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   2057篇
  免费   13篇
电工技术   24篇
综合类   2篇
化学工业   101篇
金属工艺   2篇
机械仪表   3篇
建筑科学   13篇
能源动力   18篇
轻工业   5篇
水利工程   3篇
石油天然气   1篇
无线电   42篇
一般工业技术   51篇
冶金工业   1770篇
自动化技术   35篇
  2023年   2篇
  2022年   7篇
  2021年   7篇
  2020年   4篇
  2019年   9篇
  2018年   7篇
  2017年   7篇
  2016年   8篇
  2015年   8篇
  2014年   10篇
  2013年   34篇
  2012年   14篇
  2011年   21篇
  2010年   20篇
  2009年   17篇
  2008年   8篇
  2007年   17篇
  2006年   7篇
  2005年   14篇
  2004年   7篇
  2003年   15篇
  2002年   11篇
  2001年   11篇
  2000年   6篇
  1999年   52篇
  1998年   606篇
  1997年   318篇
  1996年   208篇
  1995年   129篇
  1994年   76篇
  1993年   101篇
  1992年   13篇
  1991年   18篇
  1990年   23篇
  1989年   19篇
  1988年   10篇
  1987年   15篇
  1986年   8篇
  1985年   22篇
  1984年   1篇
  1983年   2篇
  1982年   12篇
  1981年   9篇
  1980年   13篇
  1978年   4篇
  1977年   48篇
  1976年   90篇
  1966年   1篇
  1955年   1篇
排序方式: 共有2070条查询结果,搜索用时 0 毫秒
51.
Acute appendicitis caused by Ascaris lumbricoides is an uncommon variant of a common disease. We describe a case in which sonography was used for preoperative diagnosis of ascaris appendicitis.  相似文献   
52.
53.
54.
The folic acid antagonists, methotrexate and aminopterin, are known to be teratogenic in humans. The critical period for their teratogenecity is suspected to be between 6 to 8 weeks post-conception. Fetal exposure from 10 to 32 weeks weeks post-conception to methotrexate alone or in combination with other anti-cancer drugs has not resulted in obvious teratogenic effects. Methotrexate is often used to treat cancers but is occasionally used as an abortifacient. The long-term outcome of the fetal aminopterin syndrome has been published in only four adults. We report on a 28-year-old man with fetal methotrexate syndrome and two children with mild manifestations of the syndrome. One child was inadvertently exposed to methotrexate from 7 1/2 through 30 weeks post-conception because his mother was receiving it for treatment of breast cancer. The other was exposed from 11 weeks and 5 days through 25 weeks in an attempt to induce abortion. The 28-year-old man has craniofacial and digital anomalies, growth retardation but normal intelligence as noted in the previously reported cases. These cases remind us of the teratogenicity of methotrexate and should serve as a warning that if methotrexate is used as an abortifaciant and an abortion does not ensue, there is a teratogenic risk.  相似文献   
55.
A diffusion cell with an artificial membrane and the single-pass perfused rabbit ear were used to evaluate the percutaneous absorption of clonazepam from various 2-hydroxyethyl acetate (HEA) patches. The influence on drug permeation of the various type of enhancers (isopropylmyristate, lauryl alcohol, propylene glycol and water) in the patches was tested. A comparison between the two types of systems of percutaneous absorption of clonazepam has been done. The results showed that HEA patches produce controlled uniform drug release, modulated by the addition of enhancers.  相似文献   
56.
57.
The liver S9 head space vial equilibration technique is an in vitro alternative that holds promises for a satisfactory in vivo extrapolation of liver metabolism of volatile organic chemicals. The aim of this study was to investigate the suitability of this methodology for the extrapolation of in vitro metabolic data from rodent to man by allometry with the two highly metabolized organic solvents toluene and n-hexane as model substances. The calculated hepatic clearance of toluene in man from rodent liver S9 in this study was equal to the reported total body clearance of toluene in man, suggesting insignificant extrahepatic clearance of toluene in humans. The calculated hepatic clearance of n-hexane was less than the reported values of total body clearance of n-hexane in man, indicating an about 80% extrahepatic clearance of n-hexane in humans. Both results are in line with our present knowledge of the metabolism of the two organic solvents in man. Allometric scaling from rodent liver S9 head space incubations to in vivo metabolism of toluene and n-hexane in man thus seems promising and could be a method of choice for scaling of organic solvent metabolism in general.  相似文献   
58.
59.
60.
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