氧化镁和氧化钇掺杂对纳米氧化铝粉末的影响

本文研究了用均相共沉淀法合成氧化铝陶瓷粉末的同时合成氧化镁、氧化钇等掺杂氧化物,发现在掺杂量不大时,同时合成的掺杂氧化物以填隙固溶体方式固溶于立方γ氧化铝中,并且几乎不影响铝氧键性质、晶格常数和衍射波矢,但掺杂使氧化物细化,比表面增大,用此法合成的粉末聚集比较厉害,在粉末中有晶化颗粒存在．     

Effects of periodic carbohydrate ingestion on endurance and cognitive performances during a 40-km cycling time-trial under normobaric hypoxia in well-trained triathletes

The purpose of this study was to examine CHO ingestion on a cognitive task using a field-simulated time-trial (TT) under hypoxia in well-trained triathletes. Ten male triathletes (age: 22.1 ± 1.1 years; VO₂max: 59.4 ± 1.4 ml/kg/min) participated in this double-blind/crossover/counter-balanced design study. Participants completed 3 TT trials: 1) normoxic placebo (NPLA; FiO₂ = 20.9%), 2) hypoxic placebo (HPLA; FiO₂ = 16.3%), and 3) hypoxic CHO (HCHO; 6% CHO provided as 2 ml/kg/15 min; FiO₂ = 16.3%). During the TT, physiological responses (SpO₂, HR, RPE, and blood glucose/lactate), cognitive performance, and cerebral haemodynamics were measured. Hypoxia reduced TT performance by ~3.5–4% (p < 0.05), but CHO did not affect TT performance under hypoxia. For the cognitive task, CHO slightly preserved exercise-induced cognitive reaction speed but did not affect response accuracy during hypoxic exercise. However, CHO did not preserve the decreased Hb-Diff (cerebral blood flow, CBF) and increased HHb in the prefrontal lobe (p < 0.05) during hypoxic exercise, and CHO failed to preserve hypoxia-suppressed prefrontal CBF and tissue oxygen saturation. In conclusion, the present study demonstrates that CHO is effective in sustaining reaction speed for a cognitive task but not promoting TT performance during hypoxic exercise, which would be important for strategy-/decision-making when athletes compete at moderate high-altitude.     

ORIGINAL PRINT PAINTING RISES WITH POTENTIAL VALUES FOR COLLECTION

Printing painting usually refers to varieties of painting printed on wood, stone, linoleum, copper and zinc blocks carved by knife or etched by chemicals. China is generally recognized as the inventor of printing painting, but for quite a long time, it has had a poor market for print painting trade, with only few collectors dedicated to for this type of painting. In recent years, with print paintings by master artists gaining outstanding performance in the international market, values of original print painting have begun to be recognized in China＇s collection market.     

去势雌性大鼠骨生物力学性能在运动负荷下的变化

对切除卵巢大鼠各组骨密度(BMD)和生物力学有关指标进行检测,并进行比较分析。结果表明:1)运动组BMD为0.316,运动1 组为0.305,显著高于模型组的0.275,制动组BMD均显著低于各实验组;2)生物力学实验显示:运动各组骨整体的生物力学性能优于服钙组和激素组;激素组的生物力学性能显示韧性差;制动组的各项指标显示该组骨的生物力学性能较差。由此可知,运动可增加去势前大鼠骨量的储备,减缓去势后大鼠骨量的丢失,维持骨良好的生物力学性能     

从宣传画看中国现代体育

备受世界关注的第29届奥林匹克运动会即将在北京举办,与奥运相关的体育藏品受到收藏者的青睐,新中国建国早期的体育宣传画在今天也倍显珍贵,引发了人们对新中国体育发展历程的回顾。     

羽毛球运动健身价值的分析

随着经济的不断发展,人们对健康有了很大的认识,健康的重要性越来越被人们所重视.通过文献资料法收集资料,对羽毛球运动的一些问题进行了解,加以分析研究.通过对羽毛球教师的询问了解羽毛球的技战术及运动特征,加以分析处理.进一步阐述羽毛球的健康价值,让更多的人参与到羽毛球运动当中去从而促进社会的和谐发展.     

论文化背景知识在英语教学中的重要性

语言是文化的载体,文化依托语言得以传承和发展;文化又影响着语言,对于语言的形成和发展有着至关重要的作用。要学好一门语言,不能仅仅依靠词汇的累积和语法知识的背诵,对其所扎根的文化也要有深刻的了解,英语学习也是如此。教师应当深刻地认识到这一点,将文化背景知识的讲解充分融入到日常的教学活动当中去,才能够使英语教学发挥出应有的效果。     

普通话机测中“说话”项的测评分析及教学培训

随着计算机辅助普通话测试的实施和推广,＂说话＂项的测试增加了相应的难度,也出现了一些新情况、新问题。文章对机测＂说话＂项进行了测评状况的调查分析,并对机测方式下的＂说话＂教学培训提出了应对措施。     

数字图书馆门户的构建与服务

针对当前数字图书馆建设中亟需整合海量资源和数字化服务,以便为用户提供更为准确、方便、快捷的学术信息服务的需求,概括国外数字图书馆门户的建设情况,论述了数字图书馆服务及其门户的定义、定位、功能要素、内容结构、特点、设计原则及其服务运行等内容,并结合北京大学数字图书馆的建设案例进行了分析,为这方面的发展提供了参考。     

消息报道传播效果的优化——一种语言学角度的分析

本文从语言学的角度,分析了消息语篇优化传播效果的两大编码策略:语义场理论的运用和义素分析法的运用.