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   2172篇
  免费   74篇
  2246篇
  2023年   8篇
  2022年   9篇
  2021年   20篇
  2020年   25篇
  2019年   27篇
  2018年   61篇
  2017年   48篇
  2016年   62篇
  2015年   47篇
  2014年   49篇
  2013年   248篇
  2012年   89篇
  2011年   99篇
  2010年   65篇
  2009年   69篇
  2008年   83篇
  2007年   95篇
  2006年   79篇
  2005年   83篇
  2004年   82篇
  2003年   74篇
  2002年   72篇
  2001年   36篇
  2000年   35篇
  1999年   32篇
  1998年   35篇
  1997年   30篇
  1996年   31篇
  1995年   28篇
  1994年   32篇
  1993年   35篇
  1992年   28篇
  1991年   18篇
  1990年   31篇
  1989年   32篇
  1988年   30篇
  1987年   20篇
  1986年   17篇
  1985年   24篇
  1984年   26篇
  1983年   23篇
  1982年   27篇
  1981年   25篇
  1980年   19篇
  1979年   11篇
  1978年   26篇
  1977年   13篇
  1976年   18篇
  1975年   16篇
  1973年   11篇
排序方式: 共有2246条查询结果,搜索用时 0 毫秒
61.
62.
The severe shortage of organs for transplantation and the continual reluctance of the public to voluntarily donate has prompted consideration of alternative strategies for organ procurement. This paper explores the development of market approaches for procuring human organs for transplantation and considers the social and moral implications of organ donation as both a “gift of life” and a “commodity exchange.” The problematic and paradoxical articulation of individual autonomy in relation to property rights and marketing human body parts is addressed. We argue that beliefs about proprietorship over human body parts and the capacity to provide consent for organ donation are culturally constructed. We contend that the political and economic framework of biomedicine, in western and non-western nations, influences access to transplantation technology and shapes the form and development of specific market approaches. Finally, we suggest that marketing approaches for organ procurement are and will be negotiated within cultural parameters constrained by several factors: beliefs about the physical body and personhood, religious traditions, economic conditions, and the availability of technological resources.  相似文献   
63.
64.
65.
Cornell University Medical College, Westchester Division, The New York Hospital, White Plains, New York It is well established that there is a complex timekeeping mechanism in the human brain. This mechanism is associated with a variety of physiological and psychological rhythms having a period of about a day, and thus referred to as circadian rhythms. The circadian system has recently been modeled in terms of two underlying oscillators, one much more resistant to changes in routine than the other. These oscillators are considered to be endogenous, that is, internal to the organism, and not reliant for their existence upon changes in the person’s environment or general behavior. They thus continue to run even when the sleep/wake cycle is suspended, as in sustained operations. Thus, by their very nature, sustained operations require the individual to override the inputs that are coming from his or her circadian system (especially the indication that sleep is required). The aim of this paper is to provide a background to the area of circadian rhythms research, including a section on the methodology, so that the impact of the circadian system on sustained operations can be better understood.  相似文献   
66.
67.
68.
Nondepressed human subjects were divided into seven groups. On a series of discrimination problems, a helplessness group received insoluble problems, a solvable group received contingent feedback, and a no treatment control group received no feedback. For two other groups insoluble problems were preceded by success feedback on a different task presented according to a fixed ratio (FR) or variable ratio (VR) schedule of reinforcement. Two control groups received either FR or VR schedules of success but were not examined on the discrimination problems. All groups were tested for escape/avoidance performance on a human shuttle box. Both FR and VR schedules produced an inoculation against learned helplessness; escape performance by the helplessness group was significantly worse than that of FR and VR inoculation groups. These latter groups performed similar to the solvable and three control groups. Significantly worse than that of FR and VR inoculation groups. These latter groups performed similar to the solvable and three control groups. Significantly fewer subjects in the VR inoculation group exhibited avoidance responses than their counterparts in the FR inoculation group. despite similar escape performance. The findings indicate that learned helplessness can be prevented in humans and suggest different sources of interference produced by unpredictable and uncontrollable events.  相似文献   
69.
This article takes a sociological approach to a problem that has usually been considered as a psychological phenomenon. It addresses the problem of male—female interactions in work situations utilizing the organizational concepts of division of labor and legitimacy. Traditional explanations evoking sex-role socialization are reviewed and rejected for purposes of experimentation and intervention. An alternative argument, focusing on the structural arrangements of organizational settings, is presented as an explanation for behavioral effects previously attributed to inherent sex differences. The results of a pilot study are briefly described, and directions for further experimentation and possible intervention strategies are suggested.The bibliographic search and initial conceptualization of this research was supported by a grant from the Ford Foundation under the auspices of the Center for Research on Women at Stanford University. We are grateful to Miriam Rosen for much of the bibliographic work. The pilot study was supported in part by funds from the Guggenheim Foundation and by a grant from the Spencer Foundation. We also wish to thank Richard Torres and Christie Timberlake for their invaluable assistance on this project.  相似文献   
70.
Mental rotation in the congenitally blind was investigated with a haptic letter-judgment task. Blind subjects and blindfolded, sighted subjects were presented a letter in some orientation between 0° to 300° from upright and timed while they judged whether it was a normal or mirror-image letter. Both groups showed an increasing response time with the stimulus’s departure from upright; this result was interpreted as reflecting the process of mental rotation. The results for the blind subjects suggest that mental rotation can operate on a spatial representation that does not have any specifically visual components. Further research showed that for the sighted subjects in the haptic task, the orientation of a letter is coded with respect to the position of the hand. Sighted subjects may code the orientation of the letter and then translate this code into a visual representation, or they may use a spatial representation that is not specifically visual.  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