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21.
Eiichi Masumoto Hiroshi Maruoka Fumi Okabe Sho Nishida Yuki Yoshimura Toshihiro Fujioka Kenji Yamagata 《Journal of heterocyclic chemistry》2011,48(1):96-104
Dihydropyridazinones 4a , 4b , N‐substituted dihydropyrazoles 5b , 5c , 5d , and O‐substituted pyrazoles 6a , 6b , 6c , 6d have been synthesized starting from spirocyclopropanepyrazole derivative 2 . Treatment of 2 with α‐chloro esters, e.g., methyl chloroacetate, ethyl chloroacetate, isopropyl chloroacetate, and tert‐butyl chloroacetate, in potassium carbonate/sodium iodide system caused ring opening and subsequent C‐ or N‐attack nucleophilic substitution to give the corresponding dihydropyridazinones 4a , 4b and N‐substituted dihydropyrazoles 5b , 5c , 5d . On the other hand, in the absence of sodium iodide, O‐substituted pyrazoles 6a , 6b , 6c , 6d were obtained from 2 via an O‐attack nucleophilic substitution. J. Heterocyclic Chem., 2011. 相似文献
22.
A. Yoshioka K. Nomura M. Takeya K. Shimura K. Masumoto M. Yagi 《Journal of Radioanalytical and Nuclear Chemistry》1988,122(1):175-182
Determination of carbon in copper has been studied by photon activation analysis using 30 MeV bremsstrahlung. Chemical separation of carbon as CO2 was performed by the combustion method in a high flow rate of oxygen stream. It has been demonstrated that the trace amount of carbon in copper can be determined accurately and precisely, and that the detection limit is 0.02 g. 相似文献
23.
Yasuaki Masumoto Haruo Kunitomo Shigeo Shionoya Hiro Munekata Hiroshi Kukimoto 《Solid State Communications》1984,51(4):209-212
Photoluminescence of aSixC1?x:H (x~0.2) is studied with a particular interest on the localization of carriers. Taking the polarization memory of luminescence as a probe, we clarify the localized character of photo-generated carriers as functions of excitation photon energy, emitted photon energy, temperature and time. The picosecond time-resolved measurement of the polarization memory is shown useful to study dynamical relaxation processes of carriers in disordered systems. 相似文献
24.
Pico-second time-resolved measurements of the two-photon resonant Raman scattering via excitonic molecules in CuCl were carried out for the first time. The Raman scattering leaving transverse excitons decays as fast as the laser light. When the energy of the incident light falls in the vicinity of the two-photon resonant absorption, both Raman and luminescence lines are simultaneously observed. In case of just resonant excitation, the transient response indicates that the secondary radiation can be decomposed into the Raman and the luminescence components as regards its temporal and spectral behavior. 相似文献
25.
The temperature dependence of magnetization and magnetic susceptibility and hydrostatic pressure effect on the Surie temperature (dTc/dP) are measured for (Co1-xMnx)2B (0?x?0.4) amorphous alloys and the results are compared with those of crystalline compounds with the same composition. The Curie temperature decreases linearly with an increasing Mn content but magnetization shows a maximum around x=0.15. The reciprocal magnetic susceptibility of all the prepared alloys obeys the Curie-Weiss law above Tc. The magnitude of the negative value of dTc/dP decreases linearly with increasing x from about 1.1 K/kbar (x=0) to zero (x=0.4), the composition dependence of which is opposite to that of the crystalline compound. The composition dependence of the average magnetic moment per transition metal atom and the Curie temperature and dTc/dP are analysed on the basis of the local environment and the pair order interaction mode, respectively. 相似文献
26.
Kazuaki Fukamichi Hidetoshi Hiroyoshi Michio Kikuchi Tsuyoshi Masumoto 《Journal of magnetism and magnetic materials》1979,10(2-3):294-299
The thermal expansion and magnetic properties of Fe-B and Fe-P amorphous alloys prepared from melts have been investigated. These amorphous alloys show distinct Invar characteristics. heir magnetic properties are also very similar to those of Fe-Ni crystalline Invar alloys; that is, the high-field susceptability and forced-volume magnetostriction are remarkably large, the magnetic moment per Fe atom does not increase linearly, the Curie temperature decreases with a decrease in concentration of B or P, and their reduced their magnetization curves are much flatter than those of crystalline pure Fe. 相似文献
27.
