全文获取类型
收费全文 | 3122篇 |
免费 | 52篇 |
国内免费 | 2篇 |
专业分类
教育 | 2274篇 |
科学研究 | 185篇 |
各国文化 | 23篇 |
体育 | 464篇 |
文化理论 | 69篇 |
信息传播 | 161篇 |
出版年
2023年 | 30篇 |
2022年 | 51篇 |
2021年 | 74篇 |
2020年 | 128篇 |
2019年 | 194篇 |
2018年 | 247篇 |
2017年 | 240篇 |
2016年 | 181篇 |
2015年 | 118篇 |
2014年 | 112篇 |
2013年 | 657篇 |
2012年 | 132篇 |
2011年 | 81篇 |
2010年 | 78篇 |
2009年 | 79篇 |
2008年 | 68篇 |
2007年 | 53篇 |
2006年 | 60篇 |
2005年 | 47篇 |
2004年 | 32篇 |
2003年 | 44篇 |
2002年 | 30篇 |
2001年 | 25篇 |
2000年 | 22篇 |
1999年 | 23篇 |
1998年 | 27篇 |
1997年 | 18篇 |
1996年 | 26篇 |
1995年 | 22篇 |
1994年 | 24篇 |
1993年 | 17篇 |
1992年 | 11篇 |
1991年 | 15篇 |
1990年 | 14篇 |
1989年 | 21篇 |
1988年 | 20篇 |
1987年 | 14篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 8篇 |
1983年 | 6篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1979年 | 7篇 |
1978年 | 7篇 |
1977年 | 6篇 |
1976年 | 8篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1971年 | 5篇 |
排序方式: 共有3176条查询结果,搜索用时 750 毫秒
991.
International Organization for Standardization (ISO) standard 3297 governs the assignment of International Standard Serial Numbers (ISSNs) for continuing resources worldwide. It is subject to systematic review every five years and, in 2017, an ISO Working Group was set up to review the standard. This working group took the decision to survey the views of stakeholders including publishers, libraries, and others. This article reports on the global survey that was undertaken, describing the questions and answers about which the committee sought opinions. It also sought details on the respondents to provide context. The replies are summarised in chart form with conclusions and an appraisal of the key issues, which suggest that whilst respondents are supportive of expanding the ways in which the ISSN is deployed, they are less convinced of the need for more ISSNs for any given title. They are split on the need for the structure of the ISSN to be revised but there is strong support for the notion of a “Family ISSN” that would describe resources that are linked through, for example, title changes or geography or language. The article notes the next steps to be taken. 相似文献
992.
Cultural Studies of Science Education - In this article, we compared French and Cameroonian schoolchildren’s initial conceptions and comprehension of the night and day cycle in order to test... 相似文献
993.
José Antonio García-Pérez Salvador Llana Belloch Ángel Gabriel Lucas-Cuevas Daniel Sánchez-Zuriaga 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(3):259-266
The effects of treadmill running on impact acceleration were examined together with the interaction between running surface and runner's fatigue state. Twenty recreational runners (11 men and 9 women) ran overground and on a treadmill (at 4.0 m/s) before and after a fatigue protocol consisting of a 30-minute run at 85% of individual maximal aerobic speed. Impact accelerations were analysed using two lightweight capacitive uniaxial accelerometers. A two-way repeated-measure analysis of variance showed that, in the pre-fatigue condition, the treadmill running decreased head and tibial peak impact accelerations and impact rates (the rate of change of acceleration), but no significant difference was observed between the two surfaces in shock attenuation. There was no significant difference in acceleration parameters between the two surfaces in the post-fatigue condition. There was a significant interaction between surface (treadmill and overground) and fatigue state (pre-fatigue and post-fatigue). In particular, fatigue when running overground decreased impact acceleration severity, but it had no such effect when running on the treadmill. The effects of treadmill running and the interaction need to be taken into account when interpreting the results of studies that use a treadmill in their experimental protocols, and when prescribing physical exercise. 相似文献
994.
Alexander Nicolaides Nathan Elliott John Kelley Mauro Pinaffo Tom Allen 《Sports Engineering》2013,16(3):181-188
Topspin has become a vital component of modern day tennis. Ball-to-string bed and inter-string friction coefficients can affect topspin generation from a racket. The aim of this research was to determine the effect of string bed pattern on topspin generation. Tennis balls were projected onto nine head-clamped rackets with different string bed patterns. The balls were fired at 24 m/s, at an angle of 26° to the string bed normal with a backspin rate of 218 rad/s and outbound velocity, spin and angle were measured. Outbound velocity was shown to be independent of string bed pattern. Outbound angle increased with the number of cross strings, while outbound topspin decreased. In the most extreme case, decreasing the number of cross strings from 19 to 13 increased rebound topspin from 117 to 170 rad/s. 相似文献
995.
During tennis-specific movements, such as accelerating and side stepping, the dynamic traction provided by the shoe–surface combination plays an important role in the injury risk and performance of the player. Acrylic hard court tennis surfaces have been reported to have increased injury occurrence, partly caused by increased traction that developed at the shoe–surface interface. Often mechanical test methods used for the testing and categorisation of playing surfaces do not tend to simulate loads occurring during participation on the surface, and thus are unlikely to predict the human response to the surface. A traction testing device, discussed in this paper, has been used to mechanically measure the dynamic traction force between the shoe and the surface under a range of normal loading conditions that are relevant to real-life play. Acrylic hard court tennis surfaces generally have a rough surface topography, due to their sand and acrylic paint mixed top coating. Surface micro-roughness will influence the friction mechanisms present during viscoelastic contacts, as found in footwear–surface interactions. This paper aims to further understand the influence micro-roughness and normal force has on the dynamic traction that develops at the shoe–surface interface on acrylic hard court tennis surfaces. The micro-roughness and traction of a controlled set of acrylic hard court tennis surfaces have been measured. The relationships between micro-roughness, normal force, and traction force are discussed. 相似文献
996.
