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Dean M. Philipp William A. Goddard Michael J. Mullins Phillip S. Athey 《Tetrahedron letters》2004,45(28):5441-5444
We have been engaged in a search for coordination catalysts for the copolymerization of polar monomers (such as vinyl chloride and vinyl acetate) with ethylene. We have been investigating complexes of late transition metals with heterocyclic ligands. In this report we describe the synthesis of a symmetrical bis-thiadiazole. We have characterized one of the intermediates using single crystal X-ray diffraction. Several unsuccessful approaches toward 1 are also described, which shed light on some of the unique chemistry of thiadiazoles. 相似文献
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We propose a model for the electrostatics of globular proteins in which the low dielectric region is replaced by concentric spheres of the appropriate size. The method uses analytical formulas for the dielectric sphere and allows an efficient and accurate treatment of bulk charges. For surface charges, we propose a numerical determination of the sphere radius based on the solvent exposure of the individual atoms. The present implementation of the sphere model yields a good approximation of finite-difference Poisson solvation and interaction energies for a test set of 12 proteins. 相似文献
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Victor Callegari Philipp M. Nellen Roland Hauert Francisco Hernández-Ramírez 《Applied Surface Science》2007,253(22):8969-8973
Focused ion beam physical sputtering and iodine-enhanced etching of indium phosphide (InP) were performed. Up to 15× enhanced etching rates over sputtering were measured at room temperature, due to the addition of iodine to the sputter-process. Reaction mechanisms and products are discussed and characterized. The reaction is limited by the desorption of indium triiodide (InI3) at room temperature. InI3 has to be removed by sputtering, which simultaneously amorphizes the underlying substrate. Surface roughness and stoichiometry of InP are compared for sputtering and etching. Gallium-contamination and the damaged zone in InP are significantly reduced by iodine-enhanced etching. Based on the reaction mechanisms, an optimum beam scanning strategy is proposed which allows precise microfabrication in reduced time and minimizes damage to the substrate. The method is also applicable for other halide gas etching processes of III-V semiconductors. 相似文献
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Philipp Frank 《Transformation Groups》2013,18(3):639-684
We classify those manifolds of positive Euler characteristic on which a Lie group G acts with cohomogeneity one, where G is classical simple. 相似文献
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