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991.
The complete diagonalization (of energy matrix) method (CDM) and the perturbation theory method (PTM) are applied to calculate the spin-Hamiltonian (SH) parameters (electron paramagnetic resonance g factors g //, g ⊥ and zero-field splitting D) of the trigonal Mo 3+ centers in Y 3Al 5O 12 and Lu 3Al 5O 12 crystals. Both methods are based on the cluster approach in which the covalence effect due to the admixture between the d orbitals of central d n ion and p orbitals of ligands is considered. The g factors calculated by both methods are close to each other and agree with the experimental values. However, the calculated zero-field splittings D from PTM for both crystals are about 84% those from CDM. The reasons that the CDM is preferable to the PTM in the calculations of SH parameters are discussed. The angular distortions of Mo 3+ centers in both garnet crystals are predicted. 相似文献
992.
ABSTRACTThe specific activities of 226Ra, 232Th and 40K of 26 samples of granite produced in Xinjiang of China were measured by a high-purity germanium detector, and their radiological hazards of radium equivalent, external hazard index, internal hazard index, absorbed dose rate, annual effective dose rate, gamma index and alpha index were evaluated. The results indicate that the overall average specific activities of 226Ra, 232Th and 40K obtained in the investigated samples are below the world’s average granite values. The average radium equivalent is within the recommended limit of 370?Bq?kg?1. The results obtained further show that the mean values of external hazard index, internal hazard index, absorbed dose rate, annual effective dose rate, gamma index and alpha index are 0.65, 0.77, 111.7?nGy?h?1, 0.55 mSv?y?1, 0.89 and 0.23, respectively. These mean values established that radiological hazards are also found to be below the international recommended values. The results are compared with granite samples from other countries or China-Taiwan province. It can be noticed that the specific activity values of granite samples produced in China are lower or similar to that of other countries or China-Taiwan province, however there are higher specific activity values for 226Ra and 232Th in individual samples, which need to provide proper radiation monitoring before use considering the long term health effect. 相似文献
993.
994.
研究了低(1mg/kg/d)、中(5mg/kg/d)、高(25mg/kg/d)三个剂量组全氟辛酸(Perfluorooctanoic acid,PFOA)致小鼠肝脏脂质过氧化损伤的作用.结果发现,PFOA能抑制小鼠体重的增长,对肝组织造成一定的脂质过氧化损伤.各组小鼠出现不同程度的体重增长缓慢甚至减轻,中、高剂量组出现明显的减轻(P<0.01);低、中、高剂量组肝脏系数,均明显高于对照组(P<0.01);与对照组相比,各剂量组的肝组织中MDA、NO及LDH含量明显增高,SOD、SDH及GSH-Px活性均明显降低(P<0.05). 相似文献
995.
铁皮石斛药用成分研究进展 总被引:2,自引:0,他引:2
在系统的文献调研基础上,结合该实验室先前的科研工作,对兰科石斛属植物铁皮石斛的药用成分和药理活性加以综述.据该文统计,铁皮石斛药用成分的报道主要集中于近20年,主要药用成分有铁皮石斛多糖、生物碱、氨基酸、微量元素.因其具有广泛的药效作用、卓越的经济价值和良好的观赏价值,备受世人关注.该文对其药用成分和药理活性做了详细而全面的总结,为今后铁皮石斛更好的开发利用提供参考. 相似文献
996.
In this paper, we study Toeplitz operators T μ from one Fock space \({F^{p}_{\alpha}}\) to another \({F^{q}_{\alpha}}\) for 1 < p, q < ∞ with positive Borel measures μ as symbols. We characterize the boundedness (and compactness) of \({T_\mu: F^{p}_{\alpha} \to F^{q}_{\alpha}}\) in terms of the averaging function \({\widehat{\mu}_r}\) and the t-Berezin transform \({\widetilde{\mu}_t}\) respectively. Quite differently from the Bergman space case, we show that T μ is bounded (or compact) from \({F^{p}_{\alpha}}\) to \({F^{q}_{\alpha}}\) for some p ≤ q if and only if T μ is bounded (or compact) from \({F^{p}_{\alpha}}\) to \({F^{q}_{\alpha}}\) for all p ≤ q. In order to prove our main results on T μ , we introduce and characterize (vanishing) (p, q)-Fock Carleson measures on C n . 相似文献
997.
