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Cyclic plasticity experiments were conducted on a pure polycrystalline copper and the material was found to display significant cyclic hardening and nonproportional hardening. An effort was made to describe the cyclic plasticity behavior of the material. The model is based on the framework using a yield surface together with the Armstrong–Frederick type kinematic hardening rule. No isotropic hardening is considered and the yield stress is assumed to be a constant. The backstress is decomposed into additive parts with each part following the Armstrong–Frederick type hardening rule. A memory surface in the plastic strain space is used to account for the strain range effect. The Tanaka fourth order tensor is used to characterize nonproportional loading. A set of material parameters in the hardening rules are related to the strain memory surface size and they are used to capture the strain range effect and the dependence of cyclic hardening and nonproportional hardening on the loading magnitude. The constitutive model can describe well the transient behavior during cyclic hardening and nonproportional hardening of the polycrystalline copper. Modeling of long-term ratcheting deformation is a difficult task and further investigations are required. 相似文献
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用微波辐照的方法制备了均分散BIiOCl微粒,本文介绍了制备的过程呼条件,对微波的作用机理也进行了初步的讨论。 相似文献
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Yun Yang Li Zhang Lang Liu Guangfei Liu Jixi Guo Dianzeng Jia 《Structural chemistry》2007,18(6):909-915
Three new manganese complexes, [Mn(PPeAP-INH)(CH3OH)2]n(CHCl3) (1) [PPeAP-INH=N-(1-phenyl-3-phenylethyl-4-ethylene-5-pyrazolone isoniazid, INH = isoniazid], [Mn2(PM4MbP-INH)2(CH3OH)4](CH3OH) (2·CH3OH), [PM4MbP-INH=N-(1-phenyl-3-methyl-4-(p-methylbenzoylene)-5-pyrazolone) isoniazid)] and [Mn2(PPePeP-INH)2(CH3OH)4] (3) [PPePeP-INH=N-(1-phenyl-3-phenylethyl-4-phenylethylene-5-pyrazolone) isoniazid] have been prepared, aiming at the formation
of extended coordination polymer with Mn(II) ions. Formation of the corresponding manganese-ligand complexes has been monitored
and characterized by chemical and spectroscopic techniques. X-ray diffraction analyses of available single crystals revealed
1D polymeric patterns of supramolecular system. Among them, the dimers of 2 and 3, bridged by two methanol molecules, are extended by hydrogen bond of O–H···N to form the 1D chain. In these three new complexes
which are all octahedral coordination environments, the N(5) atom of the pyridine heterocycles plays a very important role
in building the bridged polymeric chain. 相似文献
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介绍一个涵盖有机合成、药物化学与仪器分析等学科的研究探索型综合实验,本实验选择具有抗癌、抗菌、抗糖尿病和抗病毒活性的喹喔啉酮类烯胺酮分子作为合成与研究对象,首次使用可循环的酸性树脂Amberlyst15为非均相催化剂,在可见光的协同催化下,利用Mannich反应一步合成喹喔啉酮类JNK3 (c-Jun N-terminal kinase 3)抑制剂。本实验取材于学科前沿热点且已有较多验证的研究前沿成果,不仅有助于学生可以学习到经典Mannich反应的实验操作方法,巩固了专业知识的理解,同时也紧跟时事,学习非均相催化和光催化的相关知识,结合拓展阅读,提高了他们的探索创新意识。建议纳入本科高年级和研究生低年级的综合化学实验课程。 相似文献
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人类文明的历程就是人与自然协调的过程,人类改造自然的历史就是一部环境保护与破坏的冲突史。进入21世纪,人类对自然的侵害、对环境的破坏、对资源的浪费到了非常严重的时期。当我们不得不面对日益严重的水荒、煤荒、电荒时,我们才清楚地意识到,危机真的到来了。 相似文献
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浮选药剂BET在煤与黄铁矿表面作用的ESCA分析 总被引:1,自引:2,他引:1
经ESCA谱图解析分析,证明了BET在煤表面的吸附,并随BET的用量增加而增加.BET在黄铁矿表面基本不吸附;煤系黄铁矿与矿系黄铁矿最大的区别在于碳谱,煤系黄铁矿的峰强度明显大于矿系黄铁矿的.矿系黄铁矿碳主要以杂质碳形式存在,且其表面含量在30%左右.煤系黄铁矿在化学计量组成中含有碳的矿物,其表面的含碳量均大于40%.高碳质含量对于煤系黄铁矿的浮选行为起了十分重要的作用;以石灰为黄铁矿的抑制剂,经超声强化后,黄铁矿表面钙的吸附量增加的更大,钙元素含量由0.95%增加到2.95%.证明了超声波强化煤炭脱硫降灰作用,是促进Ca(OH)2在黄铁矿表面的吸附,达到进一步抑制黄铁矿的目的. 相似文献
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针对目前大采高的特点,提出顺槽巷道采用大断面六边形巷道,并采用相似模拟实验研究了该巷道应力分布及围岩的变形破坏方式;得出巷道围岩水平与垂直位移规律、围岩裂隙演化及破坏规律;从巷道稳定性理论出发,提出六边形巷道最优断面的设计方法;分析了大断面六边形巷道的可行性、适用性及其优越性。为大采高顺槽巷道的维护提供了全新的理论和方法。 相似文献
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