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   12644篇
  免费   17篇
教育   9822篇
科学研究   1282篇
各国文化   11篇
体育   372篇
文化理论   395篇
信息传播   779篇
  2022年   8篇
  2021年   14篇
  2020年   11篇
  2019年   23篇
  2018年   2191篇
  2017年   2093篇
  2016年   1589篇
  2015年   117篇
  2014年   132篇
  2013年   371篇
  2012年   232篇
  2011年   705篇
  2010年   846篇
  2009年   449篇
  2008年   662篇
  2007年   1166篇
  2006年   86篇
  2005年   412篇
  2004年   469篇
  2003年   376篇
  2002年   166篇
  2001年   29篇
  2000年   41篇
  1999年   22篇
  1998年   12篇
  1997年   34篇
  1996年   15篇
  1995年   17篇
  1994年   18篇
  1993年   14篇
  1992年   14篇
  1991年   20篇
  1990年   18篇
  1989年   20篇
  1988年   16篇
  1987年   14篇
  1986年   9篇
  1985年   11篇
  1984年   15篇
  1983年   10篇
  1982年   18篇
  1981年   10篇
  1980年   16篇
  1979年   14篇
  1978年   10篇
  1977年   11篇
  1976年   17篇
  1975年   8篇
  1968年   7篇
  1967年   8篇
排序方式: 共有10000条查询结果,搜索用时 281 毫秒
261.
Academic performance (i.e., grade point average) determines career entry factors as well as career success and is thus crucial for students’ future careers. Besides individual factors such as personality traits, individuals’ social embeddedness has been shown to enhance performance. Regarding academic performance, relationships to fellow students (peers), which bundle into one’s developmental network, are a valuable source of psychosocial and career support because occupying central positions within a social network provides the benefit of being able to access career-enhancing resources. Integrating individual and social-contextual factors for the purpose of examining academic performance is therefore plausible. Research results indicate that personality, especially extraversion, might predict performance through network centrality. In this study, we examined this assumption by focusing on extraversion and centrality in the peer developmental network of recently acquainted German psychology bachelor students (N?=?47, 15% male). In a longitudinal design, we analyzed the impact of extraversion and centrality on students’ academic performance at the end of their studies. Results revealed that centrality (i.e., popularity) mediates the relationship of extraversion with academic performance, indicating that extraverted students (regardless of their agreeableness) are more popular among their peers, which, in turn, enhances their academic performance. That is, the likelihood of getting superior final grades depends on whether students manage to attract peers at the very beginning of their university life, which is easier for extraverts. These findings emphasize the importance of the social embeddedness of people, highlight its long-term effects on performance, and yield several implications for research and practice.  相似文献   
262.
Four pigeons responded on a two-component multiple token-reinforcement schedule, in which tokens were produced according to a random-interval 30-sec schedule and exchanged according to a variable-ratio 4 schedule in both components. To assess the effects of contingent token loss, tokens were removed after every second response (i.e., fixed-ratio 2 loss) in one of the components. Response rates were selectively lower in the loss components relative to baseline (no-loss) conditions, as well as to the within-condition no-loss components. Response rates were decreased to a greater degree in the presence of tokens than in their absence. To control for the effects of changes in the density of token and food reinforcement, two parts consisted of additional conditions where food density and token loss were yoked to those in a previous loss condition. In the yoked-food condition, tokens were produced as usual in both components, but the overall density of food reinforcement in one of the components was yoked to that obtained during a previous token-loss condition. In the yoked token-loss condition, tokens were removed during one component of the multiple schedule at a rate that approximately matched the obtained rate of loss from a previous token-loss condition. Response rates in these yoked components were less affected than those in comparable loss components, despite similar densities of token, exchange, and food reinforcement. On the whole, the results support the conclusion that contingent token loss serves as an effective punisher with pigeons.  相似文献   
263.
Based on the complex dispersion relation for the two-dimensional free-surface waves generated by a moving body in the steady Oseen flows, the effect of viscosity on wavelength and wave amplitude was investigated by means of an asymptotic method and a numerical analysis. A comparison between the asymptotic and numerical analysis for the viscous decay factor demonstrates the validity of the perturbation expansions for the wave profile. The numerical result shows that the wavelength of viscous wave is slightly elongated in comparison with that of inviscid wave.  相似文献   
264.
