全文获取类型
收费全文 | 19178篇 |
免费 | 274篇 |
国内免费 | 123篇 |
专业分类
教育 | 13359篇 |
科学研究 | 2292篇 |
各国文化 | 182篇 |
体育 | 1664篇 |
综合类 | 12篇 |
文化理论 | 156篇 |
信息传播 | 1910篇 |
出版年
2021年 | 147篇 |
2020年 | 272篇 |
2019年 | 420篇 |
2018年 | 556篇 |
2017年 | 518篇 |
2016年 | 511篇 |
2015年 | 329篇 |
2014年 | 437篇 |
2013年 | 3491篇 |
2012年 | 408篇 |
2011年 | 431篇 |
2010年 | 321篇 |
2009年 | 336篇 |
2008年 | 364篇 |
2007年 | 391篇 |
2006年 | 368篇 |
2005年 | 363篇 |
2004年 | 343篇 |
2003年 | 322篇 |
2002年 | 308篇 |
2001年 | 304篇 |
2000年 | 330篇 |
1999年 | 333篇 |
1998年 | 182篇 |
1997年 | 191篇 |
1996年 | 240篇 |
1995年 | 217篇 |
1994年 | 179篇 |
1993年 | 172篇 |
1992年 | 266篇 |
1991年 | 259篇 |
1990年 | 273篇 |
1989年 | 289篇 |
1988年 | 239篇 |
1987年 | 249篇 |
1986年 | 244篇 |
1985年 | 272篇 |
1984年 | 243篇 |
1983年 | 226篇 |
1982年 | 200篇 |
1981年 | 194篇 |
1980年 | 185篇 |
1979年 | 262篇 |
1978年 | 210篇 |
1977年 | 192篇 |
1976年 | 167篇 |
1975年 | 146篇 |
1974年 | 170篇 |
1973年 | 148篇 |
1971年 | 130篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Jonathan S. Jones Anna-Lynne R. Adlam Abdelmalek Benattayallah Fraser N. Milton 《Child development》2022,93(3):815-830
Working memory training improves children's cognitive performance on untrained tasks; however, little is known about the underlying neural mechanisms. This was investigated in 32 typically developing children aged 10–14 years (19 girls and 13 boys) using a randomized controlled design and multi-modal magnetic resonance imaging (Devon, UK; 2015–2016). Training improved working memory performance and increased intrinsic functional connectivity between the bilateral intraparietal sulci. Furthermore, improvements in working memory were associated with greater recruitment of the left middle frontal gyrus on a complex span task. Repeated engagement of fronto-parietal regions during training may increase their activity and functional connectivity over time, affording greater working memory performance. The plausibility of generalizable cognitive benefits from a neurobiological perspective and implications for neurodevelopmental theory are discussed. 相似文献
2.
Research in Higher Education - Increasingly, undergraduates take more than 4 years to complete a baccalaureate, a situation widely perceived as a waste of time and money, for students,... 相似文献
3.
4.
Fadhaa A. Ghafil Bassim I. Mohammad Hussain S. Al-Janabi Najah R. Hadi Hayder A. Al-Aubaidy 《Indian journal of clinical biochemistry : IJCB》2021,36(1):81
Genetic variation in the angiotensin II type 1 receptor (AT1R) has an important effect on the outcome of acute coronary syndrome (ACS) initiated treatment with captopril. This study aims to investigate the impact of genetic polymorphism of AT1R (rs5186 and rs275651) on the ACS outcome in Iraqi patients treated with captopril. A total of 250 Iraqi individuals with ACS were included in this case—control study and they were divided into two study groups; Study group 1 included 125 participants who were prescribed captopril, 25 mg twice daily and study group 2 included 125 participants who received no captopril as part of their ACS treatment (control study). The AT1R gene (rs5186) CC genotype was found to be associated with ST-elevation myocardial infarction (STEMI) (Odd’s ratio (O.R) = 1.2, P = 0.7), while AC was associated with Non-ST-elevation myocardial infarction (NSTEMI) and unstable angina (UA) (O.R = 1.2, P = 0.8). AC genotype is more prone to have Percutaneous coronary intervention (PCI) after ACS attack (O.R = 1.2, P = 0.6). CC genotype had a risk to get less improvement (O.R = 1.6, P = 0.5), so might require higher doses of captopril during acute coronary insult. The AT1R gene (rs275651) AA genotype was associated with UA (O.R = 1.3, P = 0.9). AA and AT genotypes were more prone to have PCI after ACS attack (O.R = 3.9 P = 0.2, O.R = 3.5, P = 0.3 respectively) and thus requiring higher doses of captopril. We conclude that the AT1R rs5186, rs275651 genetic polymorphisms might partially affect the clinical outcome of ACS patients treated with captopril and might have captopril resistance which requires higher doses. 相似文献
5.
