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61.
Camps P Gómez T Muñoz-Torrero D Rull J Sánchez L Boschi F Comes-Franchini M Ricci A Calvet T Font-Bardia M Clercq ED Naesens L 《The Journal of organic chemistry》2008,73(17):6657-6665
A series of novel N,O-psiconucleosides has been prepared in both enantiomeric forms by resolution of an advanced racemic synthetic intermediate using (R)-N-phenylpantolactam as a chiral resolution agent. The absolute configuration of all of these compounds has been unequivocally established by chemical correlation with the novel (R)- or (S)-1-methyl-5-phenylpyrrolidine-2,3-dione, prepared from the known (R)- and (S)-1-methyl-5-phenylpyrrolidin-2-one, respectively. 相似文献
62.
Ramon Mercè Merce Pujol Josep M. Ribó Francesc R. Trull Genis Valera Asunción Vallès 《Monatshefte für Chemie / Chemical Monthly》1986,117(5):631-652
The influence of the disubstitution at the exocyclic carbon atom of 5-methylene-3-pyrrolin-2-ones upon the configurational and conformational equilibria is studied. The results obtained confirm and extend the observations reported in the literature about the factors determining the configurational and conformational equilibria in monosubstituted systems, i.e.: 5-arylmethylene-3—pyrrolin-2-ones and 5(1H)-pyrromethenones.
Zur Konfiguration und Konformation von einigen 5-Methylen-disubstituierten-3-pyrrolin-2-onen
Zusammenfassung Es wird der Einfluß der Disubstitution des exocyclischen C-Atoms von 5-Methylen-3-pyrrolin-2-onen auf das Konfigurations- und Konformationsgleich-gewicht untersucht. Die erhaltenen Resultate stehen im Einklang mit der Literatur, die sich auf monosubstituierte Verbindungen [5-Arylmethylen-3-pyrrolin-2-one, 5 (1H)-Pyrromethenone und strukturverwandte Gallenpigmente] beziehen, und vertiefen das Verständnis der Faktoren, die für diese Gleichgewichte maßgebend sind.相似文献
63.
In this paper, we present a threshold proportional reinsurance strategy and we analyze the effect on some solvency measures: ruin probability and time of ruin. This dynamic reinsurance strategy assumes a retention level that is not constant and depends on the level of the surplus. In a model with inter-occurrence times being generalized Erlang(n)-distributed, we obtain the integro-differential equation for the Gerber?CShiu function. Then, we present the solution for inter-occurrence times exponentially distributed and claim amount phase-type(N). Some examples for exponential and phase-type(2) claim amount are presented. Finally, we show some comparisons between threshold reinsurance and proportional reinsurance. 相似文献
64.
A kinetic study on the thermal behaviour of chitosan 总被引:1,自引:0,他引:1
F. A. López A. L. R. Mercê F. J. Alguacil A. López-Delgado 《Journal of Thermal Analysis and Calorimetry》2008,91(2):633-639
The thermal behaviour of chitosan was studied by means of thermogravimetry, mass spectrometry and infrared spectrometry. Kinetic
parameters were obtained by advanced kinetic evaluation (differential isoconversional analysis) from DSC curves, in non-isothermal
conditions, at several heating rates, between 5 and 30°C min−1. The results showed that the decomposition of chitosan does not follow a single mechanism because both the activation energy
and the pre-exponential factor are not constant during the course of the reaction. A comparison with the results obtained
by applying different conventional calculating methods is also shown. 相似文献
65.
Esteban J Alcázar L Torres-Molina M Monfort M Font-Bardia M Escuer A 《Inorganic chemistry》2012,51(10):5503-5505
In the present work, we report a family of Ni(14) and unprecedented Ni(13) clusters linked by end-on azido and oximato bridges. Ferrimagnetic response gives S = 6 and 9 ground states, resulting in the largest nuclearities and spins in nickel oximato chemistry. 相似文献
66.
A complete computational study of the magnetic properties of the two known phases of the bistable (BDTA)(2)[Co(mnt)(2)] compound is presented. The origin of their different magnetic properties can be traced to a variation in the values of the g tensor, together with a hitherto unknown change in the J(AB) values and their magnetic topology. 相似文献
67.
Escuer A Cordero B Font-Bardia M Calvet T Roubeau O Teat SJ Fedi S Fabrizi de Biani F 《Dalton transactions (Cambridge, England : 2003)》2010,39(20):4817-4825
Reactions of 2,6-diacetylpyridine dioxime (dapdoH?) with Mn(NO?)? or Mn(SO?CF?)? under a variety of conditions or co-ligands yield compounds with the formula [Mn?O?(OMe)?(dapdo)?(dapdoH)?](X)? in which X = NO?? (1) or SO?CF?? (2), [Mn?O?(dapdo)?(NO?)?]·H?O (3) and [Mn(dapdoH?)(N?)?](n) (4). Compounds 1, 3 and 4 were structurally characterized and equivalent structures for 1 and 2 were inferred from spectroscopic and analytical results. Compounds 1 and 2 consist of hexanuclear Mn?(II)Mn?(III) complexes whereas 3 consists of an octanuclear Mn?(II)Mn?(III) cluster in which the manganese atoms exhibit a rare bicapped elongated octahedral topology. Compound 4 consists of a 1D system bridged by double end-on azido ligands. Variable temperature magnetic studies were performed between 2-300 K, confirming the ground state S = 5 for 1 and 2, S = 0 for 3 and ferromagnetic response for 4. 相似文献
68.
P Camps T Gómez D Lozano T Calvet M Font-Bardia 《Molecules (Basel, Switzerland)》2012,17(8):8795-8803
Reaction of 1,3-diphenylisobenzofuran (DPIBF) with 2-(iodoethynyl)(phenyl)-iodonium triflate at room temperature gave the expected Diels-Alder adduct, but using an excess of DFIBF (2 equiv.) and performing the reaction at 55 °C or heating at this temperature during the concentration stage, the initial orange solution or product mixture became dark brown and the products 1,2-phenylene-1,2-bis(phenylmethanone) and 2-(3-iodo-1,4-diphenylnaphthyl)(phenyl)iodonium triflate were obtained, which suggests an oxygen transfer between DPIBF and the initial adduct. 相似文献
69.
Gómez-Segura J Prieto MJ Font-Bardia M Solans X Moreno V 《Inorganic chemistry》2006,45(25):10031-10033
rac-[Co(ambi)3]Cl3.3H2O corresponds to a tris-chelate complex bearing 2-(aminomethyl)benzimidazole (ambi) ligands bound to the Co(III) ion in a facial-type fashion. The high metal q/r ratio and electronic delocalization between coordination heterocyclic functionalities can provide powerful tools to minimize DNA condensation, which arises from the neutralization of the negatively charged sugar phosphate backbone in the presence of multivalent [Co(ambi)3]3+. 相似文献
70.
We establish upper and lower bounds on the rank and the dimension of the kernel of perfect binary codes. We also establish some results on the structure of perfect codes. 相似文献