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   123929篇
  免费   1638篇
  国内免费   241篇
教育   86001篇
科学研究   13433篇
各国文化   1975篇
体育   9539篇
综合类   194篇
文化理论   1066篇
信息传播   13600篇
  2021年   943篇
  2020年   1643篇
  2019年   2539篇
  2018年   3090篇
  2017年   3377篇
  2016年   3420篇
  2015年   2302篇
  2014年   3166篇
  2013年   27178篇
  2012年   2409篇
  2011年   2818篇
  2010年   2367篇
  2009年   2611篇
  2008年   2435篇
  2007年   2201篇
  2006年   2413篇
  2005年   2410篇
  2004年   3059篇
  2003年   2366篇
  2002年   2213篇
  2001年   2083篇
  2000年   1723篇
  1999年   1637篇
  1998年   1466篇
  1997年   1523篇
  1996年   1686篇
  1995年   1462篇
  1994年   1463篇
  1993年   1463篇
  1992年   1510篇
  1991年   1432篇
  1990年   1435篇
  1989年   1358篇
  1988年   1231篇
  1987年   1139篇
  1986年   1175篇
  1985年   1442篇
  1984年   1309篇
  1983年   1295篇
  1982年   1249篇
  1981年   1168篇
  1980年   1159篇
  1979年   1259篇
  1978年   1211篇
  1977年   1123篇
  1976年   1007篇
  1975年   813篇
  1974年   810篇
  1973年   782篇
  1971年   629篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
Even where a total allocation of resources is fixed, it is often possible to vary the distribution of the given resources. This distribution can have important, if sometimes hidden, consequences. In the case of universities, considering the mean class size as given, three nonobvious consequences of the amount of variation in class size are examined. (1) The average class size experienced by students is directly related to the amount of variation in class size. (2) Overall student attendance is inversely related to the amount of variation in class size. (3) Overall student participation time is directly related to the amount of variation in class size. The logic of these relationships is explored, and data on 49 departments and interdisciplinary programs at one university are used to illustrate the nature and extent of the class size paradox at one university.  相似文献   
993.
Interaction and learning: Theorizing on the art of teaching   总被引:1,自引:0,他引:1  
  相似文献   
994.
Self-concept development and educational degree attainment   总被引:1,自引:0,他引:1  
The present study explores changes in the academic, social, and artistic self-concept of college students over a nine-year period. While the findings demonstrate a positive relationship between the educational degree attainment levels of students and their formation of a more healthy self-concept, the findings further indicate that the relationship is not consistent for males and females. In general, the findings suggest that the collegiate experience does not diminish self-concept gender differences that exist at the time of matriculation. The degree to which changes in students' self-concept is related to selected aspects of their collegiate experience and characteristics of their undergraduate institutions is also explored. The findings indicate that changes in students' self-concept is related to their level of social and academic integration during their undergraduate careers and to the size and selectivity of colleges they attend. The implications of these findings for enhancing students' self-concept during the college years are discussed.  相似文献   
995.
While much criticism has been leveled at graduate education in major United States colleges and universities in the recent past, this study investigated the style and format variables related to preparation of the dissertation and associated matters. The results of this study indicate that a significant amount of introspective evaluation of the dissertation process and product has taken place over the last five years. Technological advances, quality concerns, and increased student involvement in the preparation process have been recognized and incorporated into new dissertation requirements, and a trend toward decentralized monitoring of dissertation preparation is evident from the results. Also presented are comparative information and data contrasting current practices with those reported in a 1975–76 survey of the same population. In both cases the response rate for the survey was greater than 85%, thus providing a very definitive picture of the current status of dissertation preparation.  相似文献   
996.
997.
There is increasing interest in the role of social support in determining risk for child abuse and neglect. The present study assessed the relationship between maternal social support and two areas: stress in the mother-child relationship: and level of stimulation provided in the home. Maternal social support was assessed prenatally and at a two-year follow-up, while the latter variables were compiled at the two-year follow-up. The data were obtained from 38 urban, low SES (80% on public assistance) mothers and their 2-year-old children. Maternal social support correlated positively with level of stimulation and negatively with level of mother-child stress, and was the best predictor of both, relative to any SES, mother or child variables. In addition, high stress, low support mothers provided significantly less stimulation to their children. The theoretical implications for social support as a mediator variable as well as its implications for early identification and prevention efforts in abuse and neglect are discussed.  相似文献   
998.
Linear conversions were developed relating scores on two recent forms of the homogeneous GRE Quantitative Test (GRE-Q) and the specially constituted heterogeneous GRE Verbal-plus-Quantitative Test (GRE-V+Q), using randomly equivalent groups of about 13, 000 taking each form. Specially defined homogeneous subpopulations were then identified, and conversions between scores on the two forms were again calculated, this time based on l000-case samples drawn at random from the subpopulations. Finally, in order to develop empirical measures of equating error, I00 samples of 1, 000 cases each were drawn at random from the two total groups and used to calculate 100 conversions between scores on the two forms. The conversions based on the specially selected subpopulations were then compared with the total-group conversions and evaluated in terms of the empirical standard errors. The results showed that the conversions for the subpopulations agreed with the total-group conversion quite satisfactorily for the GRE-Q and almost as well for the GRE-V+Q. It was concluded that the data clearly support the assumption of population independence for homogeneous tests, but not quite so clearly for heterogeneous tests.  相似文献   
999.
1000.
Signaled avoidance was studied in individual honeybees that visited the laboratory regularly to take sucrose solution from a target set on the sill of an open window. During feeding, substrate vibration or airstream was used to signal a brief shock that could be avoided by breaking off contact with the food for a few seconds. Aversive conditioning of the context was measured in terms of return time (the time between successive visits). In Experiment 1, experience with unsignaled shock was found to lengthen return time—which experience with signaled shock did not—and to impair performance in subsequent avoidance training with signaled shock (the US-preexposure effect). In Experiment 2, experience with unsignaled shock given after signaled avoidance training lengthened return time but had no effect on response to the signal in a subsequent extinction test. These results closely resemble the results obtained in analogous experiments with vertebrates.  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