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991.
The inclusion of dulcin in alpha- and beta-cyclodextrin has been studied by fluorescence spectroscopy. To quantitatively describe complex formation between the beta-cyclodextrin and dulcin, an association constant of 290 M(-1) at 21 degrees was obtained. The thermodynamics associated with the complex formation between dulcin and beta-cyclodextrin in aqueous solution has been studied. The obtained value of DeltaG(0) = -13.7 kJ/mole at 21 degrees , together with DeltaH(0) = -33.6 +/- 2.3 kJ/mole and DeltaS(0) = -67.2 +/-8.3 Jmole(-1) K(-1) indicate that dulcin has a very marked tendency to associate with beta-cyclodextrin in water. The inclusion complex of dulcin in beta-cyclodextrin has been used to determine dulein in the range 0.13-5 mug/ml the method has been applied to determine dulcin in soft drinks. 相似文献
992.
Zusammenfassung Die Polymerisation des Phosphornitrilchlorids in Substanz erweist sich als thermisch gestartete Radikalpolymerisation, die mit gleicher Geschwindigkeit und gleicher Temperaturabhängigkeit wie die durch Sauerstoff aktivierte Polymerisation in Lösung verläuft. Schon geringer Lösungsmittelzusatz bringt die thermische Polymerisation zum Erliegen. Ein Reaktionsschema mit Start-Kette-Abbruch wird diskutiert, das sowohl die Substanz- wie die Lösungspolymerisation wiedergibt. Der seinerzeit beschriebene Einfluß von Sauerstoff auf den Ablauf der Polymerisation erfährt dadurch eine wesentliche Korrektur.Die Depolymerisation von polymerem Phosphornitrilchlorid wird von 350 bis 600° C verfolgt und als gegenläufige Reaktionsfolge zur Polymerisation gefunden. Für das aus Polymerisation und Depolymerisation resultierende Gleichgewicht werden Druck- und Temperaturabhängigkeit festgestellt.Mit 8 Abbildungen.Herrn Prof. Dr.A. Klemenc zu seinem 70. Geburtstage gewidmet.Als I soll die ArbeitPatat-Kollinsky
1 Über die Polymerisation des Phosphornitrilchlorids1 gelten, die im folgenden Text auch mit (I) bezeichnet wird.— Eine Literaturzusammenstellung Phosphornitrilchlorid findet sich in der Monographie vonL. F. Audrieth, R. Steinmann undA. O. F. Toy, Chem. Rev.32, 109 (1943). 相似文献
993.
Raquel F. P. Nogueira Ronaldo A. Pilli Nelson durÁn 《Applied biochemistry and biotechnology》1992,33(3):169-176
Growth of the ascomyceteChrysonilia sitophila during degradation of lignin model dimers and monomers was compared to a glucose control. An inhibition of growth by Cα-carbonyl
monomers and stimulation by β-O-4 lignin model and vanillyl alcohol were observed. A comparison of the degradation by this
ascomycete with the basidiomycetePhanerochaete chrysosoporium showed similarities in relation to the type of degradation caused. 相似文献
994.
Nitrogen position and internal heavy atom effects on the radiative and radiationless transitions from the lowest excited states of the isomeric azaphenanthrenes and some of their methyl, chlorine and bromine derivatives have been studied in E.P.A. solutions at 77 K. The nitrogen position affects the fluorescence and S1-T1 intersystem crossing rates more than the phosphorescence and T1-S0 intersystem crossing rates. Small differences in the behaviour of 9-azaphenanthrene are enhanced in non-hydroxylic solvents and at room temperature, and it is inferred that (n, π*) states play a more important role in the photophysical behaviour of this isomer. Halogen, substitution in all the isomers increases the phosphorescence rate, induces a smaller increase in the T1-S0 intersystem crossing rates and has a negligible effect on the fluorescence rate. 相似文献
995.
Oxidation of 4-[3-(dimethylamino)propyl]-3,4-dihydro-2-(1-hydroxyethyl)-3-phenyl-2H-1,4-benzothiazine, hydrochloride (I) with hydrogen peroxide yielded a mixture of two sulfoxides (II). Since this mixture exhibited antiinflammatory activity, the two components (Isomers A and B) were prepared in purified form by oxidation of I with N-chlorosuccinimide and hydrogen peroxide, respectively. Isomer A was more potent than Isomer B in the carrageenin-induced edema test. 相似文献
996.
