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如何给“运动员”问题建模
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作者 钱呈祥 《物理通报》 2003年第4期44-45,共2页
所谓理想化模型,就是为能够比较顺利地解决问题,保留对所研究问题起决定影响的主要因素,而建立起来的科学抽象模型.这种模型可以清晰地反映被研究问题的本质特性,呈现问题所包含的主要矛盾,便于我们分析和发现规律.要注意的是,同一个物... 所谓理想化模型,就是为能够比较顺利地解决问题,保留对所研究问题起决定影响的主要因素,而建立起来的科学抽象模型.这种模型可以清晰地反映被研究问题的本质特性,呈现问题所包含的主要矛盾,便于我们分析和发现规律.要注意的是,同一个物体现象在不同情况下理想化处理的方法不同,某一因素可能在这种情况下是次要因素,不予考虑.但在另一种情况下可能是主要方面,就必须考虑.如研究地球绕太阳运转时,其大小是次要因素,看作质点处理.但研究地球本身的自转时,其大小就成为主要因素,地球就不能看作质点. 展开更多
关键词 理想化模型 “运动员”问题 建模方法 理科综合测试题 中学 解题方法
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Women's football:Player characteristics and demands of the game
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作者 Vanessa Martínez-Lagunas Margot Niessen Ulrich Hartmann 《Journal of Sport and Health Science》 SCIE 2014年第4期258-272,共15页
The number of scientific investigations on women's football specific to the topics of player characteristics and demands of the game has considerably increased in recent years due to the increased popularity of the w... The number of scientific investigations on women's football specific to the topics of player characteristics and demands of the game has considerably increased in recent years due to the increased popularity of the women's game worldwide, although they are not yet as numerous as in the case of men's football. To date, only two scientific publications have attempted to review the main findings of studies published in this area. However, one of them was published about 20 years ago, when women's football was still in its infancy and there were only a few studies to report on. The other review was more recent. Nonetheless, its main focus was on the game and training demands of senior elite female players. Thus, information on female footballers of lower competitive levels and younger age groups was not included. Consequently, an updated review is needed in this area. The present article therefore aims to provide an overview of a series of studies that have been published so far on the specific characteristics of female football players and the demands of match-play. Mean values reported in the literature for age (12-27 years), body height (155-174 cm), body mass (48-72 kg), percent body fat (13%-29%), maximal oxygen uptake (45.1-55.5 mL/kg/min), Yo-Yo Intermittent Recovery Test Level l (780-1379 m), maximum heart rate (189-202 bpm), 30 m sprint times (4.34-4.96 s), and counter- movement jump or vertical jump (28-50 cm) vary mostly according to the players' competitive level and positional role. There are also some special considerations that coaches and other practitioners should he aware of when working with female athletes such as the menstrual cycle, potential pregnancy and lactation, common injury risks (particularly knee and head injuries) and health concerns (e.g., female athlete triad, iron deficiency, and anemia) that may affect players' football performance, health or return to play. Reported mean values for total distance covered (4-13 km), distance covered at high-speed (0.2-1.7 km), average/peak heart rate (74%-87%/94%-99% HRmax), average/peak oxygen uptake (52%-77%/96%-98% VO2max), and blood lactate (2.2-7.3 mmol/L) during women's football match-play vary according to the players' competitive level and positional role. Methodological differences may account for the discrepancy of the reported values as well. Finally, this review also aims to identify literature gaps that require further scientific research in women's football and to derive a few practical recom-mendations. The information presented in this report provides an objective point of reference about player characteristics and game demands at various levels of women's football, which can help coaches and sport scientists to design more effective training programs and science-based strategies for the further improvement of players' football performance, health, game standards, and positive image of this sport. 展开更多
关键词 Female soccer players Match-play requirements Physical and physiological profiles
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