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   11592篇
  免费   15篇
教育   8993篇
科学研究   1209篇
各国文化   1篇
体育   341篇
文化理论   385篇
信息传播   678篇
  2022年   3篇
  2021年   7篇
  2020年   10篇
  2019年   15篇
  2018年   2182篇
  2017年   2090篇
  2016年   1570篇
  2015年   109篇
  2014年   118篇
  2013年   92篇
  2012年   217篇
  2011年   694篇
  2010年   836篇
  2009年   432篇
  2008年   638篇
  2007年   1148篇
  2006年   67篇
  2005年   392篇
  2004年   448篇
  2003年   357篇
  2002年   131篇
  2001年   5篇
  2000年   20篇
  1999年   1篇
  1998年   1篇
  1997年   16篇
  1991年   6篇
  1986年   1篇
  1976年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
The yeast strain (Y18) was isolated from a soil sample collected from Fildes Peninsula, Antarctica. The strain is a psychrophilic yeast with optimum and maximum growth temperatures of 10 ℃ and 18 ℃, respectively. Teliospores were formed after 7 d on malt agar, when the germination of teliospores was observed. Both inositol and D-glucuronate were assimilated. Positive results of the DBB (diazonium blue B) color reaction, urease test, and starch formation were observed. The major CoQ is Qs. All results indicated that Y18 belongs to the genes of Mrakia. The 18S rDNA sequence analyses showed that Y18 is closely related to Mrakiafrigida. DNA-DNA relatedness study, and some biochemistry characteristics indicated that Y18 represents a new species for which Mrakia psychrophila sp. nov. is proposed.  相似文献   
152.
Phonological awareness, phonological memory, and phonological access to lexical storage play important roles in acquiring literacy. We examined the convergent, discriminant, and predictive validity of these phonological processing abilities (PPA) in 389 3-, 4-, and 5-year-old children. Confirmatory factor analysis supported the validity of each PPA as separate from general cognitive ability and separate from each other. Multigroup structural equation modeling (SEM) with mean structure demonstrated that older preschoolers have better developed latent PPA than younger preschoolers but that the structure of PPA is equivalent. RAN was found uniquely associated with letter knowledge and text discrimination in younger preschoolers, and PA was found uniquely associated with word reading skills in older preschoolers. Finally, general cognitive ability was only indirectly associated with emergent literacy via PPA. These results highlight the importance of PPA in the early literacy development of English-speaking preschool children.  相似文献   
153.
Considering the uncertainty of material performance, geometric characteristic and analysis method, the analysis of statistical parameters of the resistance of cast ball-and-socket support joints and the reliability analysis are carried out by JC method (improved first-order second-moment method) based on the relevant experimental data. Results show that the resistance partial factor of the joint increases with the increase of the reliability index. The resistance partial factors are suggested corresponding to the reliability index under different load combinations. Moreover, the suggested resistance partial factor is adopted in reliability design, and it is found that the reliability index of the joint is larger than the target reliability index. The optimal load combination is the one in which live load plays an important control role. Finally, based on the suggested resistance partial factors, the reliability analysis of cast ball-and-socket support joints of a project is conducted.  相似文献   
154.
Existing research highlights conflicting results attempting to capture gender preferences with respect to unimodal versus multimodal designs in online learning. As online learning continues to expand, more research examining the role of gender in multimedia design holds considerable potential. However, the presence of multimedia in online learning contexts presents a more complex problem when taking into consideration the concept of learner interest. The current study sought to investigate gender differences in situational interest (SI) with respect to three different but related designs of an online, multimedia learning environment for continuing, professional education in emergency medical services. The content in these designs was identical, but applied different combinations of the redundancy and modality multimedia principles. A two-way analysis of variance was used to examine the types of SI by gender and type of multimedia design. While no significant difference or interaction effect was identified between gender and triggered SI, an interaction effect was observed for females and the different multimedia designs. Specifically, females reported a higher maintained SI when animation, narration and text were effectively combined. The findings of this study provide insight into best practices for instructional and media designers developing multimedia learning environments as well as future research implications.  相似文献   
155.
