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多相物质粉末衍射的物相检索 总被引:1,自引:1,他引:0
余焜 《理化检验(物理分册)》2003,39(2):92-95
讨论了多相物质粉末衍射的物相检索问题,介绍了XRDS的物相检索软件。这是一种智能型的物相检索程序,考虑了测试数据的不确定度,以及粉末样品和块状样品衍射图谱各自的特点,不仅注意到实际样品中微量物相存在的可能,也注意到块状样品结构有序性的可能。XRDS能够帮助材料工作者同时检出样品中所含的多种物相及其含量,操作简单、结果可靠。 相似文献
24.
Associations (dimer or aggregate) of anthracene (An) fluorophores tend to interrupt the monomer emission and reduce the quantum yield (ΦPL); therefore, poly(methyl methacrylate) (PMMA) chain was used in this study to chemically link to anthracene and to block the mutual associations among the anthracene fluorophores. With this aim, the target polymers were prepared by anionic polymerizations with 9,10‐dibromoanthracene/s‐butyllithium as initiating system to proceed polymerizations of methyl methacrylate (MMA) directly or in the presence of 1,1‐diphenylethylene (DPE). Use of DPE before addition of MMA produces stable initiating anionic species and avoids potential side reactions during polymerization; however, it also introduces four β‐phenylene rings around the central anthracene ring, which interfere with the corresponding emission pattern and reduce the ΦPL (32%) value due to potential interactions between phenylene rings and anthracene. On the contrast, polymerization without participation of DPE results in polymer with central anthracene ring directly connected to two PMMA chains, which gives clean vibronic emission pattern with limited association emissions and enhanced ΦPL (52%) value. Physical blending of anthracene by PMMA is less efficient to restrain the associations and results in a film of lower ΦPL (20%). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
25.
This study analyzed the effects of polyurethane (PU) resin treatments on surface homogeneity, dimensional stability, and finishing performances of medium‐ and small‐diameter softwoods produced in Taiwan. Two‐pack PU resins were prepared by combing short castor oil‐modified alkyd resin serving as a polyol with polymeric 4,4′‐diphenymethane diisocyanate (PMDI) serving as a hardener, by the molar ratio of NCO/OH+COOH of 1.2. Four types of short oil‐modified alkyd resins with different polyhydric alcohols (glycerin and pentaerythritol) and polybasic acids (phthalic anhydride and isophthalic acid) were synthesized. Three kinds of medium‐ and small‐diameter softwoods, including China fir, Taiwanina, and Japanese fir with a diameter of 10–15 cm were obtained from Hui‐Sun Forest Station, Taiwan. The wood coating of nitrocellulose (NC) lacquer including sanding sealer and top clear was used. Results show that the surface hardness, homogeneity, moisture excluding efficiency, and antiswelling efficiency of woods were enhanced by PU resin treatments. Among all the PU resins, the isophthalic acid and pentaerythritol‐containing PU resin (IPA‐P‐MDI) achieved the best improved efficiency on dimensional stability of woods. Results of two types of finishing procedure, i.e. NC lacquer sanding sealer plus top clear and top clear only, applied onto the PU‐treated woods revealed that the hardness, adhesion, and durability of NC lacquer films on the PU‐treated wood were superior to those of untreated one, especially for top clear finishing alone. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
26.
The self-assembly of various nanostructures is recently attracting a great deal of research attention. In this paper, we demonstrate that a palladium chloride aqueous solution, mixed with a proper ammonia solution, can produce Tetra-amminepalladous chloride (Pd(NH3)4Cl2·H2O) nanowires. These nanowires can spontaneously form the two-dimensional hexagon-oriented Pd(NH3)4Cl2·H2O arrays on mica surfaces. We can control the length and height of these nanowires by adjusting their deposit time on the mica substrate. This method can be potentially used in making sensors or in making templates to wire and position nanodevices. 相似文献
27.
用高能球磨采用两种方案制备了FeCo MnO体系,并用X射线衍射和振动样品磁强计对其结构和磁性质做了分析.发现采用直接氧化Mn而得到MnO的方法,所得体系的MnO较纯;而通过分解MnCO3得到MnO的体系,MnO纯度较低,有较多Mn3O4杂质,两种方法制备的FeCo MnO体系的矫顽力和剩磁比都比单纯FeCo体系的增加很多,且前一种方法比后一种方法制备的FeCo MnO体系的矫顽力和剩磁比较大.然后研究了球磨时间及退火处理对FeCo MnO体系矫顽力及剩磁比的影响,发现球磨时间为120h体系的矫顽力和剩磁比最大;经过退火处理后,体系的矫顽力和剩磁比都有较大幅度的增加. 相似文献
28.
Real-time homogenous translucent material editing 总被引:4,自引:0,他引:4
This paper presents a novel method for real-time homogenous translucent material editing under fixed illumination. We consider the complete analytic BSSRDF model proposed by Jensen et al. [ [JMLH01] ], including both multiple scattering and single scattering. Our method allows the user to adjust the analytic parameters of BSSRDF and provides high-quality, real-time rendering feedback. Inspired by recently developed Precomputed Radiance Transfer (PRT) techniques, we approximate both the multiple scattering diffuse reflectance function and the single scattering exponential attenuation function in the analytic model using basis functions, so that re-computing the outgoing radiance at each vertex as parameters change reduces to simple dot products. In addition, using a non-uniform piecewise polynomial basis, we are able to achieve smaller approximation error than using bases adopted in previous PRT-based works, such as spherical harmonics and wavelets. Using hardware acceleration, we demonstrate that our system generates images comparable to [ [JMLH01] ]at real-time frame-rates. 相似文献
29.
首先对3G室内分布系统特点进行介绍,然后对其设计过程中的关键问题进行分析,并给出在后续网络优化过程中的常见问题和相应解决方案。 相似文献
30.
随着企业内部网络应用的深入,Intranet内部的信息资源越来越庞大,怎样为这些数据信息构建索引是我们面If缶的主要任务,而全文检索的产生解决了这一问题。目前越来越多的中小企业采用Linux系统作为Web平台,并且利用检索系统来管理内部繁多的文本和HTML文件。文章对www搜索引擎的全文检索及其相关技术进行了分析和讨论,实现了一个基于Linux环境的Intranet搜索引擎LISE(Linux Intranet Search Engine)。LISE利用了基于词表的索引方法,为用户提供了更加准确的信息,能满足多种中小企业用户的需求。 相似文献