全文获取类型
收费全文 | 20959篇 |
免费 | 275篇 |
国内免费 | 17篇 |
专业分类
教育 | 15019篇 |
科学研究 | 1872篇 |
各国文化 | 143篇 |
体育 | 1771篇 |
综合类 | 22篇 |
文化理论 | 209篇 |
信息传播 | 2215篇 |
出版年
2022年 | 152篇 |
2021年 | 231篇 |
2020年 | 359篇 |
2019年 | 561篇 |
2018年 | 760篇 |
2017年 | 788篇 |
2016年 | 708篇 |
2015年 | 453篇 |
2014年 | 543篇 |
2013年 | 3907篇 |
2012年 | 604篇 |
2011年 | 615篇 |
2010年 | 432篇 |
2009年 | 379篇 |
2008年 | 472篇 |
2007年 | 402篇 |
2006年 | 404篇 |
2005年 | 324篇 |
2004年 | 286篇 |
2003年 | 270篇 |
2002年 | 310篇 |
2001年 | 420篇 |
2000年 | 378篇 |
1999年 | 325篇 |
1998年 | 202篇 |
1997年 | 209篇 |
1996年 | 241篇 |
1995年 | 213篇 |
1994年 | 179篇 |
1993年 | 193篇 |
1992年 | 286篇 |
1991年 | 268篇 |
1990年 | 254篇 |
1989年 | 280篇 |
1988年 | 278篇 |
1987年 | 241篇 |
1986年 | 240篇 |
1985年 | 255篇 |
1984年 | 228篇 |
1983年 | 252篇 |
1982年 | 201篇 |
1981年 | 187篇 |
1980年 | 178篇 |
1979年 | 265篇 |
1978年 | 216篇 |
1977年 | 192篇 |
1976年 | 168篇 |
1975年 | 146篇 |
1974年 | 139篇 |
1973年 | 140篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
David Sánchez-Oliva Rebecca M. Leech Alberto Grao-Cruces Irene Esteban-Cornejo Carmen Padilla-Moledo Oscar L. Veiga 《Journal of sports sciences》2020,38(9):1062-1069
ABSTRACTThe aims of this study were to identify profiles of sedentary behaviour (SB) patterns, based on leisure-time self-reported SB modalities (screen, educative, social, and relaxing) and to evaluate changes in these profiles over 2 years among Spanish youth aged 8–18 years. Latent profile analysis (LPA), a data-driven analytic approach, was used to identify groups of boys and girls (n = 1553; 48% girls; mean±SD age: 12.56 ± 2.49 y) with distinct SB profiles using the SB modalities (time/d) as input variables. Latent transition analysis, an extension of LPA that uses longitudinal data, was used to analyse 2-year changes in these profiles. At baseline, four and three SB profiles were found among boys (labelled: screen, educative, social, and relaxing) and girls (labelled: screen/social, educative, and relaxing), respectively. Overall, more girls (range: 48%-67%) had the same profile over time, than boys (40%-52%). Participants with a screen or relaxing SB profile at baseline were more likely to have an educative profile after 2 years. Youth with a social and an educative SB profile at baseline were more likely to transition to profiles characterized by higher screen and social SB, respectively. Using a novel and person-centered approach, this study identified gender-specific SB profiles that were moderately stable over time. 相似文献
2.
Research in Higher Education - State financial aid grant programs are commonly categorized as either need-based, merit-based, or both, but their initial eligibility requirements include many more... 相似文献
3.
Edgardo Ferretti Leticia Cagnina Viviana Paiz Sebastián Delle Donne Rodrigo Zacagnini Marcelo Errecalde 《Information processing & management》2018,54(6):1169-1181
In this work, we present the first quality flaw prediction study for articles containing the two most frequent verifiability flaws in Spanish Wikipedia: articles which do not cite any references or sources at all (denominated Unreferenced) and articles that need additional citations for verification (so-called Refimprove). Based on the underlying characteristics of each flaw, different state-of-the-art approaches were evaluated. For articles not citing any references, a well-established rule-based approach was evaluated and interesting findings show that some of them suffer from Refimprove flaw instead. Likewise, for articles that need additional citations for verification, the well-known PU learning and one-class classification approaches were evaluated. Besides, new methods were compared and a new feature was also proposed to model this latter flaw. The results showed that new methods such as under-bagged decision trees with sum or majority voting rules, biased-SVM, and centroid-based balanced SVM, perform best in comparison with the ones previously published. 相似文献
4.
5.
ABSTRACTThe preservation of artefacts in museum collections is profoundly affected by fluctuations in temperature and, especially, relative humidity (RH). Since the late nineteenth century, many studies have been carried out on the best way to control hygrothermal conditions. In old buildings located in maritime temperate climate zones (such as Portugal) with strong thermal inertia, and which have low ventilation rate (relative to the volume and number of visitors), daily and seasonal hygroscopic inertia may help to assure the maintenance of RH stabilization conditions. The use of expensive active systems may be minimized through the passive behaviour of internal finishing building materials. This work presents the results of an experimental laboratory study conducted in a flow chamber to demonstrate the enormous potential of hygroscopic materials in stabilizing interior relative humidity. Based in these results and in-situ monitoring in a museum housed in a building, located in Porto, with a typical construction of the 1950s (granite masonry and reinforced concrete slabs), a numerical analysis was done to quantify the influence of hygroscopic materials in stabilizing the interior relative humidity. 相似文献
6.
María Inés Tato 《档案与原稿》2020,48(2):200-215
ABSTRACT This paper aims to analyse the initiatives undertaken by some immigrant communities residing in Latin America to record their mobilisation around the First World War. After the armistice, European communities in Argentina, Bolivia, Brazil, Chile, Mexico, Paraguay, Peru, Uruguay and other countries gathered detailed information about their activities during the conflict, published as profusely illustrated books of remembrance, offered to their governments as proof of their loyalty. The article intends to establish the peculiar nature of these publications as records of the war effort, and analyse the agents and processes of their elaboration, and their role as commemorative but also as archival documents. 相似文献
7.
8.
James D. T. Tannock 《Higher Education Quarterly》1992,46(1):108-123
This article describes the Engineering Professors' Conference (EPC) approach to quality assurance for Higher Education Institutions, which is currently the only formalized alternative to British Standard 5750 'Quality Systems'. The EPC approach is based on principles of quality assurance and Total Quality Management which have been developed in industry. These ideas are briefly outlined, and an opinion expressed on the interpretation and application of BSS7S0 for HE. The EPC model is explained, illustrated with example elements taken from the EPC Specification and Guidelines for Quality Assurance in Higher Education. A top-down approach to the development of an institutional quality system is described, based on a quality policy statement. Areas of activity which have an important impact on the quality of education are identified, emphasising the quality assurance requirements of academic departments. Supporting and administrative quality system requirements are also described, as these also play an important role in the quality of education. Formal quality procedures and documentation in key areas are proposed. 相似文献
9.
10.