Measurements of magnetization, electrical resistivity, thermal expansion and differential thermal change were made on amorphous Fe100-xBx (9 ≦ X ≦ 21) alloys prepared by rapid quenching from the liquid state.With decreasing boron content in the alloys, the Curie temperature falls remarkably, while the magnetic moment increases sluggishly. The thermal expansion curves exhibit the invar characteristics below the Curie temperature due to a large positive spontaneous volume magnetostriction, and the reduced magnetization curves decrease much more rapidly with increasing temperature than those of other ferromagnetic amorphous alloys. 相似文献
28.
Masaaki Hori Harushi Mori Shigeki Aoki Osamu Abe Tomohiko Masumoto Satoshi Kunimatsu Kuni Ohtomo Hiroyuki Kabasawa Nobuyuki Shiraga Tsutomu Araki 《Magnetic resonance imaging》2010
Object
Although three-dimensional (3D), high-spatial resolution susceptibility-weighted imaging (SWI) appears to be valuable in the evaluation of central nervous system gliomas, several evaluation methods are proposed in the literature. The purpose of this study was to evaluate the use of 3D SWI for grading intracranial gliomas with various analysis methods.Materials and Methods
Twenty-three patients suspected of having gliomas participated in this study. SWI was performed in addition to conventional MR sequences. In 15 cases, post-gadolinium enhanced SWI was also obtained. Imaging evaluation criteria were conventional grade, hypointensity ratio in the tumor-dominant structure of hypointensity on SWI (hemorrhage or vascular structure) and presence of abnormal enhancement surrounding the tumor.Results
Mean grading scores of conventional grade showed no statistically significant difference among WHO grades. Mean grading scores of hypointensity ratios in the tumor were higher for WHO Grades 3 and 4 than for lower grade tumors (P=.05, Mann–Whitney U test). Hemorrhagic foci were more frequently seen in the higher grade tumor. Post-contrast susceptibility-weighted images of five of 11 WHO Grade 3 and 4 cases showed bright enhancement surrounding the tumor, suggesting a breakdown of the blood–brain barrier.Conclusions
SWI at 3 T may be a useful method to analyze the structural characteristics of gliomas and to evaluate pathology in vivo. Assessment of hypointensity ratios in the glioma was the most preferable method in grading glioma. However, more studies, specifically concerning a suitable method for image analysis, are needed to establish SWI at 3 T as a useful tool in clinical routine. 相似文献29.
Prof. Isao Fujii Dr. Makoto Hashimoto Kaori Konishi Akiko Unezawa Haruka Sakuraba Kenta Suzuki Harue Tsushima Miho Iwasaki Satsuki Yoshida Akane Kudo Rina Fujita Aika Hichiwa Koharu Saito Dr. Takashi Asano Dr. Jun Ishikawa Dr. Daigo Wakana Dr. Yukihiro Goda Ayumi Watanabe Mamoru Watanabe Yui Masumoto Dr. Junichiro Kanazawa Dr. Hajime Sato Prof. Masanobu Uchiyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(22):8542-8548
Shimalactones A and B are neuritogenic polyketides possessing characteristic oxabicyclo[2.2.1]heptane and bicyclo[4.2.0]octadiene ring systems that are produced by the marine fungus Emericella variecolor GF10. We identified a candidate biosynthetic gene cluster and conducted heterologous expression analysis. Expression of ShmA polyketide synthase in Aspergillus oryzae resulted in the production of preshimalactone. Aspergillus oryzae and Saccharomyces cerevisiae transformants expressing ShmA and ShmB produced shimalactones A and B, thus suggesting that the double bicyclo-ring formation reactions proceed non-enzymatically from preshimalactone epoxide. DFT calculations strongly support the idea that oxabicyclo-ring formation and 8π-6π electrocyclization proceed spontaneously after opening of the preshimalactone epoxide ring through protonation. We confirmed the formation of preshimalactone epoxide in vitro, followed by its non-enzymatic conversion to shimalactones in the dark. 相似文献