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   1569190篇
  免费   26110篇
  国内免费   7077篇
电工技术   35235篇
综合类   6460篇
化学工业   275880篇
金属工艺   66133篇
机械仪表   46101篇
建筑科学   47612篇
矿业工程   11856篇
能源动力   50456篇
轻工业   119671篇
水利工程   15975篇
石油天然气   38437篇
武器工业   162篇
无线电   199674篇
一般工业技术   296508篇
冶金工业   184457篇
原子能技术   34660篇
自动化技术   173100篇
  2021年   15585篇
  2020年   11902篇
  2019年   14687篇
  2018年   18817篇
  2017年   18652篇
  2016年   22826篇
  2015年   17568篇
  2014年   28708篇
  2013年   88049篇
  2012年   37595篇
  2011年   52552篇
  2010年   45760篇
  2009年   53673篇
  2008年   48278篇
  2007年   46203篇
  2006年   46048篇
  2005年   42026篇
  2004年   43257篇
  2003年   42850篇
  2002年   41627篇
  2001年   38206篇
  2000年   36542篇
  1999年   35761篇
  1998年   51119篇
  1997年   43082篇
  1996年   37742篇
  1995年   32250篇
  1994年   29944篇
  1993年   29752篇
  1992年   26531篇
  1991年   23732篇
  1990年   24073篇
  1989年   23147篇
  1988年   21657篇
  1987年   19887篇
  1986年   19255篇
  1985年   22612篇
  1984年   22556篇
  1983年   20534篇
  1982年   19436篇
  1981年   19505篇
  1980年   18162篇
  1979年   18665篇
  1978年   17874篇
  1977年   17960篇
  1976年   19294篇
  1975年   16122篇
  1974年   15597篇
  1973年   15705篇
  1972年   13179篇
排序方式: 共有10000条查询结果,搜索用时 11 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