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151.
M Mitsukuchi T Ikemoto M Taguchi S Higuchi S Abe H Yasui K Hatayama 《Chemical & pharmaceutical bulletin》1990,38(3):786-789
A series of 21-(alkylthio)acetates and 21-(methylthio)methoxides of corticosteroids were synthesized and examined for vasoconstrictive activities. The activities of seven compounds were equal to or greater than that of 9 alpha-fluoro-11 beta,21-dihydroxy-16 beta-methyl-17 alpha-valeryloxy-1,4-pregnadiene-3,20-dione (betamethasone 17-valerate, BV). Among them, betamethasone 21-(methylthio)acetate 17-propanoate (2Ca) was found to have the most potent activity, which is superior to that of BV. A structure-activity relationship study revealed that substitution of the 21-hydroxy group of corticosteroids with the (methylthio)acetate function is a useful approach for obtaining potent activity. 相似文献
152.
153.
Takashi Yasui Nozomu Komatsu Kazuki Egami Hiromichi Yamada Akio Yuchi 《Analytical sciences》2007,23(8):1011-1014
Bidentate and tridentate heterocyclic azo compounds with and without a long alkyl chain were prepared and examined for cation exchange chromatography of manganese, zinc, and cadmium; these ions could not be separated by reversed phase HPLC following precolumn derivatization with heterocyclic azo compounds owing to the dissociation of the complexes. The newly prepared azo compounds having a long alkyl chain favorably orientate in the reversed-phase stationary phase such that the coordinating parts of the ligand may make contact with metal ions in the mobile phase. Bidentate ligands showed sharp peaks but almost no resolution of manganese and cadmium. A tridentate ligand strongly retained all the three metal ions, which could be separated within 10 min by a competing ligand and by optimizing the pH. 相似文献
154.
Yusuke Nakashima Kazunori Hirabayashi Masanori Yasui Fujiko Iwasaki 《Tetrahedron letters》2004,45(11):2301-2303
An optically pure seleninic acid was isolated as stable crystals for the first time by chiral crystallization. The relationship between the absolute configurations and the circular dichroism spectra of the enantiomers could be determined by X-ray crystallographic analysis. 相似文献
155.
The reversed-phase high-performance liquid chromatography of 8-quinolinethiol (Hqt) complexes of Fe, Co, Ni, Cu, Zn, Hg and Pb on an octadecyl-bonded silica gel stationary phase was examined. The Pb complex dissociated in the column. The retention and separation of other complexes depended on the composition of the mobile phase. EDTA as an additive displaced the Zn complex and eliminated its peak. All the other metal complexes and also Hqt and its disulphide were separated in 23 min by using methanol-water (82:18, v/v) as the mobile phase. The complexes formed by the reaction of Co(II) and Hqt gave three peaks, which were assigned as fac(S)-CoIII(qt)3, mer(S)-CoIII(qt)3 and CoII(qt)2, respectively. This method is applicable to the simultaneous determination of Fe, Co, Ni, Cu and Hg. 相似文献
156.
We propose the enhancement of Λ
c yield in heavy ion collisions at RHIC and LHC as a novel signal for the existence of diquarks in the strongly coupled quark-gluon
plasma produced in these collisions as well as in the Λ
c
. Assuming that stable bound diquarks can exist in the quark-gluon plasma, we argue that the yield of Λ
c would be increased by two-body collisions between [ud] diquarks and c quarks, in addition to normal three-body collisions among u, d and c quarks. A quantitative study of this effect based on the coalescence model shows that including the contribution of diquarks
to Λ
c
production indeed leads to a substantial enhancement of the Λ
c
/D ratio in heavy ion collisions. 相似文献
157.
We discuss the mass spectrum of doubly charmed mesons as hadronic molecules composed by D and D* meson. Considering the heavy quark symmetry and chiral symmetry, we introduce the one-boson ( ${\pi , \rho , \omega}$ ) exchange potential between D and D* meson. For all possible quantum numbers I(J P ) with isospin I, total angular momentum J( ≤ 2) and parity P, we solve the fully coupled channel Schrödinger equation. We find that in many quantum numbers the bound and resonant states composed by D or D* meson can exist near the DD, DD* and D*D* thresholds. 相似文献
158.
T. Minamisono Y. Yasui T. Ohtsubo A. Kitagawa Y. Matsuo Y. Nojiri K. Matsuta S. Takeda 《Hyperfine Interactions》1990,59(1-4):153-156
The nuclear electric quadrupole moment of41Sc(Iπ=7/2−) was experimentally determined by use of the NMR detection in which the asymmetric β-ray distribution from spin polarized
nuclei was monitored. The magnetic interaction of the state with high external magnetic field and the nuclear quadrupole interaction
with the electric field gradient obtained in TiO2 crystal were studied. The field gradient seen to the implanted41Sc was measured independently by the high field NMR detection on the stable isotope45Sc located in the equivalent41Sc site with. |Q(41Sc;Iπ=7/2−)|=(0.120±0.006) b was determined. 相似文献
159.
The cyanoamidation of olefins was achieved. When N-(2-vinylphenyl)cyanoformamides were treated with palladium catalyst, intramolecular cyanoamidation took place to give corresponding 3,3-disubstituted oxindoles. P(t-Bu)3 showed a remarkable effect on this reaction. When it was used with Pd(dba)2, the reaction was completed in 15 min at 100 °C for many substrates. Furthermore, the enantioselective cyanoamidation was accomplished with Pd(dba)2 and an optically active phosphoramidite to provide optically active 3,3-disubstituted oxindoles. Manipulation of the resulting oxindoles has been studied. 相似文献
160.
We propose the enhancement of Lambdac as a novel quark-gluon plasma signal in heavy ion collisions at the BNL Relativistic Heavy Ion Collider and the CERN Large Hadron Collider. Assuming a stable bound diquark state in the strongly coupled quark-gluon plasma near the critical temperature, we argue that the direct two-body collision between a c quark and a [ud] diquark would lead to an enhanced Lambdac production in comparison with the normal three-body collision among independent c, u, and d quarks. In the coalescence model, we find that the Lambdac/D yield ratio is enhanced substantially due to the diquark correlation. 相似文献