Characterization of dynamic and steady-state protein phosphorylation using a fluorescent phosphoprotein gel stain and mass spectrometry 总被引:4,自引:0,他引:4
Protein phosphorylation plays a vital role in the regulation of most aspects of cellular activity, being key to propagating messages within signal transduction pathways and to modulating protein function. Pro-Q Diamond phosphoprotein gel stain is suitable for the fluorescence detection of phosphoserine-, phosphothreonine-, and phosphotyrosine-containing proteins directly in sodium dodecyl sulfate (SDS)-polyacrylamide gels. The technology is especially appropriate for profiling steady-state and dynamic phosphorylation on a proteome-wide scale, as demonstrated through detection of the native phosphorylation of cardiac mitochondrial phosphoproteins and changes in this profile arising from the activity of a protein kinase. For example, Pro-Q Diamond phosphoprotein gel stain was employed to demonstrate that among the 46 subunits of the mitochondrial respiratory chain complex, NADH:ubiquinone oxidoreductase (complex I), a 42 kDa subunit is phosphorylated in the steady-state. However, exposure of mitochondria to cAMP-dependent protein kinase increases phosphorylation of this 42 kDa subunit and results in de novo phosphorylation of an 18 kDa subunit as well. Since Pro-Q Diamond dye binds to phosphorylated residues noncovalently, the staining technology is fully compatible with modern microchemical analysis procedures, such as peptide mass profiling by matrix assisted laser desorption/ionization-time of flight (MALDI-TOF) mass spectrometry and post-source decay analysis of peptide phosphorylation. 相似文献
997.
998.
The absorption intensities of two infrared active lattice modes of crystalline N2O have been measured. Both the frequencies and intensities of the external modes of N2O have been found to be very similar to those of CO2, and most of the differences between the spectra of CO2 and N2O can be explained by the differences in the quadrupole moments. 相似文献
999.
Walter K. Dean Gary L. Simon Paul M. Treichel Lawrence F. Dahl 《Journal of organometallic chemistry》1973,50(1):193-207
The accidental but intriguing synthesis of acetatobis(triphenylphosphine)dicarbonylmanganese(I), (CH3CO2)Mn(CO)2[P(C6H5)3]2, has been accomplished by the reaction of NaMn(CO)5 with (CH3)3SiCl followed by the addition of triphenylphosphine and acetic acid. A three-dimensional single-crystal X-ray diffraction analysis has shown an octahedral-like molecule containing a symmetrically oxygen-chelating acetate group, the first such group to be reported in a metal carbonyl complex. The two triphenylphosphine ligands occupy mutually trans positions with the two carbonyl ligands possessing the remaining cis sites in the octahedral complex. The compound crystallizes with four molecules in a monoclinic unit cell of space group symmetry and of dimensions a = 17.744(2) Å, b = 9.692(1) Å, c = 20.004(2) Å, and β = 106.195(4)°. The relatively long MnO(acetate) bond lengths [2.066(6) and 2.069(7) Å] and the relatively short MnCO bond lengths [1.701(12) and 1.760(13) Å] and the relatively short MnP(C6H5)3 bond lengths [2.260(3) and 2.275(3) Å], compared to the corresponding MnCO and MnP(C6H5)3 bond lengths in other manganese carbonyl triphenylphosphine complexes, are rationalized on the basis that the acetate ligand in this molecule functions primarily as a σ-donor. 相似文献
1000.
Zusammenfassung Mo3CoB3, Mo3NiB3, W3CoB3 und W3NiB3 kristallisieren in einem eigenen Typ (W3CoB3-Struktur). Das trigonal prismatische Bauelement [T
6B]* ist zu Ketten vereinigt, wobei B3-Gruppen entstehen. Die Phasen sind vermutlich Bor-reicher als obiger Formel entspricht.
Mit 2 Abbildungen 相似文献
The crystal structure of W3CoB3 and the isotypic phases Mo3CoB3, Mo3NiB3, and W3NiB3
Mo3CoB3, Mo3NiB3, W3CoB3, and W3NiB3 were found to possess a new type of crystal structure (W3CoB3-structure type). Trigonal prismatic groups [T 6B]* are linked together forming chains in such a way that B3-groups occur. These borides do probably exist with a larger amount of boron as to compared with the formula.
Mit 2 Abbildungen 相似文献