全文获取类型
收费全文 | 8141篇 |
免费 | 110篇 |
国内免费 | 283篇 |
专业分类
教育 | 5455篇 |
科学研究 | 1687篇 |
各国文化 | 29篇 |
体育 | 474篇 |
综合类 | 500篇 |
文化理论 | 8篇 |
信息传播 | 381篇 |
出版年
2024年 | 1篇 |
2023年 | 31篇 |
2022年 | 63篇 |
2021年 | 102篇 |
2020年 | 130篇 |
2019年 | 106篇 |
2018年 | 77篇 |
2017年 | 78篇 |
2016年 | 74篇 |
2015年 | 156篇 |
2014年 | 438篇 |
2013年 | 545篇 |
2012年 | 644篇 |
2011年 | 745篇 |
2010年 | 635篇 |
2009年 | 711篇 |
2008年 | 644篇 |
2007年 | 651篇 |
2006年 | 594篇 |
2005年 | 458篇 |
2004年 | 343篇 |
2003年 | 309篇 |
2002年 | 242篇 |
2001年 | 194篇 |
2000年 | 130篇 |
1999年 | 82篇 |
1998年 | 43篇 |
1997年 | 60篇 |
1996年 | 39篇 |
1995年 | 22篇 |
1994年 | 29篇 |
1993年 | 27篇 |
1992年 | 22篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 13篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 7篇 |
1985年 | 13篇 |
1984年 | 16篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 5篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有8534条查询结果,搜索用时 15 毫秒
41.
42.
基于P2P的适应性信息检索系统的设计 总被引:3,自引:1,他引:3
江淇 《现代图书情报技术》2005,21(9):41-44
针对现有搜索引擎的不足,提出了一个基于P2P的适应性信息检索系统设计方案,详细介绍了系统的各主要模块的功能和技术方法,进而分析了该模型的优势。 相似文献
43.
44.
基于词向量扩展的学术资源语义检索技术 总被引:1,自引:0,他引:1
[目的/意义] 尝试以统计的方法为指导思想,探究基于词向量扩展的语义检索技术来提升学术资源的语义检索能力。[方法/过程] 利用自然语言处理、文本挖掘技术,对采集来的学术资源(主要是学术论文)元数据进行预处理,结合word2vec词向量生成工具和elasticsearch全文检索引擎搭建语义检索系统,对学术资源进行语义检索的探索研究。[结果/结论] 本文提出的方法能够有效提升学术信息的检索效果,一定程度上实现学术资源的语义检索,并为后续语义检索的进一步研究提供借鉴。 相似文献
45.
John Andrew Ouligian 《Public Library Quarterly》2018,37(2):127-138
ABSTRACTThe Harwood Institute arrived in Youngstown, Ohio, in 1999; and today, over 18 years later, its teachings have made a profound effect upon the city. The Youngstown Public Library, through the leadership of Carlton Sears and Heidi Daniel, has wholeheartedly embraced the methods and ideology of the Harwood Institute, helping to reinvigorate and power a city working its way back to prosperity. 相似文献
46.
We have studied the efficiency of research in the EU by a percentile-based citation approach that analyzes the distribution of country papers among the world papers. Going up in the citation scale, the frequency of papers from efficient countries increases while the frequency from inefficient countries decreases. In the percentile-based approach, this trend, which is uniform at any citation level, is measured by the ep index that equals the Ptop 1%/Ptop 10% ratio. By using the ep index we demonstrate that EU research on fast-evolving technological topics is less efficient than the world average and that the EU is far from being able to compete with the most advanced countries. The ep index also shows that the USA is well ahead of the EU in both fast- and slow-evolving technologies, which suggests that the advantage of the USA over the EU in innovation is due to low research efficiency in the EU. In accord with some previous studies, our results show that the European Commission’s ongoing claims about the excellence of EU research are based on a wrong diagnosis. The EU must focus its research policy on the improvement of its inefficient research. Otherwise, the future of Europeans is at risk. 相似文献
47.
Rafael Boscolo-Berto Andrea Porzionato Carla Stecco Veronica Macchi Raffaele De Caro 《Anatomical sciences education》2021,14(6):739-751
The world has been turned upside down by a global health emergency caused by the Covid-19. Given the high contagiousness of the virus and the need to contain its spread, social distancing rules, self-isolation policies, and geographical lockdowns have been enforced globally. Over the pandemic emergency the majority of the planned in-person meetings and congresses of national and international anatomical societies have been postponed or canceled. It is unclear what the future holds, but times of crisis often present possibilities for re-thinking old ways to achieve a more critical approach. It has become increasingly clear that traditional in-person congress formats of scientific societies need to be reevaluated. Over the past year and a half, two types of congressional modalities have been trialed to address the challenge of the pandemic as far as scientific meetings are concerned: the fully virtual congress, in which case the conference program is live streamed to all of the attendees, and the hybrid congress, in which case some of the attendees physically participate at the congress's venue while others interact via a virtual platform. The current study set out to investigate the technical difficulties, social challenges, costs and sustainability, logistics and management issues linked to holding various types of congresses in the post-Covid world. Anatomical societies throughout the world are actively striving to reshape their response to the current global emergency and to uncover new types of conference modalities in the effort to keep scientific exchange alive and flourishing in the post-Covid era. 相似文献
48.
Robert Davis 《Slavic & East European Information Resources》2017,18(1-2):67-73
In fall 2016, the Columbia-Cornell collaboration in the area of Slavic & East European resource coordination and sharing celebrated its sixth year. The author reviews particulars of the development, implementation, and function of this program as well as some of the challenges that face such cross-institutional efforts. 相似文献
49.
Kevin R. Tarlow 《Teaching Statistics》2016,38(1):16-21
Analysis of variance (ANOVA) is a test of mean differences, but the reference to variances in the name is often overlooked. Classroom activities are presented to illustrate how ANOVA works with emphasis on how to think critically about inferential reasoning. 相似文献
50.
We first report discovery of the spinel-garnet-orthopyroxene granulite with pure CO2 fluid inclusions from the Fuyun region of the late Paleozoic Altay orogenic belt in Central Asia, NW China. The rock is characterized by an assemblage of garnet, orthopyroxene, spinel, cordierite, biotite, plagioclase and quartz. Symplectites of orthopyroxene and spinel, and orthopyroxene and cordierite indicate decompression under UHT conditions. Mineral chemistry shows that the or-thopyroxenes have high XMg and A12O3 contents (up to 9.23 wt%). Biotites are enriched in TiO2 and XMg and are stable under granulite facies conditions. The garnet and quartz from the rock carry monophase fluid inclusions which show peak melting temperatures of around -56.7℃, indicating a pure CO2 species being presented during the ultrahigh-T metamorphism in the Altay orogenic belt. The inclusions homogenize into a liquid phase at temperatures around 15.3-23.8℃ translating into CO2 densities of the order of 0.86-0.88 g/cm3. Based on prelim 相似文献