全文获取类型
收费全文 | 5947篇 |
免费 | 114篇 |
国内免费 | 146篇 |
专业分类
教育 | 3503篇 |
科学研究 | 1207篇 |
各国文化 | 23篇 |
体育 | 355篇 |
综合类 | 352篇 |
文化理论 | 34篇 |
信息传播 | 733篇 |
出版年
2024年 | 1篇 |
2023年 | 9篇 |
2022年 | 69篇 |
2021年 | 186篇 |
2020年 | 100篇 |
2019年 | 48篇 |
2018年 | 54篇 |
2017年 | 60篇 |
2016年 | 54篇 |
2015年 | 182篇 |
2014年 | 266篇 |
2013年 | 326篇 |
2012年 | 433篇 |
2011年 | 445篇 |
2010年 | 460篇 |
2009年 | 446篇 |
2008年 | 415篇 |
2007年 | 439篇 |
2006年 | 451篇 |
2005年 | 372篇 |
2004年 | 195篇 |
2003年 | 237篇 |
2002年 | 272篇 |
2001年 | 231篇 |
2000年 | 137篇 |
1999年 | 73篇 |
1998年 | 46篇 |
1997年 | 52篇 |
1996年 | 42篇 |
1995年 | 24篇 |
1994年 | 13篇 |
1993年 | 17篇 |
1992年 | 22篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1985年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有6207条查询结果,搜索用时 15 毫秒
171.
从河南省FDI现状及与区域GDP的比较入手,利用大量的数据资料,从产业结构、进出口贸易和劳动力就业等方面进行说明,并通过对各地市的FDI进行比较得出,FDI对河南省经济发展的影响是显著的,但它在各地的分布极不均衡。 相似文献
172.
教育研究中的系统科学进展与应用 总被引:1,自引:0,他引:1
系统科学作为教育研究的重要方法论,也是教学系统设计的理论基础之一.它虽然已经历了一般系统论、自组织理论、复杂性理论三个发展阶段,但就目前教育理论研究情况来看,系统科学思想方法的教育应用仍多停留在一般系统论的初级阶段,对系统科学的新近研究成果显得不够重视,尤其是有着丰富内涵与教育应用巨大潜力的自组织理论代表--耗散结构理论.随着后现代主义教育研究的深入,耗散结构理论已越来越多地受到课程研究领域专家的重视,相关研究成果初步显现.另外,数字化学习理论Connectivism新近获得了较大发展,它的主要观点正是耗散结构理论主要思想方法的重要体现.由此,我们相信在系统梳理系统科学自身发展状况的基础上,研究系统科学代表性观点的教育应用已显得十分必要.另外,积极吸纳耗散结构理论的思想观点去分析教学系统,有助于从教育研究方法论的角度审视教育的弊病,查找深层次原因,摸索规律,促进信息时代教育的新发展. 相似文献
173.
174.
175.
Honglei Lin Zhiping He Wei Yang Yangting Lin Rui Xu Chi Zhang Meng-Hua Zhu Rui Chang Jinhai Zhang Chunlai Li Hongyu Lin Yang Liu Sheng Gou Yong Wei Sen Hu Changbin Xue Jianfeng Yang Jie Zhong Xiaohui Fu Weixing Wan Yongliao Zou 《国家科学评论(英文版)》2020,7(5):913
Chang’E-4 landed in the South Pole-Aitken (SPA) basin, providing a unique chance to probe the composition of the lunar interior. Its landing site is located on ejecta strips in Von Kármán crater that possibly originate from the neighboring Finsen crater. A surface rock and the lunar regolith at 10 sites along the rover Yutu-2 track were measured by the onboard Visible and Near-Infrared Imaging Spectrometer in the first three lunar days of mission operations. In situ spectra of the regolith have peak band positions at 1 and 2 μm, similar to the spectral data of Finsen ejecta from the Moon Mineralogy Mapper, which confirms that the regolith''s composition of the landing area is mostly similar to that of Finsen ejecta. The rock spectrum shows similar band peak positions, but stronger absorptions, suggesting relatively fresh exposure. The rock may consist of 38.1 ± 5.4% low-Ca pyroxene, 13.9 ± 5.1% olivine and 48.0 ± 3.1% plagioclase, referred to as olivine-norite. The plagioclase-abundant and olivine-poor modal composition of the rock is inconsistent with the origin of the mantle, but representative of the lunar lower crust. Alternatively, the rock crystallized from the impact-derived melt pool formed by the SPA-impact event via mixing the lunar crust and mantle materials. This scenario is consistent with fast-cooling thermal conditions of a shallow melt pool, indicated by the fine to medium-sized texture (<3 mm) of the rock and the SPA-impact melting model [Icarus 2012; 220: 730–43]. 相似文献
176.
