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   87759篇
  免费   3414篇
  国内免费   27篇
  2019年   1055篇
  2018年   1434篇
  2017年   1431篇
  2016年   1558篇
  2015年   1123篇
  2014年   1348篇
  2013年   7316篇
  2012年   2441篇
  2011年   2611篇
  2010年   1638篇
  2009年   1606篇
  2008年   2382篇
  2007年   2313篇
  2006年   2133篇
  2005年   1854篇
  2004年   1738篇
  2003年   1692篇
  2002年   1765篇
  2001年   2764篇
  2000年   2690篇
  1999年   2070篇
  1998年   977篇
  1997年   889篇
  1996年   1009篇
  1995年   934篇
  1994年   886篇
  1993年   900篇
  1992年   1879篇
  1991年   1723篇
  1990年   1710篇
  1989年   1549篇
  1988年   1515篇
  1987年   1499篇
  1986年   1530篇
  1985年   1546篇
  1984年   1343篇
  1983年   1180篇
  1981年   895篇
  1979年   1352篇
  1978年   996篇
  1975年   1177篇
  1974年   1216篇
  1973年   1337篇
  1972年   1201篇
  1971年   1078篇
  1970年   984篇
  1969年   995篇
  1968年   1252篇
  1967年   1097篇
  1966年   1000篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
951.
Young and older adults studied lists of words under both standard and optimal study conditions for subsequent free recall. Under optimal conditions, the participants studied each word for as long as they wished, were allowed to take notes, and were encouraged to actively use whatever strategies they thought would maximize recall. Both age groups recalled more words under optimal study conditions than under standard conditions, but the improvement was greater for the young adults. This increase in the age-related recall deficit was not due to differences in study time. The results suggest that standard laboratory memory tasks do not overestimate the memory deficits of older adults because of a failure to provide either optimal learning conditions or sufficient study time.  相似文献   
952.
Models of event causation and affective processes were used to design an experimental intervention for older adults. Ss were 2 at-risk populations, recently disabled and recently bereaved, each with matched nonrisk controls. Ss were randomly assigned to a placebo-contact group, a no-contact control group, or a 4-session, 10-week intervention focused on enhancing perceived control. Dependent variables assessed were personal mastery, psychological well-being and distress, positive and negative affect, and measures of daily events and activities. The intervention was nested within a 16-month longitudinal assessment of stress and adaptation processes in a large sample of community residents. The intervention had mixed effects on reports of personal mastery, but it significantly increased engagement in desirable activities and significantly decreased psychological distress and negative affect. Effects tended to be short-lived, however. Effects of the intervention tended to be particularly significant for the disabled group.  相似文献   
953.
Age differences in the acculturation process   总被引:1,自引:0,他引:1  
Age differences were assessed in a conceptual model that seeks to explain how acculturation affects psychological well-being among Mexican Americans. The data were from a national probability sample of 859 persons of Mexican decent. It was hypothesized that low acculturation creates financial stress. Moreover, low acculturation and financial stress were in turn predicted to erode feelings of personal control and self-esteem. Finally, diminished feelings of control and low self-esteem were hypothesized to exert a negative impact on psychological well-being. When data from respondents of all ages was assessed, empirical support was found for all of the hypotheses except the linkage between acculturation and financial stress. However, few age differences emerged in the model. The authors conclude that older Mexican Americans may not be more vulnerable to the stressors associated with acculturation.  相似文献   
954.
Age, exercise, and coding performance   总被引:1,自引:0,他引:1  
We investigated the effects of exercise on the coding performance of young and older subjects. Hypotheses were tested that exercise either facilitates spatial localization or reduces susceptibility to distraction in older subjects. In a balanced design, we administered Digit Symbol and Symbol Digit coding tasks to exercisers and nonexercisers at two age levels under conditions of low or high within-task interference. The findings showed higher performance by the exercisers than by the nonexercisers only at the older age level and only with the Symbol Digit task. These findings support the hypothesis that exercise compensates for a loss of spatial localization skills with age. We found no evidence that susceptibility to distraction either increased with age or was affected by chronic exercise.  相似文献   
955.
