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   87503篇
  免费   2389篇
  国内免费   259篇
  2018年   1032篇
  2017年   1151篇
  2016年   2950篇
  2015年   6388篇
  2014年   5983篇
  2013年   5776篇
  2012年   4979篇
  2011年   2225篇
  2010年   2227篇
  2009年   2159篇
  2008年   715篇
  2007年   638篇
  2006年   702篇
  2005年   6748篇
  2004年   5459篇
  2003年   3622篇
  2002年   1171篇
  2001年   1174篇
  2000年   412篇
  1999年   1550篇
  1998年   356篇
  1997年   201篇
  1992年   1979篇
  1991年   2081篇
  1990年   2116篇
  1989年   2052篇
  1988年   2006篇
  1987年   1864篇
  1986年   1668篇
  1985年   1706篇
  1984年   1129篇
  1983年   863篇
  1982年   480篇
  1981年   440篇
  1980年   383篇
  1979年   1104篇
  1978年   782篇
  1977年   624篇
  1976年   646篇
  1975年   893篇
  1974年   1016篇
  1973年   1030篇
  1972年   969篇
  1971年   945篇
  1970年   828篇
  1969年   839篇
  1968年   740篇
  1967年   752篇
  1966年   586篇
  1965年   437篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
221.
222.
223.
Activity of phosphodiesterases disintegrating cAMP and cGMP in the cornea, sclera and ciliary body was investigated in health and in different stages of experimental herpetic keratitis. The problems concerning the role of the cyclase system in the pathogenesis of herpetic keratitis and the possibility of applying some of the drugs to the disease treatment are discussed.  相似文献   
224.
Oxidation of liposome phospholipids has been studied in the presence of cytochrome c. Sonicated vesicles of soya bean or egg-yolk lipids, or purified phospholipid preparations, were treated with oxidized cytochrome c at a 10:4 lipid/protein ratio (w/w). Lipid peroxidation was examined by oxygen polarography, gas-liquid chromatography (GLC) and the thiobarbituric acid test. Oxidized, but not reduced, cytochrome effectively catalyzes lipid oxidation under these conditions. Oxygen consumption and disappearance of unsaturated fatty acids follow closely similar patterns, the O2 consumption rate showing a maximum (1.53 mol O2/min per mol heme) shortly before fatty acid loss reaches its peak. GLC and O2 consumption data suggest that monohydroperoxides are the most abundant oxidized species in the system. The thiobarbituric acid reaction, however, appears only to be of qualitative value in peroxidation studies. In order to test the mechanism through which oxidation occurs in our system, the effect of liposome composition and the presence of antioxidants was tested, both on cytochrome c binding to bilayers and on O2 consumption. Oxidized and reduced cytochrome c bind the lipid bilayers with similar affinity, but only the oxidized form is active in autoxidation. Antioxidants do not modify either cytochrome c binding to sonicated liposomes. Lipid composition does influence considerably cytochrome binding, and O2 consumption is correspondingly altered. Studies with various antioxidants and inhibitors suggest that both free radicals and singlet oxygen may be involved in the process under study.  相似文献   
225.
226.
227.
Highly sensitive and specific erythrocyte diagnostic agents (ED) for the determination of antibodies to Proteus O-antigens have been obtained by the sensitization of formolated sheep red blood cells (SPBC) with activated lipopolysaccharides (LPS) without the use of mediators. The tannin treatment of formolated SRBC and/or the increase of temperature from 45 degrees C to 100 degrees C in the process of the preparation of ED have been found to produce no increase in effectiveness. Antibody ED permitting the detection of Proteus O- and H-antigens has been obtained by the sensitization of formolated chick red blood cells with immunoglobulin preparations to Proteus hydroxylamine antigens, carried out with the use of amidol. The experiments have shown the possibility of using this antibody ED for the determination of O-antibodies in the antigen neutralization test with nonactivated LPS used as an agglutinating agent. The passive hemagglutination test with antibody ED has proved to be a more sensitive method for the detection of O-antibodies than the antigen neutralization test with antigenic ED. The determination of Proteus etiology in the passive hemagglutination test with the use of antigenic ED has been shown to be highly effective in the examination of patients with chronic osteomyelitis at the stage of exacerbation.  相似文献   
228.
229.
230.
1. Testosterone reduces the haemolytic action of Ekatin on the morphotic blood elements by accelerating maturation of erythroblastic cells. 2. Testosterone, by accelerating the metabolism of the pesticide causes a defective defence processes of the organism by decreasing the number of macrophages. 3. Intoxication of androgenised birds with Ekatin leads to a breakdown of the systemic adaptive mechanisms by rapid and early switching on the adrenal cortex in response to the stress caused by poisoning.  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