全文获取类型
收费全文 | 13717篇 |
免费 | 193篇 |
国内免费 | 11篇 |
专业分类
教育 | 9455篇 |
科学研究 | 1688篇 |
各国文化 | 120篇 |
体育 | 1009篇 |
综合类 | 17篇 |
文化理论 | 165篇 |
信息传播 | 1467篇 |
出版年
2022年 | 96篇 |
2021年 | 142篇 |
2020年 | 206篇 |
2019年 | 283篇 |
2018年 | 414篇 |
2017年 | 436篇 |
2016年 | 397篇 |
2015年 | 267篇 |
2014年 | 383篇 |
2013年 | 2235篇 |
2012年 | 340篇 |
2011年 | 318篇 |
2010年 | 307篇 |
2009年 | 267篇 |
2008年 | 287篇 |
2007年 | 292篇 |
2006年 | 274篇 |
2005年 | 240篇 |
2004年 | 262篇 |
2003年 | 230篇 |
2002年 | 243篇 |
2001年 | 317篇 |
2000年 | 337篇 |
1999年 | 258篇 |
1998年 | 141篇 |
1997年 | 183篇 |
1996年 | 180篇 |
1995年 | 122篇 |
1994年 | 134篇 |
1993年 | 118篇 |
1992年 | 201篇 |
1991年 | 188篇 |
1990年 | 226篇 |
1989年 | 213篇 |
1988年 | 186篇 |
1987年 | 197篇 |
1986年 | 179篇 |
1985年 | 212篇 |
1984年 | 153篇 |
1983年 | 132篇 |
1982年 | 125篇 |
1981年 | 112篇 |
1980年 | 113篇 |
1979年 | 174篇 |
1978年 | 131篇 |
1977年 | 114篇 |
1976年 | 90篇 |
1975年 | 93篇 |
1974年 | 94篇 |
1973年 | 92篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
T. Le Sage A. Bindel P. P. Conway L. M. Justham S. E. Slawson A. A. West 《Sports Engineering》2011,14(1):1-14
The research outlined in this paper was conducted to allow real-time processing, transmission and presentation of data to
swimming coaches and subsequently their swimmers in a training environment, focused on providing information relevant to strokes
in free swimming. This was achieved using a wearable wireless sensor and embedded programming techniques, using accelerations
involved in the swimming stroke to provide relevant features for coaches. Current methods used do not offer real-time response
to coaches, which results in the lack of real-time feedback and significantly increased post-session analysis time. Filtering
and signal processing algorithms are described here, which allow real-time data analysis to be embedded within a wireless
sensor node. The system significantly reduces the time for processing acquired data and has delivered a novel monitoring device
suitable for operation within the harsh environment of the pool. 相似文献
962.
Profiles of emergent literacy skills among preschool children who are at risk for academic difficulties 总被引:1,自引:0,他引:1
Sonia Q. Cabell Laura M. JusticeTimothy R. Konold Anita S. McGinty 《Early childhood research quarterly》2011,26(1):1
The purpose of this study was to explore patterns of within-group variability in the emergent literacy skills of preschoolers who are at risk for academic difficulties. We used the person-centered approach of cluster analysis to identify profiles of emergent literacy skills, taking into account both oral language and code-related skills. Participants were 492 preschoolers (aged 42-60 months) enrolled in needs-based programs. In the fall of the academic year, children were administered eight measures of emergent literacy: four oral language measures (i.e., expressive and receptive grammar, expressive and receptive vocabulary) and four code-related measures (i.e., print concepts, alphabet knowledge, name writing, and rhyme). Controlling for age, hierarchical-agglomerative and K-means cluster analysis procedures were employed. Five psychometrically sound profiles emerged: highest emergent literacy (prevalence = 14%); three profiles with average oral language and differential code-related abilities (16%, 24%; 23%); and lowest oral language with broad code-related weaknesses (23%). Profiles were then compared on midyear teacher ratings of emergent literacy as well as end-of-kindergarten literacy performance; results provided convergent evidence of predictive validity. This study highlights the considerable heterogeneity of emergent literacy abilities within an “at-risk” group. The resulting profiles have theoretical and practical relevance when examining both concurrent relationships between oral language and code-related skills as well as longitudinal relationships between early patterns of performance and later reading achievement. 相似文献
963.
Andrea A. diSessa Flavio S. Azevedo Orit Parnafes 《Interactive Learning Environments》2013,21(1-2):109-159
This paper provides a review of the rhetoric behind the component movement in educational software, and a critical analysis and synthesis of issues underlying the movement. We draw on case studies of several significant recent component projects in order to assess claims and to uncover and examine issues that are less often considered. While our empirical base cannot definitively answer all the questions raised, we hope to bring some clarity and some empirically based judgments to bear on how a promising technological innovation can best serve educational ends. Our study led to a focus on three critical issues: (1) the nature of the environment in which components are configured and used; (2) the extent of modifiability that is necessary for effective re-use of components; (3) how the work of designing components and component configurations is distributed among people with different competencies. 相似文献
964.
