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通过L-丙氨酸与均苯四甲酸二酐的缩合反应得到手性酰亚胺,再与二苯基甲烷二异氰酸酯(MDI)聚合制备出基于L-丙氨酸的手性聚酰胺酰亚胺。用傅立叶红外光谱仪(FT-IR),核磁共振(1H-NMR)表征了聚合物的结构。用差示扫描量热法(DSC)和热重分析(TG)研究了共聚物的结晶性能和热稳定性,同时对聚合物的溶解性能进行了探... 相似文献
53.
A novel single-step synthetic method for the preparation of anatase N-doped TiO2 nanocrystalline at low temperature has been devoleped. The N-doped anatase TiO2 nanoparticles were synthesized by sonication of the solution of tetraisopropyl titanium and urea in water and isopropyl alcohol at 80 °C for 150 min. The as-prepared sample was characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy and UV–vis absorption spectrum. The product structure depends on the reaction temperature and reaction time. The photocatalytic activity of the as-prepared photocatalyst was evaluated via the photodegradation of an azo dye direct sky blue 5B. The results show that the N-doped TiO2 nanocrystalline prepared via sonication exhibit an excellent photocatalytic activity under UV light and simulated sunlight. 相似文献
54.
Desheng Wang Zhibo Yang Fei Li Xinghui Wang Dequan Liu Peng Wang Deyan He 《Materials Letters》2011,65(21-22):3227-3229
Si–Ni nanorod structures as anode materials for Li ion batteries have been prepared by depositing Si coatings on electrodeposited Ni nanocone arrays using plasma enhanced chemical vapor deposition. The obtained samples were characterized by field emission scanning electron microscopy and X-ray diffraction. The electrochemical performance was evaluated by a galvanostatic battery testing. It is shown that the first discharge capacity is high as 4125 mAh/g with a high first coulombic efficiency of 92% at C/20 rate. A capacity of 3249 mAh/g at C/5 rate is attained with retention of 95.7% after 30 cycles. 相似文献
55.
模拟移动床色谱技术是一种高效的现代化分离技术。该技术具有分离能力强、设备体积小、投资成本低、环境污染少、便于实现自动控制等优点,特别有利于分离热敏性物质及难分离的物系,近年来,越来越受到工业界和研究者的关注,研究不断深人,应用领域也不断扩大。对模拟移动床色谱技术在石化、食品、制药三大领域的应用研究进展进行了详细的介绍,以期为相关研究提供参考。 相似文献
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设计了一种基于西门子PLC的铅蓄电池生产控制系统,实现铅蓄电池化成液位、温度、压力等参数的智能控制.对西门子可编程控制器应用于铅蓄电池生产的设计思想做了介绍,重点论述了控制系统的硬件设计与软件编程.现场运行情况表明:该控制系统工作可靠,操作方便,大大提高了劳动生产率. 相似文献
57.
Lei Zhang Jianxing Shen Jiaoxian Yu Hongshi Zhao Zhiliang Xiu Chunlei Yan Chuanshan Li Jinmei Dong Yuan Ma 《Journal of Electroceramics》2011,26(1-4):105-111
0.94(K05Na0.5)NbO3?0.03LiNbO3?0.03LiSbO3 (KNLNS) lead-free piezoelectric ceramics were prepared by conventional mixed oxide route with normal sintering method. The samples were sintered at different temperatures with KNLNS powder atmosphere to prevent volatilization of alkali metal oxides at high temperature. The effects of sintering temperature on the density, structure and electric properties of KNLNS ceramics were studied. X-ray diffraction (XRD) results showed that the crystal structure of the crushed KNLNS ceramic powders were pure perovskite phase with tetragonal phase structure when sintered at T????1080°C. However a K3Li2Nb5O15 phase with tetragonal tungsten bronze structure began to appear when the sintering temperature was higher than 1080°C. The optimum sintering temperature was 1080°C which was determined by measuring the density of the samples. Scanning electron microscope (SEM) observation indicated that the sintering temperature had a great effect on the microstructure of the samples. The KNLNS ceramics under the optimum sintering temperature showed excellent electric properties: ???=?4.29 g/cm3, ?? r?=?826, tan???=?0.049, d 33?=?190 pC/N, k p?=?0.30, and T c?=?385°C. The results show that the KNLNS ceramics are promising candidate for lead-free piezoelectric ceramics. 相似文献
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超声振动铣削2A12表面粗糙度实验研究 总被引:2,自引:0,他引:2
利用小径立铣刀对铝合金进行超声振动铣削实验,重点探讨了超声振幅与每齿进给量对工件槽底表面粗糙度的影响.实验结果表明:槽底表面粗糙随着超声振幅的增大而增大,在每齿进给量fZ<4μm/z时槽超声振幅为主要影响因素;每齿进给量fZ>6μm/z时每齿进给量为主要影响因素.在超声振动铣削加工中应尽量选择小进给量可获得较小槽底表面粗糙度.通过扫面电镜对工件微观形貌观测证实了施加振动后脉冲切削和断续切削双重作用导致槽底表面粗糙度增大. 相似文献
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