共查询到20条相似文献，搜索用时 62 毫秒
1.
2.
3.
众所周知,档案作为一种不可再生资源,它具有原始性、唯一性的特点,尽大努力让档案信息长时间完好保存甚至是永久保存是档案管理核心内容之一环境的温湿度对保管好档案,延长档案寿命有很大关系因为温湿度对档案制成材料的影响很大,高温高湿会使纸张水解,老化速度加快,会使危害档案制成材料的霉菌、细菌繁殖,会使光化作用增强,会使有害气体、灰尘吸附能力增大档案库房的环境温度和湿度一般都有比较严格的要求,要通过控制手段,将温湿度控制在一定的范围内. 相似文献
4.
主要运用文献资料法,对影响健身效果的室内空气品质指标的进行探讨和分析,结果显示:室内污染物、温湿度及CO2浓度等指标是影响健身效果的主要室内空气品质指标。适宜的温湿度、CO2浓度及低浓度污染物的室内环境是达到良好健身效果的保证,但对于一定容积所能容纳健身人数的具体标准还未有相关研究。因此,今后的研究可以在该方面做进一步的探讨。 相似文献
5.
6.
7.
随着新能源的崛起,风能与太阳能成为了新时代的潮流,风光互补路灯已经广泛应用在市政道路、公园景区、高速公路、工业园区等地方。而风光互补控制器则是路灯系统中最核心的部件,其性能影响到整个系统的寿命和运行稳定性。主要介绍了什么是风光互补控制器,风光互补控制器的工作原理及结构图,风光互补控制器改进应具备哪些的功能及特点。 相似文献
8.
可编程序控制器,自从诞生以来,已经广泛应用于工业控制领域。通常可编程序控制器由两部分组成,即可编程序控制器本身和编程装置;近年来,随着微电子技术、计算机技术以及网络通信技术的进步和发展,也促进可编程序控制器的技术不断发展,功能极大增强。处理器速度的提高和器件的表面封装化,使得可编程序控制器的体积趋于更加小型化,其可靠性、稳定性、抗干扰能力更高,更适合于工业控制现场环境。可编程序控制器的功能也在不断扩展,从早期代替继电器的顺序逻辑控制发展到模拟量数字化的过程控制,从简单的整型数处理发展到浮点数运算、复杂函数的处理。高速计数器,高速脉冲输出功能扩展,使其应领域从早期制造领域的机械顺序控制,延伸到模拟量过程控制和机床的数控领域。以太网技术的发展和在可编程序控制器中的使用,更使得可编程序控制器通信功能、通信速度和信息处理等方面产生了质的飞跃。 相似文献
9.
模拟速滑计时控制器输出信号的软件程序研究 总被引：3，自引：3，他引：0
在调试速滑记圈器自动功能的过程中,由于没有速滑计时控制器的相关信号,因此需要模拟速滑计时控制器的切光、清表、秒时间等信号才能进行调试。研制模拟速滑计时控制器的信号发生器及其软件程序,是课题研究阶段的重点,研究解决了对速滑记圈器主控制板的调试需要。 相似文献
10.
传统PID控制在串级控制系统中当被控对象发生变化时,主控制器的参数难以自动调整。针对串级控制系统被控对象大惯性、不确定特点,提出将模糊控制与PID控制结合,在串级控制系统中将主控制器采用自适应模糊 PID控制技术,使主控制器具有较好的自适应性。使用MATLAB对系统进行仿真,结果表明在串级控制系统的主控制器中用自适应模糊控制 PID控制器来取代传统常规 PID控制器后,整个串级控制系统具有良好的动态性能。当被控对象模型结构发生变化时,控制系统的抗干扰性及鲁棒性得到较大的提升。 相似文献
11.
