排序方式: 共有17条查询结果,搜索用时 15 毫秒
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Zhimin Zhou Lanfen Qi Ying Tan 《International Journal of Infrared and Millimeter Waves》2001,22(2):255-263
Based on a new multipath channel model, a spatial-temporal combined CM equalization approach is derived at millimeter waves. Computer simulations are presented to testify the theoretical analysis. It is shown that this method can compensate the signal degradation caused by indoor multipath propagation. The convergence behavior of the spatial-temporal CMA is also analyzed. 相似文献
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Recent developments in quantitative surface analysis by Auger (AES) and x-ray photoelectron (XPS) spectroscopies are reviewed and problems relating to a more accurate quantitative interpretation of AES/XPS experimental data are discussed. Special attention is paid to consideration of elementary physical processes involved and influence of multiple scattering effects on signal line intensities. In particular, the major features of core-shell ionization by electron impact, Auger transitions and photoionization are considered qualitatively and rigorous approaches used to calculate the respective transition probabilities are analysed. It is shown that, in amorphous and polycrystalline targets, incoherent scattering of primary and signal Auger and photoelectrons can be described by solving analytically a kinetic equation with appropriate boundary conditions. The analytical results for the angular and energy distribution, the mean escape depth, and the escape probability as a function of depth of origin of signal electrons as well as that for the backscattering factor in AES are in good agreement with the corresponding Mote Carlo simulation data. Methods for inelastic background subtraction, surface composition determination and depth-profile reconstructions by angle-resolved AES/XPS are discussed. Examples of novel techniques based on x-ray induced photoemission are considered. 相似文献
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We have developed a miniature double-pass cylindrical mirror electron energy analyzer (DPCMA) with an outer diameter of 26 mm. The DPCMA consists of a shield for the electric field, inner and outer cylinders, two pinholes with a diameter of 2.0 mm, and an electron multiplier. By assembling the DPCMA in a coaxially symmetric mirror electron energy analyzer (ASMA) coaxially and confocally we developed an analyzer for Auger photoelectron coincidence spectroscopy (APECS). The performance was estimated by measuring the Si-LVV-Auger Si-1s-photoelectron coincidence spectra of clean Si(1 1 1). The electron-energy resolution of the DPCMA was estimated to be E/ΔE = 20. This value is better than that of the miniature single-pass CMA (E/ΔE = 12) that was used in the previous APECS analyzer. 相似文献
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A polyclonal antibody (Ab) for the progestin levonorgestrel (LNG) was generated, and immunochemical assays for its detection, clean-up and concentration were developed. A highly specific microplate diagnostic assay for the detection of LNG was developed that used the enzyme linked immunosorbent assay (ELISA) method. The LNG ELISA developed was sensitive and reproducible; it exhibited I50 and I20 values of 3.3 ± 1.8 ng mL−1 and 0.6 ± 0.4 ng mL−1, respectively, and the Abs did not cross react with any of the tested steroid hormones. The above Abs were used to develop a sol-gel-based immunoaffinity purification (IAP) method for concentration and clean-up of LNG that is compatible with subsequent immunochemical or instrumental chemical analytical procedures, such as liquid chromatography followed by mass spectrometry (LC-MS/MS). Development of the columns included successful entrapment of Abs within a tetramethoxysilane (TMOS)-based SiO2 polymer network. The Abs could bind the free analyte from solution, and the bound analyte could be easily eluted from the sol-gel matrix at high recoveries. The Ab selectivity towards the antigen was high, in both ELISA and the sol-gel columns, but the entrapped Abs cross-reacted with two other steroid hormones - ethynylestradiol (EE2) and nortestosterone (NT) - which share similar epitopes with LNG, despite the lack of cross reactivity in the ELISA. The validity of the method was investigated by LC-MS/MS and a good analytical correlation was obtained. 相似文献
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GuoHuaLAI RenXianZHOU XiaoXiangHAN XiaoMingZHENG 《中国化学快报》2004,15(12):1494-1496
The effect of transition metals (Cr, Mn, Fe, Co and Ni) on the hydrogenation of cinnamaldehyde over Pt/ZrO2 catalysts was studied in ethanol at 343K under 2.0MPa H2 pressure. PtCo/ZrO2 and PtFe/ZrO2 catalysts exhibit high selectivity and activity of hydrogenation for C=O (93.8% at 87.3% conversion and 83.6% at 88.6% conversion, respectively), and PtNi/ZrO2 exhibits high selectivity of hydrogenation for C=C (64.3% at 70.6% conversion). In the presence of trace H2O and NaOH, over the PtNi/ZrO2 (0.4wt%Ni) catalyst the selectivity to hydrocinnamalde hydereaches 90.6% and the conversion of cinnamaldehyde is 90.5%. 相似文献
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Co-B非晶态合金催化肉桂醛液相选择性加氢制备肉桂醇的研究 总被引:6,自引:0,他引:6
本文首次报道Co-B非晶态合金催化剂应用于肉桂醛(CMA)液相选择性加氢制备肉桂醇(CMO),考察了催化活性、CMO选择性及其得率以及不同湿度预处理的影响。实验发现,Co-B非晶态合金催化剂的催化活性和对CMO的选择性显著优于Raney Co等催化剂,加热晶化后导致其催化活性显著下降而对CMO的选择性略有升高,根据XRD,SEM,XPS,BET等一系列的表征,初步讲座了Co-B催化剂催化性能与催化剂结构的关系。 相似文献
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Constantinos Tsitsilianis George Gotzamanis Zacharoula IatridiAuthor vitae 《European Polymer Journal》2011,(4):497-510
This article is dealing with the design of novel segmented polymers comprising homopolymer and random copolymer building blocks designated as block-random. This type of polymeric materials can be prepared through macromolecular engineering by using controlled polymerization methods. By replacing a homopolymer block with a random one, in block copolymer topologies, further tuning of the copolymer properties can be achieved. The present article highlights the recent developments on block-random segmented macromolecules, bearing building blocks of tunable properties (e.g. thermo-sensitivity (LCST), hydrophobicity) and exhibiting responsive behavior in aqueous environments. Furthermore, preliminary novel results regarding pH-sensitive segmented macromolecules of various topologies, bearing random polyampholyte blocks among others, are also demonstrated and discussed. 相似文献
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This paper derives a residual based interactive stochastic gradient (ISG) parameter estimation algorithm for controlled moving average (CMA) models and studied the performance of the residual based ISG algorithm under weaker conditions on statistical properties of the noise. Compared with the residual based extended stochastic gradient algorithm for identifying CMA models, the proposed ISG algorithm can give highly accurate parameter estimates by the simulation example. 相似文献