排序方式: 共有82条查询结果,搜索用时 0 毫秒
41.
E Girard T Tassaing S Camy JS Condoret JD Marty M Destarac 《Journal of the American Chemical Society》2012,134(29):11920-11923
An enhancement of poly(vinyl ester) solubility in supercritical carbon dioxide (sc-CO(2)) can be achieved by decreasing the strength of the polymer-polymer interactions. To demonstrate this, a library of statistical copolymers of vinyl acetate and vinyl trifluoroacetate was synthesized by RAFT/MADIX polymerization with varying compositions at a given number-average molecular weight. These copolymers exhibited unprecedentedly low cloud-point pressures in sc-CO(2) at 40 °C compared with previously reported poly(vinyl esters). Surface tension measurements combined with a computational approach evidenced the prominent role played by polymer-polymer interactions. 相似文献
42.
Sophian Sahnoun Samir Messaoudi Jean-François Peyrat Jean-Daniel Brion Mouad Alami 《Tetrahedron letters》2012,53(23):2860-2863
An efficient hydration reaction of various (hetero)aryl nitriles using Cs2CO3 in pyrrolidinone is described. This new metal-free protocol proved to be highly effective and general to synthesize a variety of (hetero)aryl amides. 相似文献
43.
Boissonnat Jean-Daniel Wintraecken Mathijs 《Foundations of Computational Mathematics》2022,22(4):967-1012
Foundations of Computational Mathematics - Isomanifolds are the generalization of isosurfaces to arbitrary dimension and codimension, i.e. manifolds defined as the zero set of some multivariate... 相似文献
44.
The reaction of the N-methylpyrrolidin-2-one hydrotribromide complex (MPHT) with substituted-1-tetralones has been investigated. This safety reagent proved to be successful for selective α,α-dibromination of tetralones. Moreover, under base-free conditions, several 2-bromo-1-naphtols were obtained from tetralones in a ‘one pot’ sequence in good to excellent yields. 相似文献
45.
The first report of the palladium-catalyzed cross coupling reaction of benzyl halides with alkynyl tributyltin reagents is described. This unprecedented coupling, which involves in a single reaction a tandem Stille-carbopalladation-Stille sequence allows the formation of three carbon-carbon bonds chemo-, regio- and stereoselectively and provides an efficient synthesis of highly substituted enynes. 相似文献
46.
A general procedure for the reductive coupling of N-tosylhydrazones with amines in the presence of Cu(acac)(2) and Cs(2)CO(3) has been developed. The protocol is very effective and chemoselective with various primary and secondary aliphatic amines, aminoalcohols as well as azole derivatives to give α-branched amines in good yields. 相似文献
47.
Omid Amini Jean-Daniel Boissonnat Pooran Memari 《Discrete and Computational Geometry》2013,50(4):821-856
We consider the problem of reconstructing a compact 3-manifold (with boundary) embedded in $\mathbb R ^3$ from its cross-sections $\mathcal{S }$ with a given set of cutting planes $\mathcal P $ having arbitrary orientations. In this paper, we analyse a very natural reconstruction strategy: a point $x \in \mathbb R ^3$ belongs to the reconstructed object if (at least one of) its nearest point(s) in $\mathcal P $ belongs to $\mathcal{S }$ . We prove that under appropriate sampling conditions, the output of such an algorithm preserves the homotopy type of the original object. Using the homotopy equivalence, we also show that the reconstructed object is homeomorphic (and isotopic) to the original object. This is the first time that 3-dimensional shape reconstruction from cross-sections comes with theoretical guarantees. 相似文献
48.
Jean-Daniel Boissonnat Ramsay Dyer Arijit Ghosh 《Foundations of Computational Mathematics》2018,18(2):399-431
We present an algorithm for producing Delaunay triangulations of manifolds. The algorithm can accommodate abstract manifolds that are not presented as submanifolds of Euclidean space. Given a set of sample points and an atlas on a compact manifold, a manifold Delaunay complex is produced for a perturbed point set provided the transition functions are bi-Lipschitz with a constant close to 1, and the original sample points meet a local density requirement; no smoothness assumptions are required. If the transition functions are smooth, the output is a triangulation of the manifold. The output complex is naturally endowed with a piecewise-flat metric which, when the original manifold is Riemannian, is a close approximation of the original Riemannian metric. In this case the output complex is also a Delaunay triangulation of its vertices with respect to this piecewise-flat metric. 相似文献
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50.
Clara Fournier Jean-Daniel Marty Christian Bourgerette Alain Boudet Monique Mauzac 《Liquid crystals》2013,40(4):435-443
Ordered beads were obtained by the suspension copolymerization of amesogenic methacrylate-based monomer and methacrylic acid. The stability of these particles and the liquid crystal organization inside the particles depend mainly on the time of polymerization and on the crosslinking. Suspended droplets of monomers or polymers can be obtained as well as solid spheres. The solid particles exhibit ordered microstructures with a liquid crystal configuration that has a variable form depending on polymerization time and observation temperature. Bead characteristics such as morphology, size and polydispersity, and porosity are discussed and compared with those of non-mesomorphic beads. The mesomorphic beads are smaller and their porosity lower. The presence of a crosslinker during the polymerization process leads to more mechanically stable particles with retention of polymorphism. 相似文献