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   33083篇
  免费   675篇
  国内免费   8篇
  33766篇
  2020年   348篇
  2019年   455篇
  2018年   596篇
  2017年   565篇
  2016年   612篇
  2015年   446篇
  2014年   561篇
  2013年   2561篇
  2012年   980篇
  2011年   1102篇
  2010年   651篇
  2009年   651篇
  2008年   862篇
  2007年   872篇
  2006年   795篇
  2005年   667篇
  2004年   683篇
  2003年   640篇
  2002年   638篇
  2001年   1102篇
  2000年   1155篇
  1999年   781篇
  1998年   376篇
  1997年   323篇
  1996年   300篇
  1995年   288篇
  1992年   612篇
  1991年   589篇
  1990年   616篇
  1989年   589篇
  1988年   569篇
  1987年   504篇
  1986年   532篇
  1985年   544篇
  1984年   422篇
  1983年   403篇
  1982年   280篇
  1979年   433篇
  1978年   372篇
  1977年   277篇
  1975年   391篇
  1974年   477篇
  1973年   453篇
  1972年   421篇
  1971年   378篇
  1970年   307篇
  1969年   380篇
  1968年   440篇
  1967年   390篇
  1966年   377篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
911.
Conclusion In contemporary work, the distinction between the proposition expressed by a sentence and its psychological significance is usually motivated by a familiar kind of counterfactual argument; and the discussion of these issues usually centers around the role of external factors in determining the meaning of our words. My primary goal in this paper has been to show that a similar, though not identical, distinction between two aspects of meaning can be developed entirely on the basis of considerations internal to language users — their cognitive limitations. To make this point, I have focused on symbols introduced through stipulative definitions. In a language containing such symbols, certain expressions and their definitional reductions will seem to differ in psychological significance for creatures with limited intellects, and so in any aspect of meaning that is supposed to correlate with psychological significance; but it seems also that there is some important aspect of meaning that they share.I have argued that a distinction in meaning like this — between sense and psychological significance — should be drawn even in the kind of languages of most concern to Frege, and that his failure to do so led to tensions in his thought. Of course, this observation only touches on the many issues involved in interpreting Frege's theory of definition more generally. I have not tried to describe here, for example, the ways in which the weak interpretation of fruitfulness might interact with the more robust interpretation mentioned earlier; I have only mentioned Frege's view on explicative definitions and the paradox of analysis, and failed even to mention either his treatment of contextual definition, or his peculiar objections to conditional definitions. I do want to emphasize, however, that the distinction drawn here is not simply a matter of Frege scholarship, but that it has some contemporary relevance as well. As we have seen, Frege's semantic goals often coincide with our own; and a number of contemporary writers are explicitly concerned, like Frege, to construct a semantic theory that is able to account for differences in meaning among logically equivalent expressions. Any such theorist should recognize a distinction like that drawn here between sense and psychological significance, and should avoid subjecting an account of one notion to constraints appropriate only for the other.  相似文献   
912.
Considerable evidence has accumulated in support of the hypothesis that subclinical depression may inhibit role performance in important ways. However, interpersonal stress and marital discord often precede the development of depressive symptomatology and may independently predict deficits in family role functioning. In addition, cognitive theories suggest that persons with subclinical depression may report poor role functioning even in the absence of any real performance deficits. The current research examines the possibility (1) that the effect of depression on the fulfillment of important family roles is attributable to previously unmeasured contextual variables of ongoing interpersonal stress and/or relationship dissatisfaction or, alternatively, (2) that this relationship is the result of depressive distortion associated with self-report of symptoms and performance. Multiple regression analyses of interview data collected from 495 community-dwelling adults found, however, that depression is related to role functioning beyond any spurious effects attributable to interpersonal stress, spousal stress, or marital satisfaction. In addition, the effect of depression persists when collateral reports of role functioning utilized. Accordingly, it appears that subclinical depression is related to decrements in role performance, and this effect is not entirely due to contextual elements or shared method variance between self-report measures.The authors acknowledge research support from Research Grants R01-AA-07250 and R01-AA-07218 from the National Institute on Alcohol Abuse and Alcoholism, Research Grant R01-DA-07417 from the National Institute on Drug Abuse, and National Institutes of Mental Health Grant A-41487-07.  相似文献   
913.
Pamela K. Adelmann 《Sex roles》1993,29(3-4):195-212
Social roles have been a central focus in both sociological and developmental theories of adjustment in late life. Research on roles and well-being, however, has focused on earlier adulthood or on comparisons of tenuous roles (such as retiree) with institutional roles (such as employee), especially among men. The few studies comparing older women in the tenuous roles of homemaker and retiree all compare single-role women, and show contradictory results. One possibility is that multiple role identities are linked to greater well-being in older women, as they are among younger women. In this paper the life satisfaction, depression, and self-esteem of older women who consider themselves retired only, homemakers only, or both are compared. The sample includes 864 Black (N=242) and White (N=622) women ages 60 and over from a 1986 national survey. Retired women and homemakers did not differ in well-being; women who called themselves both had higher self-esteem and lower depression than single-role women. In analyses exploring what tenuous role content (daily activities) might explain group differences in well-being, do-it-yourself activities and volunteer activities were significant. Age, education, health, and marital status were also important factors. Recommendations include adopting a multiple role perspective with older women and encouraging their participation in instrumental, informal role activities to maximize well-being.Northwestern University  相似文献   
914.
