导数选择最优批量的应用

导数是研究函数各种性态的有效工具之一,利用导数研究函数性质往往使问题简单。求函数在一点的变化率,只需求出函数在这一点的导数;在研究函数单调性时,求出该函数的导数,找出稳定点,再根据导数在各区间的符号判别函数单调性;在讨论函数单调性的基础上判断函数极值。     

我国与中亚五国商贸合作环境评价研究

中亚五国是“一带一路”陆路发展的外部第一区域。运用变异系数TOPSIS模型和Theil指数,采集2008—2017年世界银行统计数据,完成对中亚五国商贸合作环境的实证分析,结果表明:中亚商贸合作环境水平呈现波动态势,整体水平较低,商贸合作环境国别差异显著。提出差别化区域商贸合作,优化区位选择路径,强化商贸合作软环境,提升合作适应水平,创造商贸合作新模式,建立商贸示范区,建立商贸合作基金会,提升合作规模级别等建议。     

女子田径运动员“第二高峰期”的研究

优秀女子田径运动员婚后复出,群英辉映。她们运动能力的延伸和拓展,成绩惊人,举世瞩目。本文搜集了本世纪中叶以来,女子田径运动员结婚后复出创绩的资料,对她们的结婚年龄、“第二高峰期”、婚后创绩年限进行了分析。研究结果表明,女运动员婚后复出仍可再创佳绩。     

电工基础课中电路网络等效变换的授课探讨

通过对电路网络等效变换概念的建立、作用的理解、条件和方法的掌握等教学过程的探讨，阐述了网络等效变换在分析计算复杂电路中的授课技巧．     

沪港两地数学课堂练习之比较--熟能生巧新解

沪港2地数学课堂练习特点的主要区别表现在：上海教师主要提供解释性和探究性问题，注重覆盖面及问题之间存在的关系，以及问题的隐式的变式练习，所选用问题的变化都在数学背景下面；香港教师只重视解释性水平的问题，及显式的变式练习，所选题目的背景既有数学的也有日常生活的．熟能生巧的巧有2层含义：一是各种解题技巧，二是善于提出独特的思路和策略．     

试论名词语义的动态性

当名词进入名谓句的谓语位置时，名词空间性的语义特点就发生了变化，表现在名词空间义的失去、时间义的获得、语义值的变化和谓词语义特征的获得等四个方面。     

异乡人变奏曲——木令耆小说创作简论

木令耆的小说大多取材于她所熟悉的欧美华人的生活现实 ,努力挖掘他们复杂的心理负载 ,尤其是多重变奏的爱情纠葛和乡愁。通过一系列的人物形象的描绘 ,揭示海外华人多层次的生活现状 ,以及他们对母土、亲人及祖系文化的复杂感情。探索他们在异国他乡的生存方式和未来的发展趋向。     

变奏中的和谐--论多恩诗对彼式诗的解构

17时期英国玄学派代表诗人约翰.多恩的诗歌跳出了彼特拉克诗歌传统,从语言、情感以及音响层面上看,它标新立异,奏出了一组和谐的变奏曲。着重从多恩诗对彼式诗解构的角度来探讨多恩诗歌的主要特色及其艺术表现手段。     

Match-to-match variability in high-speed running activity in a professional soccer team

ABSTRACT

This study investigated variability in competitive high-speed running performance in an elite soccer team. A semi-automated tracking system quantified running performance in 12 players over a season (median 17 matches per player, 207 observations). Variability [coefficient of variation (CV)] was compared for total sprint distance (TSD, >25.2 km/h), high-speed running (HSR, 19.8–25.2 km/h), total high-speed running (THSR, ≥19.8 km/h); THSR when the team was in and out of ball possession, in individual ball possession, in the peak 5 min activity period; and distance run according to individual maximal aerobic speed (MAS). Variability for % declines in THSR and distance covered at ≥80% MAS across halves, at the end of play (final 15 min vs. mean for all 15 min periods) and transiently (5 min period following peak 5 min activity period), was analysed. Collectively, variability was higher for TSD versus HSR and THSR and lowest for distance run at ≥80% MAS (CVs: 37.1%, 18.1%, 19.8% and 11.8%). THSR CVs when the team was in/out of ball possession, in individual ball possession and during the peak 5 min period were 31.5%, 26.1%, 60.1% and 23.9%. Variability in THSR declines across halves, at the end of play and transiently, ranged from 37.1% to 142.6%, while lower CVs were observed in these metrics for running at ≥80% MAS (20.9–53.3%).These results cast doubt on the appropriateness of general measures of high-speed activity for determining variability in an elite soccer team, although individualisation of HSR thresholds according to fitness characteristics might provide more stable indicators of running performance and fatigue occurrence.     

两个分式不等式的推广

用二元均值不等式的变形式给出两个分式不等式的推广及证明.