共查询到20条相似文献,搜索用时 344 毫秒
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由山东大学蒋民华院士等承担的山东省科技攻关项目———纳米材料和器件的制备、表征及其应用,日前通过了山东省科技厅组织的技术鉴定。该课题首次利用多孔纳米固体研制出ZnO气敏传感器,成功解决了固扰传感器生产厂家多年的ZnO气敏传感器本征电阻过高和工作稳定性较差的问题。该项目研制的ⅢV族半导体纳米复合发光材料和氧化锌多孔纳米固体气敏传感器为国内外首创。山东大学半导体纳米复合发光材料器件研制成功@刘广荣 相似文献
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WO3纳米材料具有多种独特的功能特性。对其在气体检测领域的发展进行了简单阐述,主要介绍了WO3基纳米材料的最新合成方法,对四种常见危害气体(二氧化氮、三乙胺、氨气、丙酮)的检测能力及其传感机制,并基于国内外研究中贵金属负载、元素掺杂、组分复合等方法,对WO3基气体传感器增强选择性、降低最佳工作温度等性能提高的方式进行了归纳,系统介绍了近年来WO3基纳米材料在气敏性能改性领域的研究进展。最后,对WO3基气体传感器在实际应用中仍然存在的问题进行了总结,并提出目前已有的研究对气敏传感机制的讨论不够深入,应深度剖析并阐明传感机制。 相似文献
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Andronescu E Voicu G Ficai M Mohora IA Trusca R Ficai A 《Journal of electron microscopy》2011,60(3):253-259
Our purpose was to obtain and characterize some collagen/hydroxyapatite (COLL/HA) hybrid composite materials with desired ceramic properties. The ceramic properties of these materials were achieved by combining two drying methods: controlled air drying at 30°C followed by freeze-drying. Through the function of the air drying times, the materials morphology varies from porous materials (when the materials are freeze-dried) up to dense materials (when the materials are air-dried), while the combined drying allows us to obtain an intermediary morphology. The composite materials intended to be used as bone grafts and in a drug delivery system were characterized by XRD, FTIR, SEM, and also by determining the ceramic properties by using the Arthur method. The ceramic properties of these COLL/HA composite materials vary in large range, for instance the density of the materials varies from 0.06 up to 1.5?g/cm(3) while the porosity varies from 96.5% down to 27.5%. 相似文献
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The electromagnetic parameters of microwave absorbing materials are important criteria when appraising the properties of absorbents. For reconstruction of parameters which belongs to the inverse scattering problem, the test data in requirement of traditional impedance method are "just enough" and not "redundant" to comprehensively evaluate the electromagnetic properties of materials. A novel optimization approach involving multiple impedance measurements is introduced in this paper to implement automatic measurement for electromagnetic parameters on microwave slot-line. Some results for standard samples and microwave absorbing materials are given. 相似文献
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《AEUE-International Journal of Electronics and Communications》2014,68(9):877-882
An effective non-iterative method is developed for determination electromagnetic parameters of complex materials with anisotropy. Unlike the existing methods, the proposed method can extract the electromagnetic tensor parameters of materials with off-diagonal anisotropy using co- and cross-polarized reflection and transmission without using iterative procedures. Useful analytical expressions are derived for extracting the medium parameters of materials with off-diagonal anisotropy. The advantage of the method is that it uses state transition matrix and its properties in order to avoid nonlinearity and complexity of the problem. The method can work very well for dispersive materials since it is based on frequency-by-frequency extraction. The proposed method is validated by extraction of the complex permittivity and permeability tensors of two typical anisotropic materials. 相似文献
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电子封装使用多种性能各异的材料,这些材料的热膨胀系数各不相同.把其组合成一个整体后,当温度变化时,在不同的材料界面会产生压缩或拉伸应力.建立了完全焊点阵列形式的模型,采用局部温度加载方式,对塑料球栅阵列封装的热应力进行了数值模拟. 相似文献
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You Tianshu 《微波学报》1999,15(2)
本文介绍一种测定不能进行机械加工的“固体材料”(农产品或矿物)微波介电特性的新方法。将这类材料研碎,成为“空气-粒子”混合物,应用短路波导方法,对几种不同的“松密度”混合物测量其介电特性(介电常数和损耗因子)。当已知待测材料的“固体密度”时,利用这些测得特性与混合物“松密度”的线性函数关系进行“外推”,从而获得“固体密度”下的农产品(或矿物)的微波介电特性。 相似文献