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   55719篇
  免费   1954篇
  国内免费   19篇
  57692篇
  2018年   829篇
  2017年   826篇
  2016年   906篇
  2015年   626篇
  2014年   775篇
  2013年   4896篇
  2012年   1416篇
  2011年   1497篇
  2010年   948篇
  2009年   902篇
  2008年   1349篇
  2007年   1255篇
  2006年   1168篇
  2005年   1004篇
  2004年   985篇
  2003年   985篇
  2002年   993篇
  2001年   1764篇
  2000年   1705篇
  1999年   1310篇
  1998年   604篇
  1996年   654篇
  1995年   612篇
  1994年   618篇
  1993年   606篇
  1992年   1269篇
  1991年   1145篇
  1990年   1164篇
  1989年   1059篇
  1988年   1043篇
  1987年   1029篇
  1986年   1031篇
  1985年   1035篇
  1984年   874篇
  1983年   749篇
  1982年   591篇
  1981年   595篇
  1979年   893篇
  1978年   676篇
  1976年   576篇
  1975年   828篇
  1974年   833篇
  1973年   883篇
  1972年   819篇
  1971年   730篇
  1970年   658篇
  1969年   704篇
  1968年   832篇
  1967年   721篇
  1966年   719篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
961.
Recent studies have provided strong support for the convergent validity of the General Behavior Inventory (GBI), a case identification inventory for chronic subsyndromal affective disorders (cyclothymia and dysthymia). Fewer data are available, however, on the ability of the GBI to distinguish chronic subsyndromal affective disorders from other forms of psychopathology. In order to address this issue, outpatients with cyclothymia (n = 9), dysthymia (n = 26), nonchronic major depression (n = 16), and nonaffective psychiatric disorders (n = 30) were compared on the GBI. Diagnoses were derived blind to GBI scores using structured diagnostic interviews and DSM-III criteria. The inventory significantly discriminated cyclothymes and dysthymes from patients with nonchronic major depressions and nonaffective disorders. Using the cutoff score that maximized GBI-diagnosis concordance, the inventory correctly classified 88% of the sample. All of the cyclothymes, 92% of the dysthymes, 87% of the patients with nonaffective psychiatric disorders, and 75% of the nonchronic major depressives were correctly classified by the inventory. These data provide strong support for the discriminant validity of the GBI.  相似文献   
962.
The study of adolescent sexual development has typically focused on the incidence and age of onset of particular behaviors. Recent developments in the analysis of covariance structures permit more powerful simultaneous tests of the determinants of adolescent sexual behavior. These new methods allow the assessment and evaluation of the interrelatedness between unobserved, latent constructs. Data were obtained from 183 males and 193 females ranging in age from 12 to 18 years old, selected from three birth cohorts using a stratified random sample. Eight latent constructs--Sexual and Dating Involvement, Self-Acceptance, Feminist Sex Role Attitudes, Deviant Social Network, Importance of Dating, Lack of Heterosexual Competence, Sexually Active Social Network, and Stressful Change Events--were hypothesized to explain the variance in 26 observed variables. Several causal models were tested that specified structural relationships among the latent constructs. A theoretically meaningful model was arrived at that linked the eight, error-free factors.  相似文献   
963.
On the basis of a self-validation perspective, it was predicted that distortions in consensus estimates would vary as a function of attribute type (opinions versus abilities), relevance of the attribute, and individual differences in self-esteem and depression. Students rated themselves on seven opinion and ability dimensions using 5-point Likert scales. Then they estimated the percentage of the other students who held each opinion/ability position, and rank ordered the opinions/abilities for personal relevance. Absolute and directional accuracy scores were computed (comparing estimated percentages with actual percentages in the sample), as well as false consensus (FCE) scores (comparing estimates of subjects holding and not holding a particular position). Subjects overestimated consensus for their opinions and low abilities, but underestimated consensus for their high abilities. Although subjects exhibited a larger FCE on opinions than abilities, there was a reliable FCE for both attributes. Relevance affected the magnitude of these biases. Higher opinion relevance was associated with increased accuracy, lower FCE scores, and smaller overestimates. Higher ability relevance was associated with decreased accuracy, greater overestimation on low abilities, and greater underestimation on high abilities. Finally, low self-esteem and depressed subjects overestimated consensus on opinions and underestimated consensus on abilities less than high self-esteem and nondepressed subjects.  相似文献   
964.
