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31.
H. Kagetsu N. Shioyasu N. Fukunishi M. K. Kubo Y. Sakai T. Tominaga K. Nishiyama K. Nagamine 《Hyperfine Interactions》1994,84(1):517-520
We have carried out SR experiments on [Co(NH3)6]Cl3 and [Co(ND3)6]Cl3. At 293 K, all the muons implanted into the complexes were in the diamagnetic state. The observed Gaussian-type muon spin relaxation function proved that the internal magnetic field was caused by nuclear dipole moments of the atoms in the complexes. In addition, another exponential-type muon spin relaxation function was observed in [Co(ND3)6]Cl3 below 50 K. 相似文献
32.
As the application of a dielectric theory proposed previously (J Membrane Sci 64:153–161 (1991)), theoretical formulation and the practical procedure of dielectric analysis are developed to calculate the structural parameters such as the conductivity gradient and the thickness of the concentration polarization layer, the capacitances and the conductances of the two adjoining aqueous phases from the observed dielectric parameters. The procedure of calculation consequent upon the theoretical formulation was applied to double relaxation data observed for cation-exchange membrane systems under application of d.c. bias voltage. As a consequence, the structural parameters of concentration polarization were readily obtained with accuracy. 相似文献
33.
Katsuhiko?Kamio Yoshifumi?Kusumoto Masashi?Sakai Katumitu?HayakawaEmail author 《Colloid and polymer science》2003,281(7):608-613
The conformation of the sodium salt of poly(l-glutamic acid) (P(Glu)) in solutions of the cationic bipolar amphiphile 1, 20-isosanediylbis(alkylammonium chloride) (C 20(RA) 2) with different alkyl head groups as a function of amphiphile concentration was investigated using circular dichroism (CD). RA included methylammonium (MA), ethylammonium (EA), propylammonium (PA), butylammonium (BA), and pentylammonium (PeA) cationic groups. The CD spectrum of each C 20(RA) 2 had a double minima corresponding to the a-helix of P(Glu), which was replaced by CD spectra with a single minimum at wavelengths larger than 222 nm as concentration increased. These changes in the CD spectrum were ascribed to the conformational change from random coil to a-helix and to aggregates of helices. In C 20(EA) 2 solutions, a step-like change in the CD intensity was observed at 222 nm as a function of the ratio of C 20(RA) 2 to P(Glu). At the step, the CD spectrum of the complete a-helix was observed. At 10–35 °C, an a-helix was induced in P(Glu) in the order: C 20(EA) 2>C 20(MA) 2>C 20(PA) 2>C 20(BA) 2>C 20(PeA) 2. This order was ascribed to the best fit of ethylammonium to the P(Glu) side chain. 相似文献
34.
Chemical conversion of some natural oxindoles (pteropodine, isopteropodine and isorhynchophylline) into the corresponding indole alkaloids has been made by way of a sequence of reactions which include formation of iminoethers of the natural oxindoles with Meerwein's reagent, reduction of the iminoethers to 2,3-seco-indoles and cyclization of 2,3-seco-indoles to the desired natural indole alkaloids. Sodium borohydride in acetic acid was found to be a specific reagent for the reduction of oxindole-iminoethers to 2,3-seco-indoles which were the key intermediates in these transformations. Yohimbine-oxindole iminoether was similarly converted to yohimbine and pseudoyohimbine. A number of by-products were obtained and their structures were elucidated. 相似文献
35.
36.
Nakamura Y Asami A Ogawa T Inokuma S Nishimura J 《Journal of the American Chemical Society》2002,124(16):4329-4335
The reactions of [60]fullerene with bis-o-quinodimethane precursors 3, 4, and 5 containing a dibenzo-18-crown-6, 24-crown-8 and 30-crown-10 moiety, respectively, were investigated. Both 3 and 4 provided trans-4 bisadducts 6a and 7a, respectively, as major product, though the selectivity in the latter was lower than that in the former. As minor product, 6b (cis-2) was produced from 3, while 7c (e) as well as 7b (cis-2) were produced from 4. Precursor 5 exclusively afforded e bisadduct 8 without any other regioisomers. These bisadducts showed different ionophoric properties from one another; for instance, 6a and 7b exhibited a high complexing ability toward the K+ ion, while 6b hardly showed complexation with any alkali metal ions. The selectivity coefficients (K(Na,K)(pot)) of 6a and 7b toward K+ over Na+ ion, determined with an ion-selective electrode, were much higher than that of dibenzo-18-crown-6. 相似文献
37.
E. Miyoshi T. Iura Y. Sakai H. Tochihara S. Tanaka H. Mori 《Journal of Molecular Structure》2003,630(1-3):225-232
We investigated the interactions between the Si(111) surface and the Na, Mg, and Al atoms using cluster model calculations. Calculations were performed at levels of complete-active-space self-consistent-field (CASSCF) and multi-reference singly and doubly excited configuration interaction (MRSDCI) calculations using the model core potential method. Our calculations revealed that the most favorable sites of Na, Mg, and Al adsorption on Si(111) are on top (T1), bridge (B2), and 3-fold filled (T4) sites, respectively. The nature of chemical bonds between these metal atoms and the dangling bonds of the surface Si atoms are found to be essentially covalent. 相似文献
38.
自行研制了电子碰撞离子化的飞行时间型质量分析器(TOFMS),用于物质的化学分析。用研制的TOFMS测量了Ar离子化的飞行时间谱和离子的部分电离截面积比与碰撞电子能量的依赖关系,将它与Stepshan等人的实验结果进行了比较。 相似文献
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