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991.
Hisao Nakata Hiroshi Sakurai Hideo Yoshizumi Akira Tatematsu 《Journal of mass spectrometry : JMS》1968,1(2):199-204
Three isomeric compounds, I, II and III, were prepared and their mass spectra recorded. Comparisons of the spectra showed that the fragmentation of I proceeds only by way of II, and that II itself is transformed in part to III upon electron impact. It is suggested that selective ionization of each one of the two isolated functional groups in II may afford two isomeric radical ions, IIa and IIb. A possible interrelation to the photochemistry of these compounds is also discussed. 相似文献
992.
993.
Akiyo Tanaka Akira Hisanaga Miyuki Hirata Minoru Omura Naohide Inoue Noburu Ishinishi 《应用有机金属化学》1994,8(3):265-271
Chronic toxicity of indium arsenide (InAs) and arsenic selenide (As2Se3) was studied in male Syrian golden hamsters which received InAs or As2Se3 particles, each containing a total dose of 7.5 mg of arsenic, by intratracheal instillations once a week for 15 weeks. As a control, hamsters were treated with the vehicle, phosphate buffer solution. During their total lifespan, the cumulative body weight gain of the hamsters in the InAs group was suppressed significantly compared with that in the control group, but not in the As2Se3 group when compared with that in the control group. However, the survival rate for the InAs group was significantly higher compared with the control group, but not for the As2Se3 group when compared with the control group. During the animals' total lifespan, one lung adenoma was seen in the 27 hamsters in the InAs group and one lung adenoma in the 23 hamsters in the control group. No tumors of the lung were observed in the As2Se3 group. Malignant tumors outside the lung appeared in four hamsters in the InAs group and in two in the As2Se3 group. No non-lung malignant tumours were seen in the control group. Total tumor incidence rates were 25.9% (7/27) in the InAs group, 10.3% (3/29) in the As2Se3 group and 8.7% (2/23) in the control group. There were therefore no significant differences in tumor incidence between the InAs or the As2Se3 group, and the control group. Regarding histopathological findings in the lung, incidence rates of proteinosis-like lesions, pneumonia, metaplastic ossification and emphysema were seen only in the InAs group, and alveolar or bronchiolar cell hyperplasia observed in both the InAs and the As2Se3 groups were at significantly higher rates than those in the control group. From these results, it was concluded that InAs and As2Se3 particles could induce pulmonary toxicity when instilled intratracheally into hamsters. A great deal of attention should be paid to the toxicity of both InAs and As2Se3, even though in this study the adverse health effects of As2Se3 appeared to be less than those of InAs. 相似文献
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999.
Yusuke Sasaki Masahiko Imai Jun Tanaka Harumichi Shimizu 《Journal of polymer science. Part A, Polymer chemistry》1988,26(9):2465-2473
Polypropylene films were irradiated with 60Co γ-rays in divinylsulfone (DVS) or butadiene (BD) gases. The variations of the intrinsic viscosities of the samples irradiated in vacuum or in DVS with dose showed usual patterns but the variation of the latter was somewhat more rapid. The intrinsic viscosity of the sample irradiated in BD could not be measured due to the early appearance of gel. The gel fraction of the sample irradiated in DVS appeared at lower dose than that irradiated in vacuum, but the former did not increase as much as the latter. The gel fraction of the sample irradiated in BD increased remarkably. The concentrations of the two kinds of double bonds increased in the sample irradiated in BD but levelled off gradually with dose. ESR study showed that the polypropylene radical reacted with DVS to form anisotropic radicals. The mechanisms of the effects of both reagents on irradiation of polypropylene were discussed. 相似文献
1000.
Tamotsu Tanaka Yozo Chatani Hiroyuki Tadokoro 《Journal of Polymer Science.Polymer Physics》1974,12(3):515-531
The crystal structure of polyisobutylene was determined by x-ray analysis. The orthorhombic cell, with a = 6.88 Å, b = 11.91 Å, c (fiber axis) = 18.60 Å (space group: P212121 ? D), contains two molecular chains each consisting of eight monomeric units in the fiber identity period. The chain conformation is essentially an (8/3) helix, but deviates appreciably from the exact (8/3) helix symmetry. The symmetry of the molecular chain is only a twofold screw axis in exact sense, and a crystallographic asymmetric unit consists of four monomeric units. The torsional angles are where M denotes the methyl group. The averaged skeletal C? CH2? C and C? CM2? C bond angles are 128° and 110°, respectively. The large C? CH2? C bond angles may be due to steric respulsion between the adjacent methyl groups, giving intramolecular distances larger than 3.09 Å. 相似文献