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51.
Stereoisomeric bicyclic tert-alcohols afforded identical ring-expansion products via cationic anti-Markovnikov rearrangement from perpendicular tert-cations into identical six-membered ring secondary cations by the treatment with TiCl4. These results provide evidence that the reaction takes place by the cationic stepwise mechanism. [reaction: see text] 相似文献
52.
Hiyoshizo Kotsuki Yoshikatsu Ichikawa Mitsuhiro Iwasaki Masanori Kataoka Hitoshi Nishizawa 《高压研究》2013,33(1-3):107-118
Abstract A variety of cyclic and acyclic ethers are efficiently reacted with acyl chlorides or acyl bromides to afford the ether-cleaved compounds of ω-chloro-or ω-bromoesters under high pressure conditions. The reactivity of ethers is found to be roughly depend on the basicity of the ether oxygen atom. 相似文献
53.
Yuichiro Nishizawa Shusuke Matsui Kenji Urayama Takuma Kureha Mitsuhiro Shibayama Takayuki Uchihashi Daisuke Suzuki 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(26):8901-8905
Despite the tremendous efforts devoted to the structural analysis of hydrogel microspheres (microgels), many details of their structures remain unclear. Reported in this study is that thermoresponsive poly(N‐isopropyl acrylamide) (pNIPAm)‐based microgels exhibit not only the widely accepted core–shell structures, but also inhomogeneous decanano‐sized non‐thermoresponsive spherical domains within their dense cores, which was revealed by temperature‐controlled high‐speed atomic force microscopy (TC‐HS‐AFM). Based on a series of experiments, it is concluded that the non‐thermoresponsive domains are characteristic for pNIPAm microgels synthesized by precipitation polymerization, and plausible structures for microgels prepared by other polymerization techniques are proposed. 相似文献
54.
Jun-ichi Nishizawa Tetsuo Sasaki Ken Suto Masahiko Ito Takashi Yoshida Tadao Tanabe 《International Journal of Infrared and Millimeter Waves》2008,29(3):291-297
We developed high-resolution GaP THz signal generator using Cr:Forsterite lasers with gratings as both a pump and a signal
beam for difference-frequency generation. A line width of less than 500 MHz and a wide tunable frequency range (0.6–6.2 THz)
provide sufficient resolution for measuring materials with sharp absorption bands using the generator as the light source
for a THz spectrometer. This is suitable for materials such as gases or solid samples at low temperatures. We demonstrated
the detection of defects in organic materials, as they appear as slight deviations in the absorption frequency in the THz
region. 相似文献
55.
Yamamoto H Pandey G Asai Y Nakano M Kinoshita A Namba K Imagawa H Nishizawa M 《Organic letters》2007,9(20):4029-4032
A novel catalytic activation of the leaving group in the S(N)2 reaction is achieved as an extension of our mercuric triflate-catalyzed reactions. Derivatives of anilinoethyl 4-pentynoate reacted smoothly with catalytic amounts of Hg(OTf)(2) to give indoline derivatives in excellent yield with efficient catalytic turnovers under very mild conditions. The reaction of optically pure secondary alcohol derivatives resulted in inversion of stereochemistry, which is a definitive feature of the S(N)2 reaction. The procedure is applicable for benzoazepine synthesis. 相似文献
56.
Keiko Ohkura Hidekazu Nishizawa Takashi Obi Akira Hasegawa Masahiro Yamaguchi Nagaaki Ohyama 《Optical Review》2000,7(3):193-198
In the analysis of a medical image database aimed at formulating useful knowledge for image diagnosis requires an unsupervised image processing technique without preconceived knowledge. In this paper, we propose a method for unsupervised image segmentation, which is suitable for finding the features contained in an image. A small region around each pixel is considered as a pattern vector, and the set of pattern vectors acquired from the whole image is classified using the hierarchical clustering technique. In hierarchical clustering, the classification of pattern vectors is divided into two clusters at each node according to the statistical criterion based on the entropy in thermodynamics. Results of the test image generated by the Markov random field (MRF) model and real medical images photomicrographs of a colon tumor are shown. 相似文献
57.
The effect of stoichiometry on various features of III-V compounds are investigated. It is shown experimentally that the optimum vapor pressure of V elements minimizes the deviation from the stoichiometric composition. Vapor pressure control technology is applied not only to the liquid phase epitaxy and bulk crystal growth but also to the surface reaction in molecular layer epitaxy. The surface reaction and kinetic phenomena of GaAs mono-molecular layer growth by using chemical adsorption of Ga(CH3)3 (trimethyl gallium: TMG) and arsine (AsH3) was investigated. The growth feature was strongly influenced by the surface stoichiometry of arsenic during growth. For example, the diffusion of the doped impurity is affected by the AsH3 amount of supply, the diffusion was prevented by controlling the stoichiometry. The control of stoichiometry was examined systematically and was applied for the device fabrication such as ballistic transistor. 相似文献
58.
Determination of molecular weight of native proteins by polyacrylamide gradient gel electrophoresis 总被引:1,自引:0,他引:1
An improved method for the estimation of molecular weights of native proteins by polyacrylamide gel electrophoresis, in 9 cm x 9 cm x 0.05 mm 4-20% T fabric reinforced gradient gels, is described. Plotting the logarithm of the relative mobilities of proteins versus gel concentrations produces lines whose slopes are related to molecular weights. 相似文献
59.
This paper describes a software package for a personal computer which deals with storage records of radioactive wastes; the software keeps the records of purchase and use of radioisotopes and makes the inventory records of radioactive wastes. The records for the cargo booking of the wastes for the Japanese Radioisotope Association can be prepared by this software package. 相似文献
60.
Takeshi Miki Kaori Nishizawa Eiji Watanabe Hiroshi Taoda 《Research on Chemical Intermediates》2009,35(3):257-262
To obtain porous TiO2 film, the precursor sol was prepared by hydrolysis of Ti isopropoxide and then complexed with trehalose dihydrate. The porous
TiO2 film was fabricated by the dip-coating technique on glass substrates using this solution. The TiO2 film was calcined at 500 °C. The maximum thickness of the film from one-run dip-coating was ca. 740 nm. The film was composed
of nanosized particle and pores. The porosity of the TiO2 film was increased by addition of trehalose dihydrate to the sol. The porous TiO2 films were calcined at different temperatures. The effects of calcination temperature on the microstructure of the porous
TiO2 film were investigated. The porous film prepared from sol containing trehalose still kept the porous structure after calcination
at 950 °C. The phase transition temperature of the film from anatase to rutile was shifted from 650 to 700 °C by addition
of trehalose to the sol. 相似文献