Yanhua Qu Chunhai Chen Ying Xiong Huishang She Yong E Zhang Yalin Cheng Shane DuBay Dongming Li Per G P Ericson Yan Hao Hongyuan Wang Hongfeng Zhao Gang Song Hailin Zhang Ting Yang Chi Zhang Liping Liang Tianyu Wu Jinyang Zhao Qiang Gao Weiwei Zhai Fumin Lei 《国家科学评论(英文版)》2020,7(1):113
Known as the ‘third polar region’, the Qinghai-Tibet Plateau represents one of the harshest highland environments in the world and yet a number of organisms thrive there. Previous studies of birds, animals and humans have focused on well-differentiated populations in later stages of phenotypic divergence. The adaptive processes during the initial phase of highland adaptation remain poorly understood. We studied a human commensal, the Eurasian Tree Sparrow, which has followed human agriculture to the Qinghai-Tibet Plateau. Despite strong phenotypic differentiation at multiple levels, in particular in muscle-related phenotypes, highland and lowland populations show shallow genomic divergence and the colonization event occurred within the past few thousand years. In a one-month acclimation experiment investigating phenotypic plasticity, we exposed adult lowland tree sparrows to a hypoxic environment and did not observe muscle changes. Through population genetic analyses, we identified a signature of polygenic adaptation, whereby shifts in allele frequencies are spread across multiple loci, many of which are associated with muscle-related processes. Our results reveal a case of positive selection in which polygenic adaptation appears to drive rapid phenotypic evolution, shedding light on early stages of adaptive evolution to a novel environment. 相似文献
177.
Cong Liu Feng An Paria S M Gharavi Qinwen Lu Junkun Zha Chao Chen Liming Wang Xiaozhi Zhan Zedong Xu Yuan Zhang Ke Qu Junxiang Yao Yun Ou Zhiming Zhao Xiangli Zhong Dongwen Zhang Nagarajan Valanoor Lang Chen Tao Zhu Deyang Chen Xiaofang Zhai Peng Gao Tingting Jia Shuhong Xie Gaokuo Zhong Jiangyu Li 《国家科学评论(英文版)》2020,7(1):84
Complex oxides with tunable structures have many fascinating properties, though high-quality complex oxide epitaxy with precisely controlled composition is still out of reach. Here we have successfully developed solution-based single-crystalline epitaxy for multiferroic (1-x)BiTi(1-y)/2FeyMg(1-y)/2O3–(x)CaTiO3 (BTFM–CTO) solid solution in large area, confirming its ferroelectricity at the atomic scale with strong spontaneous polarization. Careful compositional tuning leads to a bulk magnetization of 0.07 ± 0.035 μB/Fe at room temperature, enabling magnetically induced polarization switching exhibiting a large magnetoelectric coefficient of 2.7–3.0 × 10−7 s/m. This work demonstrates the great potential of solution processing in large-scale complex oxide epitaxy and establishes novel room-temperature magnetoelectric coupling in epitaxial BTFM–CTO film, making it possible to explore a much wider space of composition, phase, and structure that can be easily scaled up for industrial applications. 相似文献
178.
179.
针对网络蠕虫的快速传播特性,运用简单流行病学模型和从监控系统获得的非法扫描数据,通过检测非法扫描流量的增长趋势,在蠕虫病毒爆发初期对其进行实时预警,运用数据挖掘技术从扫描数据中自动获取扫描特征,据此特征对蠕虫扫描进行过滤和隔离,阻断蠕虫病毒的传播。 相似文献
180.
介绍了实现运行时的多态性几个重要因素——虚函数、基类和派生类。通过实例阐述了虚函数如何实现运行时的多态性的,用运行结果数据详细分析了运行时的多态性的过程。最后说明了动态绑定实现的原理。 相似文献