Effect of hand paddles and parachute on backstroke coordination and stroke parameters

Hand paddles and parachutes have been used in order to overload swimmers, and consequently increase the propulsive force generation in swimming. However, their use may affect not only kinematical parameters (average speed, stroke length and stroke rate), but also time gaps between propulsive phases, assessed through the index of coordination (IdC). The objective of this study was to assess the effects of hand paddles and parachute use, isolated or combined, on kinematical parameters and coordination. Eleven swimmers (backstroke 50-m time: 29.16 ± 1.43 s) performed four 15-m trials in a randomised order at maximal intensity: (1) without implements (FREE), (2) with hand paddles (HPD), (3) with parachute (PCH) and (4) with hand paddles plus parachute (HPD+PCH). All trials were video-recorded (60 Hz) in order to assess average speed, stroke rate, stroke length, five stroke phases and index of coordination. When average swimming speed was compared to FREE, it was lower in PCH and HPD+PCH, and higher in HPD. Stroke rate decreased in all overloaded trials compared to FREE. The use of hand paddles and parachute increased and decreased stroke length, respectively. In addition, propulsive phase duration was increased when hand paddles were used, and time gaps shifted towards zero (no time gap), especially when hand paddles were combined with parachute. It is conceivable that the combined use of hand paddles and parachute, once allowing overloading both propulsive and resistive forces, provides a specific stimulus to improve muscle strength and propulsive continuity.     

如何培养中学生对体育课的兴趣

为了提高中学体育课的教学质量，顺利完成教学的任务，有必要大力培养中学生对体育课的兴趣。通过对宁波市部分中学学生的调查研究，指出可以通过端正学生学习的动机，明确学习的目的；合理选择教材；进行生动有趣的讲解和优美正确的示范；采用灵活多样的教学方法；搞好课外体育活动来提高中学生对体育课的兴趣。     

Anaphoric reference strategies used in written language productions of deaf teenagers

There are few researchers who analyze written productions by deaf individuals; there are also few researchers who discuss the knowledge these people have about written text comprehension and production. For the present study, the investigators analyzed 16 written productions by four deaf individuals based on the anaphoric reference concept as recently proposed in textual linguistics (see, e.g., I. V. Koch & L. A. Marcuschi, 2002). It is important to show that referential progression is one of the textual aspects capable of giving stability and continuity to written productions; referential progression is also relevant to discursive coherence. The results of the writing analysis in the present study show that deaf individuals can learn to use expressive resources that are available in the Portuguese language and can use reference strategies, as long as these individuals can interact with a partner who knows Portuguese.     

有机化学活性中间体稳定性与反应活性的关系

有机化学反应中 ,活性中间体的稳定性大小与该分子的反应活性有很大的关系 .活性中间体越稳定 ,其越容易形成 ,反应活性就越大 .本文仅就一些常见的活性中间体稳定性的分析 ,得出了稳定性与反应活性的关系     

世纪末女性作家之小说生成——女性文学论说之四

上个世纪末女性作家之小说生成，一是源于性别冲突，二是源于理想与现实的巨大反差，三是基于对女性自身经验的扩写。本对女性作家小说生成理念的大致归纳，对把握世纪末女性作家之创作具有一定的价值。     

关于推进"泉州学"研究的若干思考--兼论泉州文化与闽南文化的关系

章对“泉州学”研究中所存在的问题进行了分析梳理，并从宏观方面与操作方面提出推进泉州与闽南历史化研究的对策。     

试论反腐倡廉机制

面对当前纷繁复杂的反腐败斗争，有必要分析腐败现象产生原因及我国廉政建设前景，学习和借鉴国外廉政建设的基本经验，探索构建四个廉政机制的新举措，以期更有效地遏制腐败现象，建设和完善社会主义民主政治制度。