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61.
62.
本文通过分析新建应用型本科院校教务管理工作的特点.提出做好新建应用型本科院校教务管理工作应解决的四个重要环节,并在此基础上提出了加快新建应用型本科院校信息化教务管理的必要性和措施。 相似文献
63.
《Materials Letters》2007,61(14-15):3068-3070
Sol-gel derived Pb(Zr0.53Ti0.47)O3 (PZT) thin films were prepared on LaNiO3 (LNO) buffered titanium foils. The effect of LNO buffer layer thickness on the electric properties of PZT thin films was investigated. The room temperature dielectric constant of PZT thin films increased with increasing LNO thickness. The remnant polarization of PZT thin films on 150 and 250 nm LNO was about 20 uC/cm2. Curie temperatures of PZT thin films were 310, 330 and 340 °C for LNO of 250, 150 and 50 nm respectively. The current-voltage characteristics of PZT thin films were examined for different LNO buffer layer thicknesses, and the space charge limited conduction model was followed in PZT thin films on 50 nm LNO. 相似文献
64.
《Journal of the European Ceramic Society》2000,20(14-15):2509-2517
A modified processing route, which is based on the active filler controlled pyrolysis technique, was followed here to form a homogeneous mullite-SiC nanocomposite. An Al2O3-filled polymethylsiloxane was prepared by the in-situ formation of the SiCO network via a sol-gel process. The filled gels obtained in this way show an excellent machinability with conventional surface grinding techniques. Heat treatment up to 1500°C initiated crystallization of mullite, which showed intragranular SiC precipitation. Based on microstructure characterization in conjunction with thermal analysis, a formation mechanism is proposed which includes the glass transition temperature of SiCO as well as its phase sparation into SiO2 plus nanosized SiC crystallites, giving rise to this new mullite-SiC nanocomposite. 相似文献
65.
《International Journal of Hydrogen Energy》2020,45(28):14311-14319
Developing high efficient and cheap electrocatalysts for carbon dioxide reduction reaction (CO2RR) is the key to achieve CO2 transformation into clean energy. Herein, a series of transition metal dimer and nitrogen codoped graphene (M2N6-Gra, M = Cr–Cu) acting as electrocatalysts for CO2RR are investigated based on the density functional method. For M2N6-Gra (M = Cr, Mn), the selectivity is poor and CO poisoning is serious. Fe2N6-Gra is the best CO2RR catalyst due to the good selectivity and catalytic activity. The calculated overpotential is very small, i.e., 0.03 V for COOH channel, 0.05 V for HCOO channel. Hydrogen evolution reaction is also refrained on the Fe2N6-Gra surface, which further supports its high catalytic performance. For M2N6-Gra (M = Co, Ni, Cu), the catalytic activity is poor due to large overpotentials. These results indicate that if designed carefully, the transition metal dimer and nitrogen codoped graphene would be good candidate for the high efficient and selective CO2RR catalyst. 相似文献
66.
《AEUE-International Journal of Electronics and Communications》2014,68(2):90-96
In this paper, inner T-shaped defected microstrip structure (DMS) is studied, and new bandstop filters with a single band, dual-band and tri-band are developed. The new designs have adjustable multi-band operation and simple circuit topologies, and the symmetrical periodic T-shaped DMS introduces transmission zeros which improve the filter frequency selectivity greatly. The circuit sizes are also reduced because of the inner T-shaped DMS introduces more resonances in a frequency range of 10 GHz but without the requirement of certain coupled lines or resonators. The dual-band and tri-band designs are demonstrated by measurement. 相似文献
67.
The effect of the anion type, in an ionic liquid, on the transition of the crystalline structure when lignocellulose was pretreated in 1-ethyl-3-methylimidazolium acetate (EmimOAC) or 1-ethyl-3-methylimidazolium chloride (EmimCl) was studied. The influence of the pretreatment on the composition, the molecular structure, and the crystalline structure was observed using Fourier-transform infrared (FT-IR) compositional analysis, thermogravimetric analysis (TGA), rheological behavior, and X-ray diffraction (XRD). Compared to EmimCl, EmimOAC pretreatment substantially decreased the lignin and hemicellulose contents. The pretreatment also significantly changed the entanglement or crosslinking state of polymer chains in the lignocellulose solution. The changes in lignin content and the transformation from cellulose I to II were dependent on the anion type of the ionic liquid. The pretreated samples were recrystallized to cellulose II only in EmimOAC, whereas the samples pretreated with EmimCl had both cellulose I and II structures present at the same time. 相似文献
68.
简要介绍了DL-101系列电子水准仪的性能、特点.介绍了电子水准仪在建筑物沉降观测中的应用,并给出了实例. 相似文献
69.
A numerical investigation is conducted to predict the thermal and hydraulic performances of the microchannel heat sink (MCHS) with different geometric parameters of triangular rib in the transverse microchamber. The parametric variables of width, length and height of the triangular rib are studied to find optimum design. The flow structure and characteristics of the interrupted MCHS are interpreted in details. The dimensionless ratios of average Nusselt number, friction factor and thermal enhancement factor are evaluated. It is found that the heat transfer rate is increasing with the increase of rib width and height, but decreasing with the increase of rib length. The boundary layer interruption and redevelopment effects introduced by the triangular rib are discussed. The results of thermal enhancement factor reveals an optimum geometrical parameters for the triangular rib with width = 100 μm, length = 400 μm and height = 120 μm for about Reynolds number of 500, yielding 43% enhancement relative to non-interrupted rectangular MCHS at equal pumping power. The results of mean Nusselt number ratio reveal an optimum enhancement of 56% relative to non-interrupted MCHS. 相似文献
70.
When the Airborne Early Warning (AEW) radar transmits medial or high Pulse Repetitive Frequency (PRF) signal, the range ambiguity occurs. The clutter of short-range clutter has serious range dependence problem for non-Side Looking Airborne Radar (non-SLAR). As a result, the clutter plus noise covariance matrix can not be estimated correctly, and the performance of clutter suppression obtained by Space-Time Adaptive Processing (STAP) degrades greatly. The uniform linear array has not elevation degrees; therefore, the short-range clutter can not be suppressed directly. A short-range clutter suppression method is proposed. The method first estimate the elevation angles of the am-biguous short-range gate, then eliminates short-range clutter by space time interpolation and adds moving target protection in the procedure. This method can suppress the short-range clutter well. Simulation results show the validity of the method. 相似文献