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31.
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骨折长骨中超声导波传播特性的仿真研究 总被引:5,自引:1,他引:4
采用超声导波评价长骨骨折已成为近两年来的一个研究热点.本文采用混合边界元方法(HBEM)对超声导波在骨裂长骨中的传播情况以及各导波模式的反射系数和透射系数进行了数值分析.研究结果表明,入射导波模式经由裂纹处模式转换后依然保持为主要接收模式不变.对某一裂纹,各模式透射系数常在相近的频率点上达到局部峰值.对于不同深宽比(d/w)裂纹,某些模式透射系数曲线局部峰值所对应的频率存在着相互错开的现象,这些结果可用于选择最优入射导波模式和频率,以便更好地定量评价骨质以及骨裂状况. 相似文献
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CHEN Wu-Hua ZHOU Yun-Long TA Hong-Gui HU Zhi-Biao ZHANG Zhu-Sen QIU Ze-Hai ZHANG Li ZENG Qing-Xin 《结构化学》2009,28(12)
The title compound 1 has been synthesized by the reaction of H_2MoO_4, CdCl_2, H_3PO_4, KF, piperazine hexahydrate and water in aqueous solution under mild hydrothermal conditions. Single-crystal X-ray analysis reveals that the title compound crystallizes in the triclinic system, space group P(-1) with a = 14.049(3), b = 15.972(3), c = 20.043(4) (A), α = 85.82(3), β = 81.28(3),γ = 67.15(3)°, V= 4095.9(14) (A)~3, M_r = 3204.62, Z=2,D_c = 2.598 g/cm~3,μ = 2.360 mm~(-1), F(000) = 3124, the final R = 0.0314, wR = 0.0826 and S = 0.989 for 18592 observed reflections with I > 2σ(I). The crystal packing is stabilized by N-H…O and O-H…O intra- and intermolecular hydrogen bonds to form an infinite 3D network. 相似文献
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A convenient label-free fluorescence(FL) nanoprobe for rapid detection of cadmium(Cd) was established using glutathione-capped CdS quantum dots(QDs) and 1,10-phenanthroline(phen). The prepared CdS QDs exhibited a strong FL emission at 536 nm, which could be quenched by phen due to the photoinduced hole transfer(PHT) mechanism. The existence of Cd effectively recovered the FL intensity of CdS QDs, which was due to the easy detachment of phen from the surface of QDs to form[Cd(phen)2(H2O)2]2+ in solution. Cd concentrations were linearly correlated with the FL intensity in the range of 0.0625-1.25 μmol/L under the optimized conditions and the detection limit was 0.01 μmol/L. Finally, the Cd concentration was accurately quantified in real water sample using the proposed sensor. 相似文献
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Crystallography Reports - Ga x In1 ? x Sb solid solution single crystals (x = 0.03–0.09) have been grown. The dislocation density and electrophysical parameters are measured. A... 相似文献
36.
超声导波已被广泛应用于无损检测与评价,针对超声导波应用中普遍存在的模式混叠与频散问题,本文在采用频谱相位与信号时延函数建模导波频散信号传递系统的基础上,提出了一种单一模式的频散补偿算法。进一步地,通过将选择性频散补偿技术与导波模式分离相结合,本文算法克服了传统补偿算法所不能解决的多模式导波频散问题。板中的Lamb波A0,A1和S0混合模式仿真分析表明,本算法不仅可用于单一导波模式信号合成与频散补偿,而且可在实现多模式混合导波信号选择性频散补偿基础上,解决多模式导波信号中单一模式提取与分离。本文研究有助于超声导波多模式频散信号的分析与处理. 相似文献
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L. P. Golovkova A. I. Telyatnik V. A. Bidzilya N. E. Akhmetova V. I. Konovalova 《Theoretical and Experimental Chemistry》1985,21(2):238-242
PMR was used to investigate the reaction of water dissolved in chloroform with ten macrocyclic polyethers, differing from each other by the kind of donor atoms, the size of the cavity, and the character of the substituants in the macrocycle. The curves representing the shift of the proton signal of water as function of the concentration of the macrocyclic polyether in chloroform were used to calculate the stability constants of the associates of the macrocyclic polyethers with water with the composiiton 11. The analysis of the association constants obtained showed that, according to their ability to coordinating water, the investigated macrocyclic polyethers can be placed into the following order: diaza-18-crown-6 > dicyclohexyl-18-crown-6 > kryptand(2.2.2) > 18-crown-6 > dibenzo-18-crown-6 > dibenzo-24-crown-8 > 15-crown-6 > benzo-15-crown-5 > dithio-18-crown-6 > benzo-12-crown-4.Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 21, No. 2, pp. 248–252, March–April, 1985. 相似文献
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