In this digital ITEMS module, Dr. Jeffrey Harring and Ms. Tessa Johnson introduce the linear mixed effects (LME) model as a flexible general framework for simultaneously modeling continuous repeated measures data with a scientifically defensible function that adequately summarizes both individual change as well as the average response. The module begins with a nontechnical overview of longitudinal data analyses drawing distinctions with cross-sectional analyses in terms of research questions to be addressed. Nuances of longitudinal designs, timing of measurements, and the real possibility of missing data are then discussed. The three interconnected components of the LME model—(1) a model for individual and mean response profiles, (2) a model to characterize the covariation among the time-specific residuals, and (3) a set of models that summarize the extent that individual coefficients vary—are discussed in the context of the set of activities comprising an analysis. Finally, they demonstrate how to estimate the linear mixed effects model within an open-source environment (R). The digital module contains sample R code, diagnostic quiz questions, hands-on activities in R, curated resources, and a glossary. 相似文献
6.
Megan K. Schraedley Hamilton Bean Sarah E. Dempsey Mohan J. Dutta Kathleen P. Hunt Sonia R. Ivancic 《Journal of Applied Communication Research》2020,48(2):166-185
ABSTRACTThis forum brings together food, (in)security, and communication. The authors participating in this forum center communication as both process and tool for understanding, mitigating, and making meaning of food (in)security. The nine authors together discuss the role of communication in food (in)security, the central challenges for scholars and practitioners working on food (in)security, and the creative possibilities and impacts influencing the future of food (in)security. The forum produces a call for applied scholars to re-imagine communication frameworks in order to make meaningful differences in their communities. 相似文献
7.
In the IR field it is clear that the value of a system depends on the cost and benefit profiles of its users. It would seem obvious that different users would prefer different systems. In the TREC-9 filtering track, systems are evaluated by a utility measure specifying a given cost and benefit. However, in the study of decision systems it is known that, in some cases, one system may be unconditionally better than another. In this paper we employ a decision theoretic approach to find conditions under which an Information Filtering (IF) system is unconditionally superior to another for all users regardless of their cost and benefit profiles.It is well known that if two IF systems have equal precision the system with better recall will be preferred by all users. Similarly, with equal recall, better precision is universally preferred. We confirm these known results and discover an unexpected dominance relation in which a system with lower recall will be universally preferred provided its precision is sufficiently higher. 相似文献
8.
9.
10.
Paul Morris 《比较教育学》1996,32(1):95-110
The economic success of some of the countries within the East Asian region has generated a range of studies which have attempted to identify the sources of that growth. One strand within these analyses has focused on the critical role of schooling in the accumulation of human capital. This paper examines the role which education has played in the rapid development of the four 'Asian Tigers'; namely: Hong Kong, Taiwan, South Korea and Singapore. It is argued that whilst patterns of educational provision displayed some common features there were also significant differences in other areas such as the role of the state, sources of educational funding, the role of technical education and of the school curriculum. 相似文献