基于Multisim2001软件的数显抢答器设计与仿真

该文介绍了Multisim2001软件作为电子工作台的强大功能.并以数显抢答器设计为例,阐述如何应用该软件进行数字电路的设计与仿真.     

低压电刺激对球衣细菌生长的影响

以能积累PHB的球衣菌属菌株为材料，选用周期为1s，最大电流分别为200μA，30μA，50μA和100μA的直流脉冲和最大电压分别为1．5V，3V，4V和5V的交流脉冲为低压电刺激信号．刺激培养的结果表明：在直流脉冲刺激下，靠近正极端的菌落生长受到较强的抑制作用，越近负极抑制作用越小；交流脉冲刺激时，对菌落生长未见明显的抑制或促进作用，但菌体内PHB含量有所增加．本研究为环境工程中抑制球衣细菌生长或利用球衣细菌生产PHB创造了可能性．     

美国教师工资和激励机制改革的历史发展

美国19世纪以来教师待遇的发展历史:教师工资制度从"膳宿工资制"到"等级工资制"再到"单一工资制度"演变。甄别绩效工资制、职务工资制和其他相关改革。在重视教师个体成就与全面重视教师群体绩效、重视教师教龄和学历与重视教学能力和效果间寻找一种平衡点,以建立既体现社会发展需求又体现教师劳动特点的工资制度。     

试论高校办公室人员自主创新能力的激励机制

在高校管理体制改革不断深入、高校行政管理信息化不断加强的背景下,办公室人员自主创新能力显得尤为重要,可以从实行岗位目标管理责任制、营造良好的文化氛围、加强信息化建设、完善制度建设等方面来激发办公室人员的自主创新能力,切实提高办公室工作效能。     

建国以来我国消费与生产关系演变的历史考察

新中国成立至今,消费与生产的关系经历了三个时期：建国以来至改革开放为消费抑制时期,表现为生产控制消费,消费受到政策与供给的双重抑制;改革开放以来至上世纪末为消费释放时期,表现为生产引导消费,消费得到恢复性增长;新世纪以来至今为消费激励时期,表现为消费制约生产,消费不足成为影响国民经济发展的突出问题,刺激消费、扩大内需成为重要政策取向。在把握历史发展脉络的基础上,争取消费与生产关系的积极趋向是保障中国经济持续、健康发展的关键。     

Effects of sensory-level high-volt pulsed electrical current ondelayed-onset muscle soreness

Abstract

Ten healthy males and ten healthy females aged 21.5 ± 3.2 years (mean ± s) participated in the study, which was designed to evaluate the effectiveness of sensory level-high volt pulsed electrical current (HVPC) on delayed-onset muscle soreness (DOMS). Arm discomfort, elbow extension range of motion and isometric elbow flexion strength were obtained as baseline measurements. Delayed-onset muscle soreness was induced in the participants' dominant or non-dominant arm using two sets of 20 maximal eccentric elbow flexion contractions. After the induction of DOMS, the participants were randomly divided into an experimental condition (HVPC) or a placebo condition. The experimental condition consisted of 20 min of HVPC immediately after the induction of DOMS, and 20 min every 24 h for three consecutive days thereafter. The participants in the placebo condition received an intervention similar in design; however, no electrical current was administered. Baseline measurements were reevaluated at 24, 48, 72 and 96 h after the induction of DOMS. Three weeks later, the participants returned and the protocol was repeated on the contralateral limb, using the opposite intervention (HVPC or placebo). Repeated-measures analysis of variance revealed a significant increase in overall arm discomfort, decrease in elbow extension and decrease in isometric strength for both conditions over time. No significant main effect of treatment, or time-by-treatment interaction, was found for the HVPC condition when compared with the placebo condition for any variable. Sensory-level HVPC, as utilized in our application, was ineffective in reducing the measured variables associated with DOMS.     