Funding agencies in Canada are attempting to break down the organizational boundaries between disciplines to promote interdisciplinary research and foster the integration of the social sciences into the health research field. This paper explores the extent to which biomedical and clinician scientists’ perceptions of social science research operate as a cultural boundary to the inclusion of social scientists into this field. Results indicated that cultural boundaries may impede social scientists’ entry into the health research field through three modalities: (1) biomedical and clinician scientists’ unfavourable and ambivalent posture towards social science research; (2) their opposition to a resource increase for the social sciences; and (3) clinician scientists procedural assessment criteria for social science. The paper also discusses the merits and limitations of Tom Gieryn’s concept of boundary-work for studying social dynamics within the field of science.
Brian D. HodgesEmail:
  相似文献   
156.
Tim Ray 《Minerva》2009,47(1):75-92
Half a century after Michael Polanyi conceptualised ‘the tacit component’ in personal knowing, management studies has reinvented ‘tacit knowledge’—albeit in ways that squander the advantages of Polanyi’s insights and ignore his faith in ‘spiritual reality’. While tacit knowing challenged the absurdities of sheer objectivity, expressed in a ‘perfect language’, it fused rational knowing, based on personal experience, with mystical speculation about an un-experienced ‘external reality’. Faith alone saved Polanyi’s model from solipsism. But Ernst von Glasersfeld’s radical constructivism provides scope to rethink personal tacit knowing with regard to ‘other people’ and the intersubjectively viable construction of ‘experiential reality’. By separating tacit knowing from Polanyi’s metaphysical realism and drawing on Benedict Anderson’s concept of ‘imagined communities’, it is possible to conceptualise ‘imagined institutions’ as the tacit dimension of power that shapes human interaction. Whereas Douglass North claimed institutions could be reduced to rules, imagined institutions are known in ways we cannot tell.  相似文献   
157.
This article investigates the effect of a Tony nomination or win on the demand facing a Broadway production using a panel of weekly revenues for Broadway productions from 1996 to 2007. Our results indicate that the effect of a nomination or win is positive in the week of the announcement and gradually increases in successive weeks, presumably due to publicity and word-of-mouth. Winners experience an increase in demand as late as 1 year later when awards are publicized for the following season. Moreover, nominees that do not win the award are penalized heavily in the weeks following the Award announcements. We find that winning a Tony Award increases a production’s revenues by 12% in the week immediately following the Awards.
Lesley ChiouEmail:
  相似文献   
158.
This study considers a frailty duration approach to modelling the life-length of a sample of 360 films that went into wide release at the Australian box office from 1 January 2000 to 31 December 2005. The analysis extends previous research by considering a range of film-specific covariates relating to distribution, production, consumer signals, and weekly performance. In particular, it is shown that film success (defined in a duration context) responds to previewing, advertising, critical reviews, and US box office—but not to production budget, star power or opening-week screens. The study also reveals that it is appropriate to account for unobservable heterogeneity between films in the choice of empirical methodology.  相似文献   
159.
Nathaniel Logar 《Minerva》2009,47(4):345-366
How does the research performed by a government mission agency contribute to useable technologies for its constituents? Is it possible to incorporate science policy mechanisms for increasing benefits to users in the decision process? The United States National Institute of Standards &; Technology (NIST) promises research directed towards industrial application. This paper considers the processes that produce science and technology at NIST. The institute’s policies for science provide robust examples for how effective science policies can contribute to the emergence of useful technologies. To progress towards technologies that can be years away, the agency uses several means for integrating the needs of eventual information users into the prioritization process. To accomplish this, NIST units, such as the Materials Science and Engineering Laboratory, incorporate mechanisms for considering user need and project impact into different stages of its scientific decision processes. This, and other specific strategies that the agency utilizes for connecting the supply of science to information demand, provide lessons for generating useable science.  相似文献   
160.
Probability density function (PDF) method is proposed for analysing the structure of the reconstructed attractor in computing the correlation dimensions of RR intervals of ten normal old men. PDF contains important information about the spatial distribution of the phase points in the reconstructed attractor. To the best of our knowledge, it is the first time that the PDF method is put forward for the analysis of the reconstructed attractor structure. Numerical simulations demonstrate that the cardiac systems of healthy old men are about 6 - 6.5 dimensional complex dynamical systems. It is found that PDF is not symmetrically distributed when time delay is small, while PDF satisfies Gaussian distribution when time delay is big enough. A cluster effect mechanism is presented to explain this phenomenon. By studying the shape of PDFs, that the roles played by time delay are more important than embedding dimension in the reconstruction is clearly indicated. Results have demonstrated that the PDF method represents a promising numerical approach for the observation of the reconstructed attractor structure and may provide more information and new diagnostic potential of the analyzed cardiac system.  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