【摘 要】
：
游泳运动是一种在水中部借助外力,利用自身力量和身体动作同水的相互作用来产生推进力,促使身体在水中前进的一种活动技能。由于游泳运动的特性必须在水中进行,水的阻力是空
论文部分内容阅读
游泳运动是一种在水中部借助外力,利用自身力量和身体动作同水的相互作用来产生推进力,促使身体在水中前进的一种活动技能。由于游泳运动的特性必须在水中进行,水的阻力是空气中的800倍。因为在水中物体的受阻力于物体的运动速度成正比,也就是说游泳中游速越快所受阻力也就越大
Swimming is a kind of activity skill that uses the external force in the middle part of the water to make use of its own strength and physical action to interact with water to generate propulsion and make the body move forward in the water. Due to the nature of swimming must be carried out in the water, water resistance is 800 times in the air. Because the object in the water resistance of the object is proportional to the speed of movement, that is to say, the greater the swimming speed, the greater the resistance
其他文献
Macroporous poly (vinyl acetate-co-triallyl isocyanurate) beads were prepared with suspension polymerization method. The copolymer beads were then transformed
美国FDA批准新药数量依然在低谷徘徊,统计数据显示,2007年批准上市的新药仅有19个(表1),其中化学药物17个,生物制品2个,继1983年的14个和2002年的17个之后新药获批数量再陷低
The selective brominations of 3, 4-dimethoxytoluene with N-bromosuccinimide were reported. The nuclear and side-chain brominated products were obtained under di
顺式芳基烯和二乙腈氯化钯 ( ) [(Me CN) 2 Pd Cl2 ](10m ol% )在二氯甲烷 (0 .5 m ol/ L)中 ,室温搅拌约 14 h可得反式芳基烯 ,除 1例未反应外 ,其余 9例收率 85 %～ 97%。顺
这是一次完全剔除爆震因素的急性声创伤实验研究。各组实验豚鼠均以中心频率1000Hz的(?)频带噪声,声压级为130dB,暴露1h,然后分组分期处死制片和镜检观察。在噪声暴露前和处
我院1976～1985年收治159例眼球穿孔伤患者,其中眼球内有异物存留的89例。下面谈谈对异物摘除术的体会。临床资料 89例中,男86例,女3侧。年龄17～50 岁。右眼53例,左眼36例。磁
Several novel 3-(substituted phenyl)isoxazole derivatives were prepared from phenyl butan-1,3-dione. Their structures were confirmed by 1H NMR, IR, and CIMS. P
突发性聋的病因可涉及外耳、中耳、内耳、耳蜗神经和听觉通路的任何一部分。通常认为该症是基于多种病因引起的感觉神经性病变。突发性传导性听力损失的原因较容易确定,但如
Dissectol A, a novel monoterpene glycoside was isolated from the methanol part of the 95% EtOH extract of Incarvillea dissecfoliola and its structure was determ
本文对30例(男女各半,年龄20～60岁)急性感觉神经性重听者进行了研究和分析。全部患者除行一般临床检查,神经科、内科和眼科检查外,均行听力计和前庭功能试验的耳神经学检查。