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   1586861篇
  免费   26955篇
  国内免费   7081篇
电工技术   34941篇
综合类   6453篇
化学工业   276764篇
金属工艺   65919篇
机械仪表   45629篇
建筑科学   47692篇
矿业工程   11681篇
能源动力   50732篇
轻工业   120717篇
水利工程   16227篇
石油天然气   38167篇
武器工业   136篇
无线电   199792篇
一般工业技术   297687篇
冶金工业   200158篇
原子能技术   34451篇
自动化技术   173751篇
  2021年   15945篇
  2020年   12195篇
  2019年   14981篇
  2018年   18362篇
  2017年   17890篇
  2016年   22885篇
  2015年   17847篇
  2014年   29146篇
  2013年   88809篇
  2012年   37753篇
  2011年   52139篇
  2010年   45126篇
  2009年   53116篇
  2008年   47863篇
  2007年   45570篇
  2006年   46100篇
  2005年   41613篇
  2004年   43100篇
  2003年   42901篇
  2002年   41612篇
  2001年   38663篇
  2000年   36830篇
  1999年   36624篇
  1998年   56493篇
  1997年   46111篇
  1996年   39885篇
  1995年   33398篇
  1994年   30856篇
  1993年   30793篇
  1992年   26767篇
  1991年   24017篇
  1990年   24320篇
  1989年   23446篇
  1988年   22016篇
  1987年   20105篇
  1986年   19535篇
  1985年   22838篇
  1984年   22691篇
  1983年   20610篇
  1982年   19523篇
  1981年   19697篇
  1980年   18316篇
  1979年   18703篇
  1978年   17994篇
  1977年   18323篇
  1976年   20171篇
  1975年   16225篇
  1974年   15631篇
  1973年   15769篇
  1972年   13197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.
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