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   6223篇
  免费   117篇
  国内免费   6篇
电工技术   73篇
综合类   28篇
化学工业   1148篇
金属工艺   117篇
机械仪表   96篇
建筑科学   265篇
矿业工程   27篇
能源动力   172篇
轻工业   526篇
水利工程   51篇
石油天然气   14篇
无线电   477篇
一般工业技术   787篇
冶金工业   1757篇
原子能技术   73篇
自动化技术   735篇
  2021年   48篇
  2019年   66篇
  2018年   48篇
  2017年   61篇
  2016年   92篇
  2015年   74篇
  2014年   78篇
  2013年   298篇
  2012年   162篇
  2011年   215篇
  2010年   188篇
  2009年   189篇
  2008年   211篇
  2007年   206篇
  2006年   183篇
  2005年   207篇
  2004年   158篇
  2003年   134篇
  2002年   162篇
  2001年   105篇
  2000年   97篇
  1999年   112篇
  1998年   248篇
  1997年   196篇
  1996年   149篇
  1995年   127篇
  1994年   135篇
  1993年   124篇
  1992年   95篇
  1991年   77篇
  1990年   94篇
  1989年   88篇
  1988年   79篇
  1987年   62篇
  1986年   94篇
  1985年   110篇
  1984年   122篇
  1983年   91篇
  1982年   107篇
  1981年   88篇
  1980年   80篇
  1979年   74篇
  1978年   64篇
  1977年   107篇
  1976年   118篇
  1975年   98篇
  1974年   62篇
  1973年   67篇
  1972年   65篇
  1970年   45篇
排序方式: 共有6346条查询结果,搜索用时 0 毫秒
1.
2.
3.
Removal of gold from basic solutions containing [Au(CN)2]? has been demonstrated using the inherently conducting polymer polypyrrole. Polymers containing sulfonated aromatic dopants have been found to display a significant ability to remove gold from such solutions. Experiments performed in solutions containing both gold and copper cyanide complexes indicate that the recovery process is not highly selective. However, the polypyrroles used display significantly faster rates of gold recovery than activated carbon. © 2003 Society of Chemical Industry  相似文献   
4.
A semiconductor laser rate equation theory is presented that describes sideband injection locking under both weak optical injection and current modulation. By simultaneous optical injection and current modulation, control of both the phase and the frequency of a semiconductor laser is demonstrated. The phase-locked semiconductor laser operates at a different frequency to the optical injection source, with a frequency-difference given by the current modulation frequency. This method can be used to produce broadband sources, such as those producing ultrashort pulses and those required for coherent control, or to create high-frequency electronic oscillator sources with phase control by interference beating  相似文献   
5.
The pipelined architecture and parallel organization of the AT&T Pixel Machine image computer are described and demonstrated with applications for the visualization of multidimensional fractals, particularly linear fractals and quaternion/ stacked Julia sets. Techniques for pushing the Pixel Machine to its peak abilities are described and apply to more recent parallel image computers as well.  相似文献   
6.
7.
8.
9.
Although mechanical seals are widely used in many machines, there is no universally accepted system for establishing limits of pressure, temperature, and speed. As a result, manufacturers of mechanical seals may use different methods for establishing these limits. In turn, users of mechanical seals sometimes have their own rating system. Presented here is a general discussion of the difficulties involved in establishing limits along with some specific issues related to seals used in centrifugal pumps.  相似文献   
10.
On the basis of clinical signs and histological findings eight 9-month-old male rusa deer (Cervus timorensis) were diagnosed with sheep associated-malignant catarrhal fever. Following a variable course involving rectal temperatures around 40.5 degrees C, depression, inappetence, diarrhoea, corneal opacity and hypopyon all animals died or were euthanased over a 5-week period. Severe multifocal vasculitis, mainly periglomerular and in the arcuate vessels were consistent histological findings which in the past have been adequate to confirm clinical diagnosis of sheep associated-malignant catarrhal fever. A nested polymerase chain reaction test has been used to detect a sheep associated-malignant catarrhal fever PRC product, 238 base-pairs in size, in DNA extracted from lymphocyte preparations. The result supported the diagnosis of sheep associated-malignant catarrhal fever in these deer.  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