全文获取类型
收费全文 | 32768篇 |
免费 | 1441篇 |
国内免费 | 15篇 |
专业分类
34224篇 |
出版年
2021年 | 329篇 |
2020年 | 472篇 |
2019年 | 582篇 |
2018年 | 878篇 |
2017年 | 874篇 |
2016年 | 883篇 |
2015年 | 649篇 |
2014年 | 711篇 |
2013年 | 3053篇 |
2012年 | 1322篇 |
2011年 | 1386篇 |
2010年 | 860篇 |
2009年 | 711篇 |
2008年 | 1097篇 |
2007年 | 1079篇 |
2006年 | 935篇 |
2005年 | 844篇 |
2004年 | 712篇 |
2003年 | 704篇 |
2002年 | 713篇 |
2001年 | 868篇 |
2000年 | 842篇 |
1999年 | 636篇 |
1998年 | 310篇 |
1997年 | 268篇 |
1996年 | 301篇 |
1995年 | 257篇 |
1992年 | 519篇 |
1991年 | 507篇 |
1990年 | 489篇 |
1989年 | 446篇 |
1988年 | 470篇 |
1987年 | 420篇 |
1986年 | 418篇 |
1985年 | 440篇 |
1984年 | 356篇 |
1983年 | 303篇 |
1979年 | 397篇 |
1978年 | 299篇 |
1977年 | 254篇 |
1975年 | 315篇 |
1974年 | 386篇 |
1973年 | 401篇 |
1972年 | 315篇 |
1971年 | 307篇 |
1970年 | 303篇 |
1969年 | 264篇 |
1968年 | 363篇 |
1967年 | 321篇 |
1966年 | 294篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
181.
C B Steinberger 《Psychoanalytic review》1989,76(1):1-18
The "crossroads families" are caught between old value systems and American mainstream goals. Traditional family and sex-related roles and orientations conflict with those of the new social system. In turn, neither of the teenager's orientations--toward home or toward peer activity--is validated. In the clinical case presented, Anna, at adolescence, wants to relinquish many of her household chores and enter her social world more fully. She needs unconflictual support for such a move. If this does not take place, her autonomous movement represents an unconscious betrayal of her depleted and controlling mother as well as an abandonment of the parental coalition. This leaves her feeling resentful, guilty, and ultimately unlovable. Attitudes marked by helplessness and confusion are thus significant to the depressed affect that brings this teenager into family therapy. Teenagers of non-Hispanic background who enter family therapy reveal gross overlap with teenagers of the Hispanic "crossroads" family model. Here, the family gives mixed messages for homebound and intimate closeness as well as accomplishment in the societal mainstream. A primary difference between ethnic groups involves the freer expressions of anger and pain between husband and wife in the non-Hispanic families. This is not similar to the backgrounds of the more individuated Hispanic teenagers. While more open expressions of anger within the family do indicate higher levels of autonomy, the hostility that is expressed by the parents presents serious complications when this includes "triangulating" the child into the family tension. Here, as cited, the mother often uses her daughter as a confidant and ally at times of severe parental discord. This places additional strain on the child's conflict with separation. Importantly, the daughter experiences renewed rejection and betrayal when the mother "submits" to her spouse. These are significant family processes that heighten mixed messages around autonomy. Milagros, a depressed (more individuated) adolescent, is consistently entangled into her parent's abrasive relationship. Her interpersonal family struggles have become intrapsychic and, ultimately, transferential. 相似文献
182.
Trace mineral analysis of human hair was utilized to determine whether violent and nonviolent criminals could be differentiated on the basis of concentrations of levels of major and trace minerals. 40 violent and 40 nonviolent inmates from a prison population were selected for study. 27 mineral levels were analyzed and a discriminant function analysis correctly classified 86% of the violent and 78% of the nonviolent inmates. The results lent support to the hypothesis that significantly different levels of trace minerals could be found between the two groups. 相似文献
183.
A I Murphy P M Lehrer R Karlin L Swartzman S Hochron B McCann 《Psychological reports》1989,65(2):691-698
12 subjects from an experiment on relaxation therapy for asthma were given the Harvard Group Scale of Hypnotic Susceptibility, Form A. Full scale hypnotic susceptibility scores were positively correlated, at a borderline significance, with improvement in the methacholine challenge test, a measure of asthma severity. Performance on the amnesia item of the Harvard Group Scale was correlated with improvement in self-reported symptoms of asthma. 相似文献
184.