In this paper, a generalized diffusion model driven by the composite-subdiffusive fractional Brownian motion (FBM) is employed. Based on this stochastic process, we derive a fractional Fokker-Planck equation (FFPE) and obtain its solution. It is proved that the Generalized Einstein Relation (GER) and the Metzler and Klafter conjecture on the asymptotic behavior of stretched Gaussian hold the FFPE in a composite-subdiffusive regime. 相似文献
998.
Jianguo Lv Wanbing GongKai Huang Jianbo ZhuFanming Meng Xueping Song Zhaoqi Sun 《Superlattices and Microstructures》2011,50(2):98-106
Zinc oxide thin films are deposited on Si and quartz substrates using the sol-gel method. The thin films, annealed at 400, 600 and 800 °C respectively, are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), ultraviolet-visible spectrophotometer (UV-Vis), fluorescence spectrometer (FL) and the photocatalytic activity is tested by the decomposition of methyl orange dye under UV illumination. The results show that the mean grain size, surface-to-volume ratio, rms roughness and degradation efficiency of the thin films increases with increasing annealing temperature. In particular, ZnO thin film annealed at 800 °C exhibits the highest photocatalytic activity, degrading methyl orange by almost 88% in 180 min. Photocatalytic reaction mechanism of the ZnO thin films is discussed in detail, and the oxygen defects are proposed to be the active sites of the ZnO photocatalyst. 相似文献
999.
Shouxin Cui Xiaoguang Xiao Haiquan Hu Zengtao Lv Guiqing Zhang Zizheng Gong 《Physica B: Condensed Matter》2011,406(18):3389-3391
Investigations into the structural, electronic and elastic properties of intermetallic CuZr compound had been conducted by the plane-wave pseudopotential method. The calculated lattice constant was consistent well with the experimental value. The absence of band gap and finite value of the density of states (DOS) at the Fermi level reveal the metallic behavior of CuZr crystal, and Zr 4d states give rise to the electrical conductivity. The calculated elastic constants for single crystal CuZr at zero pressure obey the cubic mechanical stability condition, which indicates that the cubic CuZr crystal is mechanical stable at zero pressure. By analyzing the ratio between the bulk and shear moduli, we conclude that CuZr crystal is ductile in nature. The present theoretical investigations might give prediction to polycrystalline CuZr system. 相似文献
1000.
Zhang Sen Liu Qi Wang Wei Lv Hangbing Zuo Qingyun Wang Yan Li Yingtao Lian Wentai Long Shibing Wang Qin Liu Ming 《Applied Physics A: Materials Science & Processing》2011,105(4):1003-1009
The performances of bulk-heterojunction (BHJ) solar cells are investigated for time-dependent thermal annealing with different
morphology evolution scales, having special consideration for the diffusion and aggregation of fullerene derivative molecules
based on blends of poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid methyl ester (P3HT:PCBM). Meaningfully, rapid formation of dot-like and needle-like crystalline PCBM structures
of a few micrometers up to 60 μm in size is obtained with thermal annealing treatment from 2 to 15 min, which dynamically
reflects a fast process of PCBM molecule and cluster aggregation. Upon ultrasonic-assisted processing and annealing treatment,
the scale of P3HT crystals is drastically increased in view of X-ray diffraction (XRD) patterns, leading to a high hole mobility.
And, the P3HT domains can be gradually converted into larger P3HT crystals approved by the decreased full width at half-maximum
in the XRD patterns. Corresponding current–voltage curves are measured in quantity and we propose a model to explain the effect
of the crystalline degree of P3HT domains and aggregation of PCBM molecules and clusters on the phase segregation, expressing
a viewpoint towards high performance of BHJ solar cells. 相似文献