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991.
The longitudinal 13C spin relaxation times T1 and the 13C{1H} nuclear Overhauser enhancement were measured in a concentrated aqueous solution of the basic pancreatic trypsin inhibitor. The correlation time for overall rotational motions of the basic pancreatic trypsin inhibitor molecules was found to be τR ≈ 2 × 10?8 s. In connection with previous 1H n.m.r. studies of intramolecular motions of the aromatics, we were particularly interested in the correlation times τG for intramolecular segmental motions of the aromatic rings. The present experiments revealed no manifestation of intramolecular motions of the aromatics, indicating that τG ? 2 × 10?8 s for the aromatic ring carbon atoms. On the other hand, rapid segmental motions were evidenced for the peripheral carbon atoms of aliphatic amino acid sidechains. Comparison of the 1H and 13C n.m.r. data on the basic pancreatic trypsin inhibitor indicates that the time scale of high resolution 1H n.m.r. at high fields may in many instances be more appropriate for studies of the molecular dynamics in globular proteins than the time scale of spin relaxation measurements. 相似文献
992.
The reaction of (CH3NPF3)2 with mono-and bissilylatedN,N-dimethylurea yields a crystalline solid which has been identified as a cuban-like P-N-compound with two dimethylurea-bridges. The conditions of formation and the NMR-spectra are discussed. 相似文献
993.
Some aspects of the photochemistry of Δ1,9-10-methyl-2-octalone ( 1 ) were reinvestigated. In view of the hitherto neglected substantial thermal reversibility of the photolytic double bond shift under previous conditions of analysis (1) the solvent-dependent selectivity in product formation in C6H6 and t-BuOH was confirmed, (2) the essentially exclusive double bond shift and its intermolecular nature in C6F6 were established, (3) the quantum yields of the major products in these three solvents were measured, and (4) the dependence of triplet quenching data on temperature, enone concentration and conversion was shown in C6F6 for the double bond shift. In conclusion, the previously published experimental basis for the postulate of two differentially reactive triplet states of 1 is insufficient, although the postulate itself is not necessarily disproved. 相似文献
994.
Kurt Girstmair 《Archiv der Mathematik》1979,32(1):341-343
Ohne Zusammenfassung 相似文献
995.
996.
Summary The separation was studied in the presence of magnesium nitrate and compared with the separation in its absence. As a useful criterion served the expressionA/Z (part of Er in precipitate divided by the degree of decomposition). Under all conditions the separation was significantly better in the presence of magnesium nitrate. The method was used to concentrate the heavy yttrium earths (YE) Er, Tm, Yb and Lu from 38 kg to 10 kgYE
2O3. 相似文献
997.
Complex of Niobium Pentachloride with Thiazyl Chloride Preparation, Vibrational Spectrum, and Crystal Structure Niobium pentachloride reacts with trithiazylchloride in CCl4-suspension forming the complex Cl5Nb? NSCl which forms red crystals that are very sensitive to moisture. According to the vibrational spectrum and the crystal structure determination the compound consists of monomeric units in which NbCl5 is bonded to N?S? Cl in a relatively loose manner via the nitrogen atom. The crystal structure was determined with X-ray diffraction data and was refined to a residual index of R = 0.019 for 1879 reflexions. Cl5NbNSCl crystallizes in the triclinic space group P1 with the lattice constants a = 636.7, b = 1215.5, c = 1266.8 pm, α = 83.32, β = 78.52 und γ = 82.26° and with four molecules per unit cell. There are two crystallographically independent molecules which differ somewhat in their geometry. 相似文献
998.
Kurt Legrady 《Archiv der Mathematik》1971,22(1):491-500
Ohne Zusammenfassung 相似文献
999.
1000.
Ohne Zusammenfassung 相似文献