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1.
橄榄苦甙的NMR数据解析   总被引:7,自引:0,他引:7  
对橄榄苦甙进行了1H和13C MNR检测, 通过DEPT和1H-1H COSY、HMQC、HMBC、NO ESY等2D NMR对其1H和13C NMR数据进行了全归属和较详细的解析, 并指出其NMR数据特征.  相似文献
2.
制备工艺对p型碲化铋基合金热电性能的影响   总被引:1,自引:0,他引:1       下载免费PDF全文
蒋俊  李亚丽  许高杰  崔平  吴汀  陈立东  王刚 《物理学报》2007,56(5):2858-2862
利用区熔法、机械合金化、放电等离子烧结(SPS)技术、热压法等多种工艺制备了p型碲化铋基热电材料.在300—500K的温度范围内测量了各热电性能参数,包括电导率(σ)、塞贝克系数(α)和热导率(κ),研究了制备工艺对热电性能的影响.结果表明,所制备的块体材料与同组成区熔晶体相比,性能优值ZT均有不同程度的提高.其中,利用区熔法结合SPS技术可获得热电性能最佳的块体材料,其ZT值达1.15. 关键词: 碲化铋 放电等离子烧结 区熔法 热电性能  相似文献
3.
New applications of the homogeneous balance principle   总被引:1,自引:0,他引:1  
The homogeneous balance principle has been widely applied to the exploration of nonlinear transformation, exact solutions (especially solitary wave solution), dromion and similarity reduction to the nonlinear partial differential equations in mathematical physics. In this paper, we use the homogeneous balance principle to derive B?cklund transformations for nonlinear partial differential equations that have more nonlinear terms and more highest-order partial derivative terms. With the aid of the B?cklund transformations derived here, we could obtain exact solutions to the nonlinear partial differential equations. The Davey-Stewartson equation and the Nizhnik-Novikov-Veselov equation are considered as the examples.  相似文献
4.
This paper focuses on the effects of waviness on vibration of ball bearings. An experimental analysis method is developed by adopting signal coherence theory of multiple-inputs/single-output (MISO) system. The inputs are waviness excitations of the inner and outer races, and the output is vibration response of the outer ring. Waviness excitation signals are first derived from the manufacturing deviations, and found to be strongly coherent in low frequency range. Virtual input signals are then introduced by the method of orthogonalization. In both cases of vibration acceleration and speed responses, the cumulated virtual input–output coherence function verifies that the first peak region of vibration spectrum is mainly induced by the waviness excitations. In order to distinguish the contributions of the inner and outer races, coherence functions of the virtual inputs with real inputs are calculated, and the results indicate that the outer race waviness contributes more to vibration than the inner race waviness does in the example. Further, a multi-body dynamic model is constructed and employed to frequency response analyses. It is discovered that the waviness induced spectral peak frequency is close to the natural frequency of bearing.  相似文献
5.
The novel filled skutterudite materials have attracted much interest in recent years and experimental studies have revealed that electrical properties (electrical conductivity and Seebeck coefficient) in these materials are dominated by their electronic structure while the effective suppression of thermal conductivity is mainly determined by their lattice dynamics. To clarify the relationship between microstructure and properties in further, we report a systematic study of electronic structures and lattice dynamics of CoSb3 in this paper using linearized augmented plane waves based on the density functional theory of first principles. By calculating band structure and partial density of states (PDOS), effects of electronic structures of CoSb3 on electrical properties were investigated. Based on the calculated results of phonon dispersions and phonon density of states of CoSb3, lattice dynamics of CoSb3 (heat capacity, Debye temperature, mean free path and lattice thermal conductivity) are discussed in detail. The calculated results are excellently consistent with other work and experimental data.  相似文献
6.
胡永刚  肖建中  夏风  武玺旺  闫双志 《物理学报》2010,59(10):7447-7451
ZrO2固体电解质室温下各相的相对含量、高温可相变量是决定材料抗热震性和导电性能的关键因素.固体电解质抗热震性与导电性能的匹配,对低氧含量下的钢水定氧起着重要作用.以此为前提,建立了电解质材料体系的抗热震性与室温相比例之间的线性模型,提出了其高温电导率与相变之间的演化模型.为制备用于测低氧活度的高精度冶金氧传感器提供参考依据.  相似文献
7.
基于一致性几何绕射理论,对半球封闭圆柱体上半球表面的高频绕射声场进行了数值计算与分析。获得了单个点声源作用下,半球表面声场的声压分布图,其中包括一些干涉条纹,干涉条纹的区域及形状与点声源的位置和频率有关;在多个点声源作用下,发现在接近半球顶点的附近,多个声波经多途传播后在该区域的叠加声压由衰减转为增强的现象。  相似文献
8.
我们报告单晶Pr3Co在不同温度下样品的磁化情况.在低温下,磁化强度随磁场强度的变化关系曲线为回线,在高温时为直线.我们还估出了磁化过程中磁性转变(即磁矩变化)的大小.  相似文献
9.
我们报告稀土化合物La3Co的单晶样品在不同的磁场中的电阻率随温度变化的测量结果,从而得出该材料的超导转变温度随磁场的变化关系,超导转变温度随磁场的增大而降低.我们认为这是由于磁场的加大使电子间的相互作用增强,同时减弱了材料中的有效电子(3d、4f)的转移作用.  相似文献
10.
本文通过研究喷射沉积6061Al/SiCp复合材料的超声衰减系数分析材料的阻尼性能。实验结果表明:随着超声频率逐渐增大,该材料对超声吸收和散射增强;在一定范围内,SiC体积分数的增大使吸收衰减系数增大,复合材料阻尼性能增强。  相似文献
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