全文获取类型
收费全文 | 9424篇 |
免费 | 47篇 |
国内免费 | 12篇 |
专业分类
教育 | 6325篇 |
科学研究 | 1049篇 |
各国文化 | 90篇 |
体育 | 1000篇 |
综合类 | 6篇 |
文化理论 | 96篇 |
信息传播 | 917篇 |
出版年
2021年 | 77篇 |
2020年 | 130篇 |
2019年 | 185篇 |
2018年 | 237篇 |
2017年 | 253篇 |
2016年 | 224篇 |
2015年 | 153篇 |
2014年 | 217篇 |
2013年 | 1689篇 |
2012年 | 203篇 |
2011年 | 196篇 |
2010年 | 169篇 |
2009年 | 152篇 |
2008年 | 169篇 |
2007年 | 193篇 |
2006年 | 159篇 |
2005年 | 150篇 |
2004年 | 140篇 |
2003年 | 168篇 |
2002年 | 138篇 |
2001年 | 158篇 |
2000年 | 157篇 |
1999年 | 155篇 |
1998年 | 72篇 |
1997年 | 74篇 |
1996年 | 109篇 |
1995年 | 77篇 |
1994年 | 95篇 |
1993年 | 87篇 |
1992年 | 153篇 |
1991年 | 146篇 |
1990年 | 137篇 |
1989年 | 136篇 |
1988年 | 114篇 |
1987年 | 116篇 |
1986年 | 138篇 |
1985年 | 134篇 |
1984年 | 107篇 |
1983年 | 129篇 |
1982年 | 110篇 |
1981年 | 104篇 |
1980年 | 93篇 |
1979年 | 165篇 |
1978年 | 110篇 |
1977年 | 108篇 |
1976年 | 104篇 |
1975年 | 79篇 |
1974年 | 89篇 |
1972年 | 70篇 |
1971年 | 70篇 |
排序方式: 共有9483条查询结果,搜索用时 0 毫秒
221.
Little or no research has been done on the counseling practicum grade as a measure of counseling effectiveness. This study explored the intellective and nonintellective differences among males with A, B, and C grades in the counseling practicum. Significant differences among grade categories were observed on 7 of 17 variables. The nature and direction of the differences among males with grades of A, B, or C suggested that practicum grades tend to make valid discriminations between candidates with high and low potential as counselors. 相似文献
222.
223.
224.
The Graph-Theoretical Field Model provides a unifying approach for developing numerical models of field and continuum problems. The methodology examines the field problem from the first stages of conceptualization without recourse to the governing differential equations of the field problem; this is accomplished by deriving discrete statements of the physical laws which govern the field behaviour. There are generally three laws, and these are modelled by the “cutset equations”, the “circuit equations”, and the “terminal equations”. In order to establish these three sets of equations it is expedient first to spatially discretize the field in a manner similar to the finite difference method and then to associate a linear graph (denoted as the field graph) with the spatial discretization. The concept of “through” and “across” variables, which underlies the cutset and circuit equations respectively, enables one to define the graph in an unambiguous manner such that each “edge” of the graph identifies a pair of complementary variables. From a knowledge of the constitutive properties and the boundary conditions of the field it is possible to associate terminal equations with sets of edges. Since the resulting sets of equations represent the field equations, these equations provide the basis for a complete (but approximate) solution to the field or continuum problem. In fact, this system approach uses a two part model: one for the components and another for the interconnection pattern of the components which renders the formulation procedures totally independent of the solution procedure.This paper presents the theoretical basis of the model and several graph-theoretic formulations for steady-state problems. Examples from heat conduction and small- deformation elasticity are included. 相似文献
225.
226.
227.
传媒经济学研究的历史、方法与范例 总被引:4,自引:0,他引:4
本文主要回顾了传媒经济学在西方的发展历程、研究方法以及不同时期的研究议题。传媒经济学是构建于不同的经济学理论和分析方法之上的应用性学科,它致力于研究经济和金融力量如何影响传媒体系和传媒组织。西方传媒经济学创建于20世纪50年代,至今已发展成为一个活跃的和跨学科研究领域。文章认为,西方传媒经济学的主要研究范例包括理论型、应用型和批评型范例;其研究方法可分为行业市场研究、公司研究和影响力研究。在介绍西方传媒经济学研究的同时,本文还简要回顾了传媒经济学在中国的兴起与发展。 相似文献
228.
This paper is aimed to investigate the operating characteristics of a static synchronous compensator (STATCOM) integrated with superconducting magnetic energy storage (SMES) for high power applications in the transmission network level. The STATCOM controller topology comprises multi-level multi-pulse neutral-point clamped-type (NPC) voltage source inverters (VSIs) using the harmonics cancellation technique, and incorporates a SMES coil. An innovative two-quadrant multi-level dc-dc converter is proposed to effectively interface the STATCOM with the superconducting coil using a buck-boost topology with neutral point voltage control capabilities; thus enabling to simultaneously control both active and reactive power exchange with the high voltage power system. A detailed analysis of major system variables is presented, including analytical results and digital simulations using the MATLAB/Simulink environment. Moreover, a three-level control scheme is designed, including a full decoupled current control strategy in the d-q reference frame with a novel controller to prevent the STATCOM dc bus capacitors voltage drift/imbalance and an enhanced power system frequency controller. 相似文献
229.
230.
Higher education worldwide is beset by rigid budgetary constraints. Increases in governmental and student support have been insufficient to offset the severe inflationary spiral of recent years, and many institutions have been confronted by yearly gaps between estimated revenues and projected expenditures. Following 6 years of across-the-board internal budget reallocations amounting to $11.1 million, Penn State initiated a rolling 5-year planning and budget process in 1977. The new process, resulting in an additional $16.6 million in internal reductions and reallocations through 1982–83, was designed to provide for more selective budgetary decisions based on careful analysis of university priorities. As the process has evolved, it has reoriented budget decisions toward university planning issues and qualitative concerns. 相似文献