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   61084篇
  免费   5099篇
  国内免费   29篇
  66212篇
  2022年   414篇
  2021年   859篇
  2020年   533篇
  2019年   648篇
  2018年   839篇
  2017年   777篇
  2016年   1368篇
  2015年   2406篇
  2014年   2537篇
  2013年   3353篇
  2012年   4291篇
  2011年   4286篇
  2010年   2770篇
  2009年   2469篇
  2008年   3569篇
  2007年   3626篇
  2006年   3423篇
  2005年   3442篇
  2004年   3386篇
  2003年   3180篇
  2002年   3146篇
  2001年   737篇
  2000年   571篇
  1999年   759篇
  1998年   880篇
  1997年   606篇
  1996年   617篇
  1995年   602篇
  1994年   584篇
  1993年   609篇
  1992年   559篇
  1991年   482篇
  1990年   401篇
  1989年   426篇
  1988年   497篇
  1987年   363篇
  1986年   344篇
  1985年   399篇
  1984年   448篇
  1983年   379篇
  1982年   462篇
  1981年   410篇
  1980年   365篇
  1979年   243篇
  1978年   296篇
  1977年   285篇
  1976年   235篇
  1975年   220篇
  1974年   242篇
  1973年   224篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
This paper is concerned with gene survival in a population which may increase without density dependence according to a generalization of the Moran model for haploid individuals. A selective advantage to one allele and the possibility of differential reproductive rates are allowed. Simple conditions are given for ultimate homozygosity to be certain and for the possibility of ultimate polymorphism. The results complement and extend those of Heyde (1981, 1982).  相似文献   
2.
3.
4.
5.
6.

Background  

The function and viability of cultured, transplanted, or encapsulated pancreatic islets is often limited by hypoxia because these islets have lost their vasculature during the isolation process and have to rely on gradient-driven passive diffusion, which cannot provide adequate oxygen transport. Pancreatic islets (islets of Langerhans) are particularly susceptible due to their relatively large size, large metabolic demand, and increased sensitivity to hypoxia. Here, finite element method (FEM) based multiphysics models are explored to describe oxygen transport and cell viability in avascular islets both in static and in moving culture media.  相似文献   
7.
8.
9.
10.
Are we able to infer what happened to a person from a brief sample of his/her behaviour? It has been proposed that mentalising skills can be used to retrodict as well as predict behaviour, that is, to determine what mental states of a target have already occurred. The current study aimed to develop a paradigm to explore these processes, which takes into account the intricacies of real-life situations in which reasoning about mental states, as embodied in behaviour, may be utilised. A novel task was devised which involved observing subtle and naturalistic reactions of others in order to determine the event that had previously taken place. Thirty-five participants viewed videos of real individuals reacting to the researcher behaving in one of four possible ways, and were asked to judge which of the four ‘scenarios’ they thought the individual was responding to. Their eye movements were recorded to establish the visual strategies used. Participants were able to deduce successfully from a small sample of behaviour which scenario had previously occurred. Surprisingly, looking at the eye region was associated with poorer identification of the scenarios, and eye movement strategy varied depending on the event experienced by the person in the video. This suggests people flexibly deploy their attention using a retrodictive mindreading process to infer events.  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