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排序方式: 共有279条查询结果,搜索用时 15 毫秒
1.
当分析元素含量极低时,往往要求在测定之前辅以化学分离预富集手段以纯化富集待测物和除去干扰基体。实验利用邻菲罗啉和硫氰酸钾作为微痕量Co2+的络合剂,建立了一种液固体系分离富集微痕量Co2+的新方法。分别考察了邻菲罗啉溶液用量、硫氰酸钾溶液用量、酸度对分离效率的影响。结果表明,当体系中Co2+含量为100 μg时,控制体系pH=2~6,加入1.00 mL 1.5 g/L邻菲罗啉溶液、1.00 mL 0.1 mol/L硫氰酸钾溶液、1.00 mL 10 g/L EDTA溶液、1.00 mL 40 g/L硫脲溶液,震荡静置后,Co2+与邻菲罗啉、硫氰酸钾反应生成的离子缔合物定量沉淀到溶液底部,而Cd2+、Fe3+、Zn2+、Ni2+、Cu2+、Pb2+、Al3+、Ag+等离子仍留在水相中,从而实现了Co2+与这些离子的定量分离。方法成功用于合成水样中微痕量Co2+的定量分离,富集率在97.2%~98.6%之间。 相似文献
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Effect of Mode of Drying on Microstructure of Potato 总被引:2,自引:0,他引:2
Potato v. Irga was subjected to blanching, and thereafter was dried by convection, puff-drying, and freeze-drying. Microstructure of raw, blanched, and dried tissue was analyzed under the light microscope using computer image analysis. It was found that the tissue of the investigated variety is built up from cells much smaller than those described in literature for other cultivars. Blanching caused starch gelatinization and increase of cross-sectional area of cells. There was no evidence of broken cell walls. Convective drying resulted in cell shrinkage and some breaking of cell walls. It was estimated that some 12% of cells lost integrity during drying. Limited disintegration of the tissue caused by convective drying is attributed to small size of cells, large contact area, and high cohesive forces between cells. Puff-drying damaged the tissue much more than the convective drying. The most devastating to tissue microstructure was freeze-drying, probably freezing per se. 相似文献
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泸天化公司大氮肥循环冷却水系统投用以来,经优选水稳剂配方、改进加氯方式、增设旁滤池、提高补充水质量等措施,年腐蚀率从0.3366mm降至0.0241mm,换热器运行一年无结垢现象。 相似文献
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一种基于聚类分析的R~*树结点重叠判定算法 总被引:1,自引:0,他引:1
聚类分析可以对大量空间对象进行聚类划分,优化R*树的结点.根据R*树的强制重插原则,在聚类分析基础上提出一种扩展MBR的对角线段对相交算法以判定类结点的重叠.从根本上改变以往在解决R*树结点重叠时仅将MBR形状改变或单纯紧致正交MBR所存在的问题,以此为判定条件可以控制聚类算法迭代次数,减少噪声点对聚类的影响.其中判定算法时间复杂性为O(nlogn)级.实验结果表明在范围查询中引入基于聚类分析的对角线段对相交判定算法的查询效率优于基于R*树的Gain/Loss度量的贪婪算法和基于SR树的算法的查询效率. 相似文献
7.
Bohan Chen Wenxuan Zhu Tian Wang Bin Peng Yiwei Xu Guohua Dong Yunting Guo Haixia Liu Houbing Huang Ming Liu 《Advanced functional materials》2023,33(36):2302683
Inorganic/organic dielectric composites are very attractive for high energy density electrostatic capacitors. Usually, linear dielectric and ferroelectric materials are chosen as inorganic fillers to improve energy storage performance. Antiferroelectric (AFE) materials, especially single-crystalline AFE oxides, have relatively high efficiency and higher density than linear dielectrics or ferroelectrics. However, adding single-crystalline AFE oxides into polymers to construct composite with improved energy storage performance remains elusive. In this study, high-quality freestanding single-crystalline PbZrO3 membranes are obtained by a water-soluble sacrificial layer method. They exhibit classic AFE behavior and then 2D–2D type PbZrO3/PVDF composites with the different film thicknesses of PbZrO3 (0.1-0.4 µm) is constructed. Their dielectric properties and polarization response improve significantly as compared to pure PVDF and are optimized in the PbZrO3(0.3 µm)/PVDF composite. Consequently, a record-high energy density of 43.3 J cm−3 is achieved at a large breakdown strength of 750 MV m−1. Phase-field simulation indicates that inserting PbZrO3 membranes effectively reduces the breakdown path. Single-crystalline AFE oxide membranes will be useful fillers for composite-based high-power capacitors. 相似文献
8.
Lucas Alves Da Silva Eric Dekneuvel Alexandre Lewicki Benjamin Nicolle Gilles Jacquemod 《Microelectronics Journal》2012,43(2):98-109
In this paper, we propose to develop a hierarchical library associated with various simulators that can be used in a single platform, called TrustMe-ViP, which enables a unique simulation framework and full model interoperability. Such platform is dedicated to complex SoC design, such as trusted personal devices where cost and time-to-market are very important constraints. To validate this methodology, we present the estimation of BER and power consumption for a Bluetooth transceiver. 相似文献
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