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   843178篇
  免费   93938篇
  国内免费   620篇
  937736篇
  2018年   7192篇
  2016年   9689篇
  2015年   12974篇
  2014年   15346篇
  2013年   22328篇
  2012年   24782篇
  2011年   25242篇
  2010年   16946篇
  2009年   15669篇
  2008年   22216篇
  2007年   23173篇
  2006年   21787篇
  2005年   20998篇
  2004年   20803篇
  2003年   19931篇
  2002年   19463篇
  2001年   39922篇
  2000年   40242篇
  1999年   31796篇
  1998年   10482篇
  1997年   11106篇
  1996年   10302篇
  1995年   9718篇
  1994年   9436篇
  1993年   9472篇
  1992年   25710篇
  1991年   24769篇
  1990年   24026篇
  1989年   23329篇
  1988年   21677篇
  1987年   20464篇
  1986年   19239篇
  1985年   19101篇
  1984年   15838篇
  1983年   13494篇
  1982年   10416篇
  1981年   9456篇
  1980年   8893篇
  1979年   15206篇
  1978年   11862篇
  1977年   10962篇
  1976年   10096篇
  1975年   11270篇
  1974年   12369篇
  1973年   12164篇
  1972年   11199篇
  1971年   10123篇
  1970年   8755篇
  1969年   8465篇
  1968年   7883篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
191.
Extensibility, contractile function and resistance to excess calcium of the right atrium myocardium were studied in normotensive Wistar-Kyoto and August rats and in spontaneously hypertensive rats (SHR). It was shown that long-term stress results in a decrease in the measured parameters in normotensive animals. SHR do not show any stress-induced disturbances. It was discovered that in intact SHR rats, the myocardium has a greater resistance to excess calcium, indirect evidence for higher efficiency of the Ca-pump of the sarcoplasmic reticulum in cardiomyocytes of SHR animals, which is apparently a constituent part of the mechanism of such animals' heart increased resistance to stress-induced damage.  相似文献   
192.
Cryptococcosis is an often fatal opportunistic fungal infection. Despite efforts to elucidate the role of immunity in host defense against the disease, much remains to be learned. The purpose of this brief review is to provide the reader with an overview of the history of research concerned with host immunity in cryptococcosis. Both humoral and cell-mediated studies are included. An effort has been made to present the reader with a comprehensive list of references in the hope of encouraging additional reading and research in this important area.  相似文献   
193.
—A resolution of the enhancement of protein synthesis in the visual cortex of rats during first exposure to light (Richardson and Rose , 1972) was achieved by polyacrylamide gel electrophoresis using a double-labelling technique. Differential incorporation of lysine was established between exposed and control animals in two fractions of the soluble proteins and seven fractions of the insoluble proteins. This suggests that exposure to a new experience of this type involves a specific effect on protein synthesis, rather than a general stimulation across all fractions.  相似文献   
194.
195.
196.
A new gas-liquid chromatographic method was developed for the determination of diethylether in whole blood. Ether was quantitated by peak area ratio analysis with n-propanol as the internal standard using a flame ionization detector. Blood ether concentrations were determined in cats undergoing inhalational anesthesia by ether in oxygen. In normal spontaneously breathing cats, anesthesia began at ether concentrations of about 0.6 g/l, and respiratory arrest occurred at 2.4 g/l and above. Mean arterial blood pressure was well maintained throughout the entire anesthetic range. In spinal artificially respired animals, mean arterial blood pressure correlated inversely with blood ether concentration. The data suggest that decline in blood pressure may be a useful sign of ether toxicity in spinal cats.  相似文献   
197.
198.
199.
From three Fouquieria sp. 12 iridoid glucosides were isolated and identified. Eight of these were structurally related to galioside (monotropein methylester), while four were hydroxy substitution products of deoxyloganin. In three cases the glucoside occurred together with the corresponding 10-O-acetate.  相似文献   
200.
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