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21.
The solvolysis rates and products of several 7-anti-substituted 2-endo-norbornyl p-toluenesulfonates 11 have been determined and compared with those of the previously reported 6-exo-substituted 2-exo-norbornyl p-toluenesulfonates 1. Although the number of bonds between the substituent and the reaction site is the same in the two series, the inductive effect of the substitutents is transmitted far more strongly in the 6-exo-2-exo-series 1 than in the 7-anti-2-endo-series 11 ; i.e. their inductivities differ widely. It is concluded that through space induction involves graded bridging of the substituent-bearing C-atom to the incipient cationic center at C(2) and that this involves differential bridging strain. The different reactivities of unsubstituted 2-exo- and 2-endo-norbornyl derivatives can then be ascribed to a stereoelectronic effect. 相似文献
22.
Cyril W. L. Garner 《Journal of Geometry》1979,12(2):132-138
There does not exist a general theory of conics in finite projective planes, because the many definitions of conics which are equivalent in desarguesian projective planes yield different types of conics in more general situations. Thus even the use of the word conic can lead to confusion, particularly in the finite case. This note is an attempt to clarify these various definitions and give as an example in a finite projective plane a von Staudt conic which is not an Ostrom conic. We conjecture that any finite projective plane admitting an Ostrom conic must be desarguesian. 相似文献
23.
Mariem Ghali Chaima Brahmi Mahmoud Benltifa Cyril Vaulot Aissam Airoudj Philippe Fioux Frédéric Dumur Corine Simonnet-Jégat Fabrice Morlet-Savary Salah Jellali Latifa Bousselmi Jacques Lalevée 《Journal of polymer science. Part A, Polymer chemistry》2021,59(2):153-169
Different inorganic/organic photocomposites based on polyoxometalate (POM) nanoparticles have been developed for photocatalytic applications. Currently, polyoxometalate nanoparticles have been successfully in-situ embedded into an acrylate polymer network by photopolymerization upon mild visible light irradiation at 405 nm. The proposed POM/polymer photocomposites have been characterized using complementary techniques for a better understanding of their photocatalytic activity. Interestingly, the obtained photocomposites exhibit high rigidity, excellent thermal stability, a non-negligible porosity and new functionalities such as light reactivity and redox properties. Moreover, developed composites showed efficient catalytic activity for the color removal of aqueous solutions of erythrosine and rose Bengal under Light Emitting Diodes LED@375 nm irradiation reaching 80 and 90% as a final color removal, respectively. 相似文献
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Thomas Courant Valrie Gaëlle Roullin Cyril Cadiou Maït Callewaert Marie Christine Andry Christophe Portefaix Christine Hoeffel Marie Christine deGoltstein Marc Port Sophie Laurent Luce Vander Elst Robert Muller Michaël Molinari Franoise Chuburu 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2012,124(36):9253-9256
26.
Cyril Furtlehner Jean-Marc Lasgouttes Maxim Samsonov 《Journal of statistical physics》2012,147(6):1113-1144
The slow-to-start mechanism is known to play an important role in the particular shape of the Fundamental Diagram of traffic
and to be associated to hysteresis effects of traffic flow. We study this question in the context of exclusion and queueing
processes, by including an asymmetry between deceleration and acceleration in the formulation of these processes. For exclusions
processes, this corresponds to a multi-class process with transition asymmetry between different speed levels, while for queueing
processes we consider non-reversible stochastic dependency of the service rate w.r.t. the number of clients. The relationship
between these 2 families of models is analyzed on the ring geometry, along with their steady state properties. Spatial condensation
phenomena and metastability are observed, depending on the level of the aforementioned asymmetry. In addition, we provide
a large deviation formulation of the fundamental diagram which includes the level of fluctuations, in the canonical ensemble
when the stationary state is expressed as a product form of such generalized queues. 相似文献
27.
Synthesis and structure–property relationship of carbazole‐alt‐benzothiadiazole copolymers 下载免费PDF全文
Jules Oriou Feifei Ng Georges Hadziioannou Cyril Brochon Eric Cloutet 《Journal of polymer science. Part A, Polymer chemistry》2015,53(17):2059-2068
A series of four π‐conjugated carbazole‐alt‐benzothiadiazole copolymers (PCBT) were prepared by Suzuki cross‐coupling reaction between synthesized dibromocarbazoles as electron‐rich subunits and 4,7‐bis(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)?2,1,3‐benzothiadiazole as electron‐deficient subunits. The subunits were directly linked through 2,7‐ or 3,6‐ positions of the carbazole. In addition, the carbazole monomers have been N‐substituted by a branched or a linear side‐chain. The chemical structure of the copolymers and their precursors was confirmed by NMR and IR spectroscopies, and their molar masses were estimated by SEC. Thermal analysis under N2 atmosphere showed no weight loss below 329°C, and no glass transition was observed in between 0 and 250°C. The band gaps of all PCBTs evaluated by optical spectroscopies and by cyclic voltammetry analysis were consistent with expectations and ranged between 2.2 and 2.3 eV. Finally, 2,7 and 3,6 linkages were shown to influence optical properties of PCBTs. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 2059–2068 相似文献
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Melkonian JM Forget N Bretenaker F Drag C Lefebvre M Rosencher E 《Optics letters》2007,32(12):1701-1703
We report on what we believe to be the first active mode locking of near-degenerate, doubly and singly resonant cw-pumped optical parametric oscillators (OPOs). We show experimentally that a steady-state regime of short pulses is reached in a few tens of microseconds under cw pumping. The oscillation buildup dynamics of both OPOs is also explored, evidencing an unusual transient behavior in the mode-locking process. 相似文献