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71.
Hiroshi Mukai Shoji Miyazaki Shigeo Umetani Sorin Kihara Masakazu Matsui 《Analytica chimica acta》1989
Solvent extraction of europium (III), zinc (II) cobalt (II) with α-acyl-d-camphor and optically active isomers of quinine and quinidine was studied in order to obtain information on chirality recognition based on adduct formation between a chiral metal chelate and optically active isomers. It was possible to differentiate clearly between the adduct formation of quinine and that of quinidine in the synergic extraction of cobalt and europium with 3-heptafluorobutyryl- d-camphor and cobalt with 3-trifluoroacetyl-d-camphor. 相似文献
72.
Shigeo Tohyama 《Tetrahedron letters》2005,46(32):5263-5264
A new total synthesis of calothrixin B is described. The key step is an allene-mediated electrocyclic reaction involving the indole 2,3-bond for the construction of a suitable 4-oxygenated 2,3,4-trisubstituted carbazole ring system. 相似文献
73.
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75.
The cavity length of an internal-mirror HeNe laser was controlled using a thin film heater coated on the tube. The response speed was about ten times higher than that of the usual tube wound with a ribbon heater. The high response speed brought two merits in frequency stabilization of the laser; one was improvement of stability in the short time region and the other was the realization of a thermal modulation method, by which the cavity was stabilized at Lamb's dip. 相似文献
76.
To investigate the mechanism of the stimulation and quenching of the green luminescence in ZnS: Cu, Al phosphors by infrared (IR) light of 0.7–1.5 μm, stimulation and quenching spectra, IR effects on time-resolved emission spectra, and IR-induced photoconductivity are measured at 4.2 K, 77 K, and room temperature. Both the stimulation and quenching are caused by the IR transitions ascribed to excited copper acceptors. It is concluded that the stimulation is induced by the process in which holes produced by IR light migrate among copper acceptors, so that the statistical distribution of the intrapair separations of excited copper-aluminum pairs are changed to shorter distances. It is found that at low temperatures the holes migrate from one copper acceptor to another without being thermally released to the valence band. It is confirmed that the quenching is caused by the recombination of holes released to the valence band with electrons in the conduction band via some kind of nonradiative recombination centers. 相似文献
77.
Summary Stability constants of 2-mercaptohistamine (2-MH) with a number of transition metal ions were determined by a potentiometric titration method and the coordination mode of (2-MH) metal complexes were thereby characterized. With MnII, Fell, CoII, and NiII, coordination occurred through both the imidazole-nitrogen and amino groups, while with ZnII, CdII, PbII, and HgII, both thiolate and amino groups, contribute to the coordination. in the 2-MH copper complex, polymer formation is suggested on the basis of visible absorption and e.p.r. spectra. 相似文献
78.
Charles W. Jefford Danielle Jaggi John Boukouvalas Shigeo Kohmoto Grald Bernardinelli 《Helvetica chimica acta》1984,67(4):1104-1111
The dye-sensitized photo-oxygenation of 1,3-dimethylindole in the presence of aldehydes initially generates a zwitterionic peroxide which condenses with the carbonyl function to give the corresponding cis-fused 1,2,4-trioxanes. Acetaldehyde gives a pair of diastereomers, one of whose structures was determined by X-ray analysis (cis,cisisomer), whereas pivaladehyde gives only the cis,cis diastereomer. 相似文献
79.
Izhar H. Qureshi Shaheen A. Husain Radia Noorani Najma Murtaza Yoichi Iitaka Shigeo Iwasaki Shigenobu Okuda 《Tetrahedron letters》1980,21(20):1961-1962
The complete structure of a unique tricyclic sesterterpene, stellatic acid, was established by X-ray diffraction of its p-bromophenacyl ester. 相似文献
80.