全文获取类型
收费全文 | 7683篇 |
免费 | 91篇 |
国内免费 | 3篇 |
专业分类
教育 | 5287篇 |
科学研究 | 974篇 |
各国文化 | 77篇 |
体育 | 514篇 |
综合类 | 2篇 |
文化理论 | 51篇 |
信息传播 | 872篇 |
出版年
2021年 | 67篇 |
2020年 | 89篇 |
2019年 | 148篇 |
2018年 | 203篇 |
2017年 | 167篇 |
2016年 | 161篇 |
2015年 | 102篇 |
2014年 | 138篇 |
2013年 | 1436篇 |
2012年 | 148篇 |
2011年 | 145篇 |
2010年 | 125篇 |
2009年 | 116篇 |
2008年 | 137篇 |
2007年 | 106篇 |
2006年 | 121篇 |
2005年 | 106篇 |
2004年 | 122篇 |
2003年 | 91篇 |
2002年 | 96篇 |
2001年 | 125篇 |
2000年 | 123篇 |
1999年 | 107篇 |
1998年 | 73篇 |
1997年 | 75篇 |
1996年 | 84篇 |
1995年 | 66篇 |
1994年 | 56篇 |
1993年 | 89篇 |
1992年 | 110篇 |
1991年 | 120篇 |
1990年 | 112篇 |
1989年 | 97篇 |
1988年 | 90篇 |
1987年 | 107篇 |
1986年 | 94篇 |
1985年 | 106篇 |
1984年 | 98篇 |
1983年 | 100篇 |
1982年 | 95篇 |
1981年 | 78篇 |
1980年 | 77篇 |
1979年 | 104篇 |
1978年 | 95篇 |
1977年 | 87篇 |
1976年 | 79篇 |
1974年 | 70篇 |
1973年 | 68篇 |
1972年 | 55篇 |
1971年 | 58篇 |
排序方式: 共有7777条查询结果,搜索用时 15 毫秒
961.
Four pigeons pecked for food reinforcement on variable interval 1-min schedules and on the variable-interval 1-min components of multiple, concurrent, and pseudoconcurrent schedules. The pseudoconcurrent schedule provided only one schedule of reinforcement; but, any reinforcer could be collected by responding on either of two keys. The rate of responding generated by the variable interval schedule was not greater than the rates of responding generated by the components of the complex schedules. But, the rate of reinforcement obtained from the variable interval schedule was greater than the rates of reinforcement obtained from the components of the multiple schedule. These results may contradict the equation proposed by Herrnstein (1970). The equation predicts that the rate of responding generated by a schedule of reinforcement will be greater when the schedule appears alone, than when it appears as one component of a complex schedule. 相似文献
962.
Rats were tested in a specially constructed radial-arm maze that eliminated access to extramaze visual cues and allowed any effects of intramaze cues to be controlled. Despite this, choice accuracy was controlled by the spatial location of previously visited arms. Part of this control was attributed to vestibular or kinesthetic cues. This conclusion was corroborated by the finding that when explicit visual cues were moved from their standard (trained) spatial locations to novel locations, control of spatial choices was completely disrupted. The latter finding indicates that cues intrinsic to the rat (kinesthetic or vestibular information) and cues extrinsic to the rat (visual stimuli) operate in an integrated fashion. 相似文献
963.
964.
Steven F. Schomberg Darwin D. Hendel Caroline L. Bassett 《Innovative Higher Education》1983,7(2):95-104
This article describes one institution's use of the College Outcome Measures Project (COMP) in comparing outcomes for graduates of traditional and non-traditional programs. The study was designed to answer three questions concerning the use of COMP in evaluating traditional and non-traditional programs. Results obtained in a study of 96 University of Minnesota graduating seniors suggest greater potential usefulness in distinguishing among institutions than in comparing outcomes of programs within an institution. The authors conclude that as new approaches and instruments for measuring college outcomes become available, criteria for instrument selection need to be shared among individuals charged with conducting outcome studies. 相似文献
965.
966.
ABSTRACT: Decades of research have provided evidence that food irradiation is a safe technology that can decrease the incidence of foodborne diseases; however, adoption of this technology has been slow. The purpose of our study was to qualitatively explore the effectiveness of various components of a professional development training on family and consumer sciences county extension educators' understanding of food irradiation. This training included presentations by experts in the field, a tour of a food irradiation research facility and a meat processing facility, group activities, and a computer simulation model. Data were collected using qualitative research methodology through in-depth interviews conducted after the training. Results indicated that those components that allowed participants to visualize food irradiation processes seemed most beneficial to their understanding. Based on these data, implications for practice are discussed. 相似文献
967.
968.
Stellwag Helena W. F. Völcker Otto de Bousingen R. Durand Roucek Joseph R. Langeveld M. J. Maack Rudolf 《International Review of Education/Internationale Zeitschrift für Erziehungswissenschaft/Revue internationale l'éducation》1958,4(1):485-490
International Review of Education - 相似文献
969.
970.
W. F. Beasley 《Research in Science Education》1978,8(1):135-144
Some conclusions This study has demonstrated the feasibility of improving the laboratory performance of freshman chemistry students through
planned skill practice activities. However, no differences were found among the specific practice strategies which were employed.
Mental practice of laboratory techniques represents the most efficient strategy in terms of the necessary laboratory resources.
Although mental practice alone was not expected to be as effective as physical practice, this study’s findings proved to be
an exception to the implications of earlier reported literature. However, if one accepts the argument that prior experience
with the appropriate apparatus during the pretest experiment and/or high school courses was significant, then this study is
consistent with the implications of the proposed model. Thus mental practice, to be fully effective, should be associated
with prior experience of the task.
Evaluation of such findings should relate to the degree of improvement which was found relative to the investment of student
time and laboratory resources in the practice activities. A more detailed discussion of the study is provided elsewhere (Beasley,
1978). 相似文献