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   767544篇
  免费   82867篇
  国内免费   342篇
  850753篇
  2016年   8913篇
  2015年   11804篇
  2014年   13927篇
  2013年   20088篇
  2012年   22296篇
  2011年   23016篇
  2010年   15781篇
  2009年   14561篇
  2008年   20765篇
  2007年   21862篇
  2006年   20537篇
  2005年   19529篇
  2004年   19668篇
  2003年   18867篇
  2002年   18508篇
  2001年   30701篇
  2000年   30817篇
  1999年   24760篇
  1998年   9112篇
  1997年   9569篇
  1996年   8987篇
  1995年   8480篇
  1994年   8264篇
  1993年   8391篇
  1992年   21380篇
  1991年   21106篇
  1990年   20893篇
  1989年   20395篇
  1988年   19393篇
  1987年   18414篇
  1986年   17245篇
  1985年   17516篇
  1984年   14633篇
  1983年   12603篇
  1982年   9821篇
  1981年   8799篇
  1980年   8459篇
  1979年   14103篇
  1978年   11105篇
  1977年   10383篇
  1976年   9930篇
  1975年   10712篇
  1974年   11923篇
  1973年   11662篇
  1972年   10850篇
  1971年   9873篇
  1970年   8645篇
  1969年   8589篇
  1968年   8140篇
  1967年   6924篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Anatomical and neurophysiological findings have demonstrated neuronal connections between the diencephalic habenular nuclei and brain stem serotonergic raphe nuclei. Therefore we examined some neurochemical consequences of habenular lesions. Sixteen hours and one week after bilateral lesions serotonin metabolism (as reflected by concentrations of its metabolite, 5-hydroxyindoleacetic acid) was significantly increased in the dorsal but not the median raphe nuclei. Unilateral lesions produced a proportionally smaller augmentation. Motron locomotor activity was enhanced during the light and dark illumination phases in lesioned animals but only attained statistical significance during the day.  相似文献   
82.
Protein metal-binding sites.   总被引:2,自引:0,他引:2  
Metal ions have a role in a variety of important functions in proteins including protein folding, assembly, stability, conformational change, and catalysis. The presence or absence of a given metal ion is crucial to the conformation or activity of over one third of all proteins. Recent developments have been made in the understanding and design of metal-binding sites in proteins, an important and rapidly advancing area of protein engineering.  相似文献   
83.
Experiments were made on rabbit fed an atherogenic diet (0.5 g/kg cholesterol) singly for 15 and 24 h and repeatedly for 3, 9 and 30 days. At early stages of lipid metabolism distress the interrelationship was established between blood rheological disorders and microcirculatory abnormalities. The dependence of the initial reaction of some rheological characteristics on their initial level was marked.  相似文献   
84.
85.
86.
Electron microscopy of the adrenal medulla and cortex during the intermediate period of endotoxin shock has revealed severe destructive changes in parenchymal cells. These changes are the reason for synthetic, secretory and trophic disturbances of glandular functions. Ultrastructural lesions indicate that stress exposure exceeds the adaptive capacity of cells, the majority of which are exhausted and killed.  相似文献   
87.
88.
Synthesis of prenylquinones in chloroplasts   总被引:3,自引:0,他引:3  
  相似文献   
89.
Growth of fathead minnow yolk sac larvae was characterized from changes in dry weight and total content and concentrations of RNA, DNA and protein in fish exposed to a sublethal level of HCN (58 micrograms/l) and in age matched controls. Cyanide toxicosis occurred within 24 hr of exposure as evidenced by significant reductions in protein and RNA content and RNA/DNA ratio of larvae. After 96 hr exposure to HCN, larvae exhibited the same growth rate and protein synthetic rate (RNA/DNA) as control fish. HCN toxicosis and recovery is rapid and at least partial tolerance to HCN develops within 96 hr of exposure in larval fathead minnows.  相似文献   
90.
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