有限长均匀带电薄圆柱面面上的场强     

熊斌 《毕节学院学报》2006,24(4):30-34

由场强叠加原理,导出了有限长的均匀带电薄圆柱面面上场强的表达式。  相似文献   

基于GM(1,1)模型的我国R&D投入强度预测研究   总被引：1，自引：0，他引：1  

蔡济波  陈海波 《科技管理研究》2010,30(21)

20世纪90年代中期以来,我国R&D投入一直保持持续、稳定的增长,带来了科学技术的飞跃发展。从R&D投入强度,即R&D经费与国内生产总值之比入手,构建了我国R&D投入强度的GM(1,1)模型,提出了提高我国R&D投入强度的几点思考。  相似文献   

中国1991年至2007年火力发电-燃煤消耗-SO_2排放关系的分析   总被引：1，自引：1，他引：0  

王淑娜  孙根年 《资源科学》2010,32(7):1230-1235

我国电力工业以火电为主,是煤炭消耗和SO2排放的最大行业。本文依据1991年-2007年有关统计数据,构建了一个"双三角"的概念模型,一方面分析了我国火力发电量与燃煤消耗量、燃煤消耗量与SO2排放量的关系,另一方面分析了发电耗煤强度和燃煤SO2排放强度随时间的变化。结果表明:①火力发电量与燃煤消耗量为二次函数关系,但二次项系数很小,说明我国火电行业还处于外延性的规模扩张阶段;②燃煤消耗量与SO2排放量随我国国民经济"五年"规划呈周期波动,这反映了我国谋求经济增长与环境保护的动态博弈过程;③发电耗煤强度和燃煤SO2排放强度总体呈下降趋势,但当国家放松节能减排政策及关停小火电的步伐放缓时就会出现反弹期。研究结果为认清我国火电行业的节能减排问题提供了科学依据。  相似文献   

Exercise intensity and metabolic response in singles tennis     

Michael A. Christmass  Susan E. Richmond  Nigel T. Cable  Peter G. Arthur  Peter E. Hartmann 《Journal of sports sciences》2013,31(8):739-747

The aim of this study was to determine exercise intensity and metabolic response during singles tennis play. Techniques for assessment of exercise intensity were studied on-court and in the laboratory. The on-court study required eight State-level tennis players to complete a competitive singles tennis match. During the laboratory study, a separate group of seven male subjects performed an intermittent and a continuous treadmill run. During tennis play, heart rate (HR) and relative exercise intensity (72 ± 1.9% V O 2m ax ; estimated from measurement of heart rate) remained constant (83.4 ± 0.9% HR m ax ; mean s x ) after the second change of end. The peak value for estimated play intensity (1.25 ± 0.11 steps . s -1 ; from video analysis) occurred after the fourth change of end (P < 0.005). Plasma lactate concentration, measured at rest and at the change of ends, increased 175% from 2.13 ± 0.32 mmol . l -1 at rest to a peak 5.86 ± 1.33 mmol . l -1 after the sixth change of end (P < 0.001). A linear regression model, which included significant terms for %HR m ax (P < 0.001) and subject (P < 0.001), as well as a %HR max subject interaction (P < 0.05), accounted for 82% of the variation in plasma lactate concentration. During intermittent laboratory treadmill running, % V O 2peak estimated from heart rate was 17% higher than the value derived from the measured V O 2 (79.7 ± 2.2% and 69.0 ± 2.5% V O 2peak respectively; P < 0.001). The % V O 2peak was estimated with reasonable accuracy during continuous treadmill running (5% error). We conclude that changes in exercise intensity based on measurements of heart rate and a time-motion analysis of court movement patterns explain the variation in lactate concentration observed during singles tennis, and that measuring heart rate during play, in association with preliminary fitness tests to estimate V O 2 , will overestimate the aerobic response. (P < 0.001), estimated play intensity  相似文献   

