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41.
Bruce Gilligan 《Annals of Global Analysis and Geometry》1995,13(3):303-314
SupposeX=G/H is a connected homogeneous complex manifold, whereG is a Lie group andH is a closed subgroup. Assume
(X) and letG/H G/I be the holomorphic reduction ofX. If the top nonvanishing homology group ofX with coefficients in 2 is in codimension two, then either a complex Lie group acts tansitively onG/I (see [3]) orG/I is biholomorphic to the unit disk.Partially supported by NSERC Grant A3494 and by the Deutsche Forschungsgemeinschaft 相似文献
42.
Jacek R. Jachymski 《Proceedings of the American Mathematical Society》1996,124(10):3229-3233
Let be a continuous self-map of the unit interval . Equivalent conditions are given to ensure that has a common fixed point with every continuous map that commutes with on a suitable subset of . This extends a recent result of Gerald Jungck.
43.
44.
A complete solution of the following Hider-Seeker zero-sum game is obtained. The hider hides a needle of lengtha, 0<a2, in the closed unit dise, and the seeker tries to locate it by shooting in a straight line across the disc. The payoff to the seeker is 1 if he hits the needle and 0 otherwise. 相似文献
45.
One-carbon unit transfer reaction of folate cofactor model compound, 1-acetyl-2-methyl-imidazolinium, with 1,2-diaminobenzene has been studied theoretically with ONIOM method. The result shows that there are two pathways to complete this reaction because the imidazolinium ring has two breaking patterns. Both the two pathways have six steps. They are combination of two reactants, proton migration, break of five-membered ring, formation of benzimidazole derivate, another proton migration, and formation of final products. In each of the above pathways, the two proton migration steps have higher energy, which illuminate that the reaction is catalyzed by general acid-base. This fact agrees with the experimental results of enzymatic one-carbon unit transfer at oxidation level of formate. 相似文献
46.
The role of rigid unit modes in negative thermal expansion 总被引:1,自引:0,他引:1
J.Z Tao 《Journal of solid state chemistry》2003,173(2):442-448
The rigid unit mode (RUM) model provides a valuable computational method to investigate correlations of transverse thermal motions of atoms important in negative thermal expansion (NTE) materials. We report here detailed RUM calculations of ten framework oxide structures that have been studied for their negative (or ultra low) thermal expansion properties. The results negate any simple and direct correlation between presence or absence of RUMs in a structure and its NTE property. All the structures considered can be viewed as networks of polyhedral connected by corners only. All evidence supports the importance the transverse motion of the atoms at the corners, but NTE does not correlate well with the presence RUMs for the polyhedra. 相似文献
47.
《Arabian Journal of Chemistry》2022,15(9):103970
Ethnopharmacological relevanceMetabolic syndrome is closely related to the intestinal microbiota and disturbances in the host metabolome. Hyperuricemia (HUA), a manifestation of metabolic syndrome, can induce various cardiovascular diseases and gout, seriously affecting a patient’s quality of life. Astragalus membranaceus has a long history as a commonly used traditional Chinese medicine to treat kidney disease in China and East Asia.Materials and methodsWe compared the therapeutic effect of benzbromarone and two different doses Astragalus membranaceus ultrafine powder (AMUP) in rats with HUA. Ultra-performance liquid chromatography-mass spectrometer was used to analyze the AMUP metabolism in the plasma, urine, and feces. Further, 16S ribosome RNA sequencing and feces metabolomic were performed to capture the variation of the gut microbiota and metabolites changes before and after drug administration.ResultsAMUP had a notable impact on reducing blood uric acid levels while protecting the liver and kidney. Drug metabolism analysis demonstrated that effective constituent flavonoids are distributed in the blood, whereas saponins remain in the intestine. Gut microbiota analysis showed that low-dose AMUP ameliorated HUA-induced gut dysbiosis by reducing the abundance of harmful bacteria and increasing that of some beneficial bacteria with anti-inflammatory properties, such as Clostridia, Lachnospiraceae, and Muribaculaceae. In addition, HUA-induced changes in metabolite contents in bile acid and adrenal hormone biosynthesis pathways were restored after treatment with AMUP.ConclusionLow-dose AMUP exerts remarkable therapeutic effects on HUA by regulating the gut microbiome and mediating gut metabolism pathways associated with uric acid excretion. 相似文献
48.
The synthesis of an asymmetric glycocluster 1 has been achieved by coupling of a sugar unit with the β-alanine polypeptide, the principal chain, and combining a carbohydrate chain with the side chain causing it to branch from the N terminal. The synthesis of this side chain multivalent ligands is based on the scaffolding of some ω-amino acid (glycine, β-alanine, and GABA) derivatives. This method facilitated the synthesis of the cluster, of which the length of each unit differs. 相似文献
49.
Guo-Ping Chang-Chien 《中国化学会会志》1996,43(5):407-417
New alkene liquid crystals 4-[oligo(ethylene oxide)o, monomethylether)carbonyl]phenyl 4-[4(allyloxy) phenyl]benzoate(MBPBEn, n = 1-3), 4′-[oligo(ethylene oxide)o, monomethylether)carbonyl]biphenyl-4-yl 4-[4-(al1yloxy)phenyl]benzoate(MBPBPEn, n = 1-3), (S)-4-[(2-methyl-I-butoxy)carbonyl]phenyl 4[4-(allyloxy)phenyl]benzoate(MBPBKA), and (S)-4′-[(2-methyl-l-butoxy)carbonyl]biphenyl-4-yl 4-[4(allyloxy)phenyl]benzoate(MBPBPKA) were synthesized and characterized using 1H-NMR and elemental analysis methods. The thermal transition temperatures, mesomorphic properties, and mesophase textures of these compounds have been determined by differential scanning calorimetry (DSC), by polarizing optical microscopy, and by X-ray diffraction analysis. The effect of changes in chemical structure on the mesophase properties, mesophase and isotropic transition temperatures, and mesophase textures are discussed. 相似文献
50.
The conditions of formation of complex lanthanide chromate(VI)-phosphates K2R(CrO4)(PO4) were found and these compounds were synthesized by solid-state synthesis with variation of the starting compounds, the temperature
of synthesis (500–800 °C), and the annealing time (6–200 h). These salts are typical of late lanthanides, R = Dy-Lu, Y. Using
lutetium derivatives as examples, it was shown that no similar compounds with lithium or sodium are formed. All the complex
chromate(VI)-phosphates obtained decompose under static conditions at temperatures above 550 °C. They are isostructural and crystallize
in the monoclinic system. The unit cell parameters for thulium, ytterbium, and lutetium compounds were calculated. It is shown
by IR spectroscopy that PO4 tetrahedra in the crystal lattice of potassium lanthanide chromate(VI)-phosphates are substantially distorted, whereas the CrO4 tetrahedra retain the regular tetrahedron symmetry (T
d
).
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 622–626, April, 2006. 相似文献