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   1498616篇
  免费   27551篇
  国内免费   8145篇
电工技术   35640篇
技术理论   5篇
综合类   7926篇
化学工业   273650篇
金属工艺   64783篇
机械仪表   42548篇
建筑科学   46990篇
矿业工程   11956篇
能源动力   50613篇
轻工业   113611篇
水利工程   15122篇
石油天然气   38465篇
武器工业   394篇
无线电   197627篇
一般工业技术   281309篇
冶金工业   148897篇
原子能技术   33976篇
自动化技术   170800篇
  2021年   16351篇
  2020年   12271篇
  2019年   15025篇
  2018年   15535篇
  2017年   14824篇
  2016年   21472篇
  2015年   18035篇
  2014年   29464篇
  2013年   88920篇
  2012年   36305篇
  2011年   48609篇
  2010年   43409篇
  2009年   51767篇
  2008年   45464篇
  2007年   42732篇
  2006年   45693篇
  2005年   39836篇
  2004年   41611篇
  2003年   41646篇
  2002年   41220篇
  2001年   37615篇
  2000年   35822篇
  1999年   34321篇
  1998年   40058篇
  1997年   36387篇
  1996年   33441篇
  1995年   29563篇
  1994年   27882篇
  1993年   27759篇
  1992年   26044篇
  1991年   22980篇
  1990年   23356篇
  1989年   22422篇
  1988年   20970篇
  1987年   19223篇
  1986年   18570篇
  1985年   21911篇
  1984年   22276篇
  1983年   20208篇
  1982年   19198篇
  1981年   19304篇
  1980年   17876篇
  1979年   18489篇
  1978年   17704篇
  1977年   17159篇
  1976年   17863篇
  1975年   15973篇
  1974年   15510篇
  1973年   15558篇
  1972年   13052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.
Qin  Yi  Tao  Xianping  Huang  Yu    Jian 《World Wide Web》2019,22(1):1-37
World Wide Web - Rule mechanism has been widely used in many areas, such as databases, artificial intelligent and pervasive computing. In a rule mechanism, rule activation decides which rules are...  相似文献   
8.
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   
9.
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   
10.
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