This study examined the effect of carbohydrate ingestion on metabolic and performance-related responses during and after a simulated 1h cycling time trial. Eight trained male cyclists (VO 2 peak = 66.5ml kg -1 min -1 ) rode their own bicycles mounted on a windload simulator to imitate real riding conditions. At a self-selected maximal pace, the cyclists performed two 1h rides (separated by 7 days) and were fed either an 8% carbohydrate or placebo solution. The beverages were administered 25 min before (4.5ml kg -1 ) and at the end (4.5ml kg -1 ) of the ride. With carbohydrate feeding, plasma glucose tended (P = 0.21) to rise before the time trial. Compared with rest, the plasma glucose concentration decreased significantly (P < 0.05) at the end of both rides, with no statistically significant difference being observed between treatments. Thereafter, plasma glucose increased significantly (P < 0.05) at 15 and 30 min into recovery, and was significantly higher at 30 min during the carbohydrate trial compared with the placebo trial. No significant changes in plasma free fatty acids were observed during the ride. However, a significant increase (P < 0.05) in free fatty acids was found at 15 and 30 min into recovery, with no difference between trials. Mean power output was significantly (P < 0.05) greater during the carbohydrate compared with the placebo trial (mean - S.E.: 277-3 and 269-3W, respectively). The greater distance covered in the carbohydrate compared with the placebo trial (41.5-1.06 and 41.0–1.06km, respectively; P < 0.05) was equivalent to a 44s improvement. We conclude that pre-exercise carbohydrate ingestion significantly increases endurance performance in trained cyclists during a 1h simulated time trial. Although the mechanism for this enhancement in performance with carbohydrate ingestion cannot be surmised from the present results, it could be related to a higher rate of carbohydrate oxidation, or to favourable effects of carbohydrate ingestion on the central component of fatigue. 相似文献
12.
Roy J. Shephard 《Journal of sports sciences》2013,31(7):603-620
The biology and medicine of rowing are briefly reviewed. Effort in a 2000 -m race is about 70% aerobic. Because the boat (and in some instances a cox) must be propelled, successful competitors are very tall, with a large lean mass and aerobic power. Large hearts may lead to erroneous diagnoses of a cardiomyopathy. Large respiratory minute volumes must be developed by chest muscles that are also involved in rowing. The vital capacity is typically large, and breathing becomes entrained. Expiration cannot be slowed relative to inspiration (as normally occurs at high rates of ventilation) and the limiting flow velocity may be reached, with the potential for airway collapse. Performance is strongly related to the power output at the ‘anaerobic threshold’, and lactate measures provide a guide to an appropriate intensity of endurance training. Peak blood lactate levels are higher in males (commonly 11–19 mmol·l -1 and occasionally as high as 25 mmol·l -1) than in females (9–11 mmol·l -1), probably because males have a greater muscle mass in relation to blood volume. The skeletal muscles are predominantly slow twitch in type, developing an unusual force and power at low contraction velocities. Many rowers have a suboptimal diet, eating excessive amounts of fat. Lightweight rowers also have problems of weight cycling. Aerobic power and muscle endurance often change by 10% over the season, but such fluctuations can be largely avoided by a well-designed winter training programme. Injuries include back and knee problems, tenosynovitis of the wrist and, since the introduction of large blades, fractures of the costae. 相似文献
13.
14.
重新认识体育的社会关联 总被引：3，自引：1，他引：2
体育与政治之间存在一个悖论，体育的发展与经济实力之间没有直线相关，体育与教育部分重叠，体育与宗教最为近缘，体育可借用科学手段，体育的艺术禀性日益明显，体育与养生反映着两种人生观。 相似文献
15.
本文在专家访谈、问卷调查、数理统计和文献资料分析的基础上,探析了上海社区体育竞赛参与者的特点、参与者对社区体育赛事运作管理的看法等问题。在此基础上从引进社区体育赛事的志愿者、整合社区体育赛事的各种资源、开发社区体育竞赛的无形资产、组建非营利性的专业团队、规范社区体育赛事的服务管理等方面提出了进一步满足上海社区居民日益增长的体育竞赛参赛需求的对策与措施。 相似文献
16.
