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   4414篇
  免费   107篇
  国内免费   33篇
  2014年   22篇
  2013年   18篇
  2012年   388篇
  2011年   453篇
  2010年   116篇
  2009年   50篇
  2008年   311篇
  2007年   367篇
  2006年   355篇
  2005年   248篇
  2004年   241篇
  2003年   238篇
  2002年   233篇
  2001年   171篇
  2000年   182篇
  1999年   100篇
  1998年   27篇
  1997年   53篇
  1995年   10篇
  1994年   14篇
  1993年   15篇
  1992年   12篇
  1991年   12篇
  1990年   27篇
  1989年   23篇
  1988年   24篇
  1987年   25篇
  1986年   12篇
  1985年   28篇
  1984年   16篇
  1983年   22篇
  1982年   19篇
  1981年   15篇
  1979年   14篇
  1978年   12篇
  1969年   12篇
  1965年   15篇
  1964年   13篇
  1959年   27篇
  1958年   66篇
  1957年   68篇
  1956年   51篇
  1955年   43篇
  1954年   62篇
  1953年   50篇
  1952年   56篇
  1951年   40篇
  1950年   43篇
  1949年   19篇
  1948年   24篇
排序方式: 共有4554条查询结果,搜索用时 15 毫秒
41.
In a previous study of two-choice reactions, pairings of spatial stimuli with bimanual presses made on a keyboard and verbal stimuli with unimanual aimed movements made on a display screen showed higher set-level compatibility than the opposite pairings; element-level compatibility (i.e., mapping) effects were also larger for the conditions with high set-level compatibility than for those whose set-level compatibility was low. In the 4 experiments described here, the relevant factors were isolated, allowing the determinants of those compatibility differences to be evaluated in more detail. Forty-eight students participated in Experiment 1, and 24 each in Experiments 2, 3, and 4. The primary determinant of the set-level compatibility variation was whether the response alternatives involved 1 or 2 effectors, but the differences in element-level compatibility effects were determined primarily by the distinction between responding on the screen as opposed to on the keyboard. Implications for models of stimulus-response compatibility are examined.  相似文献   
42.
This paper examines ethical issues related to medical practices with children and adults who are members of a linguistic and cultural minority known as the DEAF-WORLD. Members of that culture characteristically have hearing parents and are treated by hearing professionals whose values, particularly concerning language, speech, and hearing, are typically quite different from their own. That disparity has long fueled a debate on several ethical issues, most recently the merits of cochlear implant surgery for DEAF children. We explore whether that surgery would be ethical if implants could deliver close to normal hearing for most implanted children, thereby diminishing the ranks of the DEAF-WORLD. The ethical implications of eugenic practices with the DEAF are explored, as are ethical quandaries in parental surrogacy for DEAF children, and their parallels in transracial adoption.  相似文献   
43.
The treatment of life-threatening illnesses in childhood is replete with ethical issues and with clinical issues that have ethical implications. The central issues are those involved with a child's participation in the decision-making process and with communication of information about the illness and treatments to children. This article examines the questions of patient autonomy and of parental responsibility and prerogative in the context of pediatric oncology. Included in this examination of the ethical dimensions of pediatric life-threatening illness is a discussion of the many related aspects involved, including medical, cultural, psychosocial, legal, and developmental. A multidimensional approach that considers the ways in which these multiple aspects interact with one another, and which focuses on establishing a strong working alliance between the health care team and the pediatric patient's family, can help to avoid or resolve potential ethical and clinical conflicts.  相似文献   
44.
ABSTRACT Biomedical experimentation on animals is justified, researchers say, because of its enormous benefits to human beings. Sure, animals suffer and die, but that is morally insignificant since the benefits of research incalculably outweigh the evils. Although this utilitarian claim appears straightforward and relatively uncontroversial, it is neither straightforward nor uncontroversial. This defence of animal experimentation is likely to succeed only by rejecting three widely held moral presumptions. We identify these assumptions and explain their relevance to the justification of animal experimentation. We argue that, even if non-human animals have considerably less moral worth than humans, experimentation is justified only if the benefits are overwhelming. By building on and expanding on arguments offered in earlier papers, we show that researchers cannot substantiate their claims on behalf of animal research. We conclude that there is currently no acceptable utilitarian defence of animal experimentation. Moreover, it is unlikely that there could be one. Since most apologists of animal experimentation rely on utilitarian justifications of their practice, it appears that biomedical experimentation on animals is not morally justified .  相似文献   
45.
Four homing pigeons were trained over 5 months in a zero-delay, “arbitrary” matching-to-sample procedure with sample and comparison stimuli presented on any of three response keys. Birds were also required to complete a fixed-ratio 10 requirement on both sample and comparison stimuli to terminate their presentation. The procedure resulted in the establishment of relations that were not specifically trained and that can be characterized by the property of transitivity in a stimulus equivalence context. This result was in contrast with the findings obtained from most previous research with nonhuman subjects.  相似文献   
46.
47.
48.
In this longitudinal study, the development of automatic postural responses elicited during stance following perturbation of the support surface was investigated. Infants (N = 9) unable to stand without support were tested initially: follow-up tests were performed until the infants were able to stand and walk independently. Surface electromyographic recordings of leg and trunk muscle activity following a postural perturbation induced by a forward or backward translation of the support surface were made for each infant. Muscle onset latencies following the perturbation and the proportion of trials in which muscle activity was recorded were determined. First, infants activated appropriate muscles either in isolation or in pairs and then combined these muscles into functional synergies. Although activation of all three postural muscles was recorded in infants before they were able to stand and walk independently, the three-muscle response was not consistent in the youngest children. The proportion of trials eliciting muscle activity continued to increase (p <.O5) after infants began to walk independently, with postural muscle activity recorded in virtually every trial by late independent walking. Thus. the automatic postural response elicited during stance was shown to begin with activity in single or paired muscles, followed by activation of the postural muscles in functional synergies. These data illustrate the progressive development of an effective sensory-motor organization.  相似文献   
49.
A molar theory of reinforcement schedules   总被引:16,自引:16,他引:0       下载免费PDF全文
Behavior of subjects exposed to concurrent and individual interval and ratio schedules of reinforcement may be described in terms of a set of expressions relating the value of responses to their durations, a feedback equation relating reinforcement to response duration, and the assumption that subjects allocate their time among various responses so as to maximize value.  相似文献   
50.
词典是知识的宝库。衡量词典的好坏,要看它是否完全反映了研究工作业已达到的水平。因为词典通常有很大的实用范围,所以就迫切需要对它现有的内容作出评价和分析。哲学以及作为哲学的一个分支的、研究一定社会历史阶段的道德行为和相应的道德观念的伦理学,乃是阶级利益在理论上的表现。可是,伦理学词典的编辑者却否定了这个观点。他们忠实于资产阶级伦理学的传统。编者O.霍弗是威尔茨堡大学哲学系教授。他对伦理学问题之所以越来越感兴趣,是因为他想把他的伦理学词典变成为“一个传播知识、同时作出评论的‘建议者”’(第6页)。他认为,当前人们之所以急剧地转向于对个人、社会和政治生活的伦理学问题的讨论,是有各种各样原因的。他认为这些  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