The continuous approach to optic-flow processing shows that the curvature of a moving surface is related to a second spatial derivative of the velocity field, the spin variation (Droulez & Cornilleau-Pérès, 1989). With this approach as a theoretical framework, visual sensitivity to the curvature of a cylinder in motion was measured using a task of discrimination between cylindrical and planar patches. The results confirm the predictions suggested by the theory: (1) Sensitivity to curvature was always greater when the cylinder axis and the frontal translation were parallel than when they were orthogonal. The ratio of curvature detection thresholds in the two cases was between 1.3 and 2.5; the value predicted from the spin variation theory is about 2. (2) Sensitivity to curvature increased strongly with the velocity of the motion but was only weakly affected by its amplitude and the duration of viewing for the range of values used in our experiments. 相似文献
185.
186.
B Bridgeman 《Perception & psychophysics》1989,46(3):220-226
When a fixation point moves under a row of identical targets at a speed of one target for each flash of a strobe, smooth apparent movement of the targets is seen (the "picket-fence illusion"). When the fixation point is removed, the eye continues to pursue the apparent target movement. Pursuit continues through small changes in target configuration, but is interrupted by a change to a very dissimilar target (such as 1 vs. x) in the middle of a row. This new method, the "pursuit-interruption method," showed that large differences in the number of pixels in a line did not interrupt tracking if the end points of the line were preserved. Pursuit interruption by changes in line orientation (such as /vs./) corresponded to the orientation bandwidth of orientation-sensitive cortical neurons. The maximum number of consecutive missing targets that does not interrupt pursuit depends on frequency of target presentation as well as on parameters of the pursuit system. 相似文献
187.
The incidence of secondary enuresis in 16 institutionalized conduct-disordered children was examined. In contrast to a control group of 16 noninstitutionalized conduct-disordered children, the former showed significantly more enuretic behaviour. Also, enuresis began within 6 mo. of the children's separation from their families, suggesting this problem is very likely related to the emotional trauma surrounding the change in living conditions. However, the small number of subjects limits further interpretation of the findings. 相似文献
188.
A model of perceptual classification in children and adults 总被引:4,自引:0,他引:4
L B Smith 《Psychological review》1989,96(1):125-144
The developmental trend from overall-similarity to dimensional-identity classifications is explained by a quantitative model. I begin with the assumption that objects are represented in terms of constituent dimensions and that the representation of objects changes little with development. Given this assumption, the model has three major parts. First, the similarity between objects is a function of the combination of the constituent dimensional differences. I propose developmental change in the likelihood that dimensions are differentially weighted in the calculation of similarity. Second, the perceived similarities between objects are valued for the purpose of constructing classifications. I propose that similarities are valued more dichotomously with age, such that identity becomes increasingly special. Third, the valued similarities are used to choose the best classification of those possible. The model provides good qualitative fits to the extant data. Three experiments examining classifications in 2- to 8-year-olds and in adults support specific new claims of the model. The data and the model provide new insights about development, classification, and similarity. 相似文献
189.
Bengt O. Muthén 《Psychometrika》1989,54(3):385-396
The problem of detecting instructional sensitivity (item basis) in test items is considered. An illustration is given which shows that for tests with many biased items, traditional item bias detection schemes give a very poor assessment of bias. A new method is proposed instead. This method extends item response theory (IRT) by including item-specific auxiliary measurement information related to opportunity-to-learn. Item-specific variation in measurement relations across students with varying opportunity-to-learn is allowed for.This paper was presented at the 1987 AERA meeting in Washington, DC. This research was supported by grant OERI-G-86-003 from the Office of Educational Research and Improvement, Department of Education. The author thanks Michael Hollis and Chih-fen Kao for valuable research assistance, and appreciates valuable comments made by an anonymous reviewer. 相似文献
190.
A neuroscience model of stuttering 总被引:2,自引:0,他引:2
H.B. Nudelman K.E. Herbrich B.D. Hoyt D.B. Rosenfield 《Journal of Fluency Disorders》1989,14(6):399-427
Using motor control systems analysis and a reductionist approach, we provide a unified model of stuttering. This model views stuttering as a momentary instability in a complex multiloop control system. The model predicts the temporal conditions under which this instability will occur. Furthermore, these temporal conditions account for the efficacy of fluency-evoking maneuvers, therapy, and the variability of speech output in stutterers. 相似文献