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   740586篇
  免费   83156篇
  国内免费   498篇
  824240篇
  2016年   7673篇
  2015年   10705篇
  2014年   12517篇
  2013年   18495篇
  2012年   20517篇
  2011年   20738篇
  2010年   13853篇
  2009年   13028篇
  2008年   18700篇
  2007年   19259篇
  2006年   18393篇
  2005年   17666篇
  2004年   17423篇
  2003年   16858篇
  2002年   16573篇
  2001年   33360篇
  2000年   33938篇
  1999年   27340篇
  1998年   9479篇
  1997年   9935篇
  1996年   9390篇
  1995年   8789篇
  1994年   8805篇
  1993年   8750篇
  1992年   22557篇
  1991年   21730篇
  1990年   21437篇
  1989年   21114篇
  1988年   19641篇
  1987年   18670篇
  1986年   17563篇
  1985年   17666篇
  1984年   14478篇
  1983年   12607篇
  1982年   9778篇
  1981年   8905篇
  1980年   8429篇
  1979年   14138篇
  1978年   11176篇
  1977年   10137篇
  1976年   9683篇
  1975年   10694篇
  1974年   11483篇
  1973年   11384篇
  1972年   10486篇
  1971年   9466篇
  1970年   8221篇
  1969年   7942篇
  1968年   7242篇
  1967年   6309篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Trigger finger is a relatively common clinical entity, most frequently caused by stenosing tenosynovitis. Several other conditions not related to tenosynovitis also have been described as a cause of triggering, and these have been reviewed. We present a rare anomaly of the fourth lumbrical muscle insertion as a cause of triggering of the right little finger. This was completely relieved following excision of the anomalous muscle. This rare anatomic variant should be added to the list of potential causes of trigger finger.  相似文献   
62.
63.
64.
65.
66.
67.
Isopropanol administered in a large (6 g/kg, orally) as well as in a lower dose (1 g/kg, I.P.) is slowly oxidized into acetone by the intact rat. Using two inhibitors, 3 amino-1,2,4-triazole and pyrazole, investigations on the hepatic enzymatic system involved in the oxidation of isopropanol show that catalase does not play an important part in this pathway, contrary to alcohol dehydrogenase which is the major enzyme responsible for this oxidation. Although isopropanol oxidation is mainly catalysed in the liver through alcohol dehydrogenase, no alteration of the hepatic extramitochondrial redox state occurs after the administration of a large as well as of a lower dose of isopropanol. From these experiments it may be concluded that alterations of the liver NAD+/NADH ratio, which seem to play an important part in the ethanol induced fatty liver, are not involved in the isopropanol induced one.  相似文献   
68.
69.
70.
The frequency of cytokine-producing CD4-/CD8- mononuclear cells was assessed in patients of different age groups (29 infants, aged 1-5 years; 30 schoolchildren, aged 6-14 years, 26 adults, aged > 15 years) with acute Plasmodium falciparum malaria, from Gabon. Fifteen patients were followed up before antimalarial treatment (day 0), during parasite clearance (day 3) and after resolution of parasitemia (day 10). By using flow cytometry for intracellular detection of cytokines, a striking expansion of CD4-/CD8- cells producing the type 1 cytokines interleukin (IL)-2-/interferon (IFN)-gamma+, IL-2+/IFN-gamma+ and IL-2+/IFN-gamma- was observed in adults as compared with children. Type 2 cytokine expression (IL-4+/IFN-gamma-, IL-13+/IFN-gamma-) and type 0 cells (IL-4+/IFN-gamma+, IL-13+/IFN-gamma+) were not significantly different between the three age groups. Patients with severe malaria had a significantly increased frequency of type 2 cytokine-producing CD4-/CD8- cells. Drug-induced clearance of parasitemia was characterized by a decrease of IL-2+/IFN-gamma- and type 2 cytokine expressing CD4-/CD8- cells and by a gradual increase of IL-10+/IFN-gamma- expression. The type 1/type 2 dichotomy observed within the CD4-/CD8- cell population is likely to be of significance in the host response against P. falciparum malaria.  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