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91.
The first total synthesis of a cyclic depsipeptide possessing the 3-amino-6-hydroxy-2-piperidone (Ahp) unit was successfully achieved in a convergent manner by the oxidative construction of the Ahp unit at the later stage of the synthesis. This synthetic work provides data indicating that the structure of the target Ahp-depsipeptide, micropeptin T-20, should be re-examined. 相似文献
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93.
Increasing (or decreasing) the convergence angle can shrink (or expand) the perceived size of an object without changing its retinal size. The present report deals with the question of whether such a change in perceived size affects visual acuity. We investigated the effects of perceived size on the legibility of letters, using a telestereoscope which can control the observer’s convergence angle while keeping the size of the retinal image constant. We demonstrated that letters do become more legible (illegible) as perceived size expands (shrinks), although their retinal size stays constant. Then, we measured the ‘threshold’ size of the convergence angle, at which letters became legible from illegible, for several retinal sizes (0.1 to 0.2 deg) of letters. The result shows that the threshold decreases as the retinal size of letters decreases, so that the minimum retinal size of legible letters depends on the convergence angle. This implicates contributions from the size perception at higher levels of the visual system to the determination of visual acuity. 相似文献
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95.
Mitiko Miura Hitoshi Arimori Hiromu Murata Akiko Kida Kazuaki Iishi 《Journal of Physics and Chemistry of Solids》1983,44(7):627-631
The effect of the electronic extension on the electrostatic potential was first taken into account functionally by Birman. We have applied his model to the lattice dynamics of CaO, where the degree of the electronic extension w was defined and determined with the use of the electronic charge density distribution obtained from analysis of X-ray data. Our treatment shown here not only gives a physically meaningful model including the feature of the electronic extension, but also involves essentially the same very simple process as the conventional point-charge model but with fewer adjustable parameters. Good reproduction of calculated phonon dispersion curves was obtained by taking into account the electronic extension, although the degree of the electronic extension, w, used to fit the curve was a little larger than that derived from the observed data owing to the first rough approximation for the potential energy arising from the electronic extension. 相似文献
96.
Reizo Kato Hayao Kobayashi Takehiko Mori Akiko Kobayashi Yukiyoshi Sasaki 《Solid State Communications》1985,55(5):387-392
In the crystals of the cation radical salts based on the organic donor BMDT-TTF, the charge separation is observed. This comes from (1) nonequivalency of the site potential and (2) the long range electron-electron interaction, which are related to the two-dimensional nature of the molecular arrangement. The effects of the charge separation on the elctronic structure are discussed. 相似文献
97.
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99.
Keietsu Tamagake Yoshiaki Hamada Jun Yamaguchi Akiko Y. Hirakawa Masamichi Tsuboi 《Journal of Molecular Spectroscopy》1974,49(2):232-240
Infrared absorption spectrum of NH2OH has been observed in its gaseous state, and the fine structures of the bands at 386 and 751 cm?1 assignable, respectively, to the fundamental and overtone of the torsional vibration of this molecule have been examined. Band center frequencies for the n = 1 ← 0, 2 ← 1, 3 ← 2, 2 ← 0, and 3 ← 1 transitions (where n is the vibrational quantum number of the torsional oscillation) have been determined to be 386.2, 365.1, 346.3, 751.2, and 711.3 cm?1, respectively. On the basis of these data, a discussion is given on the internal-rotation potential function. 相似文献
100.