全文获取类型
收费全文 | 10072篇 |
免费 | 114篇 |
国内免费 | 122篇 |
专业分类
教育 | 6393篇 |
科学研究 | 1234篇 |
各国文化 | 89篇 |
体育 | 1633篇 |
综合类 | 19篇 |
文化理论 | 66篇 |
信息传播 | 874篇 |
出版年
2021年 | 79篇 |
2020年 | 154篇 |
2019年 | 198篇 |
2018年 | 279篇 |
2017年 | 279篇 |
2016年 | 261篇 |
2015年 | 182篇 |
2014年 | 233篇 |
2013年 | 1554篇 |
2012年 | 212篇 |
2011年 | 223篇 |
2010年 | 190篇 |
2009年 | 208篇 |
2008年 | 189篇 |
2007年 | 180篇 |
2006年 | 198篇 |
2005年 | 170篇 |
2004年 | 379篇 |
2003年 | 349篇 |
2002年 | 335篇 |
2001年 | 400篇 |
2000年 | 240篇 |
1999年 | 162篇 |
1998年 | 106篇 |
1997年 | 97篇 |
1996年 | 96篇 |
1995年 | 107篇 |
1994年 | 101篇 |
1993年 | 77篇 |
1992年 | 152篇 |
1991年 | 118篇 |
1990年 | 135篇 |
1989年 | 149篇 |
1988年 | 110篇 |
1987年 | 129篇 |
1986年 | 120篇 |
1985年 | 135篇 |
1984年 | 119篇 |
1983年 | 123篇 |
1982年 | 96篇 |
1981年 | 81篇 |
1980年 | 90篇 |
1979年 | 134篇 |
1978年 | 87篇 |
1977年 | 72篇 |
1976年 | 89篇 |
1975年 | 65篇 |
1974年 | 72篇 |
1973年 | 68篇 |
1971年 | 66篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
861.
862.
This article describes the introductory two-semester course in electrical engineering that has been developed over a period of five years at Princeton University. The aims of the course are to provide an introduction to the field of electrical engineering via the basic concepts of electricity and magnetism (which are developed through Maxwell's equations in the integral form), to apply these concepts in developing the fundamentals of energy conversion and circuit theory, and to carry forward, in a continuous and integrated way, a modern treatment of network analysis. Thus, the treatment proceeds from field ideas to circuits and physical apparatus, and to their mathematical models. With the circuit relations formulated, attention turns to the analysis of networks, starting with network topology and extending through pole-zero ideas. The treatment stops just short of the Laplace transform. This course is intended to serve as a foundation for subsequent courses such as electronic circuits, energy conversion, and advanced network analysis and synthesis, and has been developed with the purpose of providing the student with a unifying point of view for these varied topics. 相似文献
863.
864.
865.
866.
867.
868.
869.
John P. Rickards 《Contemporary educational psychology》1977,2(2):200-206
It has been concluded in all major reviews of adjunct question research that a group given questions after related text segments (postquestions) yields greater recall than a group given questions before related text segments (prequestions) or one not given any questions at all. However, closer examination of the earlier research and an analysis of recent research reveals that for certain types of verbatim questions and for certain high level questions, postquestions produce recall equivalent to or less than prequestions. Moreover, in many studies wherein postquestions exceed prequestions, the postquestion group equals the reading-only control group in recall of nonquestioned (incidental) material. Hence, despite frequent pronouncements to the contrary, no firm recommendation can be made regarding the optimal placement of adjunct questions in text material. 相似文献
870.