Mikael Swarén Mikael Therell Anders Eriksson Hans-Christer Holmberg 《Sports Engineering》2013,16(4):255-264
The aim of the study was to develop an objective classification method for cross-country ski poles. A test device was designed to expose different pole models to maximal loading and impact tests. A load cell measured the axial forces in the pole shafts, and a laser distance meter measured shaft deflection when a load was applied via the wrist strap. In the loading tests, each shaft reached a plateau where no more force could be transferred. This maximal force transfer (MFT) value was a characteristic measure for flexural rigidity and thereby also strength. The developed test method enables a loading that is more similar to real-life skiing than a standard three-point bending test. Results show that the introduction of shaft indices for buckling strength is beneficial for comparison purposes. The MFT is a relevant parameter used in the characterization of poles. 相似文献
997.
LoI¨c Damm Daniel Low Andrea Richardson James Clarke Matt Carré Sharon Dixon 《Sports biomechanics / International Society of Biomechanics in Sports》2013,12(4):389-402
The interaction between footwear and surfaces influences the forces experienced by tennis players. The purpose of this study was to investigate traction demand and kinematic adaptation during tennis-specific movements with changes in traction characteristics of surfaces. We hypothesised that players would increase the utilised coefficient of friction (horizontal to vertical ground reaction force ratio) when the shoe surface combination had a high coefficient of friction and flex their knee after contact to facilitate braking. Eight participants performed two separate movements, side jump out of stance and running forehand. Ground reaction force was measured and three-dimensional kinematic data were recorded. Clay surface and cushioned acrylic hard court (low vs. high shoe–surface friction) were used. The peak utilised coefficient of friction was greater on clay than the hard court. The knee was less flexed at impact on clay ( ? 5.6 ± 10.2°) and at peak flexion ( ? 13.1 ± 12.0°) during the running forehand. Our results indicate that tennis players adapt the level of utilised friction according to the characteristics of the surface, and this adaptation favours sliding on the low friction surface. Less knee flexion facilitates sliding on clay, whereas greater knee flexion contributes to braking on the hard court. 相似文献
998.
Cramér-Wolrath E 《Journal of deaf studies and deaf education》2012,17(2):141-162
This case study longitudinally analyzes and describes the changes of attentional expressions in interchanges between a pair of fraternal twins, 1 deaf and 1 hearing, from the age of 10-40 months, and their Deaf family members. The video-observed attentional expressions of initiating and reestablishing interchange were grouped in 5 functional categories: "getting," "directing," "maintaining," "redirecting," and "checking" attention. Changes appear to be associated with development during the twins' ages of 10-13, 15-24, and 28-40 months, including the use of vision in communication. Although there are similarities in the changes of each twin's communicative initiations, there are also differences based on hearing status, personality, and use of modality. This is evident in the ways in which each twin's individual attention interchanges unfold over time; it is also connected with the parents' negotiating attention and arranging "seating positions" with them. Implications and findings for special educational purposes are discussed. 相似文献
999.
André Nowakowski M.A. Dries Vervecken M.Sc. PD Dr. Edith Braun Prof. Dr. Bettina Hannover 《Zeitschrift für Erziehungswissenschaft》2012,15(2):253-271
The extent to which students profit from a university course depends on the lecturers?? approach to teaching, with a student-focused approach being more supportive for student gains in competences than a teacher-focused approach. Little is known, however, about how to foster a student-focused approach to teaching. In this paper, we want to investigate how to frame the feedback lecturers obtain from students?? course evaluations in such a manner that a student-focused approach to teaching is encouraged. In two studies using either a qualitative or a quantitative methodology it can be shown that providing lecturers with a feedback on students?? subjective gain in competences (output-focused teaching evaluation) is more effective in promoting a student-focused approach to teaching than a feedback on how satisfied students were with the lecturer (process-focused teaching evaluation). Results are discussed in the context of the Bologna reforms which demand a continuous evaluation of all university courses. 相似文献
1000.
The present study assesses the performance of 54 participating countries in PISA 2006. It employs efficiency indicators that
relate result variables with resource variables used in the production of educational services. Desirable outputs of educational
achievement and undesirable outputs of educational inequality are considered jointly as result variables. A construct that
captures the quality and quantity of educational resources consumed is used as resource variables. Similarly, environmental
variables of each educational system are included in the efficiency evaluation model; while these resources are not controllable
by the managers of the education systems, they do affect outcomes. We find that European countries are characterized by weak
management, the Americans (mainly Latin Americans) by a weak endowment of resources, and the Asians by a high level of heterogeneity.
In particular, Asia combines countries with optimal systems (South Korea and Macao-China); countries with managerial problems
(Hong Kong, China-Taipei, Japan and Israel); others where the main challenge is the weak endowment of resources (Jordan and
Kyrgyzstan), and, finally, others where the main problem is in the long run since it concerns structural conditions of a socioeconomic
and cultural nature (Turkey, Thailand, and Indonesia). 相似文献