全文获取类型
收费全文 | 32687篇 |
免费 | 1390篇 |
国内免费 | 16篇 |
出版年
2020年 | 392篇 |
2019年 | 395篇 |
2018年 | 667篇 |
2017年 | 596篇 |
2016年 | 636篇 |
2015年 | 427篇 |
2014年 | 557篇 |
2013年 | 2432篇 |
2012年 | 962篇 |
2011年 | 1082篇 |
2010年 | 591篇 |
2009年 | 634篇 |
2008年 | 909篇 |
2007年 | 889篇 |
2006年 | 813篇 |
2005年 | 699篇 |
2004年 | 688篇 |
2003年 | 653篇 |
2002年 | 605篇 |
2001年 | 1162篇 |
2000年 | 1137篇 |
1999年 | 824篇 |
1998年 | 342篇 |
1997年 | 301篇 |
1995年 | 294篇 |
1992年 | 679篇 |
1991年 | 628篇 |
1990年 | 675篇 |
1989年 | 590篇 |
1988年 | 585篇 |
1987年 | 538篇 |
1986年 | 539篇 |
1985年 | 610篇 |
1984年 | 485篇 |
1983年 | 405篇 |
1982年 | 334篇 |
1979年 | 464篇 |
1978年 | 348篇 |
1977年 | 305篇 |
1976年 | 294篇 |
1975年 | 429篇 |
1974年 | 503篇 |
1973年 | 523篇 |
1972年 | 417篇 |
1971年 | 376篇 |
1970年 | 325篇 |
1969年 | 351篇 |
1968年 | 448篇 |
1967年 | 387篇 |
1966年 | 400篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
973.
974.
If rats are overtrained on a visual discrimination they generally learn the reversal of the discrimination faster than non-overtrained rats. In position discriminations, however, this effect does not generally hold—indeed several investigators have found overtraining to retard position reversal. One of the important differences between the two types of problem seems to be the presence of irrelevant cues in visual discriminations, and their absence in position discriminations. It is suggested that a second important feature of position discriminations is that overtraining usually causes control of the maze running habit to be transferred from external to proprioceptive stimuli, and that successful reversal cannot normally occur until external control is re-established. In two experiments a study by Krechevsky and Honzik (1932) is repeated with certain modifications, with results that support this hypothesis; and a third experiment provides direct evidence of transfer to proprioceptive control in a T-maze. It is shown that this analysis will explain the apparently conflicting results of all recent position reversal experiments. 相似文献
975.
Memory performance awareness in younger and older adults 总被引:2,自引:0,他引:2
Reports on the course of memory-monitoring skills across adulthood are discrepant in conclusions and limited in scope. The purpose of this study was to build a large data base (3 samples and 7 different tasks) to assess performance awareness. Younger (19-41 years) and older (59-93 years) Ss estimated performance either before (i.e., predictions) or after (i.e., postdictions) completing each task. Predictions were less accurate than postdictions at both age levels, suggesting Ss monitored performance during the study-test cycle. Overall, the data suggested no consistent age effects in performance awareness: Age differences in monitoring occurred only in predictions and only for some tasks. Between-tasks differences in age effects could not be attributed to a single mediating mechanism like those suggested in previous reports. Why previous research has produced conflicting conclusions about metacognitive development in adulthood is discussed in light of these data. 相似文献
976.
DANIEL K. LAPSLEY KENNETH G. RICE DAVID P. FitzGerald 《Journal of counseling and development : JCD》1990,68(5):561-565
We examined the concurrent relationship between late adolescent attachment to parents and peers and two broad indices of adolescent adaptation—personal and social identity and adjustment to college. Participants included 130 college freshmen and 123 upperclassmen. Although freshmen were disadvantaged relative to upperclassmen with respect to social and personal-emotional adjustment, there were no group differences on the attachment measures, on the measures of academic adjustment and goal commitment, and on the measure of social identity. Freshmen scored higher on personal identity than did upperclassmen. Women reported less alienation from peers, had more trust and better communication with peers, and had higher scores on personal and social idenitity than men. The attachment variables were significant predictors of personal and social identity. Pervasive relations were also found between attachment and adjustment to college, particularly for the upperclassmen sample. 相似文献
977.
Previous training studies of fluid intellectual abilities have involved training on either figural relations or induction tasks. In the present study, young, middle-aged, and elderly adults were given training on another measure of fluid ability--Raven's Progressive Matrices. The training involved a strategy-modeling technique that lasted no more than a few minutes. The results indicated that (a) performance on the Raven decreased with increasing age, (b) training significantly improved performance, and (c) the effect of training did not differ as a function of the age or sex of the subjects. Thus, the results indicate that performance on the Raven can be significantly improved in a single, brief training session. 相似文献
978.
Life stressors, social resources, and late-life problem drinking 总被引:2,自引:0,他引:2
Life stressors and social resources among late-middle-aged problem and nonproblem drinkers were studied. Problem drinkers (n = 501) reported more negative life events, chronic stressors, and social resource deficits than did nonproblem drinkers (n = 609). In a comparison of problem drinkers, men reported more ongoing stressors involving finances and friends, and fewer resources from children, extended-family members, and friends than did women. Women who are problem drinkers reported more negative life events, more ongoing difficulties with spouses and extended-family members, and fewer resources from spouses. Among both the problem and nonproblem drinkers, more stressors were associated with fewer social resources, but only within certain life domains. Late-middle-aged adults' chronic stressors and social resources helped explain their drinking behavior, depression, and self-confidence even after sex, marital status, and negative life events were considered. 相似文献
979.
980.
Systematic 24-hr behavioral observations of sleep and wakefulness in a skilled-care nursing facility
Sleep patterns of aged, infirm, demented, chronically institutionalized residents of a skilled-care nursing facility were studied. The purpose of this naturalistic study was to describe sleep and wakefulness (S/W) within the limits afforded by brief behavioral observations and to examine homeostasis and diurnal rhythmicity of S/W as a function of psychoactive drug intake. Observers noted S/W every 15 min, 24 hr a day for 10 days in 24 Ss. Results indicated substantial individual variation in daytime hours. Daily and weekly variation within Ss was minimal. Sleep was least likely near sunset. Ss on psychoactive drugs showed dampened diurnal variation in S/W rhythms. In Ss not on such drugs, there was a suggestion of homeostasis of S/W between sleep during the morning and evening hours. Results are discussed methodologically (viability of approach), theoretically (age-related change in sleep), and practically (potential treatments). 相似文献