无限循环群上的亚同态

给出了无限循环群上的全体亚同态映射.     

格序群的可迁性

利用格序置换群是研究格序群的重要工具之一,本文论述了在格序置换群里起重要作用的概念:n可迁性。并论述了迷向子群在其中的作用。     

从正方形中裁出最大正三角形

给出从给定正方形中裁出边长(或面积)最大的正三角形的方法及其严格证明.     

S_H型区间值模糊子群(英文)

本文在群上定义的区间值模糊集空间上,引入由T—余范数诱导的幂等区间余范数S_H,定义了S_H型区间值模糊子群,同时,讨论并研究了它的一些基本性质和结构特征,进而,给出了它的同态象和逆象定理。     

向量组的秩的概念引入教学

对于向量组的秩的概念的教学,给出了教学方法．先从分析向量组的线性相关性入手,引出向量组的秩的概念,使得向量组的秩这一抽象的概念变得简单易懂。     

步行试验推测40～49岁人群最大摄氧量回归方程的研究

目的:通过进行1 km步行试验得到步行结束时的心率和行走所用的时间,再结合受试者的性别、年龄、身高、体重等指标来推测最大摄氧量,建立回归方程。方法:受试者为年龄在40~49岁之间的健康成年人,其中男性30人、女性34人,首先进行身高、体重等静态指标的测量,然后在功率车上进行递增负荷试验并结合气体分析直接测出最大摄氧量,对完成最大摄氧量测试的受试者择日再进行1 km步行试验,此试验进行两次,记录相应的心率值和行走时间取平均值用于计算。结果:将各指标进行回归分析得到回归方程,交叉验证回归方程显示最大摄氧量实测值和推测值的相关性统计量为RLOOCV=0.826,SEELOOCV=0.378(L/min)。结论:采用1 km步行试验并使用此方程可以有效的推测40~49岁健康成年人的最大摄氧量。     

Peak aerobic power and paddling efficiency in recreational and competitive junior male surfers

Abstract

The purpose of the present study was to measure and compare peak oxygen uptake and paddling efficiency in recreational and competitive junior male surfers. Eight male recreational surfers (mean age 18 years, s=2; mass 66.8 kg, s=13.0; height 1.75 m, s=0.10) and eight male competitive surfers (mean age 18 years, s=1; mass 68.0 kg, s=11.7; height 1.72 m, s=0.10) performed an incremental paddling test consisting of four 3-min constant load work stages followed by a ramp increase in power output of 20 W · 30 s^?1 until exhaustion. The oxygen uptake–power output relationship of the four constant load work stages and peak values obtained during the incremental paddling test were used to calculate paddling efficiency. No differences (P>0.05) were observed between the recreational and competitive surfers for peak oxygen uptake (recreational: 2.52 litres · min^?1, s=0.5; competitive: 2.66 litres · min^?1, s=0.35) or efficiency (recreational: 24%, s=3; competitive: 21%, s=4). Blood lactate concentration was significantly greater in recreational (2.4 mmol · l^?1, s=0.9) than competitive surfers (1.6 mmol · l^?1, s=0.5) during submaximal paddling. There were no differences in peak oxygen uptake or paddling efficiency between recreational and competitive surfers suggesting that peak oxygen uptake and efficiency are not sensitive to differences in surfing ability. The increase in blood lactate concentration during submaximal paddling in recreational compared with competitive surfers suggests that other determinants of paddling endurance, such as blood lactate threshold, might be better at distinguishing surfers of differing ability.     

Recovery of pulmonary diffusing capacity after maximal exercise

Abstract

Pulmonary diffusing capacity (Dl_co), together with spirometric variables, arterial oxygen tension (paO₂) and cardiac output were determined before and at intervals after maximal arm cranking, treadmill running and erogmeter rowing. Independent of the type of exercise, Dl_co increased immediately post‐exercise from a median 13.6 (range 7.3–16.3) to 15.1 (9.3–19.6) mmol min^‐1 kPa^‐1 (P <0.01). However, it decreased to 11.6 (6.9–15.5) mmol min^‐1 kPa^‐1 (P <0.01) after 24 h with cardiac output and paO₂ at resting values, and Dl_co normalized after 20 h. Thoracic electrical impedance at 2.5 and 100 kHz increased slightly post‐exercise, indicating a decrease in thoracic fluid balance, and there were no echocardiographic signs of left ventricular failure at the time of the decrease in Dl_co. Also, active muscle (limb) circumference and volume, and an increase in haematocrit from 43.8 (38.0–47.0) to 47.1 (42.7–49.8) (P <0.01), had normalized at the time of the decrease in Dl_co. Vital capacity, forced vital capacity, forced expiratory volume in 1 s, peak and peak mid‐expiratory flows did not change. However, total lung capacity increased from 6.8 (5.0–7.6) to 7.0 (5.1–7.8) litres (P <0.05) immediately after exercise and remained elevated at 6.9 (5.1–8.7) litres (P <0.05) when a decrease in Dl_co was noted. The results demonstrate that independent of the type of maximal exercise, an approximate 15% reduction in Dl_co takes place 2–3 h post‐exercise, which normalizes during the following day of recovery.     

Reliability and stability of anthropometric and performance measures in highly-trained young soccer players: effect of age and maturation

Abstract

The purpose of this study was to assess both short-term reliability and long-term stability of anthropometric and physical performance measures in highly-trained young soccer players in relation to age and maturation. Data were collected on 80 players from an academy (U13–U18, pre- (n = 14), circum- (n = 32) and post- (n = 34) estimated peak height velocity, PHV). For the reliability analysis, anthropometric and performance tests were repeated twice within a month. For the stability analysis, these tests were repeated 12 times over a 4-year period in 10 players. Absolute reliability was assessed with the typical error of measurement, expressed as a coefficient of variation (CV). Relative reliability and long-term stability were assessed using the intraclass correlation coefficient (ICC). There was no clear age or maturation effect on either the CVs or ICCs: e.g., Post-PHV vs. Pre-PHV: effect size = –0.37 (90% confidence limits (CL):-1.6;0.9), with chances of greater/similar/lower values of 20/20/60%. For the long-term stability analysis, ICCs varied from 0.66 (0.50;0.80) to 0.96 (0.93;0.98) for 10-m sprint time and body mass, respectively. The short-term reliability of anthropometry and physical performance measures is unlikely to be affected by age or maturation. However, some of these measures are unstable throughout adolescence, which questions their usefulness in a talent identification perspective.     

健身健美操对大学生最大摄氧量的影响研究——以武汉科技大学为例

运用抽样调查、实验和比较研究法研究武汉科技大学学生的最大摄氧量。结论显示:健身健美操能显著改善大学生的心血管机能;足球、篮球、羽毛球和网球项目相比,改善效果更显著;对女生心血管机能的改善程度大于男生。