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991.
采用大气熔炼-机械球磨二步法制备一系列Ni-Si合金材料和Ni-Si/C复合材料,并运用X射线衍射XRD、场发射扫描电子显微镜FE-SEM和恒电流充放电等测试方法对Ni-Si合金材料和Ni-Si/C复合阳极材料的结构和电化学性能进行了研究.结果表明,Ni-Si合金材料的放电比容量随着Si含量的增加呈上升趋势,但第1周材料充放电的库仑效率下降;采用炭包覆法制备的Ni-Si/C复合阳极材料与Ni-Si合金材料相比,其电化学循环性能大幅度提升,Ni-Si/C复合阳极材料第10周放电比容量保持分数是Ni-Si合金材料的6倍左右,这是因为机械球磨使炭粉均匀地分布在合金颗粒之间,提高了复合阳极材料的导电性. 相似文献
992.
城市下水道产生大量的有害气体,最常见的是硫化氢气体,本文对下水道中产生硫化氢气体的原因进行了分析并提出了减少硫化氢产生的措施和在下水道施工作业中硫化氢气体监测的方法。 相似文献
993.
This research analyzed amino acid sequence similarity between non-self T cell epitopes recognized by mouse antibodies and mouse proteins. Using sequence alignment,we found that only 8 of 1 108 epitopes are highly similar to mouse protein sequences. The result shows that non-self T cell epitopes are not similar or have little similarity to mouse protein sequences. Furthermore,reviewing the related literature,we also found that the eight epitopes would trigger immune responses in some particular environment,which are ignored by T cells in normal condition. The result suggests that no or low-similarity peptide vaccines can reduce the chance of collateral cross-reactions and enhance the antigen-specific immune response to vaccine. 相似文献
994.
In this paper, CdS quantum dots sensitized TiO2 composite powders (QD-CdS/TiO2) were synthesized by impregnating TiO2 powder into CdS sol with different concentrations. X-ray diffraction pattern (XRD) shows the crystal structures of CdS and TiO2 are cubic phase and anatase phase separately in QD- CdS/TiO2 powder samples; the crystal size of CdS in QD- CdS/TiO2 is about 3-7 nm, while TiO2 crystal size is about 20 nm. With increasing CdS content in QD-CdS/TiO2 composite, the UV-Vis absorption spectrum shifted to the longer wavelength lines, exhibiting obvious quantum size effect. The fluorescence intensity of QD-CdS/TiO2 irradiated by blue light is weaker than that of pure CdS. When the molar ratio of CdS and TiO2 is about 1∶2, the QD-CdS/TiO2 powder has the best catalytic properties under visible-light irradiation, and the degradation rate of rhodamine B (RhB) is up to 92.2% within 60 min. 相似文献
995.
对用后铝镁碳砖再生颗粒料的组成和结构特点进行显微分析,并通过改变混料方式以及不同粒度再生料的加入量研究假颗粒对再生铝镁碳制品结构与性能的影响.结果表明:用后铝镁碳砖再生料中含有约40%与废砖相组成和结构相似、骨料与基质并存于同一颗粒的二次颗粒,即所谓的"假颗粒",假颗粒的组成、结构及外形的均匀程度均远不如一次骨料颗粒;混碾可使用后铝镁碳砖再生料中假颗粒发生二次破碎,且粒度越大,发生二次破碎的颗粒数量越多;假颗粒二次破碎导致再生制品的粒度组成发生改变,进而影响其密度和耐压强度. 相似文献
996.
Well-crystalline CeO2 nanowires were prepared via a surfactant-assisted hydrothermal process. Reaction temperature and reaction time were changed for the determination of
optimal synthesis parameters. The as-obtained products were characterized by X-ray diffraction (XRD), high-resolution transmission
electron microscopy (HRTEM), and field emission scanning electron microscopy (FESEM). The results show that single crystal
CeO2 nanowires with high yield and good uniformity can be obtained hydrothermally at 180°C for 12 h with the aid of 2.0 g surfactant
(polyvinyl pyrrolidone, PVP). The role of PVP was then discussed and a possible growth mechanism was proposed. Moreover, room
temperature photoluminescence (PL) spectra were obtained for these CeO2 nanowires, which are believed to be related to the abundant defects in these nanostructures. 相似文献
997.
A numerical method to simulate the coupled oscillations of flexible structures in flowing fluids 总被引:1,自引:0,他引:1
A numerical method is developed to simulate the coupled phenomena in a fluid-flexible-structure system. Specifically, a two-dimensional
panel method is used to calculate the hydrodynamic forces and a modal superposition method is adopted to solve the governing
equation of an Eulerian beam. The stability boundary of a single flexible beam in a uniform flow is calculated and compared
with previous results to verify the validity of the code. The flow-induced flapping of a single and two flexible bodies for
S=1.0, U*=7.0 are investigated. For the flow-induced vibration of a single beam, the oscillation frequency is close to the secondary
natural frequency of a cantilever. For two parallel flexible beams, they oscillate in phase when the non-dimensional separating
distance H<0.25. When H>0.25, the out-of-phase mode occurs with a jump in frequency. When H>1, the interaction between the two beams decouples and the frequency and forces of each beam revert to behavior associated
with a single beam in the same flow. Simulations of coupled-flapping of two tandem flexible structures proved that the drag
acting on the upstream body is reduced while for that downstream drag is obviously increased when the structures are closely
arranged. The numerical results obtained in the present work are qualitatively consistent with early experimental results. 相似文献
998.
Oskar Michalski Ewa Bidzińska Michał Borowski Krystyna Dyrek Paweł Olko Liliana Stolarczyk Jan Swakoń Piotr Tomasik Elżbieta Wenda 《科学通报(英文版)》2010,55(31):3556-3561
Cornstarch heated in the range of 230–280°C depolymerized into pyrodextrins characterized by two-component EPR signals of relatively stable free radicals. These thermally generated radicals could serve as efficient scavengers for free radicals generated from pyrodextrins with the 200 Gy dose of γ-radiation. The most efficient traps/scavengers were produced from cornstarch at 250–280°C. IR data indicated incorporation of the OH groups to the pyrodextrins. These groups most probably originated from the OH· radicals formed by the radiolysis of water. EPR spectra provided evidence for trapping free radicals generated by γ-irradiation and for their subsequent annihilation on contact with pyrodextrins. Water affected radical processes occurring in pyrodextrins caused by γ-irradiation. 相似文献
999.
高校图书馆借阅超期的原因与对策 总被引:1,自引:0,他引:1
当前高校图书馆借阅超期较为普遍,通过问卷调查得知读者的借阅超期大多无恶意行为。针对这种情况以及高校图书馆自身的条件和特点,实施"告知服务"可减少借阅超期行为,以此提高图书的利用率。 相似文献
1000.
An approach of three-dimensional seismic ray tracing is presented, which is derived from adopting two-dimensional linear traveltime
interpolation (LTI). By adjusting the forward process using the partition of grid interface, and backward step by considering
more directions, the new approach is suitable for the application of three-dimensional models. The calculation results show
that, with the same accuracy, the improved 3-D method is much faster than the method of traditional LTI directly applied in
the three-dimensional case. 相似文献