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761.
A new quassinoid, ailantinol H, was isolated from the aerial parts of Ailanthus altissima. The structure was elucidated based on spectral evidence. 相似文献
762.
Gotovac S Hattori Y Noguchi D Miyamoto J Kanamaru M Utsumi S Kanoh H Kaneko K 《The journal of physical chemistry. B》2006,110(33):16219-16224
Phenanthrene was adsorbed from ethanol solution to the surface of single wall carbon nanotubes, which were previously physically and chemically characterized. Different anionic surfactants were added in the solutions to enhance the phenanthrene solubility and apparently have also improved the dispersion of two respective nanotube samples used. Adsorbed amount was determined through the concentration difference measured by UV-visible spectrophotometry. Results suggest that adsorption of phenanthrene is extremely improved in the case of nanotube purified with higher quality. These findings were confirmed by X-ray photoelectron spectroscopy. The influence of the surfactant on the adsorption kinetics of phenanthrene is suggested to be significant as well. 相似文献
763.
Nagao Y Miyamoto S Miyamoto M Takeshige H Hayashi K Sano S Shiro M Yamaguchi K Sei Y 《Journal of the American Chemical Society》2006,128(30):9722-9729
New chiral sulfoxides (R(S),S)-3, (S(S),S)-3, (R(S),S)-4, and (S(S),S)-4 and known chiral sulfoxides (R(S))-5, (R(S))-6, and (R(S))-7 were synthesized, and the stereochemistry of the new sulfoxides (R(S),S)-3 and (R(S),S)-4 was determined by X-ray crystallographic analysis. In their crystallographic structures, the intramolecular nonbonded S...O close contacts were recognized. Analyses of several sulfoxide complexes including rac-11 with N,N-dimethylacetamide (DMAC) or N-methyl-2-pyrrolidone (NMP) in a MeOH solution utilizing cold-spray ionization mass spectrometry provided, for the first time, direct information for intermolecular nonbonded S...O interactions between sulfoxides and amide (or lactam) in a solution. Highly diastereoselective and enantioselective Pummerer reactions based on the concept of intermolecular and intramolecular nonbonded S...O interactions were performed by treatment of several chiral sulfoxides (R(S), S)-3, (S(S), S)-3, (R(S), S)-4, (S(S), S)-4, (R(S))-5, (R(S))-6, and (R(S))-7 with acetic anhydride and trimethylsilyl triflate (TMSOTf) in DMAC, NMP, N,N-dimethylformamide, and N-formylpiperidine. Mechanistic studies on these facile stereoselective Pummerer reactions revealed the necessity for the amide/TMSOTf complex, such as 26 or 27, to be an efficient activation reagent for Ac(2)O and a trapping reagent for the released acetate ion, and that DMAC and NMP had a positive effect on this highly stereoselective chiral transfer reaction. 相似文献
764.
Given a finite set of 2-dimensional points P⊆R2 and a positive real d, a unit disk graph, denoted by (P,d), is an undirected graph with vertex set P such that two vertices are adjacent if and only if the Euclidean distance between the pair is less than or equal to d. Given a pair of non-negative integers m and n, P(m,n) denotes a subset of 2-dimensional triangular lattice points defined by where . Let Tm,n(d) be a unit disk graph defined on a vertex set P(m,n) and a positive real d. Let be the kth power of Tm,n(1).In this paper, we show necessary and sufficient conditions that [ is perfect] and/or [ is perfect], respectively. These conditions imply polynomial time approximation algorithms for multicoloring (Tm,n(d),w) and . 相似文献
765.
A simple interferometric polarimeter with an integrated calibration scheme is proposed for accurate and fast mapping of the state of polarization (SOP). Conventional single-shot polarimeters that detect the amplitude and phase of orthogonally polarized field components by interferometry using Fourier fringe analysis suffers from errors caused by the imperfect reference beam and ambiguity in the spatial carrier frequency in the fringe pattern. In the proposed system, the integrated calibration scheme eliminates those error sources and enables accurate measurement of SOP without prior knowledge of the reference beam and the spatial carrier frequency. 相似文献
766.
