全文获取类型
收费全文 | 77177篇 |
免费 | 3130篇 |
国内免费 | 27篇 |
专业分类
80334篇 |
出版年
2020年 | 723篇 |
2019年 | 959篇 |
2018年 | 1299篇 |
2017年 | 1376篇 |
2016年 | 1465篇 |
2015年 | 1054篇 |
2014年 | 1230篇 |
2013年 | 5875篇 |
2012年 | 2263篇 |
2011年 | 2436篇 |
2010年 | 1526篇 |
2009年 | 1502篇 |
2008年 | 2105篇 |
2007年 | 2168篇 |
2006年 | 1955篇 |
2005年 | 1739篇 |
2004年 | 1640篇 |
2003年 | 1551篇 |
2002年 | 1663篇 |
2001年 | 2480篇 |
2000年 | 2426篇 |
1999年 | 1855篇 |
1998年 | 867篇 |
1997年 | 773篇 |
1996年 | 804篇 |
1995年 | 701篇 |
1992年 | 1576篇 |
1991年 | 1478篇 |
1990年 | 1448篇 |
1989年 | 1323篇 |
1988年 | 1324篇 |
1987年 | 1248篇 |
1986年 | 1317篇 |
1985年 | 1356篇 |
1984年 | 1121篇 |
1983年 | 1030篇 |
1982年 | 737篇 |
1981年 | 735篇 |
1979年 | 1207篇 |
1978年 | 868篇 |
1975年 | 986篇 |
1974年 | 1103篇 |
1973年 | 1216篇 |
1972年 | 997篇 |
1971年 | 952篇 |
1970年 | 875篇 |
1969年 | 866篇 |
1968年 | 1127篇 |
1967年 | 1023篇 |
1966年 | 873篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
891.
Shettleworth SJ 《Journal of the experimental analysis of behavior》1985,44(2):139-155
According to optimal foraging theory, animals should prefer food items with the highest ratios of energy intake to handling time. When single items have negligible handling times, one large item should be preferred to a collection of small ones of equivalent total weight. However, when pigeons were offered such a choice on equal concurrent variable-interval schedules in a shuttlebox, they preferred the side offering many small items per reinforcement to that offering one or a few relatively large items. This preference was still evident on concurrent fixed-cumulative-duration schedules in which choosing the alternative with longer handling time substantially lowered the rate of food intake. 相似文献
892.
893.
M J Howes J E Hokanson D A Loewenstein 《Journal of personality and social psychology》1985,49(4):1110-1113
Scores on the Beck Depression Inventory (BDI) were periodically obtained from the roommates of college students who exhibited a persistent mild depression over a 3-month period. For comparative purposes, BDI scores were also obtained from roommates of individuals who were transiently depressed and from subjects with nondepressed roommates. In comparison with control subjects, the roommates of persistently depressed persons displayed a progressive increase in BDI score over the course of the study. 相似文献
894.
895.
896.
K J Zerbe 《Psychoanalytic review》1985,72(2):301-314
The foot is a highly cathected appendage that is commonly singled out as the brunt of humorous or derisive remarks, as if it embodies repugnance and disgust. Attitudes toward the foot are overdetermined, bearing the imprint of man's early linguistic patterns and individual dynamics. This article suggests that feet are symbolic because they bear the feelings derived from earlier separations, good and bad object representations, collective memories, and genital representations. The foot's role as symbol of both the male and female genitals, repository of badness, symbol of passivity, initiator of movement, and site of self-mutilation have been briefly reviewed. As Fats Waller rhapsodizes that the "feet's too big," he finds a convenient way to displace his symbiotic and erotic anxieties vis-à-vis women. Similarly, patients who come for psychiatric treatment and psychotherapy frequently make references to their feet or use them in specific ways. An understanding of this type of communication can often provide insight into individual dynamics and enhance treatment. The weight placed on these communications depends, of course, on the vicissitudes of the previous therapeutic work as well as on the particular problems of the patient. 相似文献
897.
898.
899.
Thirty preschool children, 10 each at the 3-,4-, and 5-year-old levels, participated in two structured tasks designed to assess both comprehension and production of a full range of directive forms. In contrast to previous reports, the results indicated no significant differences in directive comprehension or production as a function of age; children in all age groups demonstrated the ability to understand and verbally encode the intent of most types of directive forms. However, the two most implicit forms, Question Directives and Hints, were complied with significantly less frequently than the more explicit forms, and were uused less often in the production task. The present findings indicate the importance of analyzing directive forms along a continuum of explicitness rather than dichotomizing them as direct versus indirect. Finally, the results are interpreted as providing indirect support for the general notion that mastery of some implicit forms may be achieved later than the acquisition of more explicit forms. 相似文献
900.