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环脲硝胺化合物的性能和电子结构之间的关系II. 水解安定性 总被引:2,自引:0,他引:2
环脲硝胺单质炸药具有密度大、能量高、爆速快等优点,但容易水解。水解安定性如何成为它们能否被实际应用或广泛应用的关键问题。文献[1]和[2]实测了系列该类化合物的水解速度常数,并从分子结构和理论有机传统观点分析了它们水解安定性的递变原因,推测了它们的水解机理.为从电子微观层次上研究该类化合物结构与性能之间的规律联系,我们用SCF-CNDO/2全价电子半经验方法进行计算,找到它们的羰基伸缩振动频率与计算参量之间的线性关系。考虑到计算结果对构型、构象的敏感依赖关系,所以将11个文献物分为具单、双和三环三类进行了仔细的优化计算,发现其水解安定性与分子中羰基C上正电荷有关,且受空间位阻效应影响很大。 相似文献
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The attractions of cantilevers made of multiwalled carbon nanotubes(MWNTs)and secured on one end are studied in the non-uniform magnetic field of a permanent magnet.Under an optical microscope,the positions and the corresponding deflections of the original cantilevers(with iron catalytic nanoparticles at the free end)and corresponding cut-off cantilevers(the free ends consisting of open ends of MWNTs)are studied.Both kinds of CNT cantilevers are found to be attracted by the magnet,and the point of application of force is proven to be at the tip of the cantilever.By measuring and comparing deflections between these two kinds of cantilevers,the magnetic moment at the open ends of the CNTs can be quantified.Due to the unexpectedly high value of the magnetic moment at the open ends of carbon nanotubes,it is called giant magnetic moment,and its possible mechanisms are proposed and discussed. 相似文献
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In this work, three-dimensional graphene foams (GFs) are synthesized and characterized by scanning electron micro- scope (SEM) and Raman spectroscopy. The SEM images indicate that after the growth of graphene, the graphene covers the surface of nickel (Ni) foam uniformly. Raman spectra show that the percentages of monolayer, bilayer, trilayer, and multilayer graphenes are - 58%, - 32%, - 8%, and ,.o 2%, respectively. The contact angle (CA) (-- 12°) of water droplet (3 p-L) on GF is found to be larger than that on Ni foam (,- 107°), indicating that graphenes have changed the surface wettability of the Ni foam. Meanwhile, the dynamic characteristics of CA of water droplet on GF are different from those on Ni foam. The mechanisms for different behaviors are discussed, which are attributed to volatilization and seepage of water droplets. 相似文献
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