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951.
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A random heterogeneous material is represented by a finite family of microstructures, the environment of each microstructure being subjected to a perfect mix condition whose validity is justified both theoretically and numerically. Necessary conditions, satisfied by any permissible strain rate field on a representative and unlimited domain of the material, are highlighted. They enable one to obtain, by solving a discrete infmax problem, a lower bound of the effective yield strength domain of the material, that is rigorous and more predictive than the classical bound of Reuss. An analytical application on a porous medium illustrates the methodology. 相似文献
954.
Abstract A high pressure-mediated route for convergent, regiospecific syntheses of (±)-l1-deoxydaunomycinone and 4-demethoxy analog, by sequential Diels-Alder cycloadditions is described. 相似文献
955.
The multi-step synthesis of 1,3,7-trisubstituted pyrimido[1,2-a]pyrimidinediones starting from isothiocyanates is described. These nitrogen bicycles were prepared by an iterative sequence of functionalization/cyclocondensation reactions. [4+2] Cycloaddition reactions took place between diazadienic chains and various acyl chlorides providing sophisticated heterobicycles. 相似文献
956.
Sylvain Achelle Álvaro Blanco Martín López‐García Riccardo Sapienza Marta Ibisate Cefe López Julián Rodríguez‐López 《Journal of polymer science. Part A, Polymer chemistry》2010,48(12):2659-2665
Monodisperse colloids have been prepared efficiently by copolymerization of methyl methacrylate and fluorescent first‐ and second‐generation poly(phenylenevinylene) dendrons under surfactant‐free emulsion polymerization conditions. The copolymers were characterized by UV–vis and fluorescence spectroscopy and size exclusion chromatography. Transmission electron microscopy revealed that the copolymers were microspheres with smooth surfaces and narrow dispersity. The bead diameter could be varied by changing the monomer/water ratio. The materials could be crystallized to give polymer opal photonic crystals. The emission was not affected by the periodic structure because of the large spectral distance between the emission and the pseudogap position. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 2659–2665, 2010 相似文献
957.
958.
Audrey Roy Pauline Fajardie Bndicte Lepoittevin Jrme Baudoux Vincent Lapinte Sylvain Caillol Benoit Briou 《Molecules (Basel, Switzerland)》2022,27(4)
Surfactants are crystallizing a certain focus for consumer interest, and their market is still expected to grow by 4 to 5% each year. Most of the time these surfactants are of petroleum origin and are not often biodegradable. Cashew Nut Shell Liquid (CNSL) is a promising non-edible renewable resource, directly extracted from the shell of the cashew nut. The interesting structure of CNSL and its components (cardanol, anacardic acid and cardol) lead to the synthesis of biobased surfactants. Indeed, non-ionic, anionic, cationic and zwitterionic surfactants based on CNSL have been reported in the literature. Even now, CNSL is absent or barely mentioned in specialized review or chapters talking about synthetic biobased surfactants. Thus, this review focuses on CNSL as a building block for the synthesis of surfactants. In the first part, it describes and criticizes the synthesis of molecules and in the second part, it compares the efficiency and the properties (CMC, surface tension, kraft temperature, biodegradability) of the obtained products with each other and with commercial ones. 相似文献
959.
This paper is the first of a three-part investigation into the behavior of analytical invariants of manifolds that can be split into the union of two submanifolds. In this article, we will show how the low eigensolutions of a self-adjoint elliptic operator over such a manifold can be studied by a splicing construction. This construction yields an approximated solution of the operator whenever we have two L2-solutions on both sides and a common limiting value of two extended L2-solutions. In Part II, the present analytic “Mayer-Vietoris” results on low eigensolutions and further analytic work will be used to obtain a decomposition theorem for spectral flows in terms of Maslov indices of Lagrangians. In Part III after comparing infinite- and finite-dimensional Lagrangians and determinant line bundles and then introducing “canonical perturbations” of Lagrangian subvarieties of symplectic varieties, we will study invariants of 3-manifolds, including Casson's invariant. © 1996 John Wiley & Sons, Inc. 相似文献
960.
The new mononuclear palladium(II) and platinum(II) [M(p-SC6F4(CF3))2(dppe)] complexes M = Pd 1a, Pt 2a; [M(o-SC6H4(CF3))2(dppe)] M = Pd 1d, Pt 2d as well as the previously known [M(SC6F5)2(dppe)] M = Pd 1b, Pt 2b and [M(p-SC6HF4)2(dppe)] M = Pd 1c, Pt 2c, have been used as metalloligands for the preparation of the heteroleptic bimetallic complexes [M2(μ-SRf)2(dppe)2](SO3CF3)2 M = Pd, Rf = p-C6F4(CF3) 3a, C6F53b, p-C6HF43c, o-C6H4(CF3) 3d; M = Pt, Rf = p-C6F4(CF3) 4a, C6F54b, p-C6HF44c and o-C6H4(CF3) 4d. Variable temperature 19F NMR experiments show that the fluorothiolate bridged bimetallic compounds are fluxional in solution whereas mononuclear complexes are not. The solid state X-ray diffraction structures of [Pd(p-SC6HF4)2(dppe)] (1c), [Pt(SC6F5)2(dppe)] (2b) and [Pt(o-SC6H4(CF3))2(dppe)] (2d) show square-planar coordination around the metal centers. The solid state molecular structure of the compound [Pt2(μ-o-SC6H4(CF3))2(dppe)2](SO3CF3)2 (4d), exhibit a planar [Pt2(μ-S)2] ring with the sulfur substituents in an anti configuration. 相似文献