Physical demand of seven closed agility drills     

Mark Atkinson  Simon Rosalie 《Sports biomechanics / International Society of Biomechanics in Sports》2016,15(4):473-480

The present study aimed to quantify the demand of seven generic, closed agility drills. Twenty males with experience in invasion sports volunteered to participate in this study. They performed seven, closed agility drills over a standardised 30-m distance. Physical demand measures of peak velocity, total foot contacts, peak impacts, completion time, and maximum heart rate were obtained via the use of wearable sensor technologies. A subjective rating of perceived exertion (RPE) was also obtained. All measures, with the exception of maximum heart rates and RPE were able to delineate drills in terms of physical and physiological demand. The findings of this study exemplify the differences in demand of agility-type movements. Drill demand was dictated by the type of agility movement initiated with the increase in repetitiveness of a given movement type also contributing to increased demand. Findings from this study suggest agility drills can be manipulated to vary physical and physiological demand. This allows for the optimal application of training principles such as overload, progression, and periodisation.  相似文献   

关于盘状物体的几个电学问题研究     

周瑞雪 《贵阳金筑大学学报》2014,(3):5-7

文章对带电圆盘状物体的电场和电势、圆盘发电机等问题,进行一个详细的研究,找出其规律和特点,将其归纳总结,计算出所需要的结果。  相似文献   

The Dark Side of Instruction: Teacher Anger as Classroom Norm Violations     

Mary B. McPherson  Patricia Kearney  Timothy G. Plax 《Journal of Applied Communication Research》2003,31(1):76-90

Based on norm violation theory, we examined students' reactions to teachers' normative and nonnormative expressions of anger. College students ( N = 301 ) judged the appropriateness and intensity of teachers' anger in the classroom for four modes of expression: Distributive Aggression, Passive Aggression, Integrative Assertion, and Nonassertive Denial. Students rated both types of aggressive expressions as highly intense and inappropriate (or nonnormative), but assertive displays as appropriate and less intense. Additionally, aggressive expressions were negatively related to students' affect, whereas assertive expressions were positively related to affect. Findings extend norm violation theory by identifying how teacher anger should be expressed and when during the semester anger is more likely to be perceived as inappropriate. Moreover, this study illustrates how normative violations of anger are associated with negative evaluations of the teacher and course.  相似文献   

连锁董事网络能够促进企业技术创新绩效吗?——基于研发投入的中介效应研究     

张丹  郝蕊 《科技管理研究》2018,(12)

基于社会关系网络视角,从网络中心度、网络强度和网络专业性三层面考察连锁董事网络对企业技术创新绩效、研发投入的直接影响以及研发投入的中介效应。采用中国2011—2015年沪深两市制造业上市公司数据为样本,研究发现连锁董事网络中心度、弱连锁程度以及网络专业性对企业技术创新绩效有显著促进作用;研发投入在连锁董事网络与企业技术创新绩效两者之间存在中介效应。连锁董事网络能提升企业技术创新绩效的作用机制可以部分解释为:连锁董事网络可以通过资源和信息在网络中的传递提高企业的研发投入比重,而研发投入的增加可以直接提高企业的技术创新绩效。  相似文献   

ISO标准砂强度试验分析     

顾磊  曾惠芬 《九江职业技术学院学报》2005,(2):22-23,28

本文通过对ISO标准砂试验中的一些关键因素进行研究，根据有关实验和数据探讨标准砂净重对强度试验的相关影响。  相似文献   

运动强度对维吾尔族中老年人血管壁上皮组织通透性影响的研究     

张洪斌 《喀什师范学院学报》2004,25(3):57-59

随着年龄的增长，机体自由基增加，而清除自由基的能力下降，造成血管内皮组织损伤及病变，通透性增高，钙离子沉积，引起动脉粥样硬化。实验证明，维吾尔族中老年人坚持一定强度的运动，可以降低血管壁内皮组织自由基水平，有效地预防冠心病。  相似文献