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   1151214篇
  免费   126398篇
  国内免费   412篇
  1278024篇
  2018年   10565篇
  2016年   14138篇
  2015年   18636篇
  2014年   22247篇
  2013年   32052篇
  2012年   35621篇
  2011年   36600篇
  2010年   24806篇
  2009年   23153篇
  2008年   32620篇
  2007年   34218篇
  2006年   31923篇
  2005年   30787篇
  2004年   30549篇
  2003年   29438篇
  2002年   28713篇
  2001年   47647篇
  2000年   47630篇
  1999年   38437篇
  1998年   14537篇
  1997年   14803篇
  1996年   14151篇
  1995年   13370篇
  1994年   13087篇
  1993年   13081篇
  1992年   32567篇
  1991年   32055篇
  1990年   31528篇
  1989年   30735篇
  1988年   28487篇
  1987年   27329篇
  1986年   25624篇
  1985年   25832篇
  1984年   21493篇
  1983年   18849篇
  1982年   14460篇
  1981年   13417篇
  1980年   12451篇
  1979年   20740篇
  1978年   16295篇
  1977年   14862篇
  1976年   14217篇
  1975年   15882篇
  1974年   16718篇
  1973年   16546篇
  1972年   15371篇
  1971年   13707篇
  1970年   11933篇
  1969年   11490篇
  1968年   10307篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
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   
92.
93.
94.
95.
96.
97.
98.
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   
99.
100.
The Saccharomyces cerevisiae SSU1 gene was isolated based on its ability to complement a mutation causing sensitivity to sulfite, a methionine intermediate. SSU1 encodes a deduced protein of 458 amino acids containing 9 or 10 membrane-spanning domains but has no significant similarity to other proteins in public databases. An Ssu1p-GEP fusion protein was localized to the plasma membrane. Multicopy suppression analysis, undertaken to explore relationships among genes previously implicated in sulfite metabolism, suggests a regulatory pathway in which SSU1 acts downstream of FZF1 and SSU3, which in turn act downstream of GRR1.  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