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   46605篇
  免费   1915篇
  国内免费   18篇
  2020年   538篇
  2019年   664篇
  2018年   936篇
  2017年   982篇
  2016年   1007篇
  2015年   698篇
  2014年   852篇
  2013年   3596篇
  2012年   1527篇
  2011年   1548篇
  2010年   990篇
  2009年   921篇
  2008年   1380篇
  2007年   1360篇
  2006年   1212篇
  2005年   1068篇
  2004年   999篇
  2003年   940篇
  2002年   974篇
  2001年   1494篇
  2000年   1424篇
  1999年   1071篇
  1998年   465篇
  1997年   443篇
  1996年   423篇
  1995年   432篇
  1992年   903篇
  1991年   831篇
  1990年   871篇
  1989年   773篇
  1988年   808篇
  1987年   747篇
  1986年   752篇
  1985年   691篇
  1984年   643篇
  1983年   577篇
  1982年   450篇
  1979年   693篇
  1978年   477篇
  1977年   428篇
  1975年   573篇
  1974年   629篇
  1973年   678篇
  1972年   528篇
  1971年   511篇
  1970年   455篇
  1969年   518篇
  1968年   620篇
  1967年   543篇
  1966年   477篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Postpartum and lactational estrus: a comparative analysis in rodentia   总被引:1,自引:0,他引:1  
Virgin rodents exhibiting cycling estrus have traditionally been used for comparative studies of reproductive behavior. However estrus occurs in other life-history contexts, some of which differ from cycling estrus (CE) in that (a) the female is disposed to behave both maternally and sexually and (b) they result in litter overlap (i.e., the simultaneous gestation and lactation of two litters). In this report, two of these other modes of estrus are examined, with emphasis on their evolutionary and ecological implications. By means of a literature search of the order Rodentia, postpartum estrus (PPE) and lactational estrus (LE) were documented in 15 families, 71 genera, and 141 species. Analysis of these data showed that PPE and LE were nonrandomly distributed across taxa. They were statistically overrepresented in the family Cricetidae and underrepresented in squirrels (Sciuridae) and in pocket mice and kangaroo rats (Heteromyidae). Analysis of the phenotypes by which PPE and LE are achieved suggests important differences between them and CE in several parameters of female reproductive effort and breeding strategy, including maternal and copulatory behavior, optimal timing of litters, and hormonal control of heat and lactation.  相似文献   
942.
943.
The traditional concept of belief is analyzed and compared with a behavior analytic concept of belief. Beliefs and belief statements are differentiated and relationships between them are examined. The often troublesome inconsistencies in people's beliefs are examined in general and explained, including the phenomena of compartmentalization and repression. Social implications are pursued relative to both punishment for inconsistency in belief and counter-controls thwarting such punishment. The role of teachers in shaping beliefs is analyzed, and appropriate teaching strategies are reviewed.  相似文献   
944.
The author focuses on the trend in the family therapy field toward an expanded view of families in the context of their social environments. Within this broader eco-system perspective attention is given to individual-family-social network interrelations with implications for the family therapist.An earlier version of this paper was presented at the American Association for Marriage and Family Therapy, Dallas, Texas, October 29, 1982. Appreciation is expressed to Alice Lynn for her comments and suggestions on an earlier draft of this paper. The author has also benefitted from discussions with Douglas Sprenkle on paradigms and contexts.  相似文献   
945.
This investigation was designed to ascertain the effects of instructions, criterion setting, and the presence of tangible rewards on the self-reinforcement process. Fifty-two third- and fourth-grade subjects were assigned to one of four treatment groups: (a) stringent instructions/criterion setting/tangible reward, (b) stringent instructions/criterion setting/no tangible reward, (c) nonstringent instructions/criterion setting/tangible reward, and (d) nonstringent instructions/no tangible reward. In the stringent-instruction conditions, subjects received social reinforcement for selecting stringent performance criteria, whereas in the non-stringent-instruction conditions, social reinforcement was withheld. Subjects in the tangible-reward groups were allowed to select a prize following the successful completion of their self-selected work performance. Subjects in the no-tangible-reward groups received no prizes for their work. All subjects performed an arithmetic task in which the number of correct problems completed, number of problems attempted, and time at task served as dependent variables across five reinforcement and two extinction trials. The results suggest that the condition of stringent instructions, criterion setting, and tangible reward was more effective in producing behavior change than the other three conditions. Perceived task difficulty and previous achievement on arithmetic task performance were shown to affect criteria selected and mathematical performance. The results are discussed in light of the contributory role of instructions, criterion setting, and tangible rewards on the self-reinforcement procedure.This study is based on a doctoral dissertation submitted to the Faculty of Arts and Sciences at the University of Pittsburgh by Helen L. Evans. Dr. Russell T. Jones was the dissertation committee chairperson. It was partially funded by an American Psychological Association Minority Fellowship awarded to the first author. Special thanks are extended to the committee members, Drs. Lloyd Bond, Robert Glaser, Johnny Matson, and Samuel M. Turner, for their assistance. The authors would like to thank Thomas DeVoge, Paul Karoly, and Samuel M. Turner for reading and commenting on an early draft of this study. Portions of this paper were presented at the 1982 APA convention.  相似文献   
946.
Three experiments are described which elaborate some of the conditions under which rats will contact and manipulate a periodically presented retractable lever. Experiment 1 demonstrated that (i) initial manipulative oral and manual contact with the lever was facilitated if the rat had previous experience of food delivery in the experimental chamber; (ii) persistence in contacting the lever on successive presentations was a function of whether food continued to be presented in the experimental environment; and (iii) food satiation significantly reduced the tendency of the rat to contact the lever even though an expectancy of food had previously been established under conditions of food deprivation. Experiment 2 suggested that the tendency to approach and contact the lever was in part a function of the local moment-to-moment conditional probability of food delivery. Experiment 3 found that the probability of contacting the lever was higher during presentation of an auditory CS signaling a high rate of food delivery than during stimuli signaling no food at all. These results are interpreted as suggesting that the food-signaling aspects of an appetitive CS and that CS's ability to generate signal-directed behaviors are experimentall separable properties.  相似文献   
947.
Introduction     
J. N. Mohanty 《Man and World》1984,17(3-4):241-243
  相似文献   
948.
949.
This essay explores the dynamics underlying the search for a Messiah in psychotherapy. It argues that the disenchantment with one's Messiah emerges primarily from the confrontation with multiple messiahs, and hence, the personal crisis of relativism. The nature of this personal crisis is investigated through the developmental scheme of William Perry. Suggestions are made as to how pastoral counselors can help those struggling with the problem of relativism.The Southeastern Illinois Center for Pastoral Counseling is located at 100 South Church Street, Carmi, Illinois, 62821.  相似文献   
950.
Unlike earlier tests of an oversimplified version of this model, the validity of W. Mobley's (1977, Journal of Applied Psychology, 62, 237-240) original turnover model was fully investigated. Constructs that were neglected in prior studies were assessed and previously examined constructs were operationalized with more reliable measures. Measures of all constructs in Mobley's model were obtained from a survey of 192 hospital employees. Turnover data were collected a year following survey administration. Following the theoretical causal ordering of Mobley's constructs, each construct was regressed on all causally prior constructs. In general, each construct was accurately predicted by the linear combination of predictors representing its causal determinants. In the majority of instances, the best predictor of a model construct was the construct's immediate causal antecedent. Further, an alternative model was evaluated and compared with Mobley's model using path analysis.  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