Four pigeons were trained on a multiple variable-interval 30-s extinction schedule with various pairs of spoken English words presented as the discriminative stimuli. The birds typically produced discrimination indices of 70% to 90% accuracy. Discrimination accuracy was improved by shortening the interval between auditory stimulus presentations, and by increasing the number of syllables in the words.  相似文献   
965.
It has been suggested that the failure to maximize reinforcement on concurrent variable-interval, variable-ratio schedules may be misleading. Inasmuch as response costs are not directly measured, it is possible that subjects are optimally balancing the benefits of reinforcement against the costs of responding. To evaluate this hypothesis, pigeons were tested in a procedure in which interval and ratio schedules had equal response costs. On a concurrent variable time (VT), variable ratio-time (VRT) schedule, the VT schedule runs throughout the session and the VRT schedule is controlled by responses to a changeover key that switches from one schedule to the other. Reinforcement is presented independent of response. This schedule retains the essential features of concurrent VI VR, but eliminates differential response costs for the two alternatives. It therefore also eliminates at least one significant ambiguity about the reinforcement maximizing performance. Pigeons did not maximize rate of reinforcement on this procedure. Instead, their times spent on the alternative schedules matched the relative rates of reinforcement, even when schedule parameters were such that matching earned the lowest possible overall rate of reinforcement. It was further shown that the observed matching was not a procedural artifact arising from the constraints built into the schedule.  相似文献   
966.
A meeting of Psychologists Against Tough-Hearted and Offensive Scientists (PATHOS) was convened to redress the damage done by judgment researchers who have degraded the art of clinical decision making. A special task force drafted a rebuttal and mission statement, which is presented in its entirety.  相似文献   
967.
The fear of success is typically interpreted as a neurosis in which the fear of change plays a central role. In spite of agreeing with the existence of this syndrome in clinical practice. this author holds that a similar ambivalence about change lurks within ourselves as well. We are especially like patients in that, in spite of their often unique conflicts, they also run away, like us, from true success. In defining the latter, the author interprets it as synonymous with living an ethical life filled with reverence and respect for all.Grateful acknowledgement is made to Stephen Getsinger, Ph.D., for having read and made numerous cogent remarks on this paper.  相似文献   
968.
This paper is a general survey of ethical issues related to the artificial heart. It begins by looking at the history of funding of the artificial heart program through the National Institute of Health in 1965. Attention is paid to the problem of the lack of planning related to social, ethical, economic, and legal implications. The paper then deals with three areas of ethical concerns. They are those issues relating to the experimental versus therapeutic benefits, the cost, and public involvement with a private interest.  相似文献   
969.
Criterion-related validity data for the Child Behavior Checklist—Teacher's Report Form are presented. These data were collected from a sample of elementary school boys. A total behavior problem score and individual factor scores were calculated from the checklist data and were related to indices of academic achievement and overall adjustment in the classroom. Significant correlations were established between the two sets of scores. The results were interpreted as supporting the criterion-related validity of the teacher-judgment measure and its use as a screening or diagnostic device in the school.  相似文献   
970.
Three untested assumptions of the impulse-variability model were examined in two experiments utilizing rapid, uni-planar limb movements. Experiment 1 varied movement distance (A) and movement time (MT) in a rapid-timing paradigm where the subject moved a lever through a certain distance in a certain time. Experiment 2 varied A in a reversal response where the S made a rapid elbow flexion and extension in a given MT. Displacement recordings were made on every trial. KR (knowledge of results) about MT was given after every trial. The results can be summarized as follows: (a) As predicted by the model, variations in impulse size and velocity were directly related to the impulses size; (b) There was no correlation between the accelerative and decelerative impulse durations recorded during the reversal response supporting the notion that the impulses might be independent; (c) Negative correlations (-.20 to -.50) were demonstrated between peak acceleration and impulse duration for both experiments, counter to the predictions of the model; and (d) Counter to the predictions of the model, timing error (VEt) increased as A decreased for rapid-timing responses. When the correlational results are taken into account, the model has the capacity to account for curvilinear relationships between relative timing error and movement speed. Overall, the results suggest that the impulse variability model requires some restructuring before it can be considered a viable model for the control of rapid limb movements.  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