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   537715篇
  免费   59961篇
  国内免费   350篇
  598026篇
  2018年   5329篇
  2017年   5172篇
  2016年   7102篇
  2015年   8993篇
  2014年   10753篇
  2013年   15601篇
  2012年   17379篇
  2011年   17800篇
  2010年   11955篇
  2009年   10962篇
  2008年   15445篇
  2007年   16045篇
  2006年   14952篇
  2005年   14330篇
  2004年   14158篇
  2003年   13537篇
  2002年   13061篇
  2001年   28394篇
  2000年   28231篇
  1999年   22009篇
  1998年   6759篇
  1997年   7339篇
  1996年   6760篇
  1995年   6235篇
  1994年   5997篇
  1993年   5974篇
  1992年   17049篇
  1991年   16301篇
  1990年   15700篇
  1989年   15217篇
  1988年   13925篇
  1987年   12942篇
  1986年   12046篇
  1985年   11819篇
  1984年   9666篇
  1983年   8088篇
  1982年   6002篇
  1981年   5381篇
  1980年   5105篇
  1979年   8945篇
  1978年   6817篇
  1977年   6290篇
  1976年   5660篇
  1975年   6248篇
  1974年   6763篇
  1973年   6549篇
  1972年   5990篇
  1971年   5432篇
  1970年   4682篇
  1969年   4409篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
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   
102.
—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   
103.
104.
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   
105.
106.
107.
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   
108.
An indwelling nasal suction tampon is described that effectively controls both intraoperative and postoperative nasal hemorrhage. The significant benefits of this device are better intraoperative control for the surgeon and less complicated postoperative recovery. I do not have any financial involvement in this device, but I would like other nasal surgeons to benefit from its particular advantages. The device is available under the trade name Instant and may be obtained from Innovations by Westmed, 3351 E. Hemisphere Loop, Tucson, Ariz. 85706; (602) 294-7987.  相似文献   
109.
110.
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