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   90011篇
  免费   2630篇
  国内免费   45篇
  2018年   1017篇
  2017年   1190篇
  2016年   2989篇
  2015年   6473篇
  2014年   6088篇
  2013年   5847篇
  2012年   5149篇
  2011年   2360篇
  2010年   2323篇
  2009年   2251篇
  2008年   869篇
  2007年   783篇
  2006年   826篇
  2005年   6879篇
  2004年   5566篇
  2003年   3730篇
  2002年   1328篇
  2001年   1233篇
  2000年   416篇
  1999年   1562篇
  1998年   371篇
  1997年   214篇
  1992年   1985篇
  1991年   2070篇
  1990年   2128篇
  1989年   2060篇
  1988年   2000篇
  1987年   1874篇
  1986年   1681篇
  1985年   1718篇
  1984年   1149篇
  1983年   867篇
  1982年   507篇
  1981年   455篇
  1980年   405篇
  1979年   1132篇
  1978年   790篇
  1977年   641篇
  1976年   671篇
  1975年   910篇
  1974年   1041篇
  1973年   1034篇
  1972年   1006篇
  1971年   963篇
  1970年   862篇
  1969年   870篇
  1968年   763篇
  1967年   785篇
  1966年   605篇
  1965年   459篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
The effects of different concentrations of L-ascorbic acid (Asc) on Na+-dependent binding of 3H-GABA and 3H-DL-glutamic acid to rat brain cortical synaptosomes were studied. Asc, at a concentration nearly equal to brain extracellular one (3 X 10(-4) M), had no effect on specific and nonspecific 5H-GABA binding. At higher concentrations (10(-3) M) Asc strongly inhibited, and at lower concentrations (10(-6) M) considerably stimulated 3H-GABA binding. At a concentration of 10(-5)-10(-3) M Asc tended to decrease 3H-DL-glutamic acid binding.  相似文献   
42.
In investigations based on the use of a highly sensitive test system permitting the detection of normal human antibodies to S. aureus peptidoglycan, the antigenic relationships between the peptidoglycans of S. aureus and other representatives of the genus Staphylococcus have been studied. Among other staphylococcal species, S. simulans, S. xylosus, S. hyicus, S. cohnii, S. hyicus s. s. chromogenes have been found to possess peptidoglycans most closely related to S. aureus peptidoglycans, while S. warneri and S. epidermidis peptidoglycans have proved to be least closely related to it.  相似文献   
43.
ESR spectra of gamma-irradiated and frozen at 77 K human oxyhemoglobin and partially denaturated methemoglobin solutions were analysed. The quartet signal ascribed to the anion-radical of proximal histidine was shown to dominate in the spectra of both solutions. The spectra of methemoglobin solution irradiated with relatively small doses have an intensive singlet ascribed to the stabilized electron. The formation mechanism of free radicals is discussed.  相似文献   
44.
Interaction between cytotoxin of the Central Asia cobra venom and dimiristoylphosphatidylcholine bilayer depending on its phase state was studied by ESR with spin label. A conclusion can be drawn that the efficiency of cytotoxin effect on the membranes depends on their phase state. Cytotoxin molecules are incorporated into myophile region of the bilayer, only if the latter is in the liquid crystal state. The interaction between cytotoxins and lipids of the bilayer in a gel state is in the main conditioned by electrostatic forces.  相似文献   
45.
46.
47.
48.
Seven patients with “coeliac axis compression syndrome” are reported. Five were treated surgically, but only two did well. A survey of 200 healthy adults showed epigastric bruits in 6·5%; only one of these had dyspepsia, though dyspepsia was present in 12·5% overall.Caution is urged in attributing a causal relationship between coeliac axis compression and pain and in proceeding to arteriography when compression is suspected on clinical grounds.  相似文献   
49.
Indomethacin and substance BW-755C in experiments on isolated myometrium striae of pregnant white rats exert an inhibiting effect on the contractile uterus function due to inhibition of cyclooxygenase or lipoxygenase ways of the arachidonic acid transformation. Prostaglandin F2 alpha is sensitive to functioning of the cyclooxygenase and lipoxygenase ways of the arachidonic acid transformation, while oxytocin--only lipoxygenase one. Conclusions rest on results from multiparametric analysis of the contractile uterus function suggested by authors and confirmed by the pattern recognition method--the Karunen-Loev orthogonal decomposition.  相似文献   
50.
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