关于电容、电感对交流电的影响实验的改进设计

如何简便而又明显的利用实验来验证或者探究电容和电感对交变电流的影响呢?我们未采用普通高中课程标准实验教科书物理<选修3-2>介绍的实验,而是利用如下的实验;实验现象明显,易于比较,效果较好.现将实验电路以及实验的具体操作方法介绍如下.     

接枝多胺聚合物制备大孔阴离子交换色谱介质及其蛋白吸附行为评价

以环氧活化聚甲基丙烯酸酯大孔微球(FastSep-epoxy)为基质,通过接枝聚(烯丙基胺)(PAA)制备了大孔阴离子交换色谱介质(FastSep-PAA)。考察了介质的合成条件对离子交换容量(IC)及蛋白结合容量的影响,发现IC随PAA浓度、反应时间和溶液pH的增加均表现为增长趋势;同时结合蛋白吸附容量的变化选择了最优合成条件。通过扫描电子显微镜观察介质的表面形貌,发现其孔隙连通性较好,且接枝前后介质孔道结构无明显变化,PAA配基密度对介质结构无明显影响。此外,通过压汞法和氮气吸附法测定接枝前后不同介质的孔径尺寸和孔径分布情况,并考察该类介质的孔径与蛋白吸附行为的关系,发现其蛋白结合容量未出现随介质孔径尺寸增加而显著下降的现象,且孔径尺寸增加更有利于蛋白在介质内部传质。在126 cm/h的流速下FastSep-PAA介质的原始孔径(即FastSep-epoxy的孔径)为400 nm时的蛋白动态结合容量(DBC)最高(70.3 g/L),该孔径下介质比表面积大,蛋白可吸附位点较多;原始孔径为700 nm及以下的介质蛋白DBC均随流速增加而均有一定下降;原始孔径为1 000 nm的介质蛋...     

Structure,Chemical State and Luminescent Properties of Ce,Gd:YAG Transparent Ceramic for Flip-chip White LED Application

Ce,Gd:YAG transparent ceramic was prepared by tape casting and solid state reaction method. Meanwhile, its crystal structure, chemical state and luminous properties were discussed. The prepared samples are identified as pure garnet structure by the XRD results. The valence states of tetravalent and trivalent Ce ions were identified distinctly by X-ray photoelectron spectroscopy. A strong broad band yellow emission was found in photoluminescence(PL) spectra. The quantum yield reached 90.2% at room temperature. When collaborated with a 1.0 mm × 1.0 mm flip-chip, a luminous efficiency(LE) as high as 116.5 lm/W with a correlated color temperature(CCT) of 6627 K at a power dissipation of 1.13 W at 350 m A was demonstrated, indicating that Ce,Gd:YAG transparent ceramics had a promising potential for high power white light-emitting diodes.     

关于增透膜和增反膜的几点说明

增透膜和增反膜在光学仪器中广泛应用，中学物理中也有增透膜和增反膜的相关课题出现．但是，有些问题容易混淆，现将几个问题明确如下：     

加速度向下就一定是失重吗?

在高中物理教材中牛顿运动定律一章中有一节课讲解了失重和超重的概念，教材中的定义为物体对支持物的压力（或对悬挂物的拉力）大于物体重力的现象为超重现象；反之，物体对支持物的压力（或对悬挂物的拉力）小于物体重力的现象为失重现象．     

Facile Synthesis,Crystal Structure,and Adsorption Property of Small Titanate Nanowires

Small titanate nanowires with NaTi_2O_4(OH) formulation were directly synthesized via the hydrothermal reaction of amorphous titanate particles with concentrated Na OH solution.The average width of these nanowires is smaller than 20 nm,and the surface area is higher than 200 m~2/g.Compared with the larger nanowires obtained by the hydrothermal treatment of crystalline titania in alkaline solution,these small nanowires exhibit larger adsorption capacities and faster adsorption rate in the removal of both heavy metal ions and dyes.