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排序方式: 共有137条查询结果,搜索用时 15 毫秒
41.
Paolo Caravaggi Alberto Leardini Claudio Belvedere 《Sports biomechanics / International Society of Biomechanics in Sports》2020,19(3):382-394
AbstractHead and neck injuries are common in contact sports such as American football. Different mechanisms can produce such injuries, including compressive impact forces on the crown of the helmet with the neck in a flexed chin-down position. The aim of this paper was developing and testing a novel Cervical Spine Protection Device (CSPD) designed to keep the neck within its safe physiological range. The cervical spine range of motion (ROM) of ten participants was measured under four conditions: free; wearing a football gear; wearing the CSPD; and wearing the CSPD underneath the gear. The CSPD was tested in terms of passive and active restraint of head motion, and for its capability to improve endurance time of the neck extensor muscles. Wearing the CSPD resulted in a significant 40–60% reduction in ROM across the three anatomical planes, and in increased endurance of the neck extensor muscles (FREE: 114 ± 57 s; CSPD: 214 ± 95 s; p = 0.004). In quasi-static loading conditions the CSPD was capable of keeping the neck within its physiological range, thus it may be used to decrease the risk of severe injuries due to dangerous chin-down positions. 相似文献
42.
Luca Paolo Ardigò Johnny Padulo Andrea Zuliani Carlo Capelli 《Journal of sports sciences》2015,33(17):1853-1858
This study aimed to apply a validated bioenergetics model of sprint running to recordings obtained from commercial basic high-sensitivity global positioning system receivers to estimate energy expenditure and physical activity variables during soccer refereeing. We studied five Italian fifth division referees during 20 official matches while carrying the receivers. By applying the model to the recorded speed and acceleration data, we calculated energy consumption during activity, mass-normalised total energy consumption, total distance, metabolically equivalent distance and their ratio over the entire match and the two halves. Main results were as follows: (match) energy consumption = 4729 ± 608 kJ, mass normalised total energy consumption = 74 ± 8 kJ · kg?1, total distance = 13,112 ± 1225 m, metabolically equivalent distance = 13,788 ± 1151 m and metabolically equivalent/total distance = 1.05 ± 0.05. By using a very low-cost device, it is possible to estimate the energy expenditure of soccer refereeing. The provided predicting mass-normalised total energy consumption versus total distance equation can supply information about soccer refereeing energy demand. 相似文献
43.
This paper describes experiments carried out to determine the influence of dovetailed cross beams on the dimensional stability of a panel painting from the Middle Ages. Besides a serious cup (transverse distortion), the panel featured an unusual longitudinal distortion, a bow, mostly originating from bending in the proximity of the middle cross beam. Because of its localized occurrence, bending appeared to be caused by the crossbeam somehow pushing on the walls of its channel. Thanks to the cooperation offered by the curator and the restorer, some non-damaging tests were performed to measure the distortions of the panel, with and without the cross beams, after conditioning it in different climates. Processing and analysis of the measurement results demonstrated that the bow of the panel increases as the wood moisture content decreases. This led to the conclusion that the bow is actually produced by forces exerted by the cross beam along the panel's length, according to a mechanism named thrust transformation. By this mechanism the cross beam partly transforms the panel's tendency towards cupping, into a bow distortion. 相似文献
44.
Gildas Avoine Luca Calderoni Jonathan Delvaux Dario Maio Paolo Palmieri 《International Journal of Information Management》2014
Modern public transportation companies often record large amounts of information. Privacy can be safeguarded by discarding nominal tickets, or introducing anonymization techniques. But is anonymity at all possible when everything is recorded? In this paper we discuss travel information management in the public transport scenario and we present a revealing case study (relative to the city of Cesena, Italy), showing that even anonymous 10-ride bus tickets may betray a user's privacy expectations. We also propose a number of recommendations for the design and management of public transport information systems, aimed at preserving the users’ privacy, while retaining the useful analysis features enabled by the e-ticketing technology. 相似文献
45.
After years of neglect and an almost complete lack of maintenance, the Racconigi Royal Park was in an inevitable and widespread state of decay. This decay also involved the waterways that were designed in the nineteenth-century by Xavier Kurten (1811–1840). The seasonal lack of water and the agricultural needs of the farms around the Park made it necessary, during the planning stage of the restoration project, to consider the practicability and the effectiveness of some measures that were conceived to optimize the operation of the restored waterways, without altering the historical structure of the system. The realization of a hydraulic numerical model of the system, which is briefly illustrated in the first part of this case study, resulted to be the most suitable tool to study different possible solutions of the problem. The model simulations in fact helped the restorers put into effect the right remedies to favour the correct flow of the water, to make the whole historical system more efficient and to make its future maintenance easier. 相似文献
46.