Acute passive stretching in a previously fatigued muscle: Electrical and mechanical response during tetanic stimulation

Abstract

The aim of this study was to assess the effects of acute passive stretching on the electrical and mechanical response of a previously fatigued muscle. Eleven participants underwent maximal tetanic stimulations (50 Hz) of the medial gastrocnemius, before and after a fatiguing protocol and after a bout of passive stretching of the fatigued muscle. During contraction, surface electromyography (EMG), mechanomyography (MMG), and force were recorded. The following parameters were calculated: (1) the EMG root mean square (RMS), mean frequency, and fibre conduction velocity; (2) MMG peak-to-peak and RMS; (3) the peak force, contraction time, half-relaxation time, peak rate of force development (dF/dt) and its acceleration (d² F/dt ²). Fatigue reduced peak force by 18% (P < 0.05) and affected the other force, EMG, and MMG parameters. After stretching: (1) all EMG parameters recovered to pre-fatigue values; (2) MMG peak-to-peak remained depressed, while RMS recovered to pre-fatigue values; (3) the peak force, peak rate of force development and its acceleration were further reduced by 22, 18, and 51%, respectively, and half-relaxation time by 40% (P < 0.05). In conclusion, acute passive stretching, when applied to a previously fatigued muscle, further depresses the maximum force-generating capacity. Although stretching does not alter the electrical parameters of the fatigued muscle, it does affect the mechanical behaviour of the muscle–tendon unit.     

Time Needed to Change the Isometric Force Production of a Response

Abstract

This study investigated the time needed to change a motor program that specified the elbow flexor muscles to gradually increase the isometric force production from 15% to 75% of one's maximum voluntary contraction (MVC). A double-stimulation paradigm was used with the restriction that subjects (N = 12) be at 15% of their MVC before the presentation of the first stimulus. Subjects reacted to the first stimulus (randomly presented) by gradually increasing their isometric force from 15% to 75% of their MVC and then reacted to the second stimulus by altering the force production in one of four ways: (a) increasing the force to the 75% level rapidly instead of gradually, (b) discontinuing the increase and maintaining the level of force attained, (c) discontinuing all force production, or (d) reversing the direction of force so that it is produced by the elbow extensors. The data revealed that more time was needed to increase the force rapidly than to perform any of the other three conditions.     

Effect of vibratory stimulation training on maximal force and flexibility

In this study, we investigated a new method of training for maximal strength and flexibility, which included exertion with superimposed vibration (vibratory stimulation, VS) on target muscles. Twenty‐eight male athletes were divided into three groups, and trained three times a week for 3 weeks in one of the following conditions: (A) conventional exercises for strength of the arms and VS stretching exercises for the legs; (B) VS strength exercises for the arms and conventional stretching exercises for the legs; (C) irrelevant training (control group). The vibration was applied at 44 Hz while its amplitude was 3 mm. The effect of training was evaluated by means of isotonic maximal force, heel‐to‐heel length in the two‐leg split across, and flex‐and‐reach test for body flexion. The VS strength training yielded an average increase in isotonic maximal strength of 49.8%, compared with an average gain of 16% with conventional training, while no gain was observed for the control group. The VS flexibility training resulted in an average gain in the legs split of 14.5 cm compared with 4.1 cm for the conventional training and 2 cm for the control groups, respectively. The ANOVA revealed significant pre‐post training effects and an interaction between pre‐post training and ‘treatment’ effects (P< 0.001) for the isotonic maximal force and both flexibility tests. It was concluded that superimposed vibrations applied for short periods allow for increased gains in maximal strength and flexibility.     

独立学院转型期师资队伍建设的探讨

独立学院进入与母体高校分离的转型期后,师资队伍建设呈现出新的特点,对独立学院的发展影响极大。从调查情况来看,独立学院转型期的师资队伍建设还存在着较多的问题,需要从师资结构、良好环境、预备数据库、激励机制、人性管理等方面加强与规范。