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81.
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Arthur H. Compton 《Journal of The Franklin Institute》1918,185(6):745-774
To sum up our argument then: It is shown, in the first place, that the arrangement of the atoms in certain crystals, as determined by the X-ray spectra, indicates definitely that in these crystals there is no molecular structure.In extending the argument to all solid matter it is pointed out, from the dependence of crystal form on chemical composition, from a consideration of the Dulong-Petit law and of the nature of cohesion, and from the evidence of X-rays as to certain crystals, that each atom in a solid oscillates about a definite position of stable equilibrium.From a further examination of the nature of cohesion and of the forces concerned in chemical combination and especially from the general relation found between the atomic heat of formation of a substance and its melting-point it is found that the forces holding the atoms in their positions of stable equilibrium are of the same nature and comparable in magnitude with the forces binding together a chemical molecule.It is seen further that the atoms in a solid are very close together so that they often come in contact. And, since an atom attracts equally all atoms of another kind which are in contact with it, an atom cannot remain combined for more than an infinitesimal interval with any other particular atom ordinary temperatures.Finally, it was shown that, since in the solid state each atom has three degrees of translational freedom and is strongly attracted by atoms other than those of its own “molecule,” it must, on the average, exert equal attractions on all the neighboring atoms.From this the conclusion is drawn that in the particular molecules cannot be definitely defined.When those properties of solid matter which have been explained by molecules are considered, nothing is found which indicates at all definitely a molecular structure.We feel justified in concluding, therefore, that the structure of solid matter is not molecular. 相似文献
84.
Arthur G. Neal 《Journal of American culture (Malden, Mass. : 2003)》2009,32(3):274-274
85.
Ann Lewis 《British Journal of Special Education》2004,31(1):3-9
The Gulliford Lecture 2003 was given by Professor Ann Lewis of the School of Education at the University of Birmingham. Professor Lewis's lecture, on which this article is based, focused on the process of listening to the views of children and, in particular, children with learning difficulties. Following the near-universal ratification of the United Nations (UN) Convention on the Rights of the Child, a plethora of recent initiatives, both in the UK and internationally, has encouraged professionals to access children's views about provision (educational, health-related, social and legal). A range of materials has been developed to support this process, often by, or in liaison with, children's charities. At the same time, research provides valuable insights into effective practice in exploring the views of children with learning difficulties. In this article, Ann Lewis reviews ten strategies for gathering the views of children and raises four challenges for the further development of policy and practice. She closes her argument with a call for greater rigour and critical evaluation in this crucial and demanding area. 相似文献
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Lewis M. Haupt 《Journal of The Franklin Institute》1887,124(4):264-272
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Arthur Bramley 《Journal of The Franklin Institute》1935,219(5):629-632
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