全文获取类型
收费全文 | 14851篇 |
免费 | 189篇 |
国内免费 | 13篇 |
专业分类
教育 | 10977篇 |
科学研究 | 1107篇 |
各国文化 | 248篇 |
体育 | 1006篇 |
综合类 | 9篇 |
文化理论 | 211篇 |
信息传播 | 1495篇 |
出版年
2022年 | 60篇 |
2021年 | 124篇 |
2020年 | 240篇 |
2019年 | 352篇 |
2018年 | 429篇 |
2017年 | 491篇 |
2016年 | 462篇 |
2015年 | 322篇 |
2014年 | 399篇 |
2013年 | 3328篇 |
2012年 | 353篇 |
2011年 | 383篇 |
2010年 | 341篇 |
2009年 | 310篇 |
2008年 | 383篇 |
2007年 | 380篇 |
2006年 | 339篇 |
2005年 | 353篇 |
2004年 | 313篇 |
2003年 | 291篇 |
2002年 | 274篇 |
2001年 | 231篇 |
2000年 | 231篇 |
1999年 | 200篇 |
1998年 | 178篇 |
1997年 | 197篇 |
1996年 | 202篇 |
1995年 | 207篇 |
1994年 | 194篇 |
1993年 | 168篇 |
1992年 | 190篇 |
1991年 | 164篇 |
1990年 | 164篇 |
1989年 | 155篇 |
1988年 | 155篇 |
1987年 | 140篇 |
1986年 | 138篇 |
1985年 | 156篇 |
1984年 | 162篇 |
1983年 | 152篇 |
1982年 | 156篇 |
1981年 | 122篇 |
1980年 | 101篇 |
1979年 | 118篇 |
1978年 | 123篇 |
1977年 | 111篇 |
1976年 | 91篇 |
1975年 | 72篇 |
1974年 | 70篇 |
1973年 | 69篇 |
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
81.
82.
This article describes the ongoing efforts at University of Nevada, Las Vegas (UNLV) Libraries to evolve the role of the institutional repository (IR) and to effectively position it within the context of the Libraries’ collections, research support, and scholarly communication services. A major component of this process is re-examining the fundamental aims of the IR and aligning it to the Libraries and the campus strategic goals. The authors situate UNLV Libraries’ experience within the context of the current literature to provide background and reasoning for our decision to pursue two, at times conflicting, aims for the IR: one for scholarly communication and another for research administration. 相似文献
83.
Elena Rudkowsky Martin Haselmayer Matthias Wastian Marcelo Jenny Štefan Emrich Michael Sedlmair 《Communication methods and measures》2018,12(2-3):140-157
ABSTRACTMoving beyond the dominant bag-of-words approach to sentiment analysis we introduce an alternative procedure based on distributed word embeddings. The strength of word embeddings is the ability to capture similarities in word meaning. We use word embeddings as part of a supervised machine learning procedure which estimates levels of negativity in parliamentary speeches. The procedure’s accuracy is evaluated with crowdcoded training sentences; its external validity through a study of patterns of negativity in Austrian parliamentary speeches. The results show the potential of the word embeddings approach for sentiment analysis in the social sciences. 相似文献
84.
This article explores the existence of a “citizen-centered journalism” that sees citizens as crucial participants in the construction of news and as co-creators of their own worlds. Through qualitative case studies of three news organizations, the article examines the motivation for using a citizen-centered approach, the news routines that are required to do so, the categories of content produced, and the perceived impact of this approach. The results suggest these news organizations are working in partnership with communities and striving to give a voice to historically marginalized communities. The journalists, however, see citizen participation as complementary to professional journalistic routines that favor verifiable information, rather than assigning inherent value to it for its own sake. 相似文献
85.
86.
87.
88.
89.
Eric R. Muoz Jaclyn B. Caccese Brittany E. Wilson Kyle T. Shuler Fernando V. Santos Carolina T. Cabn John J. Jeka Dianne Langford Matthew B. Hudson 《运动与健康科学(英文)》2021,10(2):122-130
BackgroundConsidering the potential cumulative effects of repetitive head impact (HI) exposure, we need sensitive biomarkers to track short- and long-term effects. Circulating small extracellular vesicles (sEVs) (<200 nm) traffic biological molecules throughout the body and may have diagnostic value as biomarkers for disease. The purpose of this study was to identify the microRNA (miRNA) profile in circulating sEVs derived from human plasma following repetitive HI exposure.MethodsHealthy adult (aged 18–35 years) soccer players were randomly assigned to one of 3 groups: the HI group performed 10 standing headers, the leg impact group performed 10 soccer ball trapping maneuvers over 10 min, and the control group did not participate in any soccer drills. Plasma was collected before testing and 24 h afterward, and sEVs were isolated and characterized via nanoparticle tracking analysis. Next-generation sequencing was utilized to identify candidate miRNAs isolated from sEVs, and candidate microRNAs were analyzed via quantitative polymerase chain reaction. In silico target prediction was performed using TargetScan (Version 7.0; targetscan.org) and miRWalk (http://mirwalk.umm.uni-heidelberg.de/) programs, and target validation was performed using luciferase reporter vectors with a miR-7844-5p mimic in human embryonic kidney (HEK) 293T/17 cells.ResultsPlasma sEV concentration and size were not affected across time and group following repetitive HI exposure. After 24 h, the HI read count from next-generation sequencing showed a 4-fold or greater increase in miR-92b-5p, miR-423-5p, and miR-24-3p and a 3-fold or greater decrease in miR-7844-5p, miR-144-5p, miR-221-5p, and miR-22-3p. Analysis of quantitative polymerase chain reaction revealed that leg impact did not alter the candidate miRNA levels. To our knowledge, miR-7844-5p is a previously unknown miRNA. We identified 8 miR-7844-5p mRNA targets: protein phosphatase 1 regulatory inhibitor subunit 1B (PPP1R1B), LIM and senescent cell antigen-like domains 1 (LIMS1), autophagy-related 12 (ATG12), microtubule-associated protein 1 light chain 3 beta (MAP1LC3B), integrin subunit alpha-1 (ITGA1), mitogen-activated protein kinase 1 (MAPK1), glycogen synthase kinase 3β (GSK3β), and mitogen-activated protein kinase 8 (MAPK8).ConclusionCollectively, these data indicate repetitive HI exposure alters plasma sEV miRNA content, but not sEV size or number. Furthermore, for the first time we demonstrate that previously unknown miR-7844-5p targets mRNAs known to be involved in mitochondrial apoptosis, autophagy regulation, mood disorders, and neurodegenerative disease. 相似文献
90.