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   854102篇
  免费   100860篇
  国内免费   328篇
  2016年   9837篇
  2015年   13334篇
  2014年   15852篇
  2013年   22318篇
  2012年   24944篇
  2011年   25534篇
  2010年   17234篇
  2009年   16089篇
  2008年   23005篇
  2007年   24174篇
  2006年   22581篇
  2005年   21746篇
  2004年   21720篇
  2003年   20721篇
  2002年   20204篇
  2001年   35121篇
  2000年   35490篇
  1999年   28524篇
  1998年   10468篇
  1997年   10964篇
  1996年   10487篇
  1995年   10033篇
  1994年   9857篇
  1993年   9809篇
  1992年   24531篇
  1991年   24358篇
  1990年   23916篇
  1989年   23240篇
  1988年   21858篇
  1987年   21060篇
  1986年   19782篇
  1985年   19786篇
  1984年   16697篇
  1983年   14655篇
  1982年   11391篇
  1981年   10437篇
  1980年   9958篇
  1979年   16378篇
  1978年   12935篇
  1977年   11924篇
  1976年   11379篇
  1975年   12468篇
  1974年   13448篇
  1973年   13179篇
  1972年   12423篇
  1971年   10976篇
  1970年   9710篇
  1969年   9318篇
  1968年   8666篇
  1967年   7504篇
排序方式: 共有10000条查询结果,搜索用时 493 毫秒
81.
82.
Over the past 10 years the AIDS crisis has produced a large volume of writing. Much of this is documentary. Dozens of studies of AIDS from various clinical and political perspectives have been complemented by just as many published diaries, autobiographies, novels, plays, and poems. A few of these works have risen to the surface not only as extraordinarily valuable testimonies to the changes AIDS has wrought in individual and collective life but also as first-rate literary works, worth reading because beyond their immediate purposes they articulate with extraordinary lucidity and compassion some deep truths about the human--and the modern--condition. Paul Monette's Borrowed Time is among the most distinctive of those. It speaks not only for the community of people with AIDS and those who support them but for a generation.  相似文献   
83.
84.
Reconstruction of bony structures of the face is always a problem as big as the defect and the function that must be replaced. Everything from simple grafts to sophisticated distant bone flaps has been used. Based on the studies of Cutting et al., Psillakis et al., and Casanova et al., we have developed the full-thickness galeoparietal bone flap, initially for mandibular reconstruction, but of great use for all maxillofacial reconstructions. From July of 1987 to December of 1988, 14 patients have been operated on. The experience with this flap is shown in four patients as follows: primary reconstruction of a mandible as a result of ameloblastoma, secondary reconstruction of a mandible with associated old fractures and malalignment of segments, bilateral malar reconstruction in a patient with Treacher Collins syndrome, and severe sequelae of an already treated Romberg case. Small variations could be made to best accommodate the technique used to the defect we were treating. Some technical details, the experience, the results, and possible sequelae or complications are also discussed.  相似文献   
85.
86.
87.
88.
89.
90.
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   
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