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Fuyuki Ito Nobuaki Tanaka Akio Katsuki Akikazu Kakehi Tsuneo Fujii 《Research on Chemical Intermediates》2004,30(3):331-336
Three types of flavylium salts (FVs, yellow, green and red) have been synthesized and the colors depended on recrystallization conditions. The existence of these color states was confirmed by diffuse reflectance spectra. The spectra were almost the same as the absorption spectra in ethanol solution. The molecular state of FVs in crystals will be the same as that in solutions. The crystal colors of the FVs are controlled by the recrystallization conditions. 相似文献
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R. L. Ingraham 《General Relativity and Gravitation》1997,29(1):117-140
The theory of gravitational waves in matter is given. This covers the questions of constitutive relation, number of independent polarizations, index of refraction, reflection and refraction at an interface, etc. The theory parallels the familiar optics of electromagnetic waves in material media, but there are some striking differences. The use of the Campbell-Morgan formalism in which the gauge-invariant tidal force dyads E and B rather than the gauge-dependent metric perturbations are the unknowns is essential. The main justification of the theory at the moment is as a theoretical exercise worth doing. The assumption: size L of the medium gravitational wave length (infinite medium) rules out application to the already well-understood detection problem, but there may be an application to gravitational wave propagation through molecular gas clouds of galactic or inter-galactic size. 相似文献
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Gianotti E Dellarocca V Peña M L Rey F Corma A Coluccia S Marchese L 《Research on Chemical Intermediates》2004,30(9):871-877
Mesoporous Ti-MCM-48 materials were synthesised with titanium loading varying from 1 to 3 wt% TiO2. Post-synthesis silylation treatment of the silica surface led to the transformation of silanols, (SiO)3SiOH, into (SiO)3SiOSi(CH3)3 groups, which were identified by means of 29Si-MAS-NMR and diffuse reflectance (DR) Nir spectroscopy. DR UV-Vis spectroscopy was performed to clarify the nature of Ti(IV) sites present in these samples. The UV-Vis spectra show a band at 210 nm with a shoulder at 230 nm, typically assigned to oxygen to tetrahedral Ti(IV) (LMCT) electronic transitions. Interestingly, the component at 230 nm, which was assigned to an electronic transition that involves titanium sites linked to OH groups (named as titanols), strongly decreased upon the silylation treatment. This is a clear evidence that, beside silanols, also titanols were silylated, leading to (SiO)3TiOSi(CH3)3 sites. This fact can be taken as an unequivocal assignment of the shoulder at 230 nm due to oxygen to tetrahedral Ti(IV) electronic transition related to titanol species. 相似文献
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