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191.
以硝酸锌和硫脲为原料,十二烷基硫酸钠为保护剂,通过一步水热合成反应,制备了具有核壳结构的微米级Zn S半导体材料.该Zn S材料的核、壳成分相同,晶体构造一致,均为立方闪锌矿结构;调节反应时间,可以方便地控制壳层构造的生长与闭合程度;优化反应条件得到整体尺寸约为3μm、核壳结构特征突出的形貌新颖的Zn S微粒;将Zn S材料用于亚甲基蓝的光降解反应,其对目标降解物的降解效率与形貌特征有紧密联系,壳层闭合程度越高,降解效率越低.在最优条件下,该材料对亚甲基蓝的降解率可达97.3%. 相似文献
192.
城市河网洪水过程的一维数值模拟 总被引:1,自引:0,他引:1
基于邻接矩阵和邻接表概念,提出了新的拓扑结构,即利用net、edge和node对象实现河网拓扑信息及河道断面和结点信息的储存;基于虚设河段法,推导出城市河网内边界即集中入流(雨水管出口)、闸堰的追赶系数,从而实现了基于GIS平台的城市河网非恒定流一维数值模拟程序的通用性和可移植性.最后,将温州市区“9.4”暴雨期间的河网洪水过程的计算值与实测值进行了对比,结果表明本模型可较好地模拟城市河网的洪水过程. 相似文献
193.
分析了结构失稳时P_δ试验曲线的图形性质;提出了以最大曲率计算及推算结构失稳临界荷载,并导出了相应的计算公式。运用压杆和刚架弹性稳定试验的实测数据,说明本文所述方法既精确又简便。特别是结构或模型不允许作破坏试验时,可直接推算失稳临界荷载。 相似文献
194.
195.
The B-site substituted perovskite solid solution systems Li3xLa0.67−xREyTi1−2yPyO3 (RE=Sc, Y, Nd, Sm, Eu, Yb) have been investigated. Perovskite solid solutions formed in the range of x=0.10, y<0.10 for RE=Sc3+, Y3+, Yb3+, x=0.10, y≤0.05 for RE=Nd3+, Sm3+, Eu3+. Li0.3La0.57Nd0.05Ti0.9P0.05O3 has the highest bulk conductivity of 4.31×10−4 S·cm−1 and the highest total conductivity of 2.52×10−4 S·cm−1 at room temperature in all prepared compositions. The compositions have low activation energies of about 24–30 kJ/mol in
the temperature ranges of 298–523 K. SEM studies showed that the sample made by solid-state reaction has a sphere-like morphology
and a rough particle with particle size of about 50 μm. The research results also indicated that the reaction temperature
decreases and the electrochemical stabilities of the titanate-based perovskite-type solid solutions are improved by using
RE3+ and P5+ replaced Ti4+ on B-site in the Li3xLa0.67−xTiO3 parent. 相似文献
196.
Liyun Guan Rong Cao Junfei Tian Heather McLiesh Gil Garnier Wei Shen 《Cellulose (London, England)》2014,21(1):717-727
This study investigated the stability of the primary blood typing antibodies (Anti-A, Anti-B and Anti-D IgM) on paper. This knowledge is critical to manufacture a new type of paper-based blood typing device where blood group antibodies must be kept active on paper for extended periods. Two strategies were explored. The first involved mixing additives such as polyvinylpyrrolidone (PVP), dextran and glycerol, with antibodies before sorption onto paper. While all the additives tested improved the antibody stability on paper, their protection for storage at room temperature was limited; dextran provided the longest protection, followed by PVP and then glycerol. The second strategy relied on freeze-drying to stabilize the antibodies in paper. Freeze dried antibodies sorbed into paper could be stored for long periods at ambient conditions without significantly loss of their activity. The thermal stability of antibodies in paper was also improved by freeze-drying. Our work shows that the use of additives and freeze-drying are effective approaches to retain the activities of IgM blood group antibodies on paper. These approaches will be further explored for the large scale development of a new generation of clinical and home-care blood testing devices. 相似文献
197.
Homogeneous crystal nucleation triggered by spinodal decomposition in polymer solutions 总被引:1,自引:0,他引:1
We report dynamic Monte Carlo simulations of polymer crystal nucleation initiated by prior spinodal decomposition in polymer solutions. We observed that the kinetic phase diagrams of homogeneous crystal nucleation appear horizontal in the concentration region below their crossovers with the theoretical liquid-liquid spinodal. When the solution was quenched into the temperature beneath this horizontal boundary, the time evolution of structure factors demonstrated the spinodal decomposition at the early stage of crystal nucleation. In comparison with the case without a prior liquid-liquid demixing, we found that the prior spinodal decomposition can regulate the nanoscale small polymer crystallites toward a larger population, more uniform sizes, and a better spatial homogeneity, whereas chain folding in the crystallites seems little affected. 相似文献
198.
Numerical Algorithms - In this paper, based on two-grid discretizations, two kinds of local and parallel finite element methods are proposed and investigated for the coupled Stokes/Darcy model.... 相似文献
199.
从被积函数的正负性变化规律入手,借助交错级数的敛散性,给出并证明相应反常积分的敛散性,进而推广得出一类反常积分的敛散性判定定理. 相似文献
200.
Causes of the bright cross appearing in the reconstructed field of lensless Fourier transform digital hologram (LFDH) are presented. Firstly, as LFDH's reconstruction was directly performed by Fourier transform algorithm, the intensity distribution of reconstructed image plane was just LFDH's spectrum, and three parts of the reconstructed field are imaged in the spectral plane. Meanwhile their intensities were almost the same. Hence, the ratio of signal to noise of the reconstructed image was obviously lower than that of the conventional digital hologram. Further, non-uniformity of the background intensity and random noises usually existed in a practical LFDH. Meanwhile their spectra spread through the central and the edge areas; this also led to decrease in the ratio of signal to noise of the reconstructed image. Specially, as the two-dimensional Fourier transform algorithm was performed row by row, and then column by column, the low-frequency spectrum induced by the non-uniformity of the background and random noises along the directions of rows and columns would concentrate on the central column and row, respectively, and what is gotten looked like a cross. Therefore, the cross appearing in LFDH's reconstructed field should be attributed to the combination of the background and the Fourier transform algorithm itself. 相似文献