全文获取类型
收费全文 | 2620篇 |
免费 | 47篇 |
国内免费 | 4篇 |
专业分类
教育 | 1829篇 |
科学研究 | 323篇 |
各国文化 | 32篇 |
体育 | 201篇 |
综合类 | 2篇 |
文化理论 | 45篇 |
信息传播 | 239篇 |
出版年
2022年 | 23篇 |
2021年 | 35篇 |
2020年 | 51篇 |
2019年 | 80篇 |
2018年 | 117篇 |
2017年 | 98篇 |
2016年 | 92篇 |
2015年 | 54篇 |
2014年 | 59篇 |
2013年 | 646篇 |
2012年 | 69篇 |
2011年 | 61篇 |
2010年 | 49篇 |
2009年 | 37篇 |
2008年 | 69篇 |
2007年 | 41篇 |
2006年 | 38篇 |
2005年 | 44篇 |
2004年 | 43篇 |
2003年 | 38篇 |
2002年 | 37篇 |
2001年 | 20篇 |
2000年 | 29篇 |
1999年 | 25篇 |
1998年 | 20篇 |
1997年 | 23篇 |
1996年 | 24篇 |
1995年 | 18篇 |
1994年 | 15篇 |
1993年 | 24篇 |
1992年 | 19篇 |
1991年 | 18篇 |
1990年 | 18篇 |
1989年 | 23篇 |
1988年 | 18篇 |
1987年 | 25篇 |
1984年 | 17篇 |
1983年 | 17篇 |
1982年 | 20篇 |
1981年 | 23篇 |
1980年 | 22篇 |
1979年 | 21篇 |
1978年 | 23篇 |
1976年 | 15篇 |
1974年 | 17篇 |
1972年 | 17篇 |
1971年 | 16篇 |
1968年 | 14篇 |
1967年 | 16篇 |
1966年 | 14篇 |
排序方式: 共有2671条查询结果,搜索用时 0 毫秒
91.
This article suggests how we should study media and information literacies (MIL) and do so at a time, when young people nurture these literacies through multiple media practices and across spaces of learning. Our basic argument is this: in order to gain a robust knowledge base for the development of MIL we need to study literacy practices beyond print literacy and numeracy, and we need to study these practices beyond formal spaces of learning. The argument is unfolded with particular focus on ethnic minority youth since this group routinely figures as under-achieving in studies of school literacy, such as Programme for International Student Assessment. Based on a brief overview of literacy studies in view of digitization and a critical examination of recent studies of youthful media practices and ethnicity, the argument is illustrated through an empirical analysis that draws on results from a nationally representative survey of media uses among Danes aged 13–23 years. The analysis demonstrates that ethnic minority youth offer the most serious challenge to existing literacy hierarchies found in formal education. We discuss the implications of these results for educational policy-making and for future research on MIL, advocating inclusive approaches in terms of media for learning and spaces of learning. 相似文献
92.
93.
94.
Reema George Harikrishnan Sivadasanpillai Narayani Jayakumari Anugya Bhatt Jissa V. Thulaseedharan Jaganmohan A. Tharakan 《Indian journal of clinical biochemistry : IJCB》2016,31(3):302-309
Thrombotic risk factors may contribute to premature coronary artery disease (CAD), in addition to the conventional risk factors. There is paucity of data on studies evaluating the role of thrombotic factors in premature CAD in Indian patients. Thus a case–control study was performed to evaluate the role of thrombotic and atherogenic factors in young patients with angiographically proven CAD who are on treatment with statins and anti-platelet drugs. 152 patients (≤55 years) with angiographically proven CAD and 102 asymptomatic controls were recruited. Clinical and biochemical data were obtained in both groups. Blood levels of thrombotic factors-fibrinogen, antithrombin-III, tissue-plasminogen activator (t-PA), plasminogen activator inhibitor-1 (PAI-1), von-Willebrand factor (v-WF), lipoprotein(a) [Lp(a)] and homocysteine were analyzed. Patients had high levels of conventional CAD risk factors (diabetes mellitus, smoking, hypertension, dyslipidemia and positive family history) compared to controls. Logistic regression analysis revealed that low antithrombin-III (odds ratio/OR 11.2; 95 % confidence interval/CI 2.29–54.01), high fibrinogen (OR 6.04; 95 % CI 1.09–33.21) and high Lp(a) (OR 4.54; 95 % CI 0.92–22.56), as important, independent risk factors in patients. PAI-1(OR 0.15; 95 % CI 0.03–0.69) levels were significantly lower in patients. But other thrombotic risk factors studied (t-PA, v-WF and homocysteine) were comparable among patients and controls. The treatment using statins and anti-platelet drugs might be contributing to the control of some of the thrombotic risk factors. The strategies aiming at lowering the levels of thrombotic risk factors along with conventional risk factors may be useful in primary and secondary prevention of CAD. 相似文献
95.
We analyze the impact of exercising sports during childhood and adolescence on educational attainment. The theoretical framework is based on models of allocation of time and educational productivity. Using the rich information from the German Socio-Economic Panel (GSOEP), we apply generalized ordered probit models to estimate the effect of participation in sport activities on secondary school degrees and professional degrees. Even after controlling for important variables and selection into sport, we find strong evidence that the effect of sport on educational attainment is statistically significant and positive. 相似文献
96.
Elke Achtert Christian B?hm Peer Kr?ger Peter Kunath Alexey Pryakhin Matthias Renz 《Informatik - Forschung und Entwicklung》2007,15(3):179-195
The reverse k-nearest neighbor (RkNN) problem, i.e. finding all objects in a data set the k-nearest
neighbors of which include a specified query object, has received increasing attention recently. Many
industrial and scientific applications call for solutions of the RkNN problem in arbitrary metric spaces
where the data objects are not Euclidean and only a metric distance function is given for specifying
object similarity. Usually, these applications need a solution for the generalized problem where the
value of k is not known in advance and may change from query to query. In addition, many applications
require a fast approximate answer of RkNN-queries. For these scenarios, it is important to generate
a fast answer with high recall. In this paper, we propose the first approach for efficient approximative
RkNN search in arbitrary metric spaces where the value of k is specified at query time. Our approach
uses the advantages of existing metric index structures but proposes to use an approximation of the
nearest-neighbor-distances in order to prune the search space. We show that our method scales significantly
better than existing non-approximative approaches while producing an approximation of the true query
result with a high recall. 相似文献
97.
98.
99.
100.