Dynamic squat is one of the most executed fitness exercise. Its use is widespread both for rehabilitation and training purposes. Several typologies of the squat exercise can be performed. The most important are the front squat and the back squat. In the front squat the barbell is held in front of the body across the clavicles and deltoids, while in the back squat exercise the bar is held on the back of the body at the base of the neck. In this paper we will refer to dynamic back squat. The squat exercise can be performed with or without the help of a machine that has the scope of guiding the person during the movement and ensuring his stability and safety. The use of this type of machine is often necessary when the workout is heavy and the risk of incorrect exercise and injuries is high. On the other hand, the rigid structure of this device often overconstrains the lifting movement. From all these observations, the purpose of the paper is to discuss an alternative design of a mechanism able to maintain the advantage to allow a free-body execution and to preserve the safety of the athletes as well. The proposed mechanism has been designed starting from an anthropometric study on the squat movement. This has been performed by using a motion capture system and applying computer-aided engineering techniques. The design activity started from the experimental investigation of the trajectory of the barbell during the natural execution of the unrestricted back squat exercise. The tests have been performed on several subjects with different mass, anthropometry and gender. In a second phase, the data have been processed and analyzed and a specific mechanism, able to reproduce the natural trajectories, has been synthetized. Finally, the design and optimization of the entire structure has been performed through the use of virtual prototyping techniques. 相似文献
47.
48.
AbstractIn this article, we discuss the process of standardization of Higher education (HE) initiated by the Bologna Process bringing to the forefront the temporal politics of the standardization of European Higher Education Arena (EHEA). Empirically, we perform a comparative review of the Scorecards indicators at the base of the Bologna Process monitoring project. We argue that the fabrication of EHEA could be seen as the installation of new time-space ‘time’ and ‘space’ appear inevitably intertwined. Instead of being a simple addition, the time space of EHEA interferes with the multiple time spaces of educational institutions and is characterized by being a network time, an unbroken and fragmented temporality sustained, enacted through, and controlled by the fluidity and the malleability of standards. They change recurrently over time, playing with different rhythms. What emerges is an overall arrhythmia that maintains the field permanently in tension. This reconfigures temporality as intrinsically manifold: as multiple and heterogeneous. Moreover, the temporal politics of standards reconfigures perception of past, present and especially future. The current state of implementation is constantly being (re)shaped in relation to the present and future performances, where’s one today level of EHEA targets achievement forms the basis for improvement tomorrow. In this scenario, assessing standards and headline targets become a policy instrument for synchronizing the countries performances, by locating them in a temporal framework that encodes future-oriented dispositions. 相似文献
49.
Eileen Scanlon Erica Morris Terry di Paolo Martyn Cooper 《Studies in Science Education》2013,49(1):73-114
This paper describes the current state of science education in Arab states and anticipates some of the challenges faced by those states as they reform their science education. After discussing problems of illiteracy, access and quality we provide contextual information about the structure of the educational systems and describe recent efforts to reform them. We focus on issues pertaining to science curriculum and textbooks, language, religion, student learning in science, science teacher education and science education research and summarise the challenges and opportunities for research faced in each area. We conclude the paper by proposing a set of policy and research recommendations that could aid in the development of lasting solutions for recurring problems. 相似文献
50.
Benefiting colleagues but not the city: Localized effects from the relocation of superstar inventors
Paolo Zacchia 《Research Policy》2018,47(5):992-1005
In this paper I examine episodes in which superstar inventors relocate to a new city. In particular, in order to assess whether the beneficial effects of physical proximity to a superstar have a restricted network dimension or a wider spatial breadth (spillovers), I estimate changes in patterns of patenting activity following these events for two different groups of inventors: the superstar's close collaborators, and all the other inventors in a given urban area, for both the locality where the superstar moves to and for the one that is left behind. In the case of collaborators, I restrict the attention to patents realized independently from the superstar. The results from the event study register a large and persistent positive effect on the collaborators in the city of destination, as well as a simultaneous negative trend affecting those still residing in the previous location. In the long run, these effects translate into an increased difference between the two groups of about 0.16 patents per inventor. Conversely, no city-wide spillover effect can be attested, offering little support to place-based policies aimed at inducing a positive influx of top innovators in urban areas. 相似文献