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1.
刘钝 《自然杂志》2019,41(4):294-298
1869年门捷列夫完成了世界上第一张化学元素周期表,除了把当时所知的全部63种元素按原子量大小分组(族)排列外,还在表中留下一些空位,预言了与硼、铝、硅类似的元素的存在及其性质。随后的20多年内,这些空位相继被新发现的元素填补。1877年中国首任驻英公使郭嵩焘听到了门捷列夫的预言与元素镓的发现这一故事,联想到发现海王星的经过,由衷感叹西方科学的精致与功效。  相似文献   
2.
Commentators often claim that the bodies of Spinoza’s physics resist the changes they undergo. But it’s not always clear what they mean when they say this, or whether they are entitled to say it. This article clarifies what it might mean to for Spinoza’s bodies to resist change, and examines the evidence for such a view. In the first half, the author argues that there is some limited evidence for such a view, but not nearly as much as people think. In the second half, the author proposes looking for a mental analogue to collision in the realm of ideas and argues that adequacy amounts to a meaningful concept of resistance in Spinoza, albeit one that is incomplete.  相似文献   
3.
Atelopus laetissimus is an endemic and threatened harlequin frog from the high mountain forests of Sierra Nevada de Santa Marta, Colombia. Knowledge of its reproductive biology is essential for understanding the intraspecific interactions that can help the conservation of Atelopus species. We quantified the energy, measured in body weight, invested by males and females of A. laetissimus for reproduction, and how this energetic investment is related to the survival of individuals and rainfall conditions in habitats during two years (2014 and 2015). Our results show plasticity in terms of reproductive phenology linked to rainfall with short- and long-duration breeding strategies. The first year of this study, 2014, had a precipitation level in accordance with the annual averages at the area. During this time frogs exhibit a short breeding period. Contrary to 2014, 2015 was a year with little precipitation, below the annual averages, which probably facilitated the females’ quick spawning in the creeks and a consequent reduction in the duration of amplexus and low breeding efforts by males. This, in turn, was related to a long breeding period that favors the survival and reproduction of males during the entire year. In 2014 we found a decrease of 25% to 30% body weight of potentially reproductive males, which may be attributed to a prolonged duration of amplectant events.  相似文献   
4.
通过对《傲慢与偏见》中五位男主人公的解读,可深入了解他们各自不同的社会价值观和婚姻观,他们的观念是由他们所处的社会地位以及社会背景所决定的。从五位男主人公的言行举止,我们还可了解到当时封建贵族的没落和资产阶级的发展。  相似文献   
5.
Georg Cantor, the founder of set theory, cared much about a philosophical foundation for his theory of infinite numbers. To that end, he studied intensively the works of Baruch de Spinoza. In the paper, we survey the influence of Spinozean thoughts onto Cantor’s; we discuss Spinoza’s philosophy of infinity, as it is contained in his Ethics; and we attempt to draw a parallel between Spinoza’s and Cantor’s ontologies. Our conclusion is that the study of Spinoza provides deepening insights into Cantor’s philosophical theory, whilst Cantor can not be called a ‘Spinozist’ in any stricter sense of that word.  相似文献   
6.
调频广播中预加重和去加重问题的讨论   总被引:1,自引:0,他引:1  
通过对调频广播系统噪声分布情况的分析,证明了在调频通讯系统中采取预加重和去加重的措施以改善信号传输质量的原理。  相似文献   
7.
8.
本文报道了6,7-dichlorobenzo[de]isochromene-1,3-dione的合成新方法。该路线简单易行,后处理方便,且产率较高,有较高的实用价值。  相似文献   
9.
等离子体波动方程的摄动分析   总被引:3,自引:3,他引:0  
分析了热等离子体中离子声孤子存在及传播的力学机制,并根据远方场简单波理论,采用摄动方法推导出了KdV方程。  相似文献   
10.
Summary

Records of ten species of Sosylus collected in Nigeria are given, with details of distribution, host trees and platypodid associates. The Sosylus fauna of Nigeria appears to lie between that of Ghana and the Congo in species composition. Comment is made on the close association that some Sosylus species have with their platypodid hosts.  相似文献   
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