Pure water splitting to generate H2 over strontium niobate and tantalate: A comparative study

To clarify the nature of different photocatalytic activities between niobate and tantalate,a comparative study of the water splitting into H2 over strontium niobate and tantalate was performed.These isostructural photocatalysts were prepared by a facile and simple hydrothermal reaction and characterized by powder X-ray diffraction(XRD),N2-sorption,UV-Vis diffuse reflectance spectra(UV-Vis DRS),and transmission electron microscopy(TEM).The effects of crystal structure,Brunauer-Emmett-Teller(BET) surface area,photoabsorption performance,morphology,and electronic structure are discussed.     

正常人不同年龄阶段的脑血流图

本文报道福州地区468名正常人的脑血流图额～乳导联与枕～乳导联的检查结果。对1872幅脑血流图之统计分析表明,脑血流图的波型和指标参数则随年龄增长而有所改变。表现为:波型发生一定变化,重搏波逐渐减低或消失,波幅不同程度下降,两侧波幅差百分比有所增大,主峰角逐渐变钝,上升角趋于变小,上升时间延长,流入容积速度比值减小等。可反映出不同年龄阶段的脑血管机能特点,即血管壁弹性随年龄增长而减退,血管紧张度随年龄增长而升高的生理规律。     

基于DCT的图像压缩及Matlab实现

本文介绍了基于DCT的图像压缩编码技术,并给出了具体的实现方法和步骤,既保证具有较高的压缩比,又保证了较好的图像质量。