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<正>Two new eudesmane derivatives were isolated from the leaves and flowers of Verbesina virginica,along with the known 6-O-β-E -p-coumaroyl-4α-hydroxyeudesmane(1).Their structures were determined as 6-O-β-Z-p-coumaroyl-4α-hydroxyeudesmane(2) and 6-O-α-E-p-coumaroyl-1β-4α-dihydroxyeudesmane(3) by spectroscopic methods. 相似文献
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CM Thaker S Rayaprol Krushna Mavani DS Rana MS Sahasrabudhe SI Patil DG Kuberkar 《Pramana》2002,58(5-6):1035-1039
The effect of simultaneous substitution of a fluctuating cation and a divalent cation in LaMnO3 perovskite modifies the properties of the material to exhibit large valence colossal magnetoresistance (CMR) effect. A good
example of these properties is (La1−2x
Pr
x
Ca
x
)MnO3 (LPCMO) type CMR material. In this communication it is reported that, with the increase in x (for x=0.1, 0.15, 0.2), the T
c varies between 100 and 120 K with improvisation in metal-insulator transition. Interestingly, resistance increases with x from few hundred ohms to few kilo ohms with corresponding decrease in the unit cell volume. The results of the studies using
X-ray diffraction (XRD), electrical resistivity, magnetoresistance and ac susceptibility measurements on LPCMO samples for
understanding the structural, transport and magnetic properties are discussed in detail. 相似文献
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John W.Grove 《数学物理学报(B辑英文版)》2010,30(2):563-594
This article describes mathematical models for phase separated mixtures of materials that are in pressure and velocity equilibrium but not necessarily temperature equilibrium. General conditions for constitutive models for such mixtures that exhibit a single mixture sound speed are discussed and specific examples are described. 相似文献
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A method for measuring contact pressures based on the measurement of irreversible changes in a surface microrelief by the speckle photography technique is presented. The analytic dependence between the change in the contrast of the carrying Young’s fringes and the relative area of change in the microrelief is considered. An example of a contact interaction between a cylinder end and a flat slab, the latter with a specially produced regular roughness on its contact surface, is used to experimentally verify the relation between the irreversible change in the roughness, the change in the contrast of the holographic interference fringes, and the change in the contrast of the carrying Young’s fringes. It is shown that the sensitivity of correlation speckle photography is higher than the sensitivity of the correlation holographic interferometry technique. 相似文献
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An analysis is made of a contactless method of recording the vibrations of a rough surface using the speckle effect. Dependences
of the percent modulation of the photodetector electric signal on the vibration amplitude and the parameters of the optical
system are given and this optical dependence is checked experimentally. Results of a spectral analysis of the vibrations of
an electric motor casing are presented for illustration purposes. It is noted that this method may be used to study vibrations
of heated surfaces and transparent media.
Zh. Tekh. Fiz. 67, 71–75 (August 1997) 相似文献
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M. H. Grosmann M. A. Kiryushin A. I. Larkin A. I. Lebedenko I. Yu. Lebedenko N. A. Lopatina A. V. Osincev V. P. Shchepinov I. V. Shchepinova 《Laser Physics》2010,20(6):1481-1485
The aim of this work is to demonstrate that holographic and speckle interferometry—laser photonics methods are compatible
and useful for prosthetic stomatology. These methods allow to study the deformation of the mandible after insertion of mini-implants
of various forms, and to give the practical medical recommendations. 相似文献