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991.
The structures of purinophane 1 and its higher homolog 2 were determined by X-ray crystallographic analysis. Hypochroism of 1 and 2 in various media reported. 相似文献
992.
T Harayama R Yanada T Akiyama M Tanaka Y Fujita F Yoneda 《Chemical & pharmaceutical bulletin》1991,39(3):612-615
Bromohydrins (2, 3, 4, and 5), oxidatively damaged products of thymine bases, were repaired on exposure to sunlight, heat, and/or some reagents to regenerate the thymine bases. A radical mechanism is proposed for the repair reaction with sunlight and heat. A hypothesis concerning the biological significance of thymidine in deoxyribonucleic acid is presented. 相似文献
993.
D. Kaji K. Morita K. Morimoto Y. L. Zhao A. Yoneda T. Suda A. Yoshida H. Kudo K. Katori I. Tanihata 《Journal of Radioanalytical and Nuclear Chemistry》2003,255(1):77-80
A gas-filled recoil separator for heavy element research was installed at the experimental hall of RIKEN linear accelerator facility. An acceptance of the separator was measured using a-particles from 241Am source. Measured acceptance was 12.2 msr. Transmissions of the separator were measured with low-energy Pb (0.26 AMeV) and Bi (0.11 AMeV) recoils. It was found that the transmission for Pb (0.26 AMeV) was 0.84, and that for Bi (0.11 AMeV) was 0.33. Equilibrium charge states for Pb and Bi in helium gas were deduced. 相似文献
994.
Shu Yin Hiroshi Yamaki Masakazu Komatsu Qiwu Zhang Jinshu Wang Qing Tang Fumio Saito Tsugio Sato 《Solid State Sciences》2005,7(12):1479
Yellowish TiO2−xNy was prepared by a novel mechanochemical nitrogen-doping method. The samples were prepared by a high-energy ball milling of P25 titania with different nitrogen sources such as hexamethylenetetramine, urea or ammonium carbonate, followed by calcination in air at 400 °C. The high mechanical energy accelerated the phase transformation of anatase to rutile, while the existence of the nitrogen reagents tended to block the transformation. The calcination treatment slightly increased the crystallinity of the prepared titania. The prepared powders possessed two absorption edges at around 400 and 540 nm and showed an excellent photocatalytic ability for the oxidation of nitrogen monoxide under visible light irradiation. Under the irradiation of visible light with wavelengths of >510 nm, nitrogen monoxide could be continuously removed by the nitrogen doped titania prepared from the P25 titania-hexamethylenetetramine mixture, while the powders prepared using urea and ammonium carbonate as nitrogen sources showed lower activities. This mechanochemical technique might be widely useful for doping oxides with nonmetallic elements. 相似文献
995.
For a rank 2 vector bundle E on a non-singular projective curve of genus g, the theorem of Nagata tells us that deg E-2 max deg Fg where the maximum is taken over all sub line bundles F of E. We generalize this result to vector bundles of arbitrary rank. 相似文献
996.
Keitaro Senga Misuzu Ichiba Hashime Kanazawa Sadao Nishigaki Masatsugu Higuchi Fumio Yoneda 《Journal of heterocyclic chemistry》1978,15(4):641-644
A novel synthesis of 8-arylaminotheophyllines ( 8a-e ) by the reaction of 5-arylazo-6-ethoxy-methyleneamino-1,3-dimethyluracils ( 2a-e ) or 5-arylazo-1,3-dimethyl-6-dimethylaminomethylene-aminouracils ( 3a-e ) with sodium dithionite in formic acid is described. 相似文献
997.
Misuzu Ichiba Keitaro Senga Sadao Nishigaki Fumio Yoneda 《Journal of heterocyclic chemistry》1977,14(1):175-176
The reaction of 1,3-dimethyl-6-hydrazino-5-nitrosouracil (1) with Vilsmeier reagent (dimethylformamide-phosphorus oxychloride) afforded fervenulin 4-oxide (II) in good yield. 相似文献
998.
999.
Abstract— All- trans , 11- cis and 9- cis isomers of the C17 aldehyde analogs of retinal bound with purple membrane apoprotein, probably through a Schiff base linkage at the normal retinal binding site. The complex formed from C17 aldehyde and purple membrane apoprotein was slowly decomposed by 10m M hydroxylamine. The C17 aldehyde competitively inhibited the regeneration of purple membrane from all- trans -retinal and purple membrane apoprotein. The differential ability of the different isomers to inhibit the regeneration suggests that purple membrane has a binding site for the side chain of retinal in addition to the Schiff base binding site. 相似文献
1000.
Ayako Torikai Takahiro Kobatake Fumio Okisaki Hideo Shuyama 《Polymer Degradation and Stability》1995,50(3):261-267
Wavelength dependence on the photodegradation of flame-retardant materials (Polystyrene (PSt) containing flame-retardants) was studied. The effects of nine flame-retardants containing bromine (Br) on the efficiency of photodegradation of the PSt were compared. Samples were irradiated at 23 °C in air with monochromatic radiation of wavelengths 260, 280, 300, 320, 340, 360 and 380 nm using the Okazaki Large Spectrograph (OLS). UV-visible and FTIR spectra were measured to identify photo-induced chemical structural changes in the PSt. The number of main-chain scissions and the changes in the molecular weight distribution were estimated from the results of GPC measurements. It was found that the photo-stability of PSt was reduced by the addition of flame-retardants. The most effective irradiation wavelength for main-chain scission was found to be 280 nm for each flame-retardant except one. The photo-stability of PSt containing flame-retardants appears to depend upon the chemical structure of the additive. 相似文献