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981.
A. Ujhelyiová A. Marcinčin M. Kišš T. Marcinčinová 《Journal of Thermal Analysis and Calorimetry》1996,46(2):619-626
The influence of high concentration of BaSO4 as nucleating agent on crystallization of fiber-forming polypropylene was studied by DSC. The work presents experimental and calculated values of melting and crystallization enthalpies of filled polypropylene and the influence on the formation of interface interactions between filler and polymers. These results show minimal interactions of components (BaSO4 and polypropylene) under experimental conditions. 相似文献
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983.
Guy T. Giuffredi Sophie Purser Marcin Sawicki Amber L. Thompson Véronique Gouverneur 《Tetrahedron: Asymmetry》2009,20(6-8):910-920
A highly efficient anti-SE2′ electrophilic fluorination of enantioenriched allylsilanes a subsequent dihydroxylation of the resulting allylic fluorides were used as key steps for the synthesis of three fluorinated carbohydrate analogues, 1,5-di-O-benzyl-2-deoxy-2-fluoro-d-glucitol, 2,6-di-O-benzyl-5-deoxy-5-fluoro-l-glucitol and 1,5-di-O-benzyl-2-deoxy-2-fluoro-d-mannitol. A new catalytic asymmetric route to 1-benzyloxy-4-trimethylsilyl-but-3-yn-2-ol, a common precursor to two advanced allylsilanes, is also described featuring a Noyori asymmetric transfer hydrogenation reaction. 相似文献
984.
This letter describes the first example of the synthesis of isocyanide derivatives of α-aminoalkylphosphonate diphenyl esters. This method produces the title compounds in high purity and in very good yields. It also permits the generation of an α-aminophosphonate-based library of biologically active phosphonopeptides. Preliminary experiments demonstrate their application as substrates for the Ugi-type multicomponent condensation. 相似文献
985.
JPC – Journal of Planar Chromatography – Modern TLC - Two new, simple, rapid, and accurate thin-layer chromatographic methods have been developed for determination of fluoxetine in... 相似文献
986.
In this article, we deal with the question of whether a fluorine atom can substitute a hydroxyl group in such a way that will lead to a compound showing a desired biologic activity, that is, a potential new drug. It is obvious that a fluorine atom differs from a hydroxyl group, as it cannot donate hydrogen bonds. However, it can accept them. Moreover, both fluorine and oxygen are of similar size and are the most electronegative elements. Therefore, a fluorine atom is thought to be a good substitute for a hydroxyl group. However, it was shown that for conformationally labile aliphatic compounds a replacement of a hydroxyl by a fluorine increases conformational diversity, so the fluorine‐containing aliphatic molecules are present in equilibrium at room temperature as a mixture of several different conformers. In contrast, for cyclic compounds the substitution of an OH group by an F atom does not much change shape and electrostatic potential around corresponding conformers. Moreover, these compounds are present in equilibrium at room temperature in aqueous solution as a mixture of the same most favored structures. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 相似文献
987.
We prove that the finite‐model version of arithmetic with the divisibility relation is undecidable (more precisely, it has Π01‐complete set of theorems). Additionally we prove FM‐representability theorem for this class of finite models. This means that a relation R on natural numbers can be described correctly on each input on almost all finite divisibility models if and only if R is of degree ≤ 0 ′. We obtain these results by interpreting addition and multiplication on initial segments of finite models with divisibility only. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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