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151.
Michio Tokuyama 《Physica A》1980,102(3):399-430
A new method of finding nonlinear Langevin type equations of motion for relevant macrovariables and the corresponding master equation for systems far from thermal equilibrium is presented by generalizing the time-convolutionless formalism proposed previously for equilibrium hamiltoian systems by Tokuyama and Mori. The Langevin type equation consists of a fluctuating force, and the nonlinear drift coefficients which are always identical to those of the master equation. A simple formula which relates the drift coefficients to the time correlation of the fluctuating forces is derived. This is a generalization of the fluctuation-dissipation theorem of the second kind in equilibrium systems and is valid not only for transport phenomena due to internal fluctuations but also for transport phenomena due to externally-driven fluctuations. A new cumulant expansion of the master equation is also obtained. The conditions under which a Langevin and a Fokker-Planck equation of a generalized type for non-equilibrium open systems can be derived are clarified.The theory is illustrated by studying hydrodynamic fluctuations near the Rayleigh-Bénard instability. The effects of two kinds of fluctuations, internal fluctuations of irrelevant macrovariables and external (thermal) noises, on the convective instability are investigated. A stochastic Ginzburg-Landau type equation for the order parameter and the corresponding nonlinear Fokker-Planck equation are derived. 相似文献
152.
In Pharbitis nil cotyledons, the lag phase of chlorophyll a (Chi a) accumulation which continues for about 2 h after the onset of continuous white light is eliminated by preirradiation with far-red light (FR) for 24 or 48 h. When the period of FR preirradiation is prolonged to 72 h or more, however, the lag phase is observed again (FR-induced lag phase) and the rate of Chi a accumulation during the rapid accumulation phase is lowered below the dark control level.
The application of exogenous 5-aminolevulinate (J-ALA) completely eliminates the FR-induced lag phase, but this treatment eliminates the normal lag phase in dark-grown cotyledons only partially (i.e. Chi a is accumulated but only slowly during the first few h). Application of a 5-ALA precursor, such as glycin + succinate. 2-ketoglutarate or glutamate, eliminates neither the FR-induced lag phase nor the normal lag phase.
A 24- or 48-h FR irradiation seems not only to enable the synthesis of 5-ALA but also to make the other regulatory factors favourable for Chi accumulation. When the period of FR irradiation is prolonged to 72 h or more, the ability to synthesize 5-ALA may be lost. 相似文献
The application of exogenous 5-aminolevulinate (J-ALA) completely eliminates the FR-induced lag phase, but this treatment eliminates the normal lag phase in dark-grown cotyledons only partially (i.e. Chi a is accumulated but only slowly during the first few h). Application of a 5-ALA precursor, such as glycin + succinate. 2-ketoglutarate or glutamate, eliminates neither the FR-induced lag phase nor the normal lag phase.
A 24- or 48-h FR irradiation seems not only to enable the synthesis of 5-ALA but also to make the other regulatory factors favourable for Chi accumulation. When the period of FR irradiation is prolonged to 72 h or more, the ability to synthesize 5-ALA may be lost. 相似文献
153.
Steviol 2 was transformed into stevioside 1 by applying the stereoselective methods of glycosidation. 相似文献
154.
This paper presents an advanced method for a 2-dimensional analysis of transient natural convection by finite element method. The present method, based on stream function—vorticity formulation, could get rid of numerical errors and constraint of perpendicular mesh subdivision, since we excluded a finite difference approximation of vorticity on no-slip boundaries. A considerable effect of upwind weighting function was examined. The method was successfully applied to a problem of natural convection around a horizontal hot cylinder. 相似文献
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157.
制备反相高效液相色谱法用于从杉材中分离制备倍半萜类化合物 总被引:4,自引:0,他引:4
利用制备高效液相色谱法从日本产杉材(Cryptomeria japonica D.Don)中分离制备倍半萜类化合物。在YWC-Pack C18柱上,以异丙醇-甲醇-正己烷-水(体积比为50∶35∶10∶5)为流动相,流速为5 mL/min,制备了2种倍半萜类化合物,经紫外光谱、红外光谱及核磁、质谱分析,确认它们分别为(-)-cubebol和(+)-2,7(14),10-bisa-bolatrien-1-ol-4-one。所制备的两个化合物的纯度分别为98.7%和99.1%。 相似文献
158.
Abstract Heat capacity of a 20 g sample of the mesogen 4-cyanobenzoyloxy-4′-octylbenzoyloxy-p-phenylene was measured in the temperature range 380 to 510 K by adiabatic calorimetry. The C p versus T data is interpreted in terms of thermodynamically equivalent SA1 and SAd phases whose Gibbs potential surface intersects the thermodynamically equivalent reentrant nematic and nematic Gibbs potential surface in such a way as to define the first order doubly reentrant phase sequence: SA1-N-SAd-N. The data do not allow any precise estimates of transition enthalpies. 相似文献
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