煤矿采掘面产尘模拟分析实践教学系统研发及应用

文章构建了具有自主知识产权的煤矿采掘面产尘模拟分析实践教学系统。该系统可使学生全面、直观地感受煤矿采掘面截割/钻进破煤产尘过程,并指导学生开展“截割/钻进参数调控-产尘特征监测-数据统计分析”的全过程自由探索型创新实验,量化分析截割/钻进参数对产尘特征(浓度、分散度等)的影响。对于提高学生的思考和实践能力,培养学生的创新思维,深化学生对采煤、掘进过程中粉尘灾害和产尘机理的理解,激发学生的科研兴趣,以及有针对性地提出截割/钻进减尘、优化粉尘工程控制措施和个体防尘技术具有重要意义。     

足球比赛中队员攻击性犯规行为的防止

对足球比赛中运动员攻击性行为进行分析,根据足球运动的规律结合比赛的特点提出了几条有效的防止建议。     

足球比赛中失球时间特征的心理学分析

通过对1994年、1998年和2002年近3届世界杯失球时间的统计,总结出足球比赛中失球与比赛时间的关系特征,运用心理学的有关知识对其进行了系统、深入的分析,指出热身损耗、注意力、自信心、情绪、意志品质、认识过程等心理因素可能与失球时间特征有关系,为球队解决不同时间段的失球提供建议.     

对全国体育学院足球通用教材中"局部进攻战术分类"的探讨

为了提高足球教学与训练的效果和足球教材建设。本文对现有教材的版本进行了研究，结合多年的教学训练经验，对“足球局部进攻战术分类”进行了探讨，分析了足球局部进攻战术有传切配合、二过一配合、交叉掩护配合和三人配合等方法。其中传切配合运用最多，二过一配合效果较好，三人配合形式多样，变化灵活。     

冷镦钢连铸坯的质量缺陷及控制

对冷镦钢连铸坯的质量缺陷进行了分析和描述,对产生缺陷的原因及影响因素进行了深入的分析和思考,并通过采取优化冷却、调整结晶器液面控制方式、保护渣设计、加强关键设备的管理及规范操作等工作的开展,实现了铸坯质量的有效改善,提升了冷镦钢产品在市场上的竞争力。     

科技期刊按需编制印刷版年终主题词索引的合理性——以《中华烧伤杂志》为例

为论证科技期刊按需编制印刷版年终主题词索引的合理性,本文设计问卷,调查《中华烧伤杂志》读者年龄、职称等一般信息.将调查对象按照上述内容进行分类,调查其是否知晓本刊年终主题词索引、查询本刊文章及检索医学文献的常用路径,对数据行Pearson卡方检验及Bonferroni校正.结果是:327名调查对象中,与41～50岁及51～60岁调查对象比较,21～30岁调查对象对本刊印刷版年终主题词索引的知晓比例明显下降(P值均小于0.05);与高级职称调查对象比较,无职称(研究生)、初级职称、中级职称调查对象对本刊印刷版年终主题词索引的知晓比例明显下降(P值均小于0.05).各年龄段及各种职称等级调查对象中,不足38％通过纸版期刊查询本刊文章.可见年轻读者对印刷版年终主题词索引的知晓度降低,应用率也较低,大部分读者倾向于通过网络查询期刊文章.提示科技期刊印刷版年终主题词索引的编制已失去原有的作用和意义,按需省略是合理的.     

中国足球彩票发展历程及问题研究

由于足球彩票在中国起步较晚、发行时间较短、经验缺乏等原因,中国足球彩票在其管理、法规制度、玩法以及宣传等许多方面还不够健全和成熟.通过对中国足球彩票发展历程的回顾与分析看出,中国足球彩票在销售规模上与国外足球彩票发展情况相比差距较大;中国足球彩票收益分配存在问题,足球彩票发行管理费用的比例明显高于国外;从目前制约中国足球彩票的主要因素上看,中国足球彩票在法制建设上还有待完善和加强.针对这些问题,中国足球彩票必须从中国实际出发,借鉴国外经验;加强足球彩票法制管理和法制意识;研制足球彩票新玩法,提高其吸引力;应用网络技术,形成规模销售与管理.     

农业产业化龙头企业与农户利益关系研究

龙头企业带动型农业产业化经营模式是目前中国农业产业化经营的基本组织形式之一。通过对现阶段各种典型龙头企业带动型农业产业化经营模式的分析比较，认为就龙头企业与农户的利益关系而言，在总体目标基本一致的前提条件下也会出现个体的差异。无论对龙头企业的利益维护还是农户的利益保护，其程度沿松散型、半紧密型和紧密型的路径逐渐提升。     

Body composition and hydration status changes in male and female open-water swimmers during an ultra-endurance event

Young adult soccer players often encounter difficulty progressing from youth competition to being regularly selected for high-level, open-age competition. In an attempt to increase the playing opportunities of semi-professional and amateur under-21 players in first teams, the Royal Belgian Football Association required national division teams to include at least two players younger than 21 in their match selection (under-21 rule). Over four seasons, the following variables were analysed across 2138 semi-professional and amateur soccer players aged 16?–?39 years: (1) the number of times a player was selected to be in the first team squad; (2) the number of times a player was selected to play in the starting line-up; and (3) the number of minutes played. Chi-square analysis demonstrated that second and third division teams had complied with the new selection regulations. However, two-way analysis of variance of individual player data revealed no increase in the number of playing minutes in the under-21 group. It would appear that many teams had complied with the new regulations by selecting young players as substitutes. The results highlight the difficulties that talented young soccer players experience progressing from youth to senior competition. We conclude that the rule imposed by the Royal Belgian Football Association has failed to improve the playing opportunities of young adult soccer players. Alternative strategies for increasing playing opportunities for young talented players are required.     

Factors influencing physiological responses to small-sided soccer games

Abstract

The aim of this study was to examine the effects of exercise type, field dimensions, and coach encouragement on the intensity and reproducibility of small-sided games. Data were collected on 20 amateur soccer players (body mass 73.1 ± 8.6 kg, stature 1.79 ± 0.05 m, age 24.5 ± 4.1 years, [Vdot]O_2max 56.3 ± 4.8 ml · kg^?1 · min^?1). Aerobic interval training was performed during three-, four-, five- and six-a-side games on three differently sized pitches, with and without coach encouragement. Heart rate, rating of perceived exertion (RPE) on the CR10-scale, and blood lactate concentration were measured. Main effects were found for exercise type, field dimensions, and coach encouragement (P < 0.05), but there were no interactions between any of the variables (P > 0.15). During a six-a-side game on a small pitch without coach encouragement, exercise intensity was 84 ± 5% of maximal heart rate, blood lactate concentration was 3.4 ± 1.0 mmol · l^?1, and the RPE was 4.8. During a three-a-side game on a larger pitch with coach encouragement, exercise intensity was 91 ± 2% of maximal heart rate, blood lactate concentration was 6.5 ± 1.5 mmol · l^?1, and the RPE was 7.2. Typical error expressed as a coefficient of variation ranged from 2.0 to 5.4% for percent maximal heart rate, from 10.4 to 43.7% for blood lactate concentration, and from 5.5 to 31.9% for RPE. The results demonstrate that exercise intensity during small-sided soccer games can be manipulated by varying the exercise type, the field dimensions, and whether there is any coach encouragement. By using different combinations of these factors, coaches can modulate exercise intensity within the high-intensity zone and control the aerobic training stimulus.