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   325438篇
  免费   5534篇
  国内免费   1375篇
电工技术   5731篇
综合类   1297篇
化学工业   50233篇
金属工艺   11261篇
机械仪表   10079篇
建筑科学   9939篇
矿业工程   1261篇
能源动力   8538篇
轻工业   32775篇
水利工程   3081篇
石油天然气   3127篇
武器工业   23篇
无线电   41473篇
一般工业技术   59132篇
冶金工业   55871篇
原子能技术   4042篇
自动化技术   34484篇
  2022年   4660篇
  2021年   6252篇
  2020年   4663篇
  2019年   5874篇
  2018年   4370篇
  2017年   3870篇
  2016年   3951篇
  2015年   3145篇
  2014年   4897篇
  2013年   14669篇
  2012年   8665篇
  2011年   12915篇
  2010年   10043篇
  2009年   11012篇
  2008年   11058篇
  2007年   11064篇
  2006年   10371篇
  2005年   9566篇
  2004年   10160篇
  2003年   9862篇
  2002年   9453篇
  2001年   9170篇
  2000年   7778篇
  1999年   8072篇
  1998年   17510篇
  1997年   12440篇
  1996年   9474篇
  1995年   7409篇
  1994年   6672篇
  1993年   6373篇
  1992年   4817篇
  1991年   4297篇
  1990年   4189篇
  1989年   4080篇
  1988年   3849篇
  1987年   3117篇
  1986年   3074篇
  1985年   3790篇
  1984年   3317篇
  1983年   3089篇
  1982年   2847篇
  1981年   2814篇
  1980年   2544篇
  1979年   2391篇
  1978年   2295篇
  1977年   2626篇
  1976年   3085篇
  1975年   1940篇
  1974年   1802篇
  1973年   1786篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
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   
2.
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   
3.
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   
4.
Clean Technologies and Environmental Policy - Food production and consumption is one of the major causes of global environmental degradation. One way to address environmental impacts in the food...  相似文献   
5.
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   
6.
Journal of Communications Technology and Electronics - Abstract—The article presents a rigorous numerical solution, using the Wiener–Hopf method, to the problem of plane wave...  相似文献   
7.

Surface integrity characterization of manufactured component is very important as it significantly affects the in-service performance of the component. Till now, surface integrity was evaluated using conventional measurement technique like microhardness tester, X-ray diffraction, optical microscopy and surface roughness tester. But, this technique being laboratory based cannot be used for in-service monitoring of the surface integrity. The present study focuses on the characterization of surface integrity upon electric discharge machined sample using non-destructive magnetic Barkhausen noise technique. Electric discharge machining was performed in die-sinking mode on die steel using copper–tungsten electrode (negative polarity). Experiment was performed by selecting different levels of peak current, gap voltage and pulse on time. Surface integrity characteristics like microhardness change, residual stress, microstructural alteration and surface roughness were analysed using microhardness tester, X-ray diffraction, optical microscopy and surface roughness tester, respectively, and were then correlated with magnetic parameter like root mean square value and peak value obtained from Barkhausen noise signal. The results show a good correlation between magnetic parameter (RMS and Peak value) of Barkhausen noise with the microhardness and surface roughness of the machined sample.

  相似文献   
8.
Russian Journal of Non-Ferrous Metals - Rolling bearing rings comprise a large reserve for expanding powder metallurgy production. This reserve is being incompletely implemented. The hot forging of...  相似文献   
9.
Metallurgical and Materials Transactions B - The process of obtaining titanium tetrachloride (TiCl4) from the quartz-leucoxene concentrate (QLC) from the Yaregskoe oil-titanium field was studied....  相似文献   
10.
Photonic Network Communications - Optical packet switching is a prominent technology proposing not only a reduction in the energy consumption by the elimination of numerous...  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