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   1573632篇
  免费   27139篇
  国内免费   7059篇
电工技术   34687篇
综合类   6565篇
化学工业   276883篇
金属工艺   65149篇
机械仪表   44423篇
建筑科学   47782篇
矿业工程   11595篇
能源动力   50749篇
轻工业   122392篇
水利工程   15822篇
石油天然气   37929篇
武器工业   151篇
无线电   198512篇
一般工业技术   293447篇
冶金工业   194627篇
原子能技术   34272篇
自动化技术   172845篇
  2021年   16160篇
  2020年   12336篇
  2019年   15093篇
  2018年   17625篇
  2017年   16976篇
  2016年   22568篇
  2015年   17895篇
  2014年   29267篇
  2013年   89016篇
  2012年   37802篇
  2011年   51424篇
  2010年   44502篇
  2009年   52350篇
  2008年   47385篇
  2007年   44736篇
  2006年   46167篇
  2005年   41098篇
  2004年   42975篇
  2003年   42734篇
  2002年   41532篇
  2001年   38609篇
  2000年   36811篇
  1999年   36468篇
  1998年   55267篇
  1997年   45410篇
  1996年   39231篇
  1995年   32961篇
  1994年   30612篇
  1993年   30530篇
  1992年   26714篇
  1991年   23793篇
  1990年   24082篇
  1989年   23173篇
  1988年   21676篇
  1987年   19936篇
  1986年   19242篇
  1985年   22559篇
  1984年   22511篇
  1983年   20464篇
  1982年   19451篇
  1981年   19617篇
  1980年   18225篇
  1979年   18625篇
  1978年   17913篇
  1977年   18088篇
  1976年   19744篇
  1975年   16073篇
  1974年   15547篇
  1973年   15665篇
  1972年   13123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.
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   
9.
The aim of the present study was to determine mathematical relationships between pH changes in beef 24 h post-slaughter and changes in the intensity of electrical current flowing through bull and heifer carcasses during high-voltage electrical stimulation. The electrical stimulation was applied 40 min postmortem for 120 s. The pH values of m. longissimus thoracis et lumborum were analyzed in the function of electrical current intensity changes and its change during electrical stimulation. Mathematical linear correlations of the y = ax ± b type were demonstrated between pH values at 2, 6, and 24 h postmortem and the initial (Ii) and ultimate (Iu) electrical current intensity values, the difference between them and the initial pH values determined before electrical stimulation. High multiple correlation coefficients (R2 = 0.416, α ≤ 0.001) between Iu and pH values 24 h post-slaughter enabled concluding that there is a possibility to predict a pH value of stimulated carcass with high accuracy, and thus also beef quality, based merely on the ultimate electrical current intensity values.  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