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   1589963篇
  免费   26574篇
  国内免费   7225篇
电工技术   35478篇
综合类   6507篇
化学工业   276917篇
金属工艺   66592篇
机械仪表   46747篇
建筑科学   47885篇
矿业工程   11972篇
能源动力   50559篇
轻工业   122111篇
水利工程   16298篇
石油天然气   38557篇
武器工业   159篇
无线电   200520篇
一般工业技术   299990篇
冶金工业   194694篇
原子能技术   34716篇
自动化技术   174060篇
  2021年   15768篇
  2020年   12051篇
  2019年   14818篇
  2018年   19302篇
  2017年   19171篇
  2016年   23128篇
  2015年   17692篇
  2014年   28807篇
  2013年   88223篇
  2012年   38148篇
  2011年   53501篇
  2010年   46205篇
  2009年   54110篇
  2008年   48975篇
  2007年   47089篇
  2006年   46431篇
  2005年   42615篇
  2004年   43629篇
  2003年   43248篇
  2002年   41865篇
  2001年   38575篇
  2000年   36808篇
  1999年   36314篇
  1998年   54680篇
  1997年   45133篇
  1996年   39101篇
  1995年   32950篇
  1994年   30513篇
  1993年   30381篇
  1992年   26708篇
  1991年   23910篇
  1990年   24227篇
  1989年   23315篇
  1988年   21830篇
  1987年   20054篇
  1986年   19425篇
  1985年   22771篇
  1984年   22639篇
  1983年   20625篇
  1982年   19473篇
  1981年   19588篇
  1980年   18242篇
  1979年   18702篇
  1978年   17930篇
  1977年   18143篇
  1976年   19621篇
  1975年   16182篇
  1974年   15638篇
  1973年   15757篇
  1972年   13227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