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进行了3种应力水平下2024-T62铝合金的疲劳裂纹扩展试验,利用试验数据对疲劳裂纹扩展的分散性进行了统计分析。分析结果表明:2024-T62铝合金的疲劳裂纹扩展试验数据服从对数正态分布;随着载荷循环数的增加,疲劳裂纹尺寸的标准差和变异系数都增大;试验应力水平对疲劳裂纹尺寸的分散性有一定的影响,随着载荷循环数的增加,高应力水平下疲劳裂纹尺寸的标准差大于低应力水平下疲劳裂纹尺寸的标准差,且高应力水平下疲劳裂纹尺寸标准差与变异系数的增加速度比低应力水平下疲劳裂纹尺寸标准差与变异系数的增加速度快;利用疲劳裂纹扩展试验数据使随机疲劳裂纹扩展模型得到了验证。 相似文献
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To construct superoxide dismutase (SOD) mimetics, three Cu(Ⅱ) coordination polymers (CPs), [Cu3(L1)4(OH)2(H2O)2]n (CP 1), [Cu(L2)(OH)]n (CP 2) and [Cu(L2)(CH3O)]n (CP 3), in which n is a positive integer, are synthesized by solvothermal method using nicotinate N-oxide (HL1) or isonicotinate N-oxide (HL2) as organic ligands and Cu(OAc)2·H2O as metal salt. Their structures and properties are characterized by single crystal X-ray diffraction, X-ray powder diffraction, infrared spectroscopy, elemental analysis, thermogravimetric analysis and ultraviolet spectroscopy. CPs 1~3 are synthesized under similar solvothermal conditions, but show a multi-dimensional configurations from one-dimensional, two-dimensional to three-dimensional, respectively, exploring the possible mechanisms of the relative position of functional groups in ligand, the coordination mode of ligand and the solvent system on the structural diversity of CPs. Thermogravimetric analysis shows that CPs 1~3 can be stabilized up to 202, 228, and 250 ℃, respectively, which display good thermal stability, and the higher the dimension of CPs 1~3, the better the thermal stability. Nitrotetrazolium blue chloride (NBT) photoreduction test shows that the semi-inhibitory concentration values (IC50) of CPs 1~3 are 0.21, 0.26 and 0.62 μmol/L, respectively, which display certain SOD activity, and the lower the dimension of CPs 1~3, the better the SOD activity. The lower IC50 of CP 1 and CP 2 indicating that they can be used as potential SOD mimetics. 相似文献
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掘进机装载机构圆锥齿轮减速器的设计特点 总被引:1,自引:0,他引:1
着重介绍了EBJ-160型掘进机装载机构圆锥齿轮减速器的设计特点,并阐述了该减速器在结构、齿制、选材及热处理工艺和密封结构等方面采取的一些新的技术和措施。 相似文献
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北京市贯彻落实国务院关于稳增长、调结构、惠民生、促改革的相关部署,2013年下半年以来,制定落实了一系列的政策措施,催生新产业新业态新技术培育消费新热点新需求,努力使信息消费成为北京扩大内需拉动增长的重要力量。 相似文献
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GSM技术诞生至今,以其成熟、稳定、高性价比和全球占据绝对优势的用户基础等特点,在无线网络发展中显示出旺盛的生命力。随着无线技术的发展,很多先进的技术理念如B3G(后3G)技术被引入到当前的2G网络中来,旨在提高网络的无缝演进能力、提升网络性能,为人类提供更优质的无线通信服务。 相似文献