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151.
A single phase solid solution of Ce-Zr-O can be made by using NH4HCO3 solution as precipitating agent. The influence of preparation conditions, such as pH, Zr4+/(CO3
2-+HCO3
-) and Ce3+/Zr4+ ratio on the formation of the solid solution were investigated. The results show that a single phase Ce-Zr-O solid solution
can be formed only under a narrow window of preparation conditions, indicating that some compounds are formed in the precipitating
process. The compound may contain Ce3+, Zr4+, CO3
2-, HCO3-, and OH-. The solid solution so prepared can be described as Ce0.37Zr0.63O2.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
152.
Shuang‐Jun Lin Chang‐Heng Tan Shan‐Hao Jiang Yi‐Ming Li Da‐Yuan Zhu 《Helvetica chimica acta》2006,89(11):2789-2793
Four new iridoids, buergerinins B–E ( 1 – 4 ), along with three known iridoids, were isolated from the roots of Scrophularia buergeriana. Their structures were identified on the basis of spectroscopic analysis. 相似文献
153.
Slow pyrolysis of walnut shell which is a cheap and abundantly available solid waste was carried out using thermogravimetric
analysis. The effects of raw material heating rate on the pyrolysis properties and kinetic parameters were investigated. A
two-step consecutive reaction model were used to simulate the pyrolysis process. The kinetic parameters were established by
using the pattern search method. Comparison between experimental data and the model prediction indicated that the two-step
consecutive reaction model can better describe the slow pyrolysis of walnut shell as the formation of an intermediate during
the pyrolysis process was taken into account. 相似文献
154.
采用温和条件下的溶胶-凝胶技术,成功制备了阴离子交换-反相混合模式硅胶基质毛细管电色谱整体柱.通过调整反应液中不同前体的比例,优化了整体柱的制备条件.通过扫瞄电镜,对柱床进行了表征和分析.实验发现,所制备的整体柱电渗流的方向和大小可随流动相pH值的改变而改变,在酸性和中性条件下,具有从阴极流向阳极的电渗流;当流动相pH值升至约7.5时,电渗流方向发生了反转(由阳极流向阴极).在优化的实验条件下,用所制备的整体柱对所考察的酸性(中性)化合物实现了快速分离,并获得了高达160,000 N/m的柱效. 相似文献
155.
Guo Hua GAO Jin Bao GAO Wen Juan ZHOU Liang LU Ming Yuan HE 《中国化学快报》2006,17(10):1293-1296
Since much more attention has been paid to the sustainable development, many researchers try to improve conventional chemical process and find new and more, environmentally friendly routes1. Aqueous-phase reactions are of interest as environ- mentally ben… 相似文献
156.
硫氰酸根的结构为N≡C-S-,其两端的N原子和S原子分别有一对和三对孤对电子,因此,硫氰酸根可采用多种不同的配位模式与金属离子发生配位。硫氰酸根可作为单齿配体与一个金属离子配位,形成M-SCN或M-NCS的单核配合物,也可以作为桥联配体同时与两个、三个甚至四个金属离子配位形成多核配合物犤1~3犦;另一方面,硫氰酸根是一个具有一定共轭性的偶极子,可传递磁相作用。因此,选择硫氰酸根作为桥联配体,将多个顺磁金属离子桥联形成一维、二维或三维结构的多核金属配合物分子,并研究它们的磁性已成为分子磁学的一个研究领域… 相似文献
157.
A simple and novel method was developed to successfully synthesize N-succinyl-O-carboxymethylchitosan (NSOCMCS) using N-acylation of chitosan with succinic anhydride. The NSOCMCS structure was characterized by Fourier transform infrared and
1H nuclear magnetic resonance. The aggregation behaviors of NSOCMCS were studied using fluorescence spectroscopy, dynamic light
scattering, and atomic force microscopy techniques. The critical aggregation concentration of NSOCMCS in water was determined
to be 0.2–0.3 mg/ml. The apparent hydrodynamic radium of an NSOCMCS aggregate was dependent on the concentration. The aggregates
demonstrated a much swollen association conformation in aqueous solution. The possible aggregation mechanisms for the NSOCMCS
in water are discussed. Moreover, a driving force to form an open aggregation morphology was revealed in this study. Aggregation
behaviors are important physicochemical properties of NSOCMCS, which impact the potential application in the biomedical field. 相似文献
158.
159.
固相萃取-气相色谱-质谱分析肉样中盐酸克伦特罗的残留量 总被引:25,自引:12,他引:25
建立了固相萃取 气相色谱 质谱联机分析肉样中盐酸克伦特罗残留量的方法。对盐酸克伦特罗在C1 8和离子交换固相萃取柱上的保留行为进行了研究 ,发现不同浓度盐酸克伦特罗的固相萃取回收率在 75 %~ 95 %之间 ;肉样中的加标回收率在 70 %~ 83 % ;相对标准偏差在 4 .95 %~ 1 3 .4 % ;最低检出限为 1 μg kg。盐酸克伦特罗的硅烷化产物 ,采用选择离子的模式进行检测 ( 86、2 4 3、2 62、2 77) ,衍生物的峰面积与样品浓度在0 .0 0 2 5 2~ 2 .0 2mg L范围内呈良好的线性关系 ,线性回归系数大于 0 .9999。 相似文献
160.
Shiling Yuan Yijian Chen Guiying Xu 《Colloids and surfaces. A, Physicochemical and engineering aspects》2006,280(1-3):108-115
Molecular dynamics simulations on surfactant octadecylammonium chloride at the air/liquid interface were performed. It was found that the alkyl chains of octadecylammonium would change to order with increasing the concentration of octadecylammonium at the air/liquid interface. Some functions, such as the concentration distributions, the radial distribution function and the mean squared displacement (MSD) were evaluated to investigate the structural properties of interface. We found that the salts can affect octadecylammonium aggregate at the interface: (1) univalent ions, such as chloride and sodium ions, affect slightly the structure of monolayer and (2) bivalent ions, such as sulfate or calcium ions, affect greatly, especially for the bivalent negative ions. 相似文献