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Polaron tunnelling is studied in xPA/nPPP/xPA (PA for polyacetylene and PPP poly (p-phenylene)) triblock copolymer, which has a well-barrier-well structure. An extended tight-binding Hamiltonian including external electric field is adopted. Without electric field, the injected electrons would not extend over the whole copolymer chain but instead be confined in the segments of PA. This is different from the behaviour of the traditional semiconductors. It is found that the polaron can transfer to the potential barrier-PPP segment when the applied electric field reaches a certain value. The critical polaron tunnelling electric fields depend upon the lengths of PPP segments. 相似文献
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刘德胜 《科技情报开发与经济》2011,21(31):218-219
变电站站址选择是变电站设计的核心。介绍了如何选择一个合理的站址,既节约投资,又安全可靠;分析了变电站站址存在不良地基的原因,提出了相应的处理措施。 相似文献
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Based on non-equilibrium Green's function formalism and density functional theory calculations, we investigate the electronic transport properties of 15,16dinitrile dihydropyrene/cyclophanediene bridged between two zigzag graphene nanoribbon electrodes. Our results demonstrate that the system can exhibit good switching behavior with the maximum on-off ratio high up to 146 which is improved dramatically compared with the case of gold electrodes. Moreover, an obvious negative differential resistance behavior occurs at 0.3 V, making the system have more potential in near future molecular circuits. 相似文献
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刘德胜 《中国新技术新产品精选》2010,(10):69-70
本文通过对公路桥梁工程施工案例的成功应用,采用铜桁架双导粱架桥机进行桥梁预制T型粱体的架设安装施工,因其构件具有设计先进、拆装方便、操作简单、安全可靠、自动化程度高、控制灵活、经济性好等突出特点,使工程生产取得了较明显的效益。 相似文献
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在紧束缚模型的基础上, 研究了由聚乙炔(PA)和聚对苯撑(PPP)组成的准一维多嵌段共聚物系列材料的电子特性, 发现它们具有量子阱或超晶格特征. 各单体的尺度、单体间界面耦合以及电子-声子相互作用的强弱对共聚物的电子性质都有显著的影响, 与传统半导体量子阱和超晶格相似, 沿链方向外加电场的作用, 可导致量子隧穿的发生以及Franz-Keldysh效应和量子约束效应的出现. 相似文献
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本文对《互换性与测量技术》的教学提出几点体会。指出在加强直观性教学激发学生学习兴趣的同时,适当采用形象案例启发性教学来提高学生的学习主动性和积极性,突出重点,讲清难点,加强基本知识的教学。 相似文献