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991.
Zeghida W Debray J Chierici S Dumy P Demeunynck M 《The Journal of organic chemistry》2008,73(6):2473-2475
A novel and simple method of preparation of 2-alkylaminoquinazolin-4-ones with fused heteroaromatic rings from easily accessible (hetero)aromatic amines is described. The method is very efficient, and the 2-alkylaminoquinazolinone derivatives are obtained in three steps without chromatographic purification. The key step is the ring closure of the N-protected guanidine intermediates by intramolecular Friedel-Craft's type substitution. 相似文献
992.
Ridley AR Stewart AI Adamczyk K Ghosh HN Kerkeni B Guo ZX Nibbering ET Pickett CJ Hunt NT 《Inorganic chemistry》2008,47(17):7453-7455
Ultraviolet (UV) photolysis of (mu-S(CH 2) 3S)Fe 2(CO) 6 ( 1), a model compound of the Fe-hydrogenase enzyme system, has been carried out. When ultrafast UV-pump infrared (IR)-probe spectroscopy, steady-state Fourier transform IR spectroscopic methods, and density functional theory simulations are employed, it has been determined that irradiation of 1 in an alkane solution at 350 nm leads to the formation of two isomers of the 16-electron complex (mu-S(CH 2) 3S)Fe 2(CO) 5 within 50 ps with evidence of a weakly associated solvent adduct complex. 1 is subsequently recovered on timescales covering several minutes. These studies constitute the first attempt to study the photochemistry and reactivity of these enzyme active site models in solution following carbonyl ligand photolysis. 相似文献
993.
Moine B Réhault J Aloïse S Micheau JC Moustrou C Samat A Poizat O Buntinx G 《The journal of physical chemistry. A》2008,112(21):4719-4726
The photophysical and photochemical properties of four 3,3-diphenyl-3H-naphtho[2,1- b]pyrans substituted, via an acetylenic junction, to (thiophene) n oligomers (n = 0-3 units) were investigated by transient absorption in the femtosecond to microsecond time domain and by stationary absorption and fluorescence. The decay of the initially produced excited S1(pi pi*) state is found to occur via three competing processes: fluorescence, intersystem crossing, and a ring-opening reaction leading to a colored merocyanine product, with relative yields varying drastically with n. Whereas ultrafast (sub-picosecond) reaction dynamics and high product quantum yield are observed for n = 0 and 1, the reaction is considerably slowed down on going to the n = 2 (105 ps) compound and does not occur for n = 3. A reaction scheme that accounts for this behavior is proposed and the effect of the oligothiophenic chain length on the photoinduced properties is discussed. It is suggested that increasing the chain length from 1 to 3 thiophene units stabilizes the S1(pi pi*) state by pi conjugation and induces an excited-state potential barrier along the reaction pathway. 相似文献
994.
Laurent Boudin Julien Mathiaud 《Numerical Methods for Partial Differential Equations》2012,28(6):1729-1746
In this work, we investigate the numerical approximation of the one‐dimensional pressureless gases system. After briefly recalling the mathematical framework of the duality solutions introduced by Bouchut and James (Comm. Partial Differential Equations 24 (1999), 2173–2189), we point out that the upwind scheme for density and momentum does not satisfy the one‐sided Lipschitz (OSL) condition on the expansion rate required for the duality solutions. Then we build a diffusive scheme which allows the OSL condition to be recovered by following the strategy described by Boudin (SIAM J Math Anal 32 (2000), 172–193) for the continuous model. © 2011 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2011 相似文献
995.
996.
997.
Julien Ferté Vincent Pilaud Michel Pocchiola 《Discrete and Computational Geometry》2011,45(2):279-302
We describe an incremental algorithm to enumerate the isomorphism classes of double pseudoline arrangements. The correction of our algorithm is based on the connectedness under mutations of the spaces of one-extensions of double pseudoline arrangements, proved in this paper. Counting results derived from an implementation of our algorithm are also reported. 相似文献
998.
Julien Leroy 《Advances in Applied Mathematics》2012,48(1):79-98
In [S. Ferenczi, Rank and symbolic complexity, Ergodic Theory Dynam. Systems 16 (1996) 663-682], S. Ferenczi proved that the language of any uniformly recurrent sequence with an at most linear complexity is S-adic. In this paper we adapt his proof in a more structured way and improve this result stating that any such sequence is itself S-adic. We also give some properties on the constructed morphisms. 相似文献
999.
1000.
Julien Duval 《Mathematische Annalen》2016,364(3-4):1361-1363