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951.
The first total synthesis of (±)-abieta-8, 11, 13-trien-7β-ol (7) was accomplished via a strategy of AC→ABC, in which the reduction of the ketone 6 with LiAlH4 gave exclusively the title compound. 相似文献
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954.
合成了以1,1′-双(二苯基膦)二茂铁(dppf)为双齿配体的双核配合物Pd(dppf)Cl_2,并通过红外、元素分析、热重分析.电子光谱对其进行了表征.该配合物及dppf的循环伏安研究结果给出两条可逆性较好的单电子氧化还原曲线.dppf形成配合物后,茂基氧化峰电位值显著增加.Pd(dppf)Cl_2的X-射线晶体结构表明,该配合物属单斜晶系,P2_1/n空间群.晶胞参数a=12.281(2)(?),b=16.497(2)(?).c=16.896(3)(?),β=93.6(2.6)°,Z=4,D_(?)=1.423g/cm~3.与Pd(dppe)Cl_2的晶体结构进行了比较讨论,进一步研究了配体dppf和dppe的配位性能的差别. 相似文献
955.
Electroosmotic flow with Joule heating effects 总被引:9,自引:0,他引:9
Electroosmotic flow with Joule heating effects was examined numerically and experimentally in this work. We used a fluorescence-based thermometry technique to measure the liquid temperature variation caused by Joule heating along a micro capillary. We used a caged-fluorescent dye-based microfluidic visualization technique to measure the electroosmotic velocity profile along the capillary. Sharp temperature drops close to the two ends and a high-temperature plateau in the middle of the capillary were observed. Correspondingly, concave-convex-concave velocity profiles were observed in the inlet-middle-outlet regions of a homogeneous capillary. These velocity perturbations were due to the induced pressure gradients resulting from axial variations of temperature. The measured liquid temperature distribution and the electroosmotic velocity profile along the capillary agree well with the predictions of a theoretical model developed in this paper. 相似文献
956.
Yan Ying Liang Bo Li Xuan Xu Feng Long Gu Chaoyuan Zhu 《Journal of computational chemistry》2019,40(9):971-979
In this work, we investigated the nonlinear optical (NLO) properties of excess electron electride molecules of M[Cu(Ag)@(NH3)n](M = Be, Mg and Ca; n = 1–3) using density functional theory (DFT). This electride molecules consist of an alkaline-earth (Be, Mg and Ca) together with transition metal (Cu and Ag) doped in NH3 cluster. The natural population analysis of charge and their highest occupied molecular orbital suggests that the M[Cu(Ag)@(NH3)n] compound has excess electron like alkaline-earth metal form double cage electrides molecules, which exhibit a large static first hyperpolarizability () (electron contribution part) and one of which owns a peak value of 216,938 (a.u.) for Be[Ag@(NH3)2] and vibrational harmonic first hyperpolarizability () (nuclear contribution part) values and the ratio of /, namely, η values from 0.02 for Be[Ag@(NH3)] to 0.757 for Mg[Ag@(NH3)3]. The electron density contribution in different regions on values mainly come from alkaline-earth and transition metal atoms by first hyperpolarizability density analysis, and also explains the reason why values are positive and negative. Moreover, the frequency-dependent values β(−2ω,ω,ω) are also estimated to make a comparison with experimental measures. © 2018 Wiley Periodicals, Inc. 相似文献
957.
本文研究了Mn(Ⅱ)催化KIO_4氧化二苯胺磺酸钠的显色反应。在NaAc-HCl介质中,以氨三乙酸作活化剂,当测定波长为510nm时,锰浓度在0~150ng/25mL范围内与吸光度呈线性关系。该法已用于测定茶叶、莲子、黄豆等样品中的痕量锰,结果个人满意。 相似文献
958.
959.
A new method of SS-RTP for the determination of trace silver has been established. This method is based on the fact that Ag+, when activated by ,-bipyridyl (bipy) in a media of HAc–NaAc (pH=4.9), can catalyze the reaction of Rhodamine B (RhoB) oxidized by K2S2O8, thus causing the Solid Substrate Room-Temperature Phosphorescence (SS-RTP) of RhoB to be quenched. The activating efficiency of bipy is 6.7 times higher than that of o-phenanthroline (phen). The reduction of the phosphorescence intensity (Ip) of RhoB is directly proportional to the concentration of Ag+ ions in the range of 1.6016.0agspot–1 (0.40µLspot–1). The regression equation of the working curve can be expressed as Ip=18.78+5.100mAg+ (agspot–1) (r=0.9994, n=6), the detection limit is 0.28agspot–1. This rapid, accurate and sensitive method has been successfully applied to the determination of trace silver in tea and human hair samples, and the results agree well with the Atomic Absorption Spectroscopy (AAS) method. The mechanism of the catalyzing reaction is also discussed. 相似文献
960.
Guo Jin-xin Cui Yu Song Xin-yu Li Xue-mei Sun Xuan Fan Wei-liu Sun Guo-xin Sun Si-xiu 《Journal of Radioanalytical and Nuclear Chemistry》2003,257(2):317-321
Interfacial tension and interfacial adsorption parameters for benzyloctadecyldimethyl ammonium chloride (BODMAC) in three organic diluents were determined and interpreted. The interfacial activity of BODMAC is affected by the type of the organic diluent and the composition of the aqueous phase. The general order of interfacial activity of BODMAC is n-heptane (5% isobutanol) > carbon tetrachloride > chloroform. The effectiveness of adsorption of BODMAC is not only dependent on the organic diluent, but also on the inorganic electrolytes in the aqueous phase. 相似文献