对全面把握游泳训练环节的探讨 总被引：4，自引：0，他引：4
从系统观点出发,结合训练实践,对全面把握游泳训练环节进行探讨。认为应强化非智力因素在运动员多年训练中的作用,在育材全过程中不断选材,从整体上把握动态训练的全过程,把培养高水平运动员的整个过程置于一个严格的科学控制之下。 相似文献
17.
18.
影响和限制耐力性运动项目的成绩的生理因素是复杂的和多方面的,取决于训练的强度和运动成绩.大强度持续性运动可导致呼吸肌疲劳.运动性呼吸疲劳可能在决定运动耐量方面起到关键的作用：一方面通过直接影响运动肌力量的生成（外周疲劳）,另一方面,通过肢体用力自感不安反馈引起工作肌运动单位输出功率下降（中枢疲劳）.对呼吸肌进行训练,可能有助于提高耐力性项目的运动成绩. 相似文献
19.
青少年业余足球运动员运动倾向性5因素结构模型初探 总被引：3，自引：0，他引：3
根据Scanlan等人最新提出的运动倾向性理论模型,结合我国实际情况建立了青少年足球运动员运动倾向性5因素结构模型。运动倾向性被定义为:渴望和决心继续参加足球运动的心理状态。所建立的5因素结构模型认为,运动倾向性是由运动乐趣、参与选择、个人投入、社会约束及参与机会5个因素决定。经确定5个决定因素和运动倾向性的操作定义,编制了相应调查问卷,通过对北京市252名青少年足球运动员实测结果,建立运动倾向性及其影响因素的协方差结构模型,用Lisre 18分析的结果表明:该运动倾向性模型比较符合北京青少年足球运动员。其中运动乐趣、个人投入、参与机会和参与选择4因素对运动倾向性有影响;社会约束对运动倾向性影响不大。 相似文献
20.
The aim of this study was to assess the sensitivity of the lactate minimum speed test to changes in endurance fitness resulting from a 6 week training intervention. Sixteen participants (mean +/- s :age 23 +/- 4 years;body mass 69.7 +/- 9.1 kg) completed 6 weeks of endurance training. Another eight participants (age 23 +/- 4 years; body mass 72.7 +/-12.5 kg) acted as non-training controls. Before and after the training intervention, all participants completed: (1) a standard multi-stage treadmill test for the assessment of VO 2max , running speed at the lactate threshold and running speed at a reference blood lactate concentration of 3 mmol.l -1 ; and (2) the lactate minimum speed test, which involved two supramaximal exercise bouts and an 8 min walking recovery period to increase blood lactate concentration before the completion of an incremental treadmill test. Additionally, a subgroup of eight participants from the training intervention completed a series of constant-speed runs for determination of running speed at the maximal lactate steady state. The test protocols were identical before and after the 6 week intervention. The control group showed no significant changes in VO 2max , running speed at the lactate threshold, running speed at a blood lactate concentration of 3 mmol.l -1 or the lactate minimum speed.In the training group, there was a significant increase in VO 2max (from 47.9 +/- 8.4 to 52.2 +/- 2.7 ml.kg -1 .min -1 ), running speed at the maximal lactate steady state (from 13.3 +/- 1.7 to 13.9 +/- 1.6 km.h -1 ), running speed at the lactate threshold (from 11.2 +/- 1.8 to 11.9 +/- 1.8 km.h -1 ) and running speed at a blood lactate concentration of 3 mmol.l -1 (from 12.5 +/- 2.2 to 13.2 +/- 2.1 km.h -1 ) (all P ? 0.05). Despite these clear improvements in aerobic fitness, there was no significant difference in lactate minimum speed after the training intervention (from 11.0 +/- 0.7 to 10.9 +/- 1.7 km.h -1 ). The results demonstrate that the lactate minimum speed,when assessed using the same exercise protocol before and after 6 weeks of aerobic exercise training, is not sensitive to changes in endurance capacity. 相似文献