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331.
A series of hydrous zirconia samples were prepared by the hydrothermal method, and the Pt/WO3-ZrO2 catalyst was prepared by impregnation. The effects of hydrothermal temperature of Zr(OH)4 on the isomerization activity of the catalyst was investigated. The crystalline structure, acidity, and reduction properties of the catalyst were characterized by X-ray diffraction, NH3 temperature-programmed desorption, and H2 temperature-programmed reduction, respectively. The results indicated that the crystalline structure of hydrous zirconia and the catalyst varied with the hydrothermal temperature, and the increase of hydrothermal temperature reduced the fraction of tetragonal zirconia. Strong acid sites on the catalyst and the isomerization activity increased with the crystallization of Zr(OH)4. It was proposed that the higher isomerization activity may be related to the existence of large numbers of strong acid sites.  相似文献   
332.
用超声分散的方法将Fe2O3超微粒分散于硬脂酸/正己烷/氯仿溶液中,用LB膜技术进行组装。结果表明:Fe2O3超微粒能均匀地分散在有机溶剂中,并且能够被硬脂酸包裹;Fe2O3超微粒/硬酯酸单分子膜的成膜性能良好,Fe2O3超微粒/硬脂酸复合LB膜具有层状结构;在Fe2O3超微粒的晶格结构和硬脂酸单分子膜的晶格结构相匹配的情况下,Fe2O3超微粒能够被有序组装。  相似文献   
333.
A scanning transmission electron microscope (STEM) study of silicon–germanium alloying using annular dark field (ADF) or Z-contrast imaging and electron energy loss spectroscopy (EELS) is presented. Results and techniques are discussed. Growth of 11 equivalent monolayers of germanium on silicon at 650 °C results in dome-shaped islands or quantum dots that contain up to ∼40% silicon. The interface between the as-grown island and substrate shows a highly disordered or amorphous zone ∼1.5-nm wide directly under the island. Annealing for 60 min at 650 °C gives larger pyramidal islands with diffuse crystalline interfaces and an equilibrium distribution of up to ∼70% silicon in the islands. PACS 61.16.Bg; 68.35.Dv; 68.35.Rh  相似文献   
334.
The master-slave surveillance system uses stationary-dynamic camera assemblies to achieve wide-area surveillance and selective focus-of-interest. In such a system, a stationary fish-eye camera monitors a panoramic field of environment from a distance, while a dynamic PTZ (Pan–Tilt–Zoom) dome camera is commanded to acquire high-resolution images from a focused direction and provide multi-scale zoomed-in information. In order to achieve the precise interaction, pre-processing spatial calibration between these two cameras is required. This paper introduces a novel vision based calibration approach to automatically calculate a transformation matrix model between the fish-eye coordinate system and the PTZ dome coordinate system by matching feature points in the scene. The experiment has demonstrated the effectiveness of using this method with high accuracy in short calibration time.  相似文献   
335.
We report on the remote sensing capability of an integrated path differential absorption lidar (IPDIAL) instrument, for multi-species gas detection and monitoring in the 3.3–3.7 µm range. This instrument is based on an optical parametric source composed of a master oscillator-power amplifier scheme—whose core building block is a nested cavity optical parametric oscillator—emitting up to 10 µJ at 3.3 µm. Optical pumping is realized with an innovative single-frequency, 2-kHz repetition rate, nanosecond microchip laser, amplified up to 200 µJ per pulse in a single-crystal fiber amplifier. Simultaneous monitoring of mean atmospheric water vapor and methane concentrations was performed over several days by use of a topographic target, and water vapor concentration measurements show good agreement compared with an in situ hygrometer measurement. Performances of the IPDIAL instrument are assessed in terms of concentration measurement uncertainties and maximum remote achievable range.  相似文献   
336.
337.
本文探讨在留曼边界条件下带有两食饵趋向和功能Ⅱ反应函数的三物种食物链模型,此模型的主要特征是捕食者捕食速度空间上的临时变化是由食饵的梯度决定的.应用压缩原理,抛物方程的Schauder估计和Lp估计,证明了此模型古典解的全局存在性.  相似文献   
338.
Russell??s critique of substance monism is an ideal starting point from which to understand some main concepts in Spinoza??s difficult metaphysics. This paper provides an in-depth examination of Spinoza??s proof that only one substance exists. On this basis, it rejects Russell??s interpretation of Spinoza??s theory of reality as founded upon the logical doctrine that all propositions consist of a predicate and a subject. An alternative interpretation is offered: Spinoza??s substance is not a bearer of properties, as Russell implied, but an eternally active, self-actualizing creative power. Eventually, Spinoza the Monist and Russell the Pluralist are at one in holding that process and activity rather than enduring things are the most fundamental realities.  相似文献   
339.
    
Azoimidazolium dyes were used as precursors for mesoionic carbene ligands (Azo‐MICs). The properties of these ligands were examined by synthesizing RhI, AuI, and PdII complexes. Experimental (NMR, IR) and theoretical investigations show that Azo‐MICs are potent σ‐donor ligands. Yet, they feature a small singlet–triplet gap and very low‐lying LUMO levels. The unique electronic properties of Azo‐MICs allow for reversible one‐electron reductions of the metal complexes, as evidenced by cyclic voltammetry.  相似文献   
340.
    
The reduced graphene oxide‐Bi2WO6 (rGO‐BWO) photocatalysts with the different RF/O values (molar ratio of the F molar mass and the O's molar mass of Bi2WO6) had been successfully synthesized via one‐step hydrothermal method. The F‐doped rGO‐BWO samples were characterized by X‐ray diffraction patterns (XRD), field‐emission scanning electron microscopy (FE‐ESEM), transmission electron microscopy (TEM), Brunauer–Emmett–Teller surface area (BET), X‐ray photoelectron spectroscopy (XPS) and UV–vis diffuse reflectance spectra (DRS). The results indicate that F? ions had been successfully doped into rGO‐BWO samples. With the increasing of the RF/O values from 0 to 2%, the evident change of the morphology and the absorption edges of F‐doped rGO‐BWO samples and the photocatalytic activities had been enhanced. Moreover, the photocatalytic activity of F‐doped rGO‐BWO with RF/O = 0.05 were better than rGO‐BWO and the other F‐doped rGO‐BWO under 500 W Xe lamp light irradiation. The enhanced photocatalytic activity can be attributed to the morphology of the intact microsphere that signify the bigger specific surface area for providing more possible reaction sites for the adsorption–desorption equilibrium of photocatalytic reaction, the introduction of F? ions that may cause the enhancement of surface acidity and creation of oxygen vacancies under visible light irradiation, the narrower band gap which means needing less energy for the electron hole pair transition.  相似文献   
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