全文获取类型
收费全文 | 4475篇 |
免费 | 94篇 |
国内免费 | 133篇 |
专业分类
教育 | 2470篇 |
科学研究 | 829篇 |
各国文化 | 47篇 |
体育 | 316篇 |
综合类 | 203篇 |
文化理论 | 41篇 |
信息传播 | 796篇 |
出版年
2024年 | 2篇 |
2023年 | 6篇 |
2022年 | 57篇 |
2021年 | 144篇 |
2020年 | 98篇 |
2019年 | 59篇 |
2018年 | 64篇 |
2017年 | 65篇 |
2016年 | 58篇 |
2015年 | 134篇 |
2014年 | 186篇 |
2013年 | 293篇 |
2012年 | 337篇 |
2011年 | 336篇 |
2010年 | 321篇 |
2009年 | 285篇 |
2008年 | 293篇 |
2007年 | 333篇 |
2006年 | 343篇 |
2005年 | 263篇 |
2004年 | 141篇 |
2003年 | 125篇 |
2002年 | 130篇 |
2001年 | 126篇 |
2000年 | 108篇 |
1999年 | 78篇 |
1998年 | 54篇 |
1997年 | 62篇 |
1996年 | 59篇 |
1995年 | 38篇 |
1994年 | 22篇 |
1993年 | 21篇 |
1992年 | 17篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 15篇 |
1988年 | 6篇 |
1987年 | 1篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 1篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1957年 | 1篇 |
1946年 | 1篇 |
排序方式: 共有4702条查询结果,搜索用时 9 毫秒
61.
根据“三个代表”的重要思想和“与时俱进,开拓创新”的时代精神,运用组织健康运转原理,通过对我党约束机制进行历史性的分析,把自律系统和他律系统的结合类型可分为三种类型:利益一致直属相交型,利益对抗互不相容平行型和利益一致根部相交平行型,讨论了各种类型的特点和适用条件,并对我党的组织机构改善提出了合理化建议。 相似文献
62.
In this work, synchronization of chaotic Colpitts circuits, using adaptive controllers to combat circuit parameter mismatches and channel distortions, is studied by numerical simulations. Synchronization errors caused by different main circuit components are compared, and compensation for time-constant and time-varying circuit parameter mismatches is demonstrated. Different kinds of channel distortions, including time-constant and time-varying channel attenuation, Additive White Gaussian Noise (AWGN) are all investigated by numerical simulations and discussed. Simulation results indicated that the synchronization performance of chaotic Colpitts circuits can be greatly improved by applying adaptive controllers when parameter mismatches and channel attenuation are considered as time-constant or time-varying, but have no obvious enhancements regarding the effect on AWGN channel. 相似文献
63.
杨启贵 《蒙自师范高等专科学校学报》1995,(4)
本文讨论广义Lienard系统(E):x+(f(x)+k(x)x)+g(x)=0,获得了系统(E)的极限环存在,至多有一个或两个的充分条件.这些条件不仅简单和易于验证,而且推广了〔5,6〕的结果. 相似文献
64.
印第安纳波利斯儿童博物馆基于美国K-9国家课程标准,开发了几十门项目学习课程,根据项目学习原则布置各个场景,为家长、学校、学生提供真实化情境、问题化引导、职业化体验的"Hands on"式教育。 相似文献
65.
西部大开发 ,一退三还 ,使得本来粮食短缺、经济落后的西部地区粮食安全雪上加霜 ,进而成为中国粮食安全的隐患。本文认为解决西部粮食安全的思路在于走区域大循环之路 ,并从粮食流通体制、提高粮食自给率、增加稳定的供应和提高西部农民购买力等方面采取对策 ,以实现西部和全国粮食安全的良性循环和可持续发展。 相似文献
66.
67.
OpenURL框架结构分析 总被引:5,自引:0,他引:5
OpenURL作为一种开放式链接框架结构,与传统信息链接框架相比,增加了许多新的功能,成为信息资源整合的重要工具,受到图书情报界的密切关注,也将被美国全国信息标准组织(NISO)所接收。本文在分析OpenURL框架结构和运行机制的基础上,讨论其在信息资源整合中的使用。 相似文献
68.
Ji Shen Patrick C. Gibbons John F. Wiegers Ann P. McMahon 《Journal of Science Teacher Education》2007,18(3):431-459
We present a practical way of adapting and using four research-based assessments for different purposes in an electricity
and magnetism course for K-8 science teachers. The course is designed to accomplish conceptual change toward accepted scientific
conceptions as well as introducing teachers to materials and activities appropriate for their classrooms. Our data support
that using the research-based tests to identify alternative conceptions and discuss test results with teachers is a promising
way to use the knowledge of alternative conceptions in professional development. We also identify some mismatches between
the research of conceptual change and its use in programs of professional development.
相似文献
Ji ShenEmail: |
69.
Comparison of high order aberration after conventional and customized ablation in myopic LASIK in different eyes of the same patient 总被引:4,自引:0,他引:4
Purpose: To verify whether there exists any difference in higher order aberrations after undergoing myopic LASIK (laser in situ keratomileusis) with conventional ablation and customized ablation in different eyes of the same patient. Methods: This was a prospective randomized study of 54 myopic eyes (27 patients) that underwent LASIK using the Nidek EC-5000 ex-cimer laser system (Nidek, Gamagori, Japan). Topography-guided customized aspheric treatment zone (CATz) was used in the first eye of the patient (study group) and the other eye of the same patient was operated on with conventional ablation (control group). Higher order aberrations [root-mean-square (RMS) in the 5-mm zone] of both groups were observed with the Nidek OPD-Scan aberrometer before and 3 months after LASIK. Preoperative mean refractive error was similar between two eyes of the same patient (t=?0.577, P>0.05). Results: Preoperatively, higher order aberrations (RMS in the 5-mm zone) in the CATz ablation and conventional groups were (0.3600±0.0341) μm and (0.2680±0.1421) μm, respectively. This difference was not statistically significant (t=1.292, P>0.05). Three months after LASIK, higher order aberrations (RMS in 5-mm zone) in the CATz ablation and conventional groups were (0.3627±0.1510) μm and (0.3991±0.1582) μm, respectively. No statistically significant difference was noted between pre- and postoperative higher order aberrations in the CATz group (t=?0.047, P>0.05). However, a statistically significant increase in higher order aberrations was observed after conventional ablation (t=?5.261, P<0.05). A statistically sig-nificant difference was noted in the increase of higher order aberrations after LASIK between groups (t=?2.050, P=0.045). Con-clusion: LASIK with conventional ablation and topography-guided CATz ablation resulted in the same BSCVA (best specta-cle-corrected visual acuity) 3 month after LASIK. Higher order aberrations were increased, but the increase of higher order ab-errations after customized ablation treatment was less than that after conventional ablation. 相似文献
70.