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   1731263篇
  免费   46295篇
  国内免费   17396篇
电工技术   49044篇
技术理论   31篇
综合类   23312篇
化学工业   315671篇
金属工艺   78784篇
机械仪表   58650篇
建筑科学   67352篇
矿业工程   20810篇
能源动力   57433篇
轻工业   122525篇
水利工程   19381篇
石油天然气   56212篇
武器工业   2358篇
无线电   223253篇
一般工业技术   305897篇
冶金工业   157164篇
原子能技术   36471篇
自动化技术   200606篇
  2022年   17777篇
  2021年   26428篇
  2020年   19791篇
  2019年   21262篇
  2018年   22453篇
  2017年   22866篇
  2016年   28195篇
  2015年   27846篇
  2014年   41623篇
  2013年   102698篇
  2012年   51076篇
  2011年   64127篇
  2010年   57389篇
  2009年   65033篇
  2008年   57581篇
  2007年   54209篇
  2006年   58584篇
  2005年   51449篇
  2004年   48604篇
  2003年   47498篇
  2002年   46078篇
  2001年   42073篇
  2000年   41453篇
  1999年   41496篇
  1998年   44467篇
  1997年   40517篇
  1996年   37725篇
  1995年   33296篇
  1994年   31081篇
  1993年   29828篇
  1992年   27765篇
  1991年   24222篇
  1990年   24247篇
  1989年   23079篇
  1988年   21476篇
  1987年   19599篇
  1986年   18785篇
  1985年   21992篇
  1984年   22247篇
  1983年   20174篇
  1982年   19227篇
  1981年   19294篇
  1980年   17871篇
  1979年   18421篇
  1978年   17618篇
  1977年   17126篇
  1976年   17718篇
  1975年   15938篇
  1974年   15439篇
  1973年   15508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.
6.
Feature-based methods have been developed in the past decades for the registration of optical satellite images. However, it is still a challenging problem to handle well the registration between medium and high spatial resolution images due to the large difference of the spatial structural features and local details for the same objects. In this study, an automated co-registration technique is proposed that integrates an improved SIFT (I-SIFT) and a novel matching strategy called spatial consistency constraints (SCC) to cope with the large difference in spatial resolutions between the image pair. Three constraints on angle, distance, and ratio are introduced to re the initial matching features obtained by I-SIFT. Three groups of experiments were conducted to validate the effectiveness of the proposed method. The experiments used high resolution multispectral and panoramic SPOT 5/6 images and Landsat 5/8 orthorectification images. Experimental results show that the registration error lies in about 1 pixel of high-resolution images and demonstrate that the proposed I-SIFT-SCC approach is suitable for fine registration of optical satellite images from medium spatial resolution to high spatial resolution with resolution ratio up to 6.  相似文献   
7.
本项目主要研究和实现了工业废白土在BAYAH燃煤自备电厂中的再利用,实现变废为宝,减少了环境污染,同时为企业创造了一定的经济效益。针对废白土的特性,对燃料输送系统给煤机、皮带机、煤仓、下料溜子和排渣系统进行了改造。通过修改操作规程消除废白土对锅炉运行的影响。  相似文献   
8.
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   
9.
10.
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   
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