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   1773篇
  免费   95篇
  2023年   12篇
  2022年   26篇
  2021年   21篇
  2020年   37篇
  2019年   56篇
  2018年   63篇
  2017年   84篇
  2016年   56篇
  2015年   45篇
  2014年   60篇
  2013年   203篇
  2012年   97篇
  2011年   93篇
  2010年   49篇
  2009年   64篇
  2008年   82篇
  2007年   68篇
  2006年   70篇
  2005年   79篇
  2004年   59篇
  2003年   57篇
  2002年   41篇
  2001年   20篇
  2000年   32篇
  1999年   30篇
  1998年   20篇
  1997年   14篇
  1996年   14篇
  1995年   15篇
  1994年   14篇
  1993年   14篇
  1992年   18篇
  1991年   12篇
  1990年   19篇
  1989年   12篇
  1988年   9篇
  1987年   13篇
  1986年   16篇
  1985年   14篇
  1984年   12篇
  1983年   13篇
  1982年   12篇
  1981年   10篇
  1980年   11篇
  1979年   11篇
  1977年   8篇
  1976年   9篇
  1974年   7篇
  1973年   7篇
  1972年   7篇
排序方式: 共有1868条查询结果,搜索用时 15 毫秒
151.
152.
153.
In this article, we raise ethical concerns about the potential misuse of open-source biology (OSB): biological research and development that progresses through an organisational model of radical openness, deskilling, and innovation. We compare this organisational structure to that of the open-source software model, and detail salient ethical implications of this model. We demonstrate that OSB, in virtue of its commitment to openness, may be resistant to governance attempts.  相似文献   
154.
155.
156.
    
  相似文献   
157.
A vibrotactile N-back task was used to generate cognitive load while participants were guided along virtual paths without vision. As participants stepped in place, they moved along a virtual path of linear segments. Information was provided en route about the direction of the next turning point, by spatial language ("left," "right," or "straight") or virtual sound (i.e., the perceived azimuth of the sound indicated the target direction). The authors hypothesized that virtual sound, being processed at direct perceptual levels, would have lower load than even simple language commands, which require cognitive mediation. As predicted, whereas the guidance modes did not differ significantly in the no-load condition, participants showed shorter distance traveled and less time to complete a path when performing the N-back task while navigating with virtual sound as guidance. Virtual sound also produced better N-back performance than spatial language. By indicating the superiority of virtual sound for guidance when cognitive load is present, as is characteristic of everyday navigation, these results have implications for guidance systems for the visually impaired and others.  相似文献   
158.
In the UK, substantial numbers of new HIV diagnoses are within migrant communities, especially African communities. Current surveillance shows that despite health promotion efforts and advances in therapy these communities are accessing HIV care late. This paper explores the issues influencing the access and uptake of HIV care by migrant Africans in Britain. Using Kleinman's model of health care systems (Kleinman, 1980) as a theoretical framework, we highlight the importance of placing health within its broader context if we are to make significant improvement to the health of HIV-infected Africans in Britain.  相似文献   
159.
To date, neither primates nor birds have shown clear evidence of causal knowledge when attempting to solve the trap tube task. One factor that may have contributed to mask the knowledge that subjects may have about the task is that subjects were only allowed to push the reward away from them, which is a particularly difficult action for primates in certain problem solving situations. We presented five orangutans (Pongo pygmaeus), two chimpanzees (Pan troglodytes), two bonobos (Pan paniscus), and one gorilla (Gorilla gorilla) with a modified trap tube that allowed subjects to push or rake the reward with the tool. In two additional follow-up tests, we inverted the tube 180° rendering the trap nonfunctional and also presented subjects with the original task in which they were required to push the reward out of the tube. Results showed that all but one of the subjects preferred to rake the reward. Two orangutans and one chimpanzee (all of whom preferred to rake the reward), consistently avoided the trap only when it was functional but failed the original task. These findings suggest that some great apes may have some causal knowledge about the trap-tube task. Their success, however, depended on whether they were allowed to choose certain tool-using actions. Electronic Supplementary Material Supplementary material is available for this article at  相似文献   
160.
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