990年   24047篇
  1989年   23101篇
  1988年   21615篇
  1987年   19869篇
  1986年   19208篇
  1985年   22535篇
  1984年   22532篇
  1983年   20434篇
  1982年   19349篇
  1981年   19545篇
  1980年   18153篇
  1979年   18608篇
  1978年   17857篇
  1977年   17965篇
  1976年   19428篇
  1975年   16107篇
  1974年   15570篇
  1973年   15706篇
  1972年   13119篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
This paper presents part of the work ComEd and Quanta Technology have performed to quantify the locational and temporal value of DER to avoid distribution grid upgrade investments. It focuses on the formulation of a robust and efficient algorithm for DER optimal dispatch on a distribution feeder to mitigate the violation of current and voltage limits using the allocated cost of capacity and locational marginal value of real and reactive DER injection/withdrawal.  相似文献   
2.
3.
In this paper, we present a novel memory access reduction scheme (MARS) for two-dimension fast cosine transform (2-D FCT). It targets programmable DSPs with high memory-access latency. It reduces the number of memory accesses by: 1) reducing the number of weighting factors and 2) combining butterflies in vector-radix 2-D FCT pruning diagram from two stages to one stage with an efficient structure. Hardware platform based on general purpose processor is used to verify the effectiveness of the proposed method for vector-radix 2-D FCT pruning implementation. Experimental results validate the benefits of the proposed method with reduced memory access, less clock cycle and fewer memory space compared with the conventional implementation.  相似文献   
4.
5.
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   
6.
7.
One specific class of non-linear evolution equations, known as the Tzitzéica-type equations, has received great attention from a group of researchers involved in non-linear science. In this article, new exact solutions of the Tzitzéica-type equations arising in non-linear optics, including the Tzitzéica, Dodd–Bullough–Mikhailov and Tzitzéica–Dodd–Bullough equations, are obtained using the expa function method. The integration technique actually suggests a useful and reliable method to extract new exact solutions of a wide range of non-linear evolution equations.  相似文献   
8.
9.
10.
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   
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