The longitudinal development of the intraindividual coupling between academic achievement, interest, and self-concept of ability (SCA) was analyzed in a sample of approximately 1,000 children between grades 1 and 12 (ages 6-17). Across all calculated indexes, the average level of coupling was positive. Individuals generally felt competent and interested in domains where they achieve well, and were interested in domains where they perceive their personal strengths. The degree of coupling was the highest between interest and SCA and the lowest between interest and achievement. For all indexes, evidence for an increase in coupling across time was found. Female gender was related to a lower level of coupling. There was evidence for a positive effect of conscientiousness on the amount of coupling. 相似文献
965.
The elusive neutrinos have periodically yielded their secrets to man and at each such juncture major advances have been achieved
in our understanding of the sub-atomic phenomena. These particles also carry invaluable information about the centre of the
Sun where energy is generated through nuclear fusion. In Part I of this article, history of the discovery of neutrinos is
traced, their properties and types are described. Also, the Standard Model which forms the basis of the structure of matter
and of which massless neutrinos are an integral part, is described. The role of neutrinos in solar energy generation and the
great ‘solar neutrino puzzle’ and its solution will be described later in the series. 相似文献
966.
The purpose of this study was to concurrently examine the development of written language across different writing tasks and
to investigate how writing features develop in preschool children. Emergent written language knowledge of 372 preschoolers
was assessed using numerous writing tasks. The findings from this study indicate that children demonstrate knowledge about
writing before beginning school and receiving formal instruction. There was clear evidence to support the claim that universal
writing features develop before language-specific features. Children as young as 3 years possess knowledge regarding universal
and language-specific writing features. Preschoolers appear to progress along a continuum from scribbling to conventional
spelling. Although this progression is sequential, children’s writing proficiency is task dependent. Implications of these
findings on writing development are discussed. 相似文献
967.
The experiments reported in the present study tested whether decreasing intertrial intervals (ITIs) intensifies the disruptive
effects of increasing retention intervals (RIs) in a delayed conditional discrimination by decreasing the animal’s trial tracking
accuracy (Cohen & Armstrong, 1996; Cohen & Roberts, 1996). Rats responded on a fixed ratio (FR) 1 or fixed interval (FI) 10-sec
reinforcement schedule at a second light or tone stimulus, S2, when the first light or tone stimulus, S1, had signaled an
FI 10-sec or FR 1 schedule, respectively. RIs between S1 and S2 were increased from 3 to 24 sec and never exceeded ITIs that
were reduced from 24 to 6 sec. For some rats, the trials were separated from each other by extending the lever at S1 and retracting
it at the end of S2 (ITI lever-retracted group). For other, control rats, the lever remained extended throughout the session
(lever-extended group, Experiment 1) or was extended and retracted with the onset and offset of each stimulus (RI/ITI lever-retracted
group, Experiment 2). The rats under all trial conditions learned to delay leverpressing on the FI 10-sec schedule. Latency
to begin leverpressing on the FI 10-sec schedule declined as RIs were increased, but this effect was attenuated in the ITI
lever-retracted groups in both experiments, as would be predicted by thetrial tracking hypothesis. Decreasing ITIs from 24 to 6 sec intensified the disruptive effects of increasing RIs from 3 to 6 sec in the
RI/ITI lever-retracted group (Experiment 2), as would be predicted by the trial tracking hypothesis. 相似文献
968.
S M Srivastava 《Resonance》2007,12(2):59-70
In 1931, the great Austrian mathematician Kurt Gödel proved “all consistent axiomatic formulations of number theory include undecidable propositions”. This discovery of Gödel and its proof had enormous repercussions in mathematics and computer science. The proof hinged upon the writing of a self-referential mathematical statement, in the same way as the liar’s paradox — I am lying — is a self-referential statement. In this three-part article, we describe Gödel’s discovery and his famous proof. 相似文献
969.
970.
S. Selcen Guzey Elizabeth A. Ring-Whalen 《International Journal of Science Education》2018,40(7):723-741
Engineering has been slowly integrated into K-12 science classrooms in the United States as the result of recent science education reforms. Such changes in science teaching require that a science teacher is confident with and committed to content, practices, language, and cultures related to both science and engineering. However, from the perspective of the science teacher, this would require not only the development of knowledge and pedagogies associated with engineering, but also the construction of new identities operating within the reforms and within the context of their school. In this study, a middle school science teacher was observed and interviewed over a period of nine months to explore his experiences as he adopted new values, discourses, and practices and constructed his identity as a reform-minded science teacher. Our findings revealed that, as the teacher attempted to become a reform-minded science teacher, he constantly negotiated his professional identities – a dynamic process that created conflicts in his classroom practices. Several differences were observed between the teacher’s science and engineering instruction: hands-on activities, depth and detail of content, language use, and the way the teacher positioned himself and his students with respect to science and engineering. Implications for science teacher professional development are discussed. 相似文献