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   76964篇
  免费   3098篇
  国内免费   31篇
  2020年   827篇
  2019年   980篇
  2018年   1427篇
  2017年   1426篇
  2016年   1525篇
  2015年   1077篇
  2014年   1329篇
  2013年   6344篇
  2012年   2424篇
  2011年   2486篇
  2010年   1529篇
  2009年   1530篇
  2008年   2203篇
  2007年   2117篇
  2006年   1968篇
  2005年   1658篇
  2004年   1691篇
  2003年   1629篇
  2002年   1608篇
  2001年   2410篇
  2000年   2267篇
  1999年   1741篇
  1998年   858篇
  1997年   778篇
  1996年   818篇
  1995年   753篇
  1994年   717篇
  1992年   1481篇
  1991年   1379篇
  1990年   1346篇
  1989年   1287篇
  1988年   1270篇
  1987年   1196篇
  1986年   1224篇
  1985年   1257篇
  1984年   1049篇
  1983年   907篇
  1979年   1117篇
  1978年   856篇
  1976年   719篇
  1975年   892篇
  1974年   1053篇
  1973年   1108篇
  1972年   914篇
  1971年   870篇
  1970年   783篇
  1969年   805篇
  1968年   983篇
  1967年   890篇
  1966年   873篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
952.
Three experiments were conducted with adult male Meriones unguiculatus in an attempt to demonstrate that ventral scent marking can act to transfer body heat to the object marked. Experiment 1 showed that surgical removal of the ventral gland pad reduced the amount of heat transferred by 50%, even though intact and glandless animals did not differ in the average frequency of scent marking. Experiment 2 demonstrated that the difference in heat transfer due to the presence or absence of the scent pad was not due to differential pressure applied to the substrate during marking. Experiment 3 showed that the pattern of ventral hair spread that occurs as an animal moves over an object is different between intact and glandless animals but that this difference does not account for the difference in heat transfer. It is suggested that heat transfer to the environment with ventral scent marking may increase thermoregulatory competence and also may function to volatilize sebum used in chemocommunication.  相似文献   
953.
Two adult male chimpanzees reached through a hole in the wall of their home cage and, by tracking the images of their hands and of an otherwise hidden target object in a mirror or closed-circuit television picture, moved their hands in whichever direction was necessary to make contact with the target object. They discriminated between live video images and tapes and performed effectively when the target objects were presented in novel locations and when the video picture was presented at random in different orientations. There was thus no consistent relation between the location of images on the monitor and the location of their real-world counterparts. Comparable performances in monkeys and nonprimates seem unlikely.  相似文献   
954.
Bornstein’s hypothesis that there is a loss of color discrimination in tropical areas was not supported in earlier research in the Cook Islands. Using a more sensitive color vision test (the Farnsworth-Munsell 100-Hue Test), a loss of color discrimination in the red-purple and blue-green regions of the spectrum was found. The lack of sex differences in this color discrimination loss supports a physiological rather than a genetic explanation of the observed decrement.  相似文献   
955.
Reactions to published accounts of research with human subjects, as well as research with nonhuman subjects, were assessed by examining citations in several samples of empirical articles in the Journal of the Experimental Analysis of Behavior. A stable, asymmetrical pattern emerged: Nonhuman research was cited in both human and nonhuman articles, but human research was cited primarily in human articles. Thus, human operant research appears to have had little influence on the nonhuman research which constitutes the bulk of the experimental analysis of behavior. Interpretation of this lack of impact depends on the functions one envisions for human research, several of which are discussed.  相似文献   
956.
Due to the death of a severely disabled infant from Bloomington, Indiana, a series of events set in motion by the U.S. Department of Health and Human Services has resulted in cautions to health care providers. The resulting policies and procedures warn hospital personnel against withholding nutritional sustenance or medical treatment from severely disabled infants. This article presents dimensions that might serve as a background for counselors to assist families in considering options related to disabled infants. These dimensions include the meaning of life, cost to benefit ratio, medical options, legal precedent, and a theological perspective. This issue is related to counseling practice through counselor ethics, values, and the need for information that counselors can provide to parents during the decision process.  相似文献   
957.
958.
Previous findings indicate that Norway rats (Rattus norvegicus) respond differentially to estrous chemostimuli in early infancy and that adult male sexual responsiveness to such chemostimuli depends on infantile experience with suckling odors (Fillion & Blass, in press). The development of behavioral responsiveness to estrous chemostimuli in male rats from late infancy to adulthood was examined in this study. Preweanling, adolescent, and adult males were observed for 20 min in the presence of an anesthetized estrous or an anesthetized diestrous female. This was, for adolescent and adult subjects, the first heterosexual encounter since weaning. Rats in each age-group responded differentially according to female state, but in distinct, age-related ways. Preweanling spent more time investigating the female's body if she was estrous. Adults expressed the same affinity but by more focused investigation directed perivaginally. Adolescents showed no female-directed bias but groomed themselves more if the female was estrous. These data identify developmental continuities and discontinuities in male rat behavior toward sexually receptive females.  相似文献   
959.
Catastrophe theory is a new mathematical science that permits some insight into the way in which sudden changes or discontinuities of behavior may occur even though the underlying causative forces are essentially continuous. This article aims to present a nonmathematician’s view of catastrophe applications in clinical psychology. Areas covered include anorexia nervosa, binge eating and drinking, affective disorders, schizophrenia, aggressiveness, and prison disturbances. Where appropriate, therapeutic implications and possible physiological correlates are offered. Examples are given of catastrophe theory’s ability to explain previously inexplicable findings. Attention is drawn to its refutability and predictive value, and hence its scientific respectability.  相似文献   
960.
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