The continuing controversy surrounding the Tarasoff inspired duty to protect as developed by the courts and legislatures has not adequately weighed the jurisprudential foundations of such an obligation. The authors argue that the duty's misguided thrust of social control grounded in character and status seriously violates broad principles of political morality underlying the law of social control. They conceptualize an alternative--a clinical duty to protect--that coheres with these underlying values and the limits of professional abilities. They contend that any extra-clinical intervention on the part of the psychotherapist entails a role transformation requiring independent justification.  相似文献   
915.
In this paper, we applied the behavioral-economic concept of unit price to the study of reinforcer magnitude in an attempt to provide a consistent account of the effects of reinforcer magnitude on behavior. Recent research in the experimental analysis of behavior and in behavioral pharmacology suggests that reinforcer magnitude interacts with the schedule of reinforcement to determine response rate and total consumption. The utility of the unit-price concept thus stems from its ability to quantify this interaction as a cost-benefit ratio (i.e., unit price = characteristics of the schedule of reinforcement divided by magnitude of reinforcement). Research employing the unit-price concept has shown that as unit price increases, a positively decelerating function exists for consumption (i.e., a function with an increasingly negative slope, when plotted on log coordinates) and a bitonic function exists for response rate. Based on these findings, the present analysis applied the unit-price concept to those studies of reinforcer magnitude and drug self-administration that examined the effects of reinforcer magnitude on response rate using simple schedules of reinforcement (e.g., fixed-ratio schedule). This resulted in three findings: (a) Reinforcer-magnitude manipulations and schedule manipulations interact in a manner that can be quantified in terms of unit price as benefit and cost factors, respectively; (b) different reinforcer-magnitude manipulations are functionally interchangeable as benefit factors in the unit-price ratio; and (c) these conclusions appear warranted despite the differences in reinforcers (food or drug), species (dogs, monkeys, or rats), and schedules (interval or ratio), and despite the fact that these studies were not designed for a unit-price analysis. In methodological terms, these results provide further evidence that employing the unit-price concept is a parsimonious method for examining the effects of reinforcer magnitude. In theoretical terms, these results suggest that a single process may underlie the effect of combined reinforcer-magnitude and schedule manipulations.  相似文献   
916.
917.
Analyses of biological concepts of disease and social conceptions of health indicate that they are structurally interdependent. This in turn suggests the need for a bridge theory of illness. The main features of such a theory are an emphasis on the logical properties of value terms, close attention to the features of the experience of illness, and an analysis of this experience as action failure, drawing directly on the internal structure of action. The practical applications of this theory are outlined for a number of problems in each of the three main practical areas, clinical work, teaching and research. In each case the resources of the theory suggest new models and generate new results. The full practical significance of the theory, however, is shown to consist in the way in which it ties together biological and social theories into an integrated picture of the conceptual structure of medicine as a whole. It is argued, finally, that practical efficiency of this kind is a test of theory not only in the philosophy of medicine but also in general philosophy.  相似文献   
918.
A study of 152 adolescents enrolled in school-based programs for pregnant and parenting youth in Colorado in 1987-88 found no differences in overall stress levels between these two groups; however, salient predictors of stressful life events for pregnant teens were not the same as those for teen mothers. The mean age of study subjects was 16.5 years (range 14-19 years); most were living with a parent rather than the child's father. The dependent variable, level of stress, was measured through use of an abbreviated Life Events Questionnaire. Independent variables were assessed through administration of the Inventory of Social Supportive Behaviors, Rosenberg Self-Esteem Scale, and the Adolescent Coping Orientation for Problem Experiences scale. Of the 5 sources of stress measured (family, accidents, autonomy, deviance, relocation, and distress), only stress related to accidents differed significantly between pregnant and parenting adolescents. For pregnant adolescents, self-esteem was the only significant predictor of the overall level of stress; among parents, the only significant predictor was objective social support. Among adolescents, self-esteem was associated with more frequent use of social support and coping strategies. For parenting adolescents, self-esteem was correlated with the frequency of use of social support, satisfaction resulting from such use, and frequent use of coping strategies. Overall, the independent variables of social support, self-esteem, coping, and age were stronger predictors of stress in pregnant than in parenting adolescent females. This finding suggests that parenting teens may have successfully negotiated the multiple transitions involved in this new stage of the life-cycle. An important implication of this study is the need to design separate counseling components of school-based programs for pregnant versus parenting adolescents rather than to use a single curriculum.  相似文献   
919.
The present experiment examined the shape of the attentional gradient in three-dimensional space. Subjects performed a response-compatibility task in which they were instructed to respond to a centrally located target and ignore flanking distractors. The irrelevant distractors were presented at combinations of seven different depths, three different horizontal separations, and three different vertical separations relative to the target. Depth was varied in a stereoscopic display viewed through polarized glasses. Overall, the size of the response-compatibility effect decreased with increased separation in all three dimensions. Interestingly, the response-compatibility effect was larger for horizontal separations than for vertical separations and was larger for crossed disparities than for uncrossed disparities. The results suggest an elliptical focus of attention, with steeper gradients in the vertical dimensions than in the horizontal dimensions. In addition, the results suggest, along the vertical dimension, a steeper gradient for objects located beyond the focus of attention relative to that for objects located between the observer and the focus of attention.  相似文献   
920.
The present study compared the ability of novice divers to apply decompression tables having learnt how to use them in either the same or a different environment. Those subjects who had learnt how to use the tables in a different environment (i. e. had learnt on dry land and were tested underwater or vice-versa) performed on average 64 percent worse than those who had the same environment for both learning and test. This effect could not be ascribed to the disruption brought about by changing environments. The results show that contextual effects on memory extend beyond the recall of word lists (Godden and Baddeley, 1975) to the ability to implement potentially important instructions.  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