首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   20855篇
  免费   157篇
  国内免费   154篇
教育   14019篇
科学研究   3185篇
各国文化   73篇
体育   919篇
综合类   472篇
文化理论   407篇
信息传播   2091篇
  2025年   3篇
  2024年   9篇
  2023年   14篇
  2022年   111篇
  2021年   272篇
  2020年   225篇
  2019年   122篇
  2018年   2258篇
  2017年   2166篇
  2016年   1646篇
  2015年   401篇
  2014年   585篇
  2013年   641篇
  2012年   905篇
  2011年   1438篇
  2010年   1509篇
  2009年   1077篇
  2008年   1302篇
  2007年   1865篇
  2006年   789篇
  2005年   966篇
  2004年   756篇
  2003年   680篇
  2002年   419篇
  2001年   247篇
  2000年   191篇
  1999年   152篇
  1998年   86篇
  1997年   77篇
  1996年   71篇
  1995年   46篇
  1994年   27篇
  1993年   24篇
  1992年   29篇
  1991年   14篇
  1990年   8篇
  1989年   6篇
  1988年   4篇
  1987年   4篇
  1986年   5篇
  1985年   3篇
  1984年   4篇
  1983年   2篇
  1982年   2篇
  1976年   1篇
  1957年   4篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
This phenomenological study explored six single mothers’ experiences of support at their young children’s school. Themes resulting from interpretative phenomenological analysis suggest the single mothers experienced tangible (e.g., school resources, school-wide events, structural flexibility, teachers’ formal communication) and intangible (e.g., caring relationships with school faculty and staff, experiencing teachers as parenting partners, perceiving acceptance from the school environment) forms of support from their children’s school. Furthermore, results suggest these single mothers experienced intangible supports more prominently than tangible forms of support. The support needs of these single mothers at their young children’s school were also explored including the mothers’ desire for stronger relationships with other parents and families at the school.  相似文献   
992.
Classroom data modeling involves posing questions, identifying attributes of phenomena, measuring and structuring these attributes, and then composing, revising, and communicating the outcomes. Selecting attributes is a fundamental component of data modeling, and the considerations made when selecting attributes is the focus of this paper. A teaching experiment involving 2 teacher educators and 25 pre-service teachers (PSTs) was carried out with 24 young children (5–6-year-olds) as part of a 4-day data modeling investigation. Although perceptual features of the data influenced initial approaches to attribute selection, considerations of the problem situation influenced a shift from the perceptual and towards consideration of attributes such as taxonomy, habitat, behavior, and diet. Expertise in the data context (animal kingdom) and ability to collaborate and negotiate within groups supported children in their ability to switch attributes, attend to multiple situations presented by the problem, and modify and extend their categorizations of data.  相似文献   
993.
    
We used an appetitive sensory preconditioning procedure to investigate temporal integration in rats in two experiments. In Phase 1, rats were presented with simultaneous compound trials on which a 10-sec conditioned stimulus (CS) X was embedded within a 60-sec CS A. In Group Early, CS X occurred during the early portion of CS A, whereas in Group Late, CS X occurred during the latter portion of CS A. In Phase 2, CS X was paired simultaneously with sucrose. On a subsequent test with CS A, the rate of magazine entries peaked during the early portions of the stimulus in Group Early and during the latter portions of the stimulus in Group Late (Experiments 1 and 2). Similar response peaks were not observed on tests with a control stimulus that had been presented in compound with a stimulus that did not signal reward (Experiment 2).  相似文献   
994.
    
The brachistochrone problem posed by Bernoulli and its solution highlights one of the most famous experiments in physics which illustrates the variational principle. This pedagogical study is designed to ignite a classroom discussion on the variational problem. We overview the Euler–Lagrange formalism of the variational principle and obtain the solution to the brachistochrone problem. We demonstrate the success of the variational method using brachistochrone models which were fabricated specially for this purpose.  相似文献   
995.
Research has established that adolescents both befriend peers based on their academic achievement and adjust their own achievement to that of their friends’ over time. However, these processes may be different for ethnic minority students, because some of them may adhere to an oppositional culture that rejects striving for academic success. We examine respective differences between self-identified ethnic minority and majority students using longitudinal social network analysis (stochastic actor-oriented models) in a sample of 1175 students (aged 13) from 12 grade-level networks in Germany secondary schools. Among the students, we find that academically successful students in particular prefer friends with high grades, but that students with poor grades exert more social influence on their friends to adjust their performance. Moreover, while minority students are indeed less inclined to select friends with higher grades, both ethnic majority and minority youth prefer friends with similar academic achievement and are similarly influenced by their friends’ achievement. However, social influence is stronger from same-ethnic than from inter-ethnic friends. In sum, there is mixed evidence for an oppositional culture among ethnic minority students in our sample.  相似文献   
996.
997.
提出了一种基于位置敏感哈希算法的海量文本数据查询算法,通过位置敏感哈希算法将文本数据的特征向量映射到哈希桶中,从而有效地降低了计算复杂度并提高了数据检索的效率。首先,利用TF-IDF特征表示文本的特征向量,并根据给定的哈希函数集把文本的特征向量映射至哈希桶;接下来,利用哈希表为给定的文本计算出与之对应的直方图,通过直方图距离计算文本的相似度;最后,通过计算目标文本集中的文本与待查询文本的相似度进行文本排序,排序分值高的文本作为相关文本返回给用户。实验结果表明,对比已有方法文本提出的算法在MAP以及查全率-查准率曲线两个测度上都获得了较好的性能。  相似文献   
998.
    
The uncontrollable formation of Li dendrites has become the biggest obstacle to the practical application of Li-metal anodes in high-energy rechargeable Li batteries. Herein, a unique LiF interlayer woven by millimeter-level, single-crystal and serrated LiF nanofibers (NFs) was designed to enable dendrite-free and highly efficient Li-metal deposition. This high-conductivity LiF interlayer can increase the Li+ transference number and induce the formation of ‘LiF–NFs-rich’ solid–electrolyte interface (SEI). In the ‘LiF–NFs-rich’ SEI, the ultra-long LiF nanofibers provide a continuously interfacial Li+ transport path. Moreover, the formed Li–LiF interface between Li-metal and SEI film renders low Li nucleation and high Li+ migration energy barriers, leading to uniform Li plating and stripping processes. As a result, steady charge–discharge in a Li//Li symmetrical cell for 1600 h under 4 mAh cm−2 and 400 stable cycles under a high area capacity of 5.65 mAh cm−2 in a high-loading Li//rGO–S cell at 17.9 mA cm−2 could be achieved. The free-standing LiF–NFs interlayer exhibits superior advantages for commercial Li batteries and displays significant potential for expanding the applications in solid Li batteries.  相似文献   
999.
1000.
    
The Convergence process in which European Union (EU) universities are at present involved supposes that these institutions not only have to re-structure their degree programmes, but also their teaching and learning methodologies. We study the impact of this EU process on Database teaching, comparing the practices of three different European universities and using the Convergence goals as criteria. In our discussion, we identify which aspects in each university are closer to the Convergence goals, and which are likely to help in achieving these goals.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号