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排序方式: 共有1513条查询结果,搜索用时 31 毫秒
41.
This investigation assessed the effect of dietary nitrate (NO3?) supplementation, in the form of beetroot juice (BR), on repeat-sprint performance in normoxia and normobaric hypoxia. 12 male team-sport athletes (age 22.3 ± 2.6 y, VO2peak 53.1 ± 8.7 mL.kg?1.min?1) completed three exercise trials involving a 10 min submaximal warm-up and 4 sets of cycling repeat-sprint efforts (RSE; 9 × 4 s) at sea level (CON), or at 3000 m simulated altitude following acute supplementation (140 mL) with BR (HYPBR; 13 mmol NO3?) or NO3depleted BR placebo (HYPPLA). Peak (PPO) and mean (MPO) power output, plus work decrement were recorded during the RSE task, while oxygen consumption (VO2) was measured during the warm-up. There were no significant differences observed between HYPBR and HYPPLA for PPO or MPO; however, work decrement was reduced in the first RSE set in HYPBR compared with HYPPLA. There was a moderate effect for VO2 to be lower following BR at the end of the 10 min warm-up (ES = 0.50 ± 0.51). Dietary NO3? may not improve repeat-sprint performance in hypoxia but may reduce VO2 during submaximal exercise. Therefore, BR supplementation may be more effective for performance improvement during predominantly aerobic exercise.  相似文献   
42.
Museums,schools and geographies of cultural value   总被引:1,自引:0,他引:1  
This article explores a paradox and a possibility that have emerged from two pieces of policy-related research concerning educational use of museums within England. The paradox relates to the use of museums which, whilst widely perceived as rather elitist institutions, appear from a postcode analysis of school visits to museums to be visited by large numbers of schools located in areas of social deprivation. The present analysis further explores this paradox, drawing on revised postcode analysis and governmental indices of multiple deprivation and income deprivation affecting children. The analysis supports the contention that museums attracted visits from schools located in areas with some of the highest levels of deprivation, although it suggests that this result needs to be considered in relation to regional differences in areas of social deprivation, the location of museums and the differences between individual and area-based measures of deprivation. Attention is then drawn to the potential of considering museums through a geographical perspective, and specifically through Foucault's notions of primary, secondary and tertiary spatializations. It is argued that primary spatializations encompasses how museums are conceptualized and classified; secondary spatializations concern how various elements of museums are articulated together; and tertiary spatializations relate to the placement of museums in wider societal contexts and processes. It is suggested that the postcode analysis of school visits points both to the significance of considering tertiary spatializations relating to the social circumstances of museum visitors but also raised questions concerning primary spatializations of museums. Attention is drawn to changes in the classification and grouping of museums, and how these often encompass geographically based criteria related to the social reach of museums. The article ends by considering the degree to which museums might seek to further change their primary spatialization to reflect tertiary spatializations relating to cultural value.  相似文献   
43.
In Western societies scientists are increasingly expected to seek media exposure and cooperate with industry. Little attention has been given to the way such expectations affect the role of scientific experts in society. To investigate scientists’ own perspectives on these issues eight exploratory, in-depth interviews were conducted in Denmark with reputable nutrition scientists. Additionally, eight interviews were held with ‘key informants’ from the field of nutrition policy. It was found that nutrition scientists experience two dilemmas: first, between their aspiration to make a collective impact on public health and the powerful incentives of each to appear frequently in the media with new messages; second, between their need to cooperate with the food industry for financial reasons and their fear that this may compromise their independence and scientific integrity. It is argued that the dilemmas identified in this study should be dealt with openly by the relevant groups of scientists.  相似文献   
44.
Research illustrates the positive roles of perceived competence, autonomy, and mastery climate and the negative role of performance climate in student motivation in physical education. Less research has examined perceptions of relationships within this setting (i.e., perceived teacher support and relatedness) and their role in student motivation. The purpose of this study was to test the mediating roles of perceived competence, autonomy, and relatedness in the relationship between social contextual factors and motivation in physical education students (N = 508). Results from structural equation modeling showed that perceived competence, autonomy, and relatedness partially mediated the relationship between perceived teacher support and self-determined motivation and that mastery climate related directly to self-determined motivation. The results highlight the importance of perceived teacher support, mastery climate, and relatedness to motivation in physical education.  相似文献   
45.
