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1.
Masashi Hamaguchi Kazuma TakahashiTakumi Oshima Hatsue Tamura 《Tetrahedron letters》2003,44(23):4339-4342
Reactions of tricarbonyl compounds with vinyl diazo compounds 2 were carried out. Reaction of 1,2,3-indanetrione with 2a,b,c gave the spiroindan-1,3-dione-2,2′-benzodihydrooxepin 7a,b,c, but not normal products oxirane and dihydrofuran derivatives expected from intermediate vinyl carbonyl ylides 4. Formation of 7 requires isomerization of vinyl carbonyl ylides 4 bearing a (Z)-cyanostyryl group to unstable (E)-form 5 and subsequent cyclization to oxepin 6 followed by a 1,5-hydrogen shift. However, reaction of 2 with six-membered cyclic tricarbonyl compounds 1,2,3-trioxo-2,3-dihydrophenalene 11 and dimethylalloxane 13 gave the dioxole 12 and the dihydrofuran 14, respectively, typical products expected from vinyl carbonyl ylides. 相似文献
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Q. B. Wang K. Masumoto K. Bessho H. Matsumura T. Miura T. Shibata 《Journal of Radioanalytical and Nuclear Chemistry》2007,273(1):55-58
For evaluation of radioactivity induced in the concrete samples from accelerator facilities, the residual radioactivity in
concrete sample, collected from seven accelerator facilities, was determined by γ-ray spectrometry. The tritium was extracted
by the heating method using an IR furnace, and measured with a liquid scintillation counter. It was found that the major radioisotopes
activated mainly by neutrons in the concrete samples were 152Eu, 60Co, 134Cs and 3H. The concentrations of radioactivities induced by thermal neutron capture are the highest at a depth of 10 cm in the concrete
wall. The correlation between tritium, 60Co and 152Eu activity was investigated by measuring many concrete samples for seven accelerator facilities. The results indicate that
their activities are strongly correlated with each other. So it would also be concluded that the total activity in shielding
concrete could be estimated on the basis of the activities of 60Co and 152Eu. 相似文献
6.
In order to demonstrate the usefulness of alpha-particle activation analysis, simultaneous determination of P, Cl, K and Ca in commercially available control serums has been studied fundamentally. After thick target yield curves of radionuclides produced from the element to be determined were measured as a function of alpha energy together with those of the interferences, an optimum working standard for the present experiments was provided by applying the internal standard method to a human serum under the most suitable bombardment conditions. Then, the concentrations of the above four elements in several control serums were determined efficiently and reasonably by ordinary alpha-particle activation analysis. 相似文献
7.
H. Sakurai M. Fukuda Y. Hayashibe Y. Sayama K. Masumoto T. Ohtsuki 《Journal of Radioanalytical and Nuclear Chemistry》1997,217(2):267-271
A highly sensitive determination of fluorine in standard rocks by photon activation using the19F(,n)18F reaction combined with pyrohydrolysis for the separation of18F has been reported. The irradiation energy was operated at 20 MeV to avoid the interference from Na, because Na is one of the major element in rocks and18F is also produced from Na via23Na(,n)18F reaction above its threshold energy, 20.9 MeV. After irradiation, fluorine was extracted by pyrohydrolysis and separated as LaF3 precipitate. It was ascertained that the average recovery of fluorine in standard rocks was about 90% and the precipitate was of high radiochemical purity. This method was applied to the analysis of ten GSJ rock reference samples and two USGS standard rocks issued by the Geological Survey of Japan and the United States Geological Survey, respectively. The detection limit of this method was 0.02 g/g, and the results obtained by this method were in good agreement with the recommended values. This method was easily applied to the determination of a few ppm level of fluorine in rock samples, such as ultrabasic rock and feldspar. 相似文献
8.
In order to examine effective applications of the newly developed internal standard method, determinations of Cr, Co, Ni, Zn, As, Rb, Sr, Y, Zr, Nb, Cs, Ce and Pb in three environmental materials, such as pond, lake and estuarine sediments, have been tried by means of photon activation. In these examinations, some major constituent elements in the above sediments were properly used as excellent and effective internal standards. In consequence, it was confirmed that highly accurate and precise determinations of the above 13 elements were achieved easily and favourably. 相似文献
9.
T. Kato K. Masumoto N. Sato N. Suzuki 《Journal of Radioanalytical and Nuclear Chemistry》1976,32(1):51-70
A comprehensive study on the yields of photonuclear reactions of various types has been performed, and sensitivities and the
effects of interferences in multielement photon-activation analysis have been evaluated by bremsstrahlung activation of many
elements with maximum energies ranging from 30 to 60 MeV. The applicability and reliability of the method were demonstrated
by analyzing standard round-robin samples and then by presenting the elemental abundances in several geological, biological
and environmental materials. The method was almost insensitive to matrix effects and was assessed to be promising for nondestructive
multielement determination of the materials of wide variety, giving good reproducible results for 20 or more elements. 相似文献
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