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171.
表面增强拉曼光谱(SERS)技术是一种基于贵金属纳米结构基底对被检测物进行高灵敏度检测的一种方法.具有特殊纳米结构的贵金属表面受到激光的照射时,金属表面的自由电子会受到极大的振荡,当入射光频率与振荡频率相近时,则会发生表面等离子体共振现象(SPR),使金属表面的局域电场强度极大增强,入射光强度和散射光强度都得到成倍的放大,从而使吸附在贵金属纳米结构表面的分子的拉曼散射信号得到有效的增强.使用NaBH4还原-酸刻蚀模板法,制备了八面体Au/Ag复合纳米笼,其形貌规整,尺寸均匀约为600 nm,无Cu2O模板的残留,Au元素均匀负载在Ag纳米笼上,质量分数约为16.8%;Au/Ag复合纳米笼的紫外可见吸收峰相对于Ag纳米笼发生了红移,更重要的是,Au和Ag元素协同赋予了复合纳米笼超高的SERS灵敏度和重复性,Au/Ag复合纳米笼实现了对罗丹明6G的痕量检测(5×10-14 mol/L),通过时域有限差分法(FDTD)模拟证实:这主要归因于等离子共振作用产生的高电磁场强度;此外,Au元素的加入使Au/Ag复合纳米笼具有优异的抗氧化性和化学稳定性,即使在1%的H2O2溶液中浸泡3 h,仍然能够保持优异的SERS性能.八面体Au/Ag复合纳米笼有望成为一种具有应用前景的高灵敏度、高稳定性的SERS基底. 相似文献
172.
The thermal decomposition of ammonium vanadyl oxalate supported on La2O3, MgO, SiO2, Al2O3, ZrO2, TiO2, SAPO-5, and ZSM-5 oxides in a dynamic atmosphere of dry air was compared by thermal gravimetric analysis (TG) and differential thermal analysis (DTA). The calcined catalysts were characterized by X-ray diffractometry (XRD). The TG and DTA results demonstrate that the surface acid-base properties of the oxides play a significant role in the decomposition behaviour of the supported ammonium vanadyl oxalate, i.e. the basic oxides exhibit an endothermic effect and the acidic oxides show an exothermic effect. Two mechanisms are suggested for thermal decomposition of ammonium vanadyl oxalate on basic and acidic oxides, respectively. After transformation of the ammonium vanadyl oxalate to vanadia, subsequent rearrangement of the vanadia on the surface of the supports was also observed. During the thermal treatment or calcination in air, solid state reactions of vanadia with the surface of oxides such as La2O3, ZrO2 and TiO2 took place to form new phases. 相似文献
173.
A rapid and simple method, the so-called stearic acid method (SAM) was developed to prepare nanostructured TiO2/SnO2 binary oxides by combustion of stearic acid precursors. The preparative process was studied by Fourier transform infrared spectroscopy (FT-IR). During the preparative process, metal precursors were dispersed in stearic acid at molecular level. Microstructure of the samples was investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), BET specific surface area measurement and the results were compared with those obtained by conventional sol-gel method. The photocatalytic decomposition of methyl orange was used as a model system to determine the relative influences of the preparation method and the concentration of SnO2 on the photocatalytic activities. It was found that preparative methods affected the crystalline structure of TiO2/SnO2 powders and the anatase phase of TiO2 was stabilized by the addition of SnO2 in SAM. The samples prepared by SAM showed better dispersity, larger specific surface area and the TiO2/SnO2 (r=0.15, SAM) catalyst showed higher photocatalytic activity than Degussa P25. 相似文献
174.
高硅ZSM—5沸石填充硅橡胶膜的醇—水渗透蒸发分离性质 总被引:5,自引:3,他引:5
高硅ZSM-5沸石填充疏水性硅橡胶蓦地低浓度醇-水体度醇-水体的渗透蒸发性质的研究有明,提高沸石硅铝比,增加填充量以及进行酸处理皆有利于改善膜对醇-水的分离系数和通量。料液的成,浓度以及温度对膜的分离性质也有显著影响。 相似文献
175.
Jing XU Lan Hua ZHAO Xin Guo WU Hong Mei WANG Ru Xiu CAI College of Chemistry Molecular Science Wuhan University Wuhan Stuff of Chemistry Yunyang Medical College Shiyan College of Resources Environmental Science Wuhan University Wuhan 《中国化学快报》2006,17(7):949-952
Quantification of free radical formation is critical for evaluation and interpretation of many radical-mediated biological processes1-4. Numerous studies have been devoted to the determination of free radicals, but the most of the reports have been focuse… 相似文献
176.
Xue Yuan HU Xue Sen FAN Xin Ying ZHANG Gui Rong QU Yan Zhen LI School of Chemical Environmental Sciences Henan Key Laboratory for Environmental Pollution Control Henan Normal University Xinxiang Chongqing University of Medical Sciences Chongqing 《中国化学快报》2005,(7)
Construction of tetrahydropyran rings has attracted a great deal of interests in organic synthesis in recent years1, since tetrahydropyran moiety constitutes a structural unit in a number of natural products2. In addition, tetrahydropyran derivatives possess wide range of biological activities and pharmacological properties, such as anticancer activity3 and antihypersensitivity4. Many methods for the preparation of such compounds have already been developed5. Among them, condensation of α, β… 相似文献
177.
采用动态TG-DTG,研究了铁催化剂的制备方法、前驱化合物的 种类及 热处理对其在碳-氧反应中催化活性的影响。观察到在干混法制备催化剂时,所用铁盐分解温度越低活性越高。此外还发现,热处理可明显提高由分解温度高的含氧铁盐制备的 催化剂的活性,但对于不含氧铁盐和分解温度低的含氧铁盐无影响。 相似文献
178.
本文研究了新显色剂5-Br-TAMB与铑(Ⅱ)的显色反应。在pH5.0~7.0的水溶液中,铑(Ⅱ)与5-Br-TAMB形成1:2型稳定的蓝色配合物,其最大吸收波长为674nm,表观摩尔吸光系数为1.1×10~5L·mol~(-1)·cm~(-1),铑(Ⅱ)含量在0~12μg/ml范围内服从比耳定律。采用加入适量EDTA的方法消除了Cu~(2+)、Co~(2+)、Ni~(2+)等干扰离子。建立了一个在二元配合物体系中具有高灵敏度及选择性、稳定、简便地吸光光度测定微量铑(Ⅱ)的新方法。 相似文献
179.
Xin Sheng Li Yao Jun Zhang Qin Xin Chun Xin Ji Yan Fen Miao Li Wang 《Reaction Kinetics and Catalysis Letters》1996,57(1):177-182
Volumetric H2-uptake measurements on an Mo2N (79 m2g–1) sample reduced at 673 K have been carried out and the uptake isotherms in the temperature range of 308–623 K have been determined. Both the total and reversible hydrogen uptake increased with the uptake temperature. The irreversible hydrogen uptake increased abruptly when the uptake temperature was raised up to 423 K. The maximum of irreversible hydrogen uptake was measured at 473 K. The HIR/Mo ratio calculated from the uptakes obtained in the temperature range of 308–623 K varies in the range of 0.0010–0.0202. One possible mechanism for hydrogen adsorption is proposed to be heterolytic dissociation on Mo-N paris, in which the molybdenum atoms are in unsaturated coordination. 相似文献
180.