46.
The relationship between culture and tourism has been widely investigated from different perspectives. A large strand of literature studies the role of cultural heritage to attract tourists, while a rich bulk of studies on cultural participation investigates the impact of tourism flows on the demand for culture. Another aspect worth investigating relates to the link between cultural participation and the performance of tourism destinations (TDs), as a higher cultural participation in an area could boost the performance in the management of tourism resources. However, so far, this issue has been disregarded in the literature, and this paper aims at filling this gap. Specifically, it studies the effect of cultural participation on TDs’ performance using a conditional efficiency approach that ensures robust inference on the role of environmental factors. We employ data on the Italian regions for the period 2004–2010, and we explore the role of cultural participation for tourism by using several indicators. Our findings offer empirical support to the positive role of cultural participation and, thus, suggest that public cultural policies might also boost the efficiency of the tourism sector.  相似文献   
47.
In the paper some case studies of damaged towers in Italy are presented: the Tower Masserano of Palace Ferrero - La Marmora at Biella, the bell tower of the Collegiata of San Vittore at Arcisate, and three medieval towers in Alba. A methodology is put forward for combining laboratory and nondestructive testing methods with monitoring systems in order to reach the goal of evaluating the state of conservation of historic towers and its evolution in time.  相似文献   
48.
Mercury porosimetry was applied to the study of pore structure of the historic Roman cement mortars representative of different locations in Europe and time periods as well as different application techniques from architectural castings to in situ formed renders and profiles. Three categories of pores were found to coexist in the mortars. The finest pores, with diameters below 0.1 μm, are present within the hardened aged Roman cement matrix. The larger ‘air’ pores, with diameters between 0.2–2 μm, are due to the evaporation of the excess unbound water and restricted hydration. Pores larger than 2 μm are rare and, in general, can be related to microcracking induced by shrinkage drying and mortar weathering. The mortars have rarely been found to develop a dense fine-porous microstructure characteristic of the ideal conditions of moist-curing; massive architectural castings being the only exception identified. The presence of larger ‘air’ pores was, in turn, almost universally observed. The investigations of the freshly prepared Roman cement mortars have revealed that the restricted hydration could be due to the exposure of the freshly laid surface to dry real-world external environments, a high water-to-cement ratio in the original mortars, or the drawing of water from the stucco mass due to insufficient pre-wetting of the porous masonry. The insufficient reactivity of historic cements, resulting from a high content of over-burned, non-reactive cement components or coarseness of the cement grains, could be another reason for yielding poorly hydrated mortars in the past. In general, Roman cement stuccoes are in an excellent state of preservation in spite of their usual exposure to polluted urban environments for more than a century. Therefore, the coexistence of Roman cement mortars of widely different pore structures has not brought about any problems of incompatibility which field observations could reveal. The Roman cement repair materials have been found to develop pore structures similar to those of historic mortars. Therefore, they are in broad terms compatible with historic masonry or stuccoes. However, the porosity and strength of the repair materials can be controlled by a careful manipulation of the water-to-cement ratio of the mix to adapt them better to the properties of the host material.  相似文献   
49.
50.
The aim of the paper was to evaluate changes in muscle force-velocity parameters (F-v) in elderly women subjected to physical exercise. The examinations encompassed 20 women, aged 62–71, who were students at the University of the Third Age in Wroc?aw. The evaluation of flexors and extensors of the knee joint, as well as flexors and extensors of the spine within the lumbar part, was performed under isokinetic conditions. The assessment was conducted three times: first, a preliminary evaluation; second, after four months of rehabilitation, which included march training and systemic exercises; third, was performed after another 12 months, during which the patients were subjected to various forms of individually selected physical activity. The examinations of muscles affecting the knee joint revealed that the results achieved in the second measurement, performed with load of 60°/s, revealed higher values than in the first examination and were similar or higher in the third examination. With a load of 180°/s, values achieved in the second measurement were higher than results from the first measurement and were mostly lower than registered in the measurement.

The highest values of parameters F-v for flexors and extensors of the lumbar part of the spine were registered in third examination. The results were about 20% higher than achieved within measurements 1 and 2. The increase and maintenance of muscular fitness in elderly women is possible only if a load applied exceeds threshold values and is applied for a long time.  相似文献   
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