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   81009篇
  免费   2539篇
  国内免费   21篇
  2020年   611篇
  2019年   798篇
  2018年   4206篇
  2017年   3582篇
  2016年   3202篇
  2015年   1020篇
  2014年   1055篇
  2013年   4789篇
  2012年   2381篇
  2011年   4152篇
  2010年   3526篇
  2009年   2583篇
  2008年   3314篇
  2007年   3743篇
  2006年   1676篇
  2005年   1665篇
  2004年   1504篇
  2003年   1381篇
  2002年   1458篇
  2001年   2049篇
  2000年   2067篇
  1999年   1534篇
  1998年   763篇
  1997年   670篇
  1996年   663篇
  1993年   591篇
  1992年   1283篇
  1991年   1190篇
  1990年   1168篇
  1989年   1063篇
  1988年   1036篇
  1987年   991篇
  1986年   1072篇
  1985年   1087篇
  1984年   911篇
  1983年   827篇
  1982年   605篇
  1981年   609篇
  1979年   971篇
  1978年   714篇
  1975年   799篇
  1974年   857篇
  1973年   942篇
  1972年   793篇
  1971年   741篇
  1970年   657篇
  1969年   684篇
  1968年   876篇
  1967年   799篇
  1966年   667篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
941.
In this study we combined daily diary data with interview data to investigate individual differences in the impact of stressful daily events on mood. Using a sample of 96 women in an urban community, we examined perceived neighborhood quality and major life events as possibly potentiating the effects of stressful daily events, and we viewed social supports as potentially buffering this daily process. Results confirmed that the presence of chronic ecologic stress (neighborhood perceptions) exacerbated the immediate effects of stressful daily events on mood and also increased the likelihood of enduring effects of daily stressors on next day's mood. Contrary to expectations, previous exposure to major life events decreased the impact of stressful daily events. The availability of social supports, although not buffering the impact of stressful daily events on mood, did mitigate the enduring effects of these events on next day's mood. This study also presents a method for analyzing daily time-series data, while correcting for potential problems of autocorrelated error terms. As such, this study represents a significant advance over previous analytic approaches to time-series data in the study of the stress process.  相似文献   
942.
943.
944.
A model for stimulus generalization in Pavlovian conditioning   总被引:2,自引:0,他引:2  
  相似文献   
945.
946.
This is a survey of the prevalence of weight reducing and weight gaining in high school children. Our sample of 1,373 high school girls and boys was geographically, racially, and economically diverse. On the day of the survey, 63% of the girls and 16.2% of the boys reported being on weight reducing regimens; 9.1% of the girls and 28.4% of the boys were trying to gain weight. Most female reducers and male gainers were already normal weight. Compared to other racial groups, whites and Hispanics were more likely to be reducing, whereas blacks were more likely to be gaining. Exercise and moderate caloric reduction were most popular for weight reducing, and a small but significant number were regularly using fasting, vomiting, laxatives, and appetite suppressants. The direction of weight modification for girls and boys conformed to stereotyped physical ideals. The rate of weight reducing in female high school adolescents has increased significantly since similar surveys of American youths 20 years ago.  相似文献   
947.
Cognitive maps as orienting schemata   总被引:3,自引:0,他引:3  
A "point-to-unseen-targets" task was used to test two theories about the nature of cognitive mapping. The hypothesis that a cognitive map is like a "picture in the head" predicts that (a) the cognitive map should have a preferred orientation and (b) all coded locations should be equally available. These predictions were confirmed in Experiments 1 and 3 when targets were cities in the northeastern United States and learning was from a map. The theory that a cognitive map is an orienting schema predicts that the cognitive map should have no preferred orientation and that targets in front of the body should be localized faster than targets behind the body. These predictions were confirmed in Experiments 1 and 2 when targets were local landmarks that had been learned via direct experience. In Experiment 3, when cities in the Northeast were targets and geographical knowledge had been acquired, in part, by traveling in the Northeast, the observed latency profiles were not as predicted by either theory of cognitive mapping. The results suggest that orienting schemata direct orientation with respect to local environments, but that orientation with respect to large geographical regions is supported by a different type of cognitive structure.  相似文献   
948.
This study examines the effect of different behavioral conditions on patterns of correlation between regional cerebral metabolic rates for glucose. Cerebral glucose metabolism was determined with positron emission tomography and (11C)-deoxyglucose in 29 normal subjects between the ages of 23 and 55. Seventeen subjects were studied in an unstimulated (resting) condition and 12 subjects during a phoneme monitoring language stimulation. Partial correlation coefficients, controlling for whole brain glucose metabolism, were calculated for pairs of metabolic rates in 14 cortical and 2 subcortical regions. Both stimulated and unstimulated subjects showed statistically significant correlations between left and right hemisphere homologs. The stimulated subjects also showed significant within-hemisphere correlations between left but not right hemisphere regions. These included left perisylvian regions classically associated with language functions (left inferior frontal, left superior temporal and left transverse temporal cortical regions) as well as other regions. Significant correlations between left regions and a right superior temporal region were also found. In general, these findings show a pattern of cross-hemisphere symmetry at rest and of hemisphere asymmetry during stimulation. Moreover, the asymmetry observed during stimulation appears to be superimposed upon a pattern of cross-hemisphere symmetry similar to that observed in the unstimulated state.  相似文献   
949.
When sighted persons try to identify one of two speech utterances coming from different directions, they display both a frontal position advantage, i.e., better recognition of inputs from the front than of those from the rear, and a right-side advantage, better recognition of inputs from the right than of those from the left. The present study demonstrates a dissociation of the two effects in blind subjects (N = 10) who showed no frontal position advantage together with a right-side advantage superior to that of control sighted subjects (N = 16). There was no systematic difference between congenitally blind subjects and noncongenitals. The absence of frontal position advantage in the blind is consistent with the notion that this effect originates in the habit of sighted listeners to orient toward the source of heard speech. The occurrence of at least normal right-side advantage in the blind does not support recent suggestions of reduced lateralization of language functions in such subjects.  相似文献   
950.
This project examined psychosocial characteristics of 24 preschool-aged siblings of handicapped children in relation to a control group of 22 siblings of nonhandicapped children. Subjects were matched on family size and income, sibling age, birth order, sex, age spacing, and marital status of their parents. Results indicated no statistically significant differences between groups of children on measures of perceived self-competence and acceptance, understanding of developmental disabilities, empathy, and child care responsibility. Significant group differences were found where brothers of handicapped children were rated by their mothers as being more depressed and aggressive than brothers of nonhandicapped control children. Sisters of handicapped children were rated by mothers as being more aggressive than sisters of nonhandicapped children. Sisters of handicapped children and brothers of nonhandicapped children had significantly fewer privileges and more restrictions on their home activities than other groups. Results are discussed in relation to previous research on older silbings of handicapped children and the general literature on family stress and childhood disability and disease. The importance of examining sibling functioning via multiple measures of child behavior is stressed.The authors are grateful to the children and families who participated in the project. The assistance of Dr. Ricardo Barrera, Christine DiBlasio, Lisa Kaye, Paola Bellabarba, Jeanne Logozzo, Donna Motley, Jennifer Harter, and Tina Meisell is also gratefully acknowleged. This project was funded by Grant Number G008300345 from the U.S. Department of Education.  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