全文获取类型
收费全文 | 124928篇 |
免费 | 1611篇 |
国内免费 | 238篇 |
专业分类
教育 | 86613篇 |
科学研究 | 13450篇 |
各国文化 | 1979篇 |
体育 | 9777篇 |
综合类 | 172篇 |
文化理论 | 1080篇 |
信息传播 | 13706篇 |
出版年
2021年 | 951篇 |
2020年 | 1660篇 |
2019年 | 2560篇 |
2018年 | 3129篇 |
2017年 | 3355篇 |
2016年 | 3409篇 |
2015年 | 2305篇 |
2014年 | 3171篇 |
2013年 | 27236篇 |
2012年 | 2397篇 |
2011年 | 2776篇 |
2010年 | 2333篇 |
2009年 | 2613篇 |
2008年 | 2430篇 |
2007年 | 2153篇 |
2006年 | 2408篇 |
2005年 | 2374篇 |
2004年 | 3069篇 |
2003年 | 2343篇 |
2002年 | 2185篇 |
2001年 | 2126篇 |
2000年 | 1792篇 |
1999年 | 1663篇 |
1998年 | 1474篇 |
1997年 | 1533篇 |
1996年 | 1699篇 |
1995年 | 1470篇 |
1994年 | 1481篇 |
1993年 | 1474篇 |
1992年 | 1578篇 |
1991年 | 1482篇 |
1990年 | 1466篇 |
1989年 | 1400篇 |
1988年 | 1263篇 |
1987年 | 1197篇 |
1986年 | 1216篇 |
1985年 | 1485篇 |
1984年 | 1329篇 |
1983年 | 1331篇 |
1982年 | 1272篇 |
1981年 | 1197篇 |
1980年 | 1187篇 |
1979年 | 1312篇 |
1978年 | 1232篇 |
1977年 | 1139篇 |
1976年 | 1029篇 |
1975年 | 834篇 |
1974年 | 832篇 |
1973年 | 807篇 |
1971年 | 667篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
941.
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
942.
943.
944.
Harry Adamakos M.A. Kathleen Ryan M.A. Douglas G. Ullman Ph.D. John Pascoe M.D. M.P.H. Raul Diaz Ph.D. John Chessare M.D. 《Child abuse & neglect》1986,10(4):463-470
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
945.
USING DEMOGRAPHIC SUBGROUP AND DUMMY VARIABLE EQUATIONS TO PREDICT COLLEGE FRESHMAN GRADE AVERAGE 总被引:1,自引:0,他引:1
RICHARD SAWYER 《Journal of Educational Measurement》1986,23(2):131-145
The purpose of this study was to determine whether adjustments for the differential prediction observed among sex, racial/ethnic, or age subgroups in one freshman class at a college could be used to improve prediction accuracy for these subgroups in future freshman classes. For older students, dummy variable and separate subgroup prediction equations were found, on cross-validation, to be more accurate than the total group equations. For sex subgroups, dummy variable and separate subgroup equations were only moderately effective in improving prediction accuracy. For racial/ethnic subgroups, they were more often than not less accurate, on cross-validation, than total group equations. Among all three kinds of demographic subgroupings, shifts over time in colleges' mean grade averages were found to be a more important source of prediction bias than differential prediction. 相似文献
946.
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
947.
948.
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
949.
To be successful, an instructional video presentation needs to be effective, valued, liked and efficient, and educationalists and designers should strive (explicitly and implicitly) to satisfy these criteria. In the interests of optimum teaching effect, a didactical distinction is recommended between video presentations that have to ‘instruct’, ‘explain’, ‘tell’ and ‘let encounter’. A schema or frame of reference is proposed, the use of which (it is claimed) can help to optimise communication between video producer, teacher and instructional designer 相似文献
950.
Frederick A. Hadd 《Psychology in the schools》1986,23(4):361-364
Results of the TONI, WISC-R, and WRAT were compared for a sample of 66 learning disabled children: 51 males (32 white, 19 black) and 15 females (9 white, 6 black) whose mean age was 9–5 (SD = 1–10). The mean score of the TONI was significantly different from the Performance IQ. Nonsignificant differences were found between the TONI and Full Scale IQ and between the TONI and Verbal IQ. Correlation coefficients between the TONI and WISC-R ranged from a low of .35 for the Verbal IQ to .44 for both the Full Scale and Performance IQs. The correlation coefficients between the TONI and standard scores of the WRAT were .38, .27, and .23, for Reading, Spelling, and Arithmetic, respectively. Implications of these findings are discussed. 相似文献