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101.
Lei ZH Yahara S Nohara T Tai BS Xiong JZ Ma YL 《Chemical & pharmaceutical bulletin》2000,48(2):290-292
Two new cardiac glycosides called cheiranthosides VI (2) and VII (3) were isolated together with a known one, glucoerysimoside (1) from the seeds of Erysimum cheiranthoides. Based on spectroscopic data, the structures of 2 and 3 were characterized as periplogenin 3-O-beta-D-glucopyranosyl(1-->4)-beta-D-fucopyranoside and periplogenin 3-O-beta-D-glucopyranosyl(1-->4)-beta-D-antiaropyranoside, respectively. 相似文献
102.
Potential PDP phosphors with strong absorption around 172 nm: Rare earth doped NaLaP2O7 and NaGdP2O7
Jun Lin Yuan Jiao Wang Ding Bang Xiong Jing Tai Zhao Yi Bing Fu Chao Shu Shi 《Journal of luminescence》2007,126(2):717-722
NaLaP2O7 and NaGdP2O7 powder samples are prepared by solid-state reactions at 750 and 600 °C, respectively, and the VUV-excited luminescence properties of Ln3+ (Ln=Ce, Pr, Tb, Tm, Eu) in both diphosphates are studied. Ln3+ ions in both hosts show analogous luminescence. For Ce3+-doped samples, the five Ce3+ 5d levels can be clearly identified. As for Pr3+ and Tb3+-doped samples, strong 4f-5d absorption band around 172 nm is observed, which matches well with Xe-He excimer in plasma display panel (PDP) devices. As a result, Pr3+ can be utilized as sensitizer to absorb 172 nm VUV photon and transfer energy to appropriate activators, and Tb3+-doped NaREP2O7(RE=La, Gd) are potential 172 nm excited green PDP phosphors. For Tm3+ and Eu3+-doped samples, the Tm3+-O2− charge transfer band (CTB) is observed to be at 177 nm, but the CTB of Eu3+ is observed at abnormally low energy position, which might originate from multi-position of Eu3+ ions. The similarity in luminescence properties of Ln3+ in both hosts indicates certain structural resemblance of coordination environment of Ln3+ in the two sodium rare earth diphosphates. 相似文献
103.
A direct‐forcing immersed boundary‐lattice Boltzmann method (IB–LBM) is developed to simulate fluid–particle interaction problems. This method uses the pressure‐based LBM to solve the incompressible flow field and the immersed boundary method to handle the fluid–particle interactions. The pressure‐based LBM uses the pressure distribution functions instead of the density distribution functions as the independent dynamic variables. The main idea is to explicitly eliminate the compressible effect due to the density fluctuation. In the IB method, a direct‐forcing method is introduced to capture the particle motion. It directly computes an IB force density at each lattice grid from the differences between the pressure distribution functions obtained by the LBM and the equilibrium pressure distribution functions computed from the particle velocity. By applying this direct‐forcing method, the IB–LBM becomes a purely LBM version. Also, by applying the Gauss theorem, the formulas for computing the force and the torque acting on the particle from the flows are derived from the volume integrals over the particle volume instead of from the surface integrals over the particle surface. The order of accuracy of the IB–LBM is demonstrated on the errors of velocity field, wall stress, and gradients of velocity and pressure. As a demonstration of the efficiency and capabilities of the new method, sedimentation of a large number of spherical particles in an enclosure is simulated. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
104.
105.
研究金属切削过程中的变化,对改进切削工艺、实现高速、自动化和精密加工具有重要意义。高速显微摄影是实现从宏观到微观、从定性到定量、从静态到动态研究的有效方法。 相似文献
106.
Isovaleroyl oxokadsurane, a novel dibenzocyclooctadiene lignan pos-sessing a spirobenzofuranoid skeleton was isolated from the stems of Kadsura coccinea.Its structure and relative configuration were determined by X-ray diffraction analysis. 相似文献
107.
108.
Normal mode calculation of A-type zeolite was carried out with the potential energy functions obtained from the constraint method. Mass-weighted cartesian coordinates and the pseudo-lattice method were used. The assignments of IR absorption bands were made with the calculated normal modes, by using the calculated absorption intensities of the modes and the degrees of contribution of the internal coordinates to the modes. The force constants of internal coordinate motions within the framework were also calculated and are compared with the empirical values. 相似文献
109.
The stationary and nonstationary rotating Navier-Stokes equations with mixed boundary conditions are investigated in this paper. The existence and uniqueness of the solutions are obtained by the Galerkin approximation method. Next, θ-scheme of operator splitting algorithm is applied to rotating Navier-Stokes equations and two subproblems are derived. Finally, the computational algorithms for these subproblems are provided. 相似文献
110.
The hadronic and string cascade model and the corresponding event generator LUCIAE are used to study systematically the production
of the grey particles in (14.6, 60 and 200A GeV)0 + Em, (2004 GeV)Si + Em, (200A GeV)S + Em and (11.6A GeV)Au + Em reactions. The dependences of the mean multiplicity,
the multiplicity distributions and the polar angular distributions of the grey particles on the incident energy, the projectile
mass and the collision centrality observed in emulsion experiments, respectively, are all reproduced by LUCIAE calculations.
In addition the effects of the rescattering on the grey particle production are also investigated.
Project supported by the National Natural Science Foundation of China (Grant Nos. 19575071 and 19875019) and DFG of Germany. 相似文献