Cyclic-anion salt for high-voltage stable potassium-metal batteriesOA

Electrolyte anions are critical for achieving high-voltage stable potassium-metal batteries(PMBs).However,the common anions cannot simultaneously prevent the formation of ’dead K’ and the corrosion of Al current collector,resulting in poor cycling stability.Here,we demonstrate cyclic anion of hexafluoropropane-1,3-disulfonimide-based electrolytes that can mitigate the ’dead K’ and remarkably enhance the high-voltage stability of PMBs.Particularly,even using low salt concentration(0.8 M) and addi...     

Rollback,scissor-like closure of the Mongol-Okhotsk Ocean and formation of an orocline:magmatic migration based on a large archive of age dataOA

Tracing the closure of oceans with irregular margins and the formation of an orocline are crucial for understanding plate reconstruction and continental assembly.The eastern Central Asian Orogenic Belt,where the Mongol-Okhotsk orocline is situated,is one of the world’s largest magmatic provinces.Using a large data set of U-Pb zircon ages,we updated the timing of many published igneous rocks,which allowed us to recognize tightly ’folded’ linear Carboniferous-Jurassic magmatic belts that wrap arou...     

Pedometer reliability, validity and daily activity targets among 10- to 15-year-old boys

The aims of this study were to: (1) determine whether the number of pedometer counts recorded by adolescents differs according to the adiposity of the participant or location on the body; (2) assess the accuracy and reliability of pedometers during field activity; and (3) set adolescent pedometer-based physical activity targets. Seventy-eight 11- to 15-year-old Boy Scouts completed three types of activity: walking, fast walking and running. Each type was performed twice. Participants wore three pedometers and one activity monitor during all activities. Participants were divided into groups of normal weight (BMI < 85th percentile) and at risk of being overweight (BMI > or = 85th percentile). Intra-class correlations across the three activities indicated reliability (r = 0.51 - 0.92, P < 0.001). This conclusion was supported by narrow limits of agreement that were within a pre-set range that was practically meaningful. Multivariate analysis of covariance indicated adiposity group differences, but this difference was a function of the increased stature among the larger participants (P < 0.001). Ordinary least-squares regression models and multi-level regression models showed positive associations between the number of pedometer and activity monitor counts recorded by the three groups of participants during all activities (all P < 0.001). The mean number of counts recorded for all participants during the fast walk was 127 counts per minute. In conclusion, the pedometers provided an accurate assessment of adolescent physical activity, and a conservative estimate of 8000 pedometer counts in 60 min is equivalent to 60 min of moderate to vigorous physical activity.     

Teachers' perspectives on the challenges of teaching physical education in urban schools: the student emotional filter

The purpose of this study was to analyze how the challenges of urban schools influence physical education teachers' emotional understanding and connections with their students and the implications on their teaching. Sixty-one elementary physical educators from an urban school district in the midwestern U.S. were interviewed multiple times (N = 136) over 3 years using interpretive methodology. Teachers reported five unique challenges that significantly shaped their thinking about students and their careers, along with strategies they used to overcome or manage those challenges. The challenges were: (a) insufficient instructional resources, (b) implementing culturally relevant pedagogy, (c) dealing with community violence, (d) integrating more games in curricula, and (e) teaching in a culture of basketball. Implications centered on the guilt-inducing nature of urban teaching, developing an informed and realistic vision of urban physical education, and the role of teacher preparation and professional development.     

滑翔机是怎样飞行的?

滑翔运动是最引人入胜的一种航空体育运动,也是青年们的一种体育运动。在一种没有发动机的叫做滑翔机的飞行器上面,人们可以在空中保持停留好几小时,航行数百公里的距离,不但能升得相当高,而且还能作一些优等航空术的特技表演。滑翔的这种锻炼能使人们熟悉飞行,培养出飞行人员的果断品质。许多苏联杰出的飞行员,例如,A.N.巴克雷斯金,A.N.莫洛得奇依等人,都是从滑翔飞行中锻     

石头是怎样生成的?

本文是从苏联伟大的矿物学家、通俗科学读物作家、科学院院士费尔斯曼(1883—1945)所著的“趣味矿物学”书中翻译过来的。“趣味矿物学”于1945年出版,已经有几国文字的翻译,是一本生动、活泼的通俗科学著作。我们已约请北京地质学院小塔同志负责翻译,以后将选出一部分陆续在本刊发表。原文文笔富有文艺性,在翻译上不易保持原来风格。有些地方为了使读者易于清楚明白起见,编者曾略加修改;如有错误,应由编者负责。     

介绍获得斯大林奖金的几位苏联科学家——苏联科学家羣

著名的俄罗斯科学家,植物生理学的一个创立者,特米雅热夫(Timiryazev),常常反对有人在他面前讲到“纯粹”科学和“应用”科学。他认为只有科学和科学的应用。的确,在科学工作中的每一部门,每一阶段都接触到实际的应用,这就使其     

完數

什麼叫完数(Perfect Number)啊?一箇數目如果等於它所有的除数(但不包括這個數目自己)的總和,這個数目就叫做完敷:例如,6=1+2+3,28=1+2+4+7+14。僅有的已知的完全数都是偶数,而且很少,從     

德国职业指导

Marx對於職业指導頗为留心,此文報告德國去年職業指導概况,極为中肯,用特译出,以供參考。     

伦敦补习教育概况

英人对于补习教育年来极为注意.推原其故.约有数端.普通知识程度提高。一也.个人愿望扩大.二也.职业与地位之竞争加烈.三也.欲利用余暇时间.从事有趣味之研究.四也.受欧洲大战教训.对于日常事物.希望取得广博之认识.五也.行政当局谋所以适应此要求.则对于补习教育之设施.力加推广.而以伦敦尤为发达.兹就其含有职业教育性质者述之.此项补习教育.即基于上述第二原因而成立.更占重要地位.