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   772769篇
  免费   93412篇
  国内免费   290篇
  866471篇
  2016年   8556篇
  2015年   11926篇
  2014年   14136篇
  2013年   20281篇
  2012年   22389篇
  2011年   22702篇
  2010年   15140篇
  2009年   14063篇
  2008年   20089篇
  2007年   21219篇
  2006年   19752篇
  2005年   19215篇
  2004年   19210篇
  2003年   18519篇
  2002年   17996篇
  2001年   32750篇
  2000年   33193篇
  1999年   26717篇
  1998年   9734篇
  1997年   10129篇
  1996年   9724篇
  1995年   9403篇
  1994年   9415篇
  1993年   9211篇
  1992年   23241篇
  1991年   22851篇
  1990年   22480篇
  1989年   21736篇
  1988年   20434篇
  1987年   19503篇
  1986年   18218篇
  1985年   18449篇
  1984年   15395篇
  1983年   13566篇
  1982年   10589篇
  1981年   9754篇
  1980年   9202篇
  1979年   15494篇
  1978年   11949篇
  1977年   11065篇
  1976年   10479篇
  1975年   11537篇
  1974年   12194篇
  1973年   12145篇
  1972年   11341篇
  1971年   10162篇
  1970年   8791篇
  1969年   8392篇
  1968年   7568篇
  1967年   6632篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
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   
62.
Argon laser surgery is an effective treatment for ectasias and congenital port-wine stains; however, its use in children under the age of 13 is controversial. This paper reviews 202 children under the age of 13 who underwent argon laser treatments for congenital port-wine stains, spider angiomas, epidermal nevi, and lentigines. The clinical characteristics of port-wine stains in 170 children are discussed. Good to excellent results (moderate to complete clearing) in port-wine stains were obtained in 60 percent of patients and seemed to correlate best with lack of blanchability on pressure. Hypertrophic scarring was seen in only 7 children, all of whom had undressed wounds; no significant scarring has been seen in any subsequent child who had maintained a dressed wound postoperatively.  相似文献   
63.
64.
65.
66.
67.
68.
69.
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   
70.
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