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   1677618篇
  免费   27699篇
  国内免费   7613篇
电工技术   35730篇
综合类   7228篇
化学工业   282113篇
金属工艺   66916篇
机械仪表   47893篇
建筑科学   50612篇
矿业工程   12157篇
能源动力   50991篇
轻工业   132902篇
水利工程   17203篇
石油天然气   38456篇
武器工业   194篇
无线电   202980篇
一般工业技术   310084篇
冶金工业   243241篇
原子能技术   34543篇
自动化技术   179687篇
  2021年   16540篇
  2020年   12624篇
  2019年   15474篇
  2018年   19182篇
  2017年   18619篇
  2016年   23549篇
  2015年   18148篇
  2014年   29520篇
  2013年   89294篇
  2012年   40304篇
  2011年   56177篇
  2010年   46669篇
  2009年   54097篇
  2008年   50882篇
  2007年   48883篇
  2006年   48761篇
  2005年   44090篇
  2004年   45752篇
  2003年   45474篇
  2002年   44147篇
  2001年   41521篇
  2000年   38953篇
  1999年   39254篇
  1998年   70572篇
  1997年   54618篇
  1996年   45281篇
  1995年   36663篇
  1994年   33543篇
  1993年   33470篇
  1992年   27629篇
  1991年   24945篇
  1990年   25126篇
  1989年   24250篇
  1988年   22791篇
  1987年   20850篇
  1986年   20300篇
  1985年   23632篇
  1984年   23060篇
  1983年   21029篇
  1982年   19860篇
  1981年   20054篇
  1980年   18712篇
  1979年   19012篇
  1978年   18251篇
  1977年   19263篇
  1976年   22090篇
  1975年   16369篇
  1974年   15765篇
  1973年   15951篇
  1972年   13378篇
排序方式: 共有10000条查询结果,搜索用时 15 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.
Clean Technologies and Environmental Policy - Food production and consumption is one of the major causes of global environmental degradation. One way to address environmental impacts in the food...  相似文献   
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