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101.
Yulu Jiang Taro Ozaki Mei Harada Tadachika Miyasaka Hajime Sato Kazunori Miyamoto Junichiro Kanazawa Chengwei Liu Jun‐ichi Maruyama Masaatsu Adachi Atsuo Nakazaki Toshio Nishikawa Masanobu Uchiyama Atsushi Minami Hideaki Oikawa 《Angewandte Chemie (International ed. in English)》2020,59(41):17996-18002
Lolitrems are tremorgenic indole diterpenes that exhibit a unique 5/6 bicyclic system of the indole moiety. Although genetic analysis has indicated that the prenyltransferase LtmE and the cytochrome P450 LtmJ are involved in the construction of this unique structure, the detailed mechanism remains to be elucidated. Herein, we report the reconstitution of the biosynthetic pathway for lolitrems employing a recently established genome‐editing technique for the expression host Aspergillus oryzae. Heterologous expression and bioconversion of the various intermediates revealed that LtmJ catalyzes multistep oxidation to furnish the lolitrem core. We also isolated the key reaction intermediate with an epoxyalcohol moiety. This observation allowed us to establish the mechanism of radical‐induced cyclization, which was firmly supported by density functional theory calculations and a model experiment with a synthetic analogue. 相似文献
102.
Seiichi Miyanaga Hajime Yasuda Akio Hiwara Akira Nakumura Hiroshi Sakai 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(9-11):1347-1361
New types of air-stable metal-carbon composites which contain ultrafine metal particles (Fe, Co, Ni, Pd, Pt, Rh, Cu, etc.) uniformly dispersed in a carbon matrix were obtained by pyrolysis of a variety of soluble organometallic polymers, macromolecular-metal complexes, and blends of coal pitch with metal complexes at 400-1400°C in N2. Some of their unique physical properties and functions are noted. 相似文献
103.
Hajime Asahi Shigehiko Hasegawa Yi-Kai Zhou Shuichi Emura 《Journal of luminescence》2012,132(12):3136-3140
InGaGdN layers and InGaGdN/GaN superlattice (SL) structures were grown by plasma-assisted molecular beam epitaxy. InGaGdN layers exhibited photoluminescence emission at room temperature and its peak wavelength was red-shifted with the increase of In composition. Clear hysteresis and saturation were observed in the magnetization versus magnetic field curves at room temperature for the InGaGdN layers. Si co-doping into InGaGdN layers increased the electron carrier concentration and enhanced the magnetization. In the InGaGdN/GaN SL samples, enhanced magnetization was also observed. Si doping into wide bandgap GaN layers in these SL structures further increased the magnetization, where InGaGdN layers were not doped with Si. All these results can be understood with the carrier-mediated ferromagnetism. 相似文献
104.
Back Cover: Understanding the Origins of Nucleophilic Hydride Reactivity of a Sodium Hydride–Iodide Composite (Chem. Eur. J. 21/2016) 下载免费PDF全文
105.
We study the size dependence of the nonlinear response of weakly confined excitons for the size region beyond the long wavelength approximation regime. The observed degenerate-four-wave mixing signal of GaAs thin layers exhibits an anomalous size dependence, where the signal is resonantly enhanced at a particular thickness region. The theoretical analysis elucidates that this enhancement is due to the size-resonant enhancement of the internal field with a spatial structure relevant to the nondipole-type excitonic state. These results establish the formerly proposed new type of size dependence of nonlinear response due to the nonlocality induced double resonance. 相似文献
106.
107.
Masahiro Ueda Sanae Mizuno Akio Matsumura Fumio Tohjyo 《Optics and Lasers in Engineering》1996,24(4):339-350
An optical method for measuring the thickness of heterogeneous materials has been studied. The method is based on the light attenuation theory. A complete system has been constructed in order to demonstrate the applicability of the present method for industrial use. The experimental set-up consists of semiconductor lasers, focusing lenses, photo-diodes serving as a power meter and a personal computer with an A/D converter for data acquisition. Averaging of numerous measurements is required in the present method because the heterogeneous cell structure of the foam material yields large fluctuations in transmitted light levels. The fluctuations can be reduced to below 1% of the transmitted light power by 80 times averaging. The error of the measurement is considered to be a few tens of micrometers in thickness. The present system is capable of sampling data at a rate of 400 Hz and has been successfully applied to a manufacturing process. 相似文献
108.
Hiroshi Onoue Masayuki Narisada Shoichiro Uyeo Hiromu Matsumura Kyo Okada Toshisada Yano Wataru Nagata 《Tetrahedron letters》1979,20(40):3867-3870
Allylazetidinones , , prepared by coupling of allylcoppers with chloroazetidinones , , were converted into carbapenem esters , – using an Emmons-Horner reaction to introduce the 6-side chain and an intramolecular Wittig reaction to form the carbapenem ring system. 相似文献
109.
Munetaka Nakata Masaaki Sugie Harutoshi Takeo Chi Matsumura Tsutomu Fukuyama Kozo Kuchitsu 《Journal of Molecular Spectroscopy》1981,86(1):241-249
The microwave spectra of four isotopic species of dichlorine monoxide (OCl2) have been observed, and the rotational constants have been obtained. The rm structure for each isotopic species has been determined by Watson's method. The equilibrium structure has been estimated by taking proper averages of rm structures to be and ∠eClOCl = 110.886(6)°. The general applicability and the merit of the present method for estimating the equilibrium structure are pointed out. 相似文献
110.