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   1557541篇
  免费   26053篇
  国内免费   7049篇
电工技术   35195篇
综合类   6451篇
化学工业   275316篇
金属工艺   65922篇
机械仪表   45662篇
建筑科学   47295篇
矿业工程   11845篇
能源动力   50428篇
轻工业   118371篇
水利工程   15840篇
石油天然气   38358篇
武器工业   147篇
无线电   199322篇
一般工业技术   294599篇
冶金工业   178796篇
原子能技术   34637篇
自动化技术   172459篇
  2021年   15576篇
  2020年   11881篇
  2019年   14676篇
  2018年   18516篇
  2017年   18315篇
  2016年   22667篇
  2015年   17536篇
  2014年   28662篇
  2013年   87960篇
  2012年   37273篇
  2011年   51979篇
  2010年   45413篇
  2009年   53376篇
  2008年   47823篇
  2007年   45699篇
  2006年   45863篇
  2005年   41702篇
  2004年   42998篇
  2003年   42658篇
  2002年   41474篇
  2001年   37995篇
  2000年   36351篇
  1999年   35480篇
  1998年   49291篇
  1997年   42012篇
  1996年   37058篇
  1995年   31782篇
  1994年   29595篇
  1993年   29437篇
  1992年   26467篇
  1991年   23615篇
  1990年   23970篇
  1989年   23056篇
  1988年   21557篇
  1987年   19802篇
  1986年   19164篇
  1985年   22518篇
  1984年   22506篇
  1983年   20497篇
  1982年   19404篇
  1981年   19463篇
  1980年   18105篇
  1979年   18615篇
  1978年   17845篇
  1977年   17811篇
  1976年   18985篇
  1975年   16106篇
  1974年   15580篇
  1973年   15683篇
  1972年   13150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.
In this study, amaranth flour was used as an ingredient to prepare gluten-free cookies. The production process and attributes of amaranth cookies were characterised, and the potential use of amaranth flour as a functional ingredient was analysed. Cookies exhibited a non-uniform reddish brown colour and a cookie factor ratio of 4.5 ± 0.6. Storage studies indicated that after 3 weeks at room temperature cookies presented slight variations in the texture. Simulated gastrointestinal digestion of this product was able to release peptides capable of exerting potential antithrombotic and antihypertensive activities, IC50 values of 0.22 ± 0.04 and 0.23 ± 0.03 mg mL−1 protein, respectively. This work demonstrates for the first time that food made with amaranth flour exerts potential antithrombotic and antihypertensive activity. In conclusion, these amaranth cookies could be an alternative way of incorporating potentially health beneficial products for people who choose a conscious diet, including coeliac or vegan consumers.  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