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排序方式: 共有397条查询结果,搜索用时 15 毫秒
391.
《Analytical letters》2012,45(8):1363-1373
Abstract An amperometric enzyme sensor for the determination of gluconolactone in glucose-containing samples has been developed. The interfering glucose is eliminated by an outer anti-interference layer containing hexokinase, whilst the gluconolactone reaches a glucose de-hydrogenase-glucose oxidase layer, where it is converted into glucose (by glucose dehydrogenase) and then transformed by glucose oxidase, the associated oxygen consumption can be measured at the electrode. Gluconolactone is determined over the concentration range, 0.02–1 mmo1/1, with a toleration of glucose concentration up to 2 mmo1/1. 相似文献
392.
采用共沉淀的方法制备了不同Fe 掺杂量的SO42-/SnO2-Fe2O3固体超强酸催化剂. 利用傅里叶变换红外(FTIR)光谱, 粉末X射线衍射(XRD), N2吸附-脱附实验(BET), 热重(TG)分析和扫描电镜(SEM)等方法对样品进行了表征. 考察了所得催化剂对4-叔丁基环己酮与乙二醇缩合反应的催化性能. 实验结果表明, 与未经过掺杂改性的SO42-/SnO2固体酸催化剂相比, 改性后催化剂的催化性能得到了改善. 研究了以Fe/Sn 摩尔比为0.5的SO42-/SnO2-Fe2O3固体酸为催化剂, 部分醛酮类化合物与乙二醇及1,2-丙二醇的缩合反应. 考察了反应时间、催化剂用量等因素对反应的影响. 同时, 将所得催化剂应用于环酮Baeyer-Villiger 氧化反应中, 催化剂表现出良好的催化活性, 且催化剂具有一定的循环使用性. 相似文献
393.
Vetter W Armbruster W Betson TR Schleucher J Kapp T Lehnert K 《Analytica chimica acta》2006,577(2):250-256
The δ2H- and δ13C-values of polyhalogenated compounds were determined by EA-IRMS. Most of the compounds were related to the chloropesticides DDT and its metabolites, hexachlorocyclohexanes, and toxaphene, as well as several polybrominated compounds such as bromophenols and -anisoles. δ2H-values ranged between −235‰ and +75‰ whereas δ13C-values were found in the range −22‰ to −38‰. No correlation between δ2H- and δ13C-values could be identified. Comparative analysis clarified that bromophenols and the corresponding bromoanisoles may vary in their isotopic distribution. 2H NMR was used to quantify abundances of 2H isotopomers. Quantification of isotopomers of 2,4-dibromophenol and 2,4-dibromoanisole proved that both compounds from different suppliers do not originate from the same source. Differences in the δ2H-values of two toxaphene products were further investigated by the synthesis of products of different degree of chlorination from camphene. It was shown that the δ13C-values remained mostly unaltered as was expected since no carbon is lost in this procedure. However, the reaction products became enriched in 2H with increasing degree of chlorination. Different δ2H-values of the starting material will also impact the δ2H-values of the chlorination products. 相似文献
394.
LaFe1−xNixO3−δ (x=0.1−1.0) perovskites were synthesized via citrate route. The p(O2)-stability of the perovskite phases LaFe1−xNixO3−δ has been evaluated at 1100 °C based on the results of XRD analysis of powder samples annealed at various p(O2) and quenched to room temperature. The isothermal LaFeO3−δ-“LaNiO3−δ” cross-section of the phase diagram of the La-Fe-Ni-O system has been proposed in the range of oxygen partial pressure −15<log p(O2)/atm≤0.68. The unit cell parameters of orthorhombic perovskites O-LaFe1−xNixO3−δ increase with decrease in p(O2) at fixed composition x. This behavior is explained on the basis of size factor. The decomposition temperatures of rhombohedral phases R-LaFe1−xNixO3−δ for x=0.7, 0.8, 0.9 and 1.0 in air were determined as 1137, 1086, 1060 and 995 °C, respectively. 相似文献
395.
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397.
中温复合固体电解质SDC-LSGM的制备和性能 总被引:2,自引:1,他引:1
采用甘氨酸-硝酸盐法分别制备了Ce0.85Sm0.15O2-δ(SDC)与La0.9Sr0.1Ga0.8Mg0.2O3-δ(LSGM)两种电解质材料, 并用固相混合法将两种材料按不同质量比(SDC与LSGM的质量比分别为9∶1, 8∶2, 5∶5)混合制备复合电解质材料. 采用交流阻抗技术对样品的电学性能进行研究. 实验结果表明, SDC与LSGM的质量比为9∶1(SL91)时, 样品具有较高的电导率, 在350—800 ℃温度范围内其电导率均比SDC的高. 以复合电解质为支撑体, 以Sm0.5Sr0.5CoO3 为阴极、NiO/SDC 为阳极制成单电池, 测试结果显示, 在800 ℃时以SL91为电解质的单电池的最大输出功率密度为0.25 W/cm2, 最大电流密度为1.06 A/cm2. 在电池的工作温度区间(600—800 ℃)内以复合材料为电解质的单电池的开路电压比以SDC为电解质的高. 相似文献