Intensions, belief and science: Kuhn’s early philosophical outlook (1940-1945)

Between 1940 and 1945, while still a student of theoretical physics and without any contact with the history of science, Thomas S. Kuhn developed a general outline of a theory of the role of belief in science. This theory was well rooted in the philosophical tradition of Emerson Hall, Harvard, and particularly in H. M. Sheffer’s and C. I. Lewis’s logico-philosophical works—Kuhn was, actually, a graduate student of the former in 1945. In this paper I reconstruct the development of that general outline after Kuhn’s first years at Harvard. I examine his works on moral and aesthetic issues—where he displayed an already ‘anti-Whig’ stance concerning historiography—as well as his first ‘Humean’ approach to science and realism, where his earliest concern with belief is evident. Then I scrutinise his graduate work to show how his first account of the role of belief was developed. The main aim of this paper is to show that the history of science illustrated for Kuhn the epistemic role and effects of belief he had already been theorising about since around 1941.     

电离势,电子亲和势,电负性与酸碱软硬度

本文用Lewis酸的平均电离势对其电负性作图;用Lewis碱的第一电子亲和势对其电负性作图,得出分类软酸、硬酸和软碱、硬碱的两个方程: H_A=∑I_n/n-3.1x 2.6 (1) H_B=A 3.51x-7.24 (2)运用(1)式计算了113种酸的硬度值,用(2)式计算了59种碱的硬度值。突破了复杂酸碱的标度问题。结果与Dearson根据实验所总结的分类一致,与Ahrland和Klopman结果相比较大致呈线性关系。     

Chemical reductionism revisited: Lewis, Pauling and the physico-chemical nature of the chemical bond

The wave-mechanical treatment of the valence bond, by Walter Heitler and Fritz London, and its ensuing foundational importance in quantum chemistry has been traditionally regarded as the basis for the argument that chemistry may be theoretically reduced to physics. Modern analyses of the reductionist claim focuses on the limitations to achieving full reduction in practice because of the approximations used in modern quantum chemical methods, but neglect the historical importance of the chemical bond as a chemical entity. This paper re-examines these arguments with a study of the development of the valence bond by chemist Gilbert Lewis within a chemically autonomous framework, and its extension by Linus Pauling using Heitler and London’s methods. Here, we see that the chemical bond is best described as a theoretical synthesis or physico-chemical entity, to represent its full interdisciplinary importance from the philosophical and historical perspectives.     

Highly efficient procedure for the conjugate addition of amines to electron deficient alkenes catalyzed by novel ionic liquid

A highly efficient procedure has been developed for the conjugate addition of amines to electron deficient alkenes. The novel ionic liquid [HO₃S-bPy][FeCl₄] with both Lewis and Brønsted acid sites has been synthesized successfully for the reactions. The results show that the catalyst was very efficient for the conjugate addition of amines to electron deficient alkenes with excellent yields in several minutes. This method has several key features including operational simplicity, no need of any solvent, low cost of the catalyst used, high yields, reusability, excellent chemoselectivity, and wide applicability.     

国际经济格局趋势下的中国普通劳动者权益保护问题研究

多年来,中国被称为"世界工厂"。然而中国的主要出口商品都是一些中低端产品,制造业的技术含量普遍较低,其竞争力建立在廉价的劳动力成本之上,与此对应的是中国普通劳动者权益福利的丧失。中国人口基数巨大,劳动力市场供大于求。因此,提高普通劳动者权益不能只靠单纯的行政措施,而要顺应国际经济发展的大趋势,建立层次合理的产业结构。通过产业结构调整来增加就业岗位,吸纳劳动力,依靠市场的力量提高普通劳动者的福利。     

刘易斯拐点的争辩与求证

由于近几年民工荒的出现,学术界对"刘易斯拐点"是否已经来临进行了争辩。围绕"刘易斯拐点"三个要点,即农村是否存在剩余劳动力、工资是否显著提升和城市化进行求证后发现,中国经济"刘易斯拐点"并没有来临,中国目前仍处于人口红利时期。     

The Lewis Acid-promoted Novel Cyclization Reactions Towards N-adn O-Containing Heterocycles

1 Results Nitrogen and oxygen-containing heterocyclic systems are important structures in organic chemistry because of their presence in many biologically active compounds.In this work,a new zinc and indium-promoted conjugate addition-cyclization reaction to afford nitrogen and oxygen-containing five-membered heterocycles has been developed.A Lewis acid-catalyzed cyclization of an ethenetricarboxylate derivative with propargylamines or propargyl alcohols to give methylenepyrrolidines and methylenetetrah...     

金属卟啉在不同溶剂中紫外可见吸收光谱的研究

以环己烷作为中性参比溶剂 ,采用Cary5 0紫外可见分光光度计研究了氧钒 2 ,3,7,8,12 ,13,17,18 八乙基卟啉 (VOOEP)和镍 2 ,3,7,8,12 ,13,17,18 八乙基卟啉 (NiOEP)在不同溶剂中的紫外可见吸收光谱。结果发现 ,两种金属卟啉可以与一些Lewis碱性溶剂发生轴向配位作用 ,形成轴向加合物 ,加合物的紫外可见吸收光谱红移 ,α和β吸收带的相对吸收强度比减小 ;金属卟啉和Lewis碱性溶剂之间的轴向配位作用受溶剂碱性和立体构造的影响 ,碱性强、立体阻碍小的Lewis碱性溶剂 (如正丁胺 )易于与金属卟啉发生轴向配位反应 ,VOOEP/正丁胺体系的等吸收点在 4 12 ,5 39,5 78nm处 ,NiOEP/正丁胺体系的等吸收点在 4 0 8,5 2 7,5 6 8nm处。     

Lewis酸催化三组分合成喹啉-2,4-二羧酸酯类化合物

采用价廉易得的无水三氯化铝、三氯化铁、氯化铜等Lewis酸催化取代芳胺、乙醛酸乙酯和丙酮酸甲酯三组分一步反应,高效合成了4个喹啉-2,4-二羧酸酯类化合物.产物通过柱层析分离纯化,并采用FT-IR、~1H NMR、~(13)C NMR和元素分析等手段进行了结构表征.探讨了反应机理和取代芳胺的分子结构对反应的影响规律,为该类新颖化合物的分子设计与合成方法提供参考.该方法具有原料廉价易得、反应条件温和、原子经济性高、产率高等优点.     

Encumbering the intramolecular π donation by using a bridge: A strategy for designing metal-free compounds to hydrogen activation

On the basis of the FLP (frustrated Lewis pair) principle, a new strategy has been proposed to construct the “frustration” in designing metal-free hydrogen activation compounds, by using FMO (frontier molecular orbital) analyses and quantum mechanics calculations. Unlike the known FLPs which use bulky substituents to prevent them from forming stable Lewis acid/base complexes, the new approach encumbers the intramolecular π donation from the electron donor to the acceptor (e.g. in BH₂NH₂) by using a CH₂ bridge (giving BH₂CH₂NH₂). The strategy is simple and effective. Its effectiveness is demonstrated by the small hydrogen activation energy (12.0 kcal/mol) of the model molecule (BH₂CH₂NH₂), which is significantly less than the 42.7 kcal/mol of BH₂NH₂ and also less than the 18.5 kcal/mol of BH₂PH₂ whose derivative, R₂PB(C₆F₅)₂, has been experimentally shown to be able to activate hydrogen. We also exemplified how to use the strategy to design experimentally more realizable molecules. The example shows promises as a hydrogen activation agent. The strategy can be used to design metal-free catalysts for direct hydrogenation.