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   1616141篇
  免费   27519篇
  国内免费   7065篇
电工技术   35400篇
综合类   6486篇
化学工业   280086篇
金属工艺   67082篇
机械仪表   47387篇
建筑科学   48570篇
矿业工程   11924篇
能源动力   50723篇
轻工业   126103篇
水利工程   16366篇
石油天然气   38493篇
武器工业   153篇
无线电   201206篇
一般工业技术   303080篇
冶金工业   206437篇
原子能技术   34664篇
自动化技术   176565篇
  2021年   16076篇
  2020年   12427篇
  2019年   15180篇
  2018年   20366篇
  2017年   20004篇
  2016年   23975篇
  2015年   18270篇
  2014年   29481篇
  2013年   89505篇
  2012年   39329篇
  2011年   54804篇
  2010年   47058篇
  2009年   54772篇
  2008年   50039篇
  2007年   47992篇
  2006年   46819篇
  2005年   42843篇
  2004年   44032篇
  2003年   43557篇
  2002年   42107篇
  2001年   38995篇
  2000年   37139篇
  1999年   36954篇
  1998年   58496篇
  1997年   47503篇
  1996年   40500篇
  1995年   33698篇
  1994年   31181篇
  1993年   31123篇
  1992年   26925篇
  1991年   24058篇
  1990年   24344篇
  1989年   23451篇
  1988年   21944篇
  1987年   20187篇
  1986年   19520篇
  1985年   22808篇
  1984年   22666篇
  1983年   20587篇
  1982年   19531篇
  1981年   19728篇
  1980年   18319篇
  1979年   18698篇
  1978年   17991篇
  1977年   18373篇
  1976年   20299篇
  1975年   16153篇
  1974年   15615篇
  1973年   15748篇
  1972年   13186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