全文获取类型
收费全文 | 4767篇 |
免费 | 117篇 |
国内免费 | 57篇 |
出版年
2018年 | 16篇 |
2012年 | 370篇 |
2011年 | 433篇 |
2010年 | 104篇 |
2009年 | 49篇 |
2008年 | 323篇 |
2007年 | 370篇 |
2006年 | 376篇 |
2005年 | 274篇 |
2004年 | 249篇 |
2003年 | 303篇 |
2002年 | 245篇 |
2001年 | 188篇 |
2000年 | 184篇 |
1999年 | 93篇 |
1998年 | 31篇 |
1997年 | 23篇 |
1996年 | 17篇 |
1995年 | 15篇 |
1994年 | 28篇 |
1993年 | 24篇 |
1992年 | 25篇 |
1991年 | 31篇 |
1990年 | 41篇 |
1989年 | 43篇 |
1988年 | 47篇 |
1987年 | 41篇 |
1986年 | 35篇 |
1985年 | 47篇 |
1984年 | 23篇 |
1983年 | 36篇 |
1982年 | 25篇 |
1981年 | 29篇 |
1979年 | 15篇 |
1978年 | 21篇 |
1965年 | 26篇 |
1964年 | 17篇 |
1963年 | 16篇 |
1959年 | 25篇 |
1958年 | 71篇 |
1957年 | 74篇 |
1956年 | 52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4941条查询结果,搜索用时 15 毫秒
61.
在今天这个已变得如此狭小的世界上,我们所面临的全球性问题,尤其是核灾难对人类的威胁,要求在各民族之间建立起一种理性的共存格局。从现实主义角度来看,用理性来协调人们的行为举止,不是由于其自身,而是由于明显的物质方面的生存危机,今天具有前所未见的发展机遇。最迟自十八世纪启蒙运动开始,科学已经被看作是最佳的理性 相似文献
62.
63.
Effects of differences between stimuli, responses, and reinforcer rates on conditional discrimination performance 总被引:5,自引:5,他引:0 下载免费PDF全文
In a discrete-trial conditional discrimination procedure, 4 pigeons obtained food reinforcers by pecking a key with a short latency on trials signaled by one stimulus and by pecking the same key with a long latency on trials signaled by a second stimulus. The physical difference between the two stimuli and the temporal separation between the latency values required for reinforcement were varied factorially over four sets of conditions, and the ratio of reinforcer rates for short and long latencies was varied within each set of conditions. Stimulus discrimination varied directly with both stimulus and response differences and was unaffected by the reinforcer ratio. Sensitivity to reinforcement, estimated by generalized-matching-law fits to the data within each set of conditions, varied directly with the response difference but inversely with the stimulus difference arranged between sets of conditions. Because variations in stimulus differences, response differences, and reinforcer differences did not have equivalent effects, these findings question the functional equivalence of the three terms of the discriminated operant: antecedent stimuli, behavior, and consequences. 相似文献
64.
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
65.
66.
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
67.
Ethical issues in pediatric life-threatening illness: dilemmas of consent, assent, and communication
Kunin H 《Ethics & behavior》1997,7(1):43-57
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
68.
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
69.
禁地,亦即指由于地形原因而不可进入的地区,尤其是指出于政治、宗教或其他动机而作出的决策所禁止入内的区域(场所、城市、国家)。禁地往往蒙上了一种神秘的气氛.几乎必然会引起人们的好奇。到达拉萨曾是几代探险家的梦想。这一地区不仅对外人封闭,而且对“内部人”也封闭:任何人不得离开“外出”。德川幕府对日本实行的隔绝就是这样一种双向隔离。当然.地理条件也有助于这种隔离,因而使之轻易地付诸实行。有人指出(或许这种说法不够严肃).举世闻名的中国长城不仅意味着防范匈奴入侵,更意味着防止中国人逃离。史料也表明中国过… 相似文献
70.
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