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161.
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163.
The reaction of 4-pyridone or 4-quinolone with methyl or benzyl isocyanate in the presence of triethylamine or 1,1,3,3-tetramethylguanidine base gave the corresponding 1,3,5-triazine derivative (e. g., II) in a good yield via stepwise additions.  相似文献   
164.
From commercially available quinoes, quinone epoxides and 5,6-epoxy-4-hydroxy-2-cyclohexenones were easily prepared through the retro-Diels-Alder reactions under rather mild conditions.  相似文献   
165.
A quartz crystal microbalance (QCM) has been used for in situ corrosion studies of magnetron-sputtered Co-Cr-Mo and Ni-Cr-Mo alloys, which are of great importance in various technical and medical applications. The corrosion monitoring has been performed in an oxygen-containing atmosphere and in NaCl solution. The alloys were deposited on quartz substrates by means of DC magnetron sputtering. X-ray photoelectron spectroscopy analysis showed that the composition of the deposits was similar to that of the magnetron-sputtering targets. X-ray diffraction revealed an amorphous structure of the sputtered deposits, while the casting alloys had a crystalline structure. The polarization resistance of sputtered alloys in NaCl solution was higher than the activity of conventional alloys, which implied a superior corrosion resistance of the sputtered deposits. Corrosion was initiated by supplying oxygen gas into a wet argon atmosphere and the QCM detected corrosion with nanogram resolution as the increase in mass. Corrosion currents were calculated from the mass versus time curves. The QCM appeared to be an effective tool for corrosive characterization of sputtered alloys in gaseous environments. A corrosion current calculation in solution was complicated by metal transfer to the liquid phase. Electronic Publication  相似文献   
166.
Absolute configuration of (?)-solanapyrone A was confirmed by the application of CD exciton chirality method to the dibenzoate derivative.  相似文献   
167.
Mass spectra of doubly charged mercury clusters (m/z=30-1065) were investigated by secondary ion mass spectrometry. Positively charged ions were generated from an amalgam of mercury and silver by bombardment with a xenon ion beam and mass analysis by a grand-scale sector type mass spectrometer. Hg n 2+, n=1-10 and Hg n +, n =1- 5 were observed. Some doubly charged mercury clusters, (Hg n 2+) survived at least for 0.1 ms.  相似文献   
168.
169.
By means of powder X-ray diffraction, powder neutron diffraction and transmission electron microscopy (TEM), we determined the crystal structures of a metal-ordered manganite YBaMn2O6 which undergoes successive phase transitions. A high-temperature metallic phase (Tc1=520 K<T) crystallizes in a triclinic P1 with the following unit cell: Z=2, a=5.4948(15) Å, b=5.4920(14) Å, c=7.7174(4) Å, α=89.804(20)°, β=90.173(20)°, γ=91.160(4)°. The MnO6 octahedral tilting is approximately written as a0bc, leading to a significant structural anisotropy within the ab plane. The structure for Tc2<T<Tc1 is a monoclinic P2 (Z=2, a=5.5181(4) Å, b=5.5142(4) Å, c=7.6443(3) Å, β=90.267(4)°) with an abc tilting. The structural features suggest a dx2y2 orbital ordering (OO). Below Tc2=480 K, crystallographically inequivalent two octahedra show distinct volume difference, due to the Mn3+/Mn4+ charge ordering. The TEM study furthermore revealed a unique d3x2r2/d3y2r2 OO with a modified CE structure. It was found that the obtained crystal structures are strongly correlated to the unusual physical properties. In particular, the extremely high temperature at which charge degree of freedom freezes, Tc2, should be caused by the absence of the structural disorder and by heavily distorted MnO6 octahedra.  相似文献   
170.
The reaction of pyridinium or isoquinolinium N-ylides with methoxy-substituted ethylenes gave the corresponding indolizine and pyrrolo[2,1-a]isoquinoline derivatives bearing acetyl, aroyl, cyano, ester group at the 1-position in one step. Pyrazolo[1,5-a]pyridine, pyrazolo[1,5-a]quinoline, and pyrazolo[5,1-a]isoquinolines were also synthesized in good yields from the corresponding aromatic N-imines and methoxyethylene derivatives.  相似文献   
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