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141.
Navier–Stokes equations arise in the study of incompressible fluid mechanics, star movement inside a galaxy, dynamics of airplane
wings, etc. In the case of Newtonian incompressible fluids, we propose an adaptation of such equations to finite connected
weighted graphs such that it produces an ordinary differential equation with solutions contained in a linear subspace, this
subspace corresponding to the Newtonian conservation law. We discuss the particular case when the graph is the complete graph
K
m
, with constant weight, and provide a necessary and sufficient condition for it to have solutions. 相似文献
142.
Starting from a 5D Riemann flat metric, we have induced an effective 4D Hermitian metric which has an antisymmetric part which is purely imaginary. We have worked an example in which both, non-metricity and cotorsion are zero. We obtained that the production of monopoles should be insignificant at the end of inflation and the tensor metric should come asymptotically diagonal and describing a nearly 4D de Sitter expansion. 相似文献
143.
144.
We survey the construction of the Cox ring of an algebraic variety X and study the birational geometry of X when its Cox ring is finitely generated.
Basic notation. Throughout this paper k is an algebraically closed field. 相似文献
145.
Wang P Kim YJ Navarro-Villalobos M Rohde BD Gin DY 《Journal of the American Chemical Society》2005,127(10):3256-3257
QS-21A is one of the most promising new adjuvants for immune response potentiation and dose-sparing in vaccine therapy, given its exceedingly high level of potency and its favorable toxicity profile. Melanoma, breast cancer, small cell lung cancer, prostate cancer, HIV-1, and malaria are among the numerous maladies targeted in more than 80 recent and ongoing clinical trials involving QS-21A as a critical component for immune response augmentation in microgram doses. Herein is reported the first synthesis and structure verification of QS-21Aapi, applying novel glycosylation methodologies in the convergent modular construction of this rare and potent natural product immunostimulant. 相似文献
146.
Ultrasound-assisted extraction of soy isoflavones 总被引:19,自引:0,他引:19
Efficiency in extracting four isoflavone derivatives (daidzin, glycitin, genistin and malonyl genistin) from freeze-dried ground soybeans was compared for mix-stirring extraction and ultrasound-assisted extraction, using different solvents and extraction temperatures with both. The efficiency of the extraction of soy isoflavones was improved by ultrasound but was dependent on the solvent employed. Optimization of the ratios of sample quantity to solvent volume and length of extraction time was also performed. Isoflavones can be quantitatively extracted from soybeans with 50% ethanol at 60 degrees C using ultrasound-assisted extraction in 20 min. 相似文献
147.
Khodayar Gholivand Carlos O. Della Vdova Mauricio F. Erben Fresia Mojahed Ahlam Madani Alizadehgan 《Journal of Molecular Structure》2007,840(1-3):66-70
Using phosphorus pentachloride as a substrate, a new carbacyclamidophosphate, N,N″-bis (2,6-dimethylmorpholino), N″-dichloroacetyl phosphoric triamide (1) has been synthesized and characterized by 1H, 31P and 13C NMR, IR spectroscopy and elemental analysis. Due to the presence of methyl disubstituted morpholine rings and the dichloroacetamide group, several conformers can be considered for this molecule. The 31P{1H} NMR spectra for the isomeric mixture of synthesized compound showed four signals with the ratio 67.1; 19.0; 12.2; 1.7, which indicates four independent conformers. The 1H NMR spectra confirmed these results. The conformational space and the molecular geometry of the molecule in the gaseous phase have been studied using the B3LYP method of approximation, with 6-31G and 6-311++G** basis sets. 相似文献
148.
Rafael Usón José Gimeno Luis A. Oro Mauricio Valderrama Renato Sariego Ernesto Martinez 《Transition Metal Chemistry》1981,6(2):103-107
Summary Cationic rhodium(I) complexes of the type [Rh(diolefin)(L-L)]ClO4 and [Rh(diolefin)L2]ClO4, (diolefin = 1,5-cyclooctadiene, 2,5-norbornadiene and tetrafluorobenzobarrelene; L-L = 2,2-biimidazole, 2,2-bibenzimidazole; L = pyrazole or imidazoles) are described. [Rh(CO)2(L-L)]-C1O4 complexes, which can be obtained by reaction of cyclooctadiene derivatives with CO, react with P-donor ligands in equimolar ratios to yield [Rh(CO)(P-donor)(L-L)]ClO4 monocarbonyl derivatives. The catalytic activity of some of these complexes is considered. 相似文献
149.
Rafael Uson Luis A. Oro Javier A. Cabeza Mauricio Valderrama 《Journal of organometallic chemistry》1982,231(4):C81-C83
The reaction of LAuIn (L = P(C6H5)3, P(2-MeC6H4)3 or P(4-MeC6H4)3; In = indolyl group) with the solvated complexes [(diolefin)Rh(Me2CO)x]ClO4 gives the novel heterometallic complexes [(diolefin)Rh(μ-In)AuL]ClO4. The mononuclear arene derivatives [(diolefin)Rh(η6-HIn)]ClO4 react with methanolic KOH to give the binuclear complexes [(diolefin)Rh(μ-OMe)]2, while [(COD)Rh(η6-HIn)]ClO4 reacts with KOH in water/acetone to give the hydroxo-bridged complex [(COD)Rh(μ-OH)]2. 相似文献
150.
Heleno VC Crotti AE Constantino MG Lopes NP Lopes JL 《Magnetic resonance in chemistry : MRC》2004,42(3):364-367
We describe a complete analysis of the 1H and 13C spectra of the anti-inflamatory, schistossomicidal and trypanosomicidal sesquiterpene lactone 15-deoxygoyazensolide. This lactone, with a structure similar to other important ones, was studied by NMR techniques such as COSY, HMQC, HMBC, Jres and NOE experiments. The comparison of the data with some computational results led to an unequivocal assignment of all hydrogen and carbon chemical shifts, even eliminating some previous ambiguities. We were able to determine all hydrogen coupling constants (J) and signal multiplicities and to confirm the stereochemistry. A new method for the determination of the relative position of the lactonization and the position of the ester group on a medium-sized ring by NMR was developed. 相似文献