Toddlers displaying extremely inhibited behavior may be at risk for becoming socially withdrawn. However, behavioral inhibition may be a multifaceted characteristic, and its concurrent relation to toddler wariness with peers has not been examined. In this study, 108 toddlers (54 females) and their mothers were observed in novel situations involving unfamiliar settings, adults, and peers. Vagal tone, temperament, separation-reunion behavior, and maternal oversolicitousness also were assessed. There was little consistency of inhibited behavior across the 3 situations. Consistently inhibited toddlers had fearful temperaments, showed distress following maternal separation, and had mothers who were warm and controlling but unresponsive to children's cues during interaction. Toddlers with highly fearful temperaments and highly oversolicitous mothers were the most inhibited across contexts.  相似文献   
265.
This study explored what kind of mathematics is needed in cabinetmakers’ everyday work and how problem solving is intertwined in it. The informants of the study were four Finnish cabinetmakers and the data consisted of workshop observations, interviews, photos, pictures and sketches made by the participants during the interviews. The data was analysed using different qualitative techniques. Even though the participants identified many areas of mathematics that could be used in their daily work, they used mathematics only if they were able to. The cabinetmakers’ different mathematical skills and knowledge were utilized to their skill limit. Cabinetmakers were found to constantly face problem solving situations along with the creative processes. Being able to use more advanced mathematics helped them to solve those problems more efficiently, without wasting time and materials. Based on the findings, the paper discusses the similarities and differences between problem solving and creative processes. It is suggested that the combination of craftsmanship, creativity, and efficient problem solving skills together with more than basic mathematical knowledge will help cabinetmakers in adapting and surviving in future unstable labour markets.  相似文献   
266.
INTRODUCTION Left-handed materials (LHMs), first investigated theoretically by Veselago (1968), have received sub- stantial attention in the scientific and engineering communities. The unique properties of these meta- materials are promising for a diversity of microwave applications, such as new types of beam steerers, modulators, filters, superlens (Pendry, 2000), cou- plers and antenna radoms (Smith et al., 2004). Re- cently, a transmission line (TL) approach has been successfully in…  相似文献   
267.
1 Introduction Theobjectiveofthisstudyistoexaminecompeti tionenvironmentforinterestrateandtopreviewthecompetitiontrendsaftertheinterestratehasbeenful lyliberalizedinChina .Underthedominantfixedin terestrate ,almostnorealcompetitionregardingin terestratehadeveroccurredamongcommercialbanksinChinauntilveryrecentlywhentheinterestratelib eralizationreformhasbeenunderwaysince 2 0 0 0 .Tostudythecompetition ,thepaperisstructuredasfol lows .Section 2 providesaquantitativeexaminationoftheenvironment…  相似文献   
268.
Kenneth N. Ross 《Prospects》1992,22(3):305-316
Author of numerous publications on the use of social indicators to guide decisions concerning resource allocation within education systems. Co-editor of Planning the Quality of Education (IIEP-UNESCO and Pergamon Press). His research interests are focused on indicators of the quality of basic education in developing countries.  相似文献   
269.
The step-size procedure is very important for solving optimization problems. The Armijo step-size rule, the Armijo-Goldstein step-size rule and the Wolfe-Powell step-size rule are three well-known line search methods. On the basis of the above three types of line search methods and the idea of the proximal point methods, a new class of step-size rules was proposed. Instead of a single objective function f, f +1/2(x - xk)^TBk(x-Xk) was used as the merit function in iteration k, where Sk is a given symmetric positive definite matrix. The existence of the steplength for the new rules was proved. Some convergence properties were also discussed.  相似文献   
270.
Peer-to-Peer systems are emerging as one of the most popular Internet applications. Structured Peer-to-Peer overlay networks use identifier based routing algorithms to allow robustness, load balancing, and distributed lookup needed in this environment. However, identifier based routing that is independent of Internet topology tends to be of low efficiency. Aimed at improving the routing efficiency, the super-proximity routing algorithms presented in this paper combine Internet topology and overlay routing table in choosing the next hop. Experimental results showed that the algorithms greatly improve the efficiency of Peer-to-Peer routing.  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