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   4048篇
  免费   1篇
  国内免费   1篇
电工技术   1篇
化学工业   46篇
机械仪表   2篇
建筑科学   3篇
能源动力   2篇
轻工业   14篇
石油天然气   4篇
无线电   6篇
一般工业技术   22篇
冶金工业   3940篇
自动化技术   10篇
  2021年   3篇
  2020年   1篇
  2019年   1篇
  2018年   1篇
  2017年   3篇
  2016年   1篇
  2014年   1篇
  2013年   5篇
  2012年   5篇
  2011年   6篇
  2010年   4篇
  2009年   4篇
  2008年   6篇
  2007年   6篇
  2006年   6篇
  2005年   5篇
  2004年   3篇
  2003年   11篇
  2002年   7篇
  2001年   1篇
  2000年   9篇
  1999年   108篇
  1998年   1190篇
  1997年   658篇
  1996年   466篇
  1995年   224篇
  1994年   207篇
  1993年   225篇
  1992年   26篇
  1991年   67篇
  1990年   65篇
  1989年   57篇
  1988年   53篇
  1987年   57篇
  1986年   41篇
  1985年   44篇
  1983年   10篇
  1982年   19篇
  1981年   23篇
  1980年   31篇
  1979年   2篇
  1978年   10篇
  1977年   101篇
  1976年   261篇
  1975年   6篇
  1974年   1篇
  1972年   1篇
  1964年   1篇
  1955年   7篇
排序方式: 共有4050条查询结果,搜索用时 15 毫秒
71.
72.
73.
Dosages of 20 and 10 ppm methylmercury were toxic to rabbits while 1 ppm did not produce clinical signs or death. Serum alkaline phosphatase levels were elevated in all rabbits exposed to methylmercury. Methylmercury-exposed rabbits challenged to A/PR8 influenza virus had hemagglutination inhibition titers as much as four times lower than those of controls. Histopathologic lesions were found in the cerebellum of rabbits that died. The most significant features of this study were that methylmercury chloride suppressed the humoral immune system and resulted in increased serum alkaline phosphatase levels, which may aid in diagnosis when methylmercury poisoning is suspected.  相似文献   
74.
Several viral isolates from ticks (Ornithodoros coriaceus) and from the blood of cattle which aborted after exposure to these ticks were found to be identical by reciprocal cross serum-neutralization tests. Characterization studies indicate that the virus is a member of the Togaviridae family, although specific identification is still incomplete. Whether its natural host is the tick or bovine animals is also unknown. Pregnant cows inoculated with the agent by all conventional parenteral routes, including intrafetal, delivered healthy calves at term. It was concluded, therefore, that it was not a bovine pathogen and that the abortions which occurred after tick-exposure were due to a 2nd agent in O coriaceus ticks which also harbor the virus. While several ciruses believed to be tick-borne have been isolated from cattle in various parts of the world, it is believed that the present report describes the first isolation in the Western Hemisphere for a viral agent from Argasid ticks which has been demonstrated to replicate in cattle.  相似文献   
75.
76.
Chemical models for coupling oxidation to phosphorylation are summarized and examined both from the standpoint of organic reaction mechanisms and with respect to their relevance to mitochondria and chloroplasts. In order to accelerate the progress of our research in bioenergetics, it is suggested to focus at least as much attention on structural biochemistry as on phenomenological observations of energy-transducing membranes.  相似文献   
77.
78.
79.
This paper outlines a computerized system for monitoring physiological functions during exercise, using a mass spectrometer for analyzing the concentration of the mixed expired air. Examples are provided illustrating the operation of this system in both research and clinical situations. The most remarkable aspect of the system is its versatility, coupled with its accuracy. While the applications reviewed in this paper are rather narrow, work has been initiated using the mass spectrometer to measure residual lung volumes by the oxygen dilution technique, cardiac output by the CO2 rebreathing technique, and total body density by the helium dilution technique. The application of the mass spectrometer into other areas most certainty will occur in the near future.  相似文献   
80.
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