取代喹啉新化合物的光化学合成

1-N-苯甲酰基-4-氨基-1-氮杂丁二烯在紫外光照射下进行光环化反应,制备了一些文献中未报导过的取代喹啉,全部的新化合物都经元素分析,MS,~1H和~(13)C NMR测定。     

美国《亚洲学者公报》(1976)“中国革命文学专号”绪言

过去的60年间,世界上最伟大的文化之一——中国文化在一场实质触及社会各方面的深刻革命中得到了改造,目前,当中国为完全掌握其命运、实现其革命理想而继续奋斗时,世界的其余部分,以妒忌,残存的误解、怀疑和钦佩相交织的心情,出神地注视着她.或许,中国革命最不为世界其余部分所理解和赞赏的就是中国新文学艺术的发展.即使在对当前中华人民共和国的文艺状况感兴趣的外界观察家中,对革命的文学艺术也有着截然不同的反应,从完全的敌视到诌媚的赞扬,什么都有,但最典型的反应就是迷惘地耸耸肩膀.甚至在专攻中国文学的西方学者中,认真关注20世纪中国文学作品的人也很少.考虑到现代中国文学仅仅包容了一种源远流长达三千年之久的文学传统的一小部分,上述现象也不十分奇怪.但是学者和其他各界人士对中国不容置疑的引人注目的政治经济成就兴趣却大增,总的说来,对其文艺发展的关注并没有引起相应的增长.     

Speed and surface steepness affect internal tibial loading during running

Background:Internal tibial loading is influenced by modifiable factors with implications for the risk of stress injury.Runners encounter varied surface steepness(gradients) when running outdoors and may adapt their speed according to the gradient.This study aimed to quantify tibial bending moments and stress at the anterior and posterior peripheries when running at different speeds on surfaces of different gradients.Methods:Twenty recreational runners ran on a treadmill at 3 different speeds(2.5...     

COVID-19 vaccination produces exercise-responsive SARS-CoV-2 specific T-cells regardless of infection history

Background:The mobilization and redistribution of severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) specific T-cells and neutralizing antibodies(nAbs) during exercise is purported to increase immune surveillance and protect against severe coronavirus disease 2019(COVID-19).We sought to determine if COVID-19 vaccination would elicit exercise-responsive SARS-CoV-2 T-cells and transiently alter nAb titers.Methods:Eighteen healthy participants completed a 20-min bout of graded cycling exer...     

The great catastrophe: causes of the Permo-Triassic marine mass extinctionOA

The marine losses during the Permo-Triassic mass extinction were the worst ever experienced. All groups were badly affected, especially amongst the benthos(e.g. brachiopods, corals, bryozoans, foraminifers,ostracods). Planktonic populations underwent a fundamental change with eukaryotic algae being replaced by nitrogen-fixing bacteria, green-sulphur bacteria, sulphate-reducing bacteria and prasinophytes. Detailed studies of boundary sections, especially those in South China, have resolved the cr...     

Revisiting non-linear Thomson scattering with metamaterialsOA

<正>Non-linear optics is a branch of optics that studies the intriguing and sometimes unexpected ways in which light and matter interact at high intensities, when the polarization density does not respond linearly to the electric field of the light. The pursuit of the perfect non-linear optical material has been ongoing ever since the pioneering experiment on second harmonic generation carried out by Franken in 1961 [1]. Indeed,     

俄罗斯学者眼中的新经济政策──中俄学者关于新经济政策的对话

张广翔（以下简称张）：先是苏联,继之俄罗斯进行的改革进程涉及政治、经济、文化和社会生活的所有方面,不能不触及史学。尤其在这种全方位改革情况之下,社会开始关注以往的历史,试图解释正在发生的事情,并在某种程度上猜测可能的后果,因而,新经济政策时期成为20世纪80年代下半期苏联史学界的研究热点。能否用同样方法解释今天学术界对新经济政策问题兴趣的减少呢？B刀．捷利钦（以下简称捷）：戈尔巴乔夫改革时期曾一度引起新经济政策研究骤然升温。在苏联解体之后,尤其是今天的俄罗斯对这个问题的研究完全是两样：有关20世纪20年…