Age differences in memory for the source of memories were investigated using two different experimental paradigms. Experiment 1 used a reality monitoring paradigm. A series of actions were either performed, imagined, or watched, and subjects were later tested for their ability to recognize the actions and identify their origins. Elderly subjects made more false positive responses than did young subjects, and they made more source confusion errors, attributing actions to the wrong sources. Both new and imagined actions were most often misclassified as watched. Experiment 2 used an eyewitness testimony paradigm. After watching a film, subjects read a written version of the story. A recognition test showed that elderly subjects were more often misled by false information in the story than were the younger subjects, and were more confident that their erroneous responses were correct. The findings suggest that a decline in memory for sources may diminish the accuracy of elderly witnesses.  相似文献   
956.
Deficits in semantic encoding have been described in patients with frontal lobe disease who also show memory impairments. As a group, patients with multiple sclerosis (MS) exhibit memory impairment, fail to make effective use of semantic encoding to aid memory, and perform poorly on verbal fluency and concept formation tests which are sensitive to frontal lobe damage. In the present study the semantic encoding capacity of MS patients was measured using a modification of Wicken's release from proactive interference (PI) paradigm. Individual patients varied considerably in the severity of their impairments on verbal fluency, verbal recognition memory and on Wisconsin Card Sorting Task, but even patients who evidenced both memory impairment and signs of frontal lobe dysfunction showed normal release from PI after a categorical shift. Memory disturbances in MS are unlikely to result from an incapacity for semantic encoding, which seems preserved in MS, but may arise instead from deficits in processing information rapidly.  相似文献   
957.
This study compared the temporal organization of graphic movements executed either actually or mentally. Six subjects had to perform two tasks, writing a sentence and drawing a cube, either as a real performance or as an imagined one, with either the right or the left hand, and with either a small or a large tracing amplitude. In the same subject, for the same hand, mental and actual movement times were both very stable and very close from trial to trial regardless of the tracing amplitude. Thus, mental movements mimic closely real movements in their temporal organization and are likely to involve the same planning program.  相似文献   
958.
Estimate the amount of frequency variation that affected individual and species recognition by song in territorial male field sparrows with field playbacks of neighbors' songs lowered in frequency in 6 increments between 324 and 1296 Hz. Males gave strong responses to neighbors' songs that had been lowered by about 400 Hz, which is about 11% of the mean midfrequency in field sparrow song. Territorial responses were eliminated when neighbors' songs were lowered by more than about 900 Hz. Thus, there is a fairly narrow range of frequencies within which field sparrow songs can vary while functioning in communication. Ss' responses appear to be constrained by the normal range of song frequency variation within the species, but the range of variability within songs of individuals did not influence the degree of frequency shift required to render neighbors' songs unfamiliar.  相似文献   
959.
Remedial strategies for children and adolescents with disabilities should have their roots in assessment. In this article the authors discuss improvements in assessment approaches, including new standards for psychological testing, updated and renormed cognitive assessments, and vocational assessments with increased ecological validity. The combined efforts of school psychologists, rehabilitation counselors, vocational evaluators, psychologists, and school counselors have yielded progress in the technical qualities of assessment and utilization. Through comprehensive and functional assessment, students with disabilities should find the transition from school to work with greater success.  相似文献   
960.
Prior to assuming the upright crouching posture over their pups during nursing bouts, lactating rats typically engage in several oral behaviors, including nuzzling, licking and rearranging pups. By acutely depriving dams of various aspects of perioral stimulation from pups (with anesthesia of the mystacial pads or of the tongue, with mouth suturing, or with muzzling), we found the following: (1) Distal stimulation from pups maintains proximity-seeking behavior, but is insufficient to stimulate nursing behavior. (2) Lack of tongue feedback decreases pup licking and hastens the onset of crouching. (3) Snout, but not tongue, contact with pups is required for hovering over them. (4) The position of the dam while hovering over her litter enables the pups to gain access to her ventrum, thereby provoking her upright, crouching posture. (5) Older pups are capable of bypassing the dam's perioral attentions and stimulating crouching directly by burrowing under the dam's ventrum.  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