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   3506篇
  免费   271篇
  国内免费   4篇
  2023年   17篇
  2022年   24篇
  2021年   42篇
  2020年   23篇
  2019年   29篇
  2018年   46篇
  2017年   38篇
  2016年   65篇
  2015年   97篇
  2014年   115篇
  2013年   170篇
  2012年   184篇
  2011年   182篇
  2010年   128篇
  2009年   134篇
  2008年   188篇
  2007年   211篇
  2006年   205篇
  2005年   187篇
  2004年   169篇
  2003年   162篇
  2002年   165篇
  2001年   49篇
  2000年   68篇
  1999年   83篇
  1998年   76篇
  1997年   43篇
  1996年   43篇
  1995年   39篇
  1994年   56篇
  1993年   51篇
  1992年   55篇
  1991年   44篇
  1990年   46篇
  1989年   40篇
  1988年   46篇
  1987年   27篇
  1986年   22篇
  1985年   35篇
  1984年   26篇
  1983年   27篇
  1982年   29篇
  1981年   41篇
  1980年   36篇
  1979年   33篇
  1978年   14篇
  1977年   17篇
  1976年   27篇
  1975年   16篇
  1974年   19篇
排序方式: 共有3781条查询结果,搜索用时 218 毫秒
41.
The composition of 3 species of genus Cistus L. has been analysed and compared: C. labdaniferus L. contains essentially compounds of labdane type, namely labdane-8, 15, 19-triol whose structure has been confirmed; C. monspeliensis L. contains almost exclusively compounds having a new squeleton, the cistane, with a cis-junction of A and B; no cyclic diterpenes have been isolated from C. salvifolius L. which has been found rich in unsaturated aliphatic acids one of which is a mono conjugated triethylenic acid.  相似文献   
42.
43.
44.
Various attempts to define the concept of “mental health” are examined. Value judgments permeate much mental health literature. Their use militates against obtaining an objective definition, capable of universal application. The acceptance of a definition including a value judgment implies taking an attitude toward a particular society and its social ideals.Present limits of competence only allow us to describe “mental health” conceptually. Such “untechnical” proposals are liable to be confused with “technical” (“scientific”) propositions. Multiple criteria are likely to be helpful in improving our concept of “mental health”.The intrusion of morals into the world of health is discussed as part of the contemporary intellectual dilemma of determined human behaviour versus human responsibility and the reality of moral values.It is suggested that “mental health” might consist simply of an individual''s possession of insight into his own personality, combined with an honest recognition and acceptance of his condition.  相似文献   
45.
46.
47.
48.
Ca2+ and Mn2+ activate the conversion of 1-aminocyclopropane-1-carboxylic acid (ACC) by root microsomes of Vicia lens as they do in other similar systems. The preparation of microsomes in the presence of Mn2+ greatly increases their ability to convert ACC into ethylene, without addition of Mn2+ in the reaction mixture. Ca2+ does not have this property. The effect could not be attributed to Mn2+ entrapping into membrane vesicles (sonication followed by repelleting had no effect) but, possibly, in part to Mn2+-mediated binding to microsomes of a soluble factor favouring the conversion of ACC to C2H4. Although no direct correlation could be established in vitro between ethylene-forming-enzyme (EFE) and peroxidase activities, some soluble peroxidases might be this soluble factor. Mn2+ favoured attachment to membranes of some peroxidase activity from the soluble fraction and from commercial HRP and lipoxygenase. This binding effect of Mn2+ cannot be readily distinguished from its role in the generation of a chain of free radicals and in redox mechanisms.  相似文献   
49.
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