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91.
用DSC研究纯三水铝石溶出动力学 总被引:1,自引:0,他引:1
在DSC上研究了NaOH溶液中合成三水铝石的溶出过程动力学。应用非等温反应动力学模型计算了动力学参数,分析和确定了反应机理。模型计算结果与用DSC测得的结果吻合。 相似文献
92.
Hai-Bin Tian Duan-Zhi Yin Lan Zhang Li-Hua Wang Chun-Fu Zhang Jun-Ling Li Wei Zhou Chun-Ying Wu Yong-Xian Wang 《Journal of Radioanalytical and Nuclear Chemistry》2004,262(2):383-389
The compound 3-{[4-(4-[18F]fluorophenyl)methyl]piperazin-1-yl}-methyl-1H-pyrrolo[2,3-b]pyridine ([18F]3), which is an analogue of L-745,870 binding D4
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
93.
The reaction mechanism of the l-proline-catalyzed α-aminoxylation reaction between aldehyde and nitrosobenzene has been investigated using density functional theory (DFT) calculation. Our calculation results reveal following conclusions [1]. The first step that corresponds to the formation of C–O bond, is the stereocontrolling and rate-determining step [2]. Among four reaction channels, the syn-attack reaction channel is more favorable than that of the anti one, and the TS-ss channel dominates among the four channels for this reaction in the step of C–O bond formation [3]. The intermolecular hydrogen bond between the acidic hydrogen of l-proline and the N atom of the nitrosobenzene in an early stage of the process catalyzes very effectively the C–O bond formation by a large stabilization of the negative charge that is developing at the O atom along the electrophilic attack [4]. The effect of solvent decreases the activation energy, and also, the calculated energy barriers are decrease with the enhancement of dielectric constants for C–O bond formation step. These results are in good agreement with experiment, and allow us to explain the origin of the catalysis and stereoselectivity for l-proline-catalyzed α-aminoxylation of aldehyde reaction. The addition of H2O to substituted imine proline, intermolecular proton-transfer steps, and the l-proline elimination process were also studied in this paper. 相似文献
94.
钙黄绿素蓝荧光法测定食品中的微量锌(Ⅱ) 总被引:5,自引:0,他引:5
本文研究了在CTMAB存在下,用钙黄绿素蓝荧光法测定食品中的