全文获取类型
收费全文 | 25384篇 |
免费 | 358篇 |
国内免费 | 15篇 |
专业分类
教育 | 18130篇 |
科学研究 | 2026篇 |
各国文化 | 267篇 |
体育 | 2521篇 |
综合类 | 7篇 |
文化理论 | 255篇 |
信息传播 | 2551篇 |
出版年
2021年 | 288篇 |
2020年 | 449篇 |
2019年 | 695篇 |
2018年 | 901篇 |
2017年 | 830篇 |
2016年 | 799篇 |
2015年 | 496篇 |
2014年 | 607篇 |
2013年 | 4694篇 |
2012年 | 544篇 |
2011年 | 585篇 |
2010年 | 442篇 |
2009年 | 464篇 |
2008年 | 495篇 |
2007年 | 466篇 |
2006年 | 442篇 |
2005年 | 378篇 |
2004年 | 404篇 |
2003年 | 323篇 |
2002年 | 335篇 |
2001年 | 470篇 |
2000年 | 518篇 |
1999年 | 445篇 |
1998年 | 264篇 |
1997年 | 255篇 |
1996年 | 314篇 |
1995年 | 253篇 |
1994年 | 264篇 |
1993年 | 229篇 |
1992年 | 354篇 |
1991年 | 375篇 |
1990年 | 352篇 |
1989年 | 368篇 |
1988年 | 339篇 |
1987年 | 330篇 |
1986年 | 332篇 |
1985年 | 375篇 |
1984年 | 295篇 |
1983年 | 303篇 |
1982年 | 241篇 |
1981年 | 250篇 |
1980年 | 262篇 |
1979年 | 353篇 |
1978年 | 265篇 |
1977年 | 242篇 |
1976年 | 202篇 |
1975年 | 183篇 |
1974年 | 184篇 |
1973年 | 178篇 |
1971年 | 174篇 |
排序方式: 共有10000条查询结果,搜索用时 328 毫秒
141.
Raymond J. Pingree Elizabeth Stoycheff Mingxiao Sui Jason T. Peifer 《Mass Communication and Society》2018,21(5):555-584
The mere perception that news has given certain problems more coverage can lead the audience to assume that those problems are more important. Given that the news media, at times, obsesses over relatively trivial matters, and given that the audience is increasingly able to filter media exposure, it is worth asking what happens when audience members perceive that recent media coverage has not emphasized any very important problems. In such cases, audience members might assume that any problems facing the nation must not be particularly important. We explicate this attitude of political complacency, test whether perceived media agendas lacking important problems can influence it, and explore whether complacency helps explain political disengagement. We also explore whether these effects generalize beyond news, to new media gatekeepers such as Twitter. Two experiments tested effects of a perceived absence of important problems in recent news or Twitter content. In the case of news, but not Twitter, this increased complacency in both studies. Study 2 added a no-exposure control and found that effects on complacency were driven by the cueing of nonproblem stories, not by the absence of problem story cues. Both studies validated complacency as a predictor of political disengagement. 相似文献
142.
Flávia Gomes-Franco e Silva Juliana Colussi Paula Melani Rocha 《Journal of Radio & Audio Media》2018,25(1):77-91
This study was conducted in an environment of widespread use of social media and mobile applications in the mass media. The general goal of the study was to analyze the use of WhatsApp in cybermedia, specifically in radio. A case study was proposed to examine the use of WhatsApp on the program Las mañanas de RNE, broadcast by Spanish National Radio. It was found that the public was very accepting of the program’s initiative to solicit WhatsApp voice messages, beginning in November 2015. The case study used audio files of a direct broadcast that included specific times for audience participation. The use of WhatsApp was accepted by the audience, in addition to the use of the conventional telephone, as a tool well-suited to listener participation in radio programming. Finally, the study highlights the importance of interactive, participatory spaces in broadcasts through the creation of synergies with new forms of online participation. 相似文献
143.
144.
145.
146.
147.
148.
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
149.
150.