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   1559197篇
  免费   26254篇
  国内免费   7064篇
电工技术   35217篇
综合类   6463篇
化学工业   276019篇
金属工艺   65939篇
机械仪表   45787篇
建筑科学   47329篇
矿业工程   11833篇
能源动力   50595篇
轻工业   118568篇
水利工程   15886篇
石油天然气   38386篇
武器工业   147篇
无线电   199471篇
一般工业技术   294936篇
冶金工业   178466篇
原子能技术   34667篇
自动化技术   172806篇
  2021年   15824篇
  2020年   12087篇
  2019年   14901篇
  2018年   18762篇
  2017年   18513篇
  2016年   22867篇
  2015年   17632篇
  2014年   28853篇
  2013年   88221篇
  2012年   37404篇
  2011年   52099篇
  2010年   45488篇
  2009年   53457篇
  2008年   47821篇
  2007年   45664篇
  2006年   45847篇
  2005年   41667篇
  2004年   42953篇
  2003年   42641篇
  2002年   41442篇
  2001年   37977篇
  2000年   36342篇
  1999年   35459篇
  1998年   49214篇
  1997年   41969篇
  1996年   37019篇
  1995年   31772篇
  1994年   29580篇
  1993年   29422篇
  1992年   26452篇
  1991年   23612篇
  1990年   23956篇
  1989年   23046篇
  1988年   21547篇
  1987年   19799篇
  1986年   19157篇
  1985年   22505篇
  1984年   22492篇
  1983年   20481篇
  1982年   19390篇
  1981年   19460篇
  1980年   18098篇
  1979年   18611篇
  1978年   17842篇
  1977年   17804篇
  1976年   18966篇
  1975年   16095篇
  1974年   15568篇
  1973年   15682篇
  1972年   13147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.
Russian Engineering Research - Models based on regression analysis for predicting the operational efficiency of high-pressure roller crushers are considered. A systematized and structured...  相似文献   
4.
Journal of Machinery Manufacture and Reliability - A device based on smart alloys has been designed for use in machine building items, in particular, in nuclear engineering, for preventing...  相似文献   
5.
Journal of Machinery Manufacture and Reliability - The problem of calculating the reliability and fatigue life of machine parts by the fatigue failure under random changes in the actual and limit...  相似文献   
6.
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   
7.
8.
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   
9.
10.
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   
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