Y. Miyamoto A. Kajikawa J. H. Zaidi T. Nakanishi K. Sakamoto 《Journal of Radioanalytical and Nuclear Chemistry》2000,243(3):747-765
INAA, RNAA and IPAA were employed to determine upto 26 trace elements in 32 spices of 18 species and 16 pulses of 8 species originating from different localities. The results are compared with each other and the reported values. The concentration levels, their variations and the correlations of the analysed elements in these samples were also investigated. The variability of concentrations among the samples of different origin are small. The levels and ranges of the concentration are highly variable which are found to be characteristic to each element. High elemental correlations exist in some sets of elements, reflecting characteristics of chemical nature of elements and/or of their physiological functions. 相似文献
767.
Y. Miyamoto H. Haba A. Kajikawa K. Masumoto T. Nakanishi K. Sakamoto 《Journal of Radioanalytical and Nuclear Chemistry》1999,240(1):165-175
The effect of following interferences was quantitatively assessed in terms of interference factor by irradiating samples together
with highly pure reagents at two reactor sites of diferent neutron spectra and fluxes for neutron activation analysis (NAA)
and an electron LINAC for photon activation analysis (PAA). The interfering reactions studied are 91) fast neutron-induced
reactions, (2) uranium fission (3) (n,γ) reactions of other target elements in NAA, and (4) reactions induced by secondary
neutrons in PAA. Corrections for these interferences were successfully applied to the activation analysis of some geological
reference rock samples and biological samples. 相似文献
768.
Mohamed Elbandy Tomofumi Miyamoto Clment Delaude Marie‐Aleth Lacaille‐Dubois 《Helvetica chimica acta》2002,85(9):2721-2728
Five new triterpene saponins 1 – 5 were isolated from the roots of Muraltia ononidifolia E. Mey along with the two known saponins 3‐O‐[O‐β‐D ‐glucopyranosyl‐(1→2)‐β‐D ‐glucopyranosyl]medicagenic acid 28‐[O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl] ester and 3‐O‐(β‐D ‐glucopyranosyl)medicagenic acid 28‐[O‐α‐L ‐rhamnopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl] ester (medicagenic acid=(4α,2β,3β)‐2,3‐dihydroxyolean‐12‐ene‐23,28‐dioic acid). Their structures were elucidated mainly by spectroscopic experiments, including 2D‐NMR techniques, as 3‐O‐(β‐D ‐glucopyranosyl)medicagenic acid 28‐[O‐β‐ D ‐apiofuranosyl‐(1→3)‐O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl] ester ( 1 ), 3‐O‐(β‐D ‐glucopyranosyl)medicagenic acid 28‐{[O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐[β‐D ‐apiofuranosyl‐(1→3)]‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl} ester ( 2 ), 3‐O‐[O‐β‐D ‐glucopyranosyl‐(1→2)‐β‐D ‐glucopyranosyl]medicagenic acid 28‐{O‐β‐D ‐xylopyranosyl‐(1→4)‐O‐[β‐D ‐apiofuranosyl‐(1→3)]‐O‐α‐L ‐rhamnopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl} ester ( 3 ), 3‐O‐[O‐β‐D ‐glucopyranosyl‐(1→2)‐β‐D ‐glucopyranosyl]medicagenic acid 28‐[O‐α‐L ‐rhamnopyranosyl‐(1→2)‐α‐L ‐arabinopyranosyl] ester ( 4 ), and 3‐O‐[O‐β‐D ‐glucopyranosyl‐(1→2)‐β‐D ‐glucopyranosyl]medicagenic acid ( 5 ). 相似文献
769.
Satoko Wada Hidetaka Yuge Takeshi Ken Miyamoto 《Acta Crystallographica. Section C, Structural Chemistry》2003,59(9):m369-m370
The stable title trifluoromethyl‐substituted carbenyl metalloporphyrin, [Ru(C15H8F6)(C48H36N4)], has a five‐coordinate Ru atom which is displaced from the porphyrin N4 plane towards the axial carbene ligand by 0.230 (3) Å. The Ru—C(carbene) bond coincides with a crystallographic twofold axis and its length of 1.841 (6) Å is notably shorter than the value of 1.868 (3) Å in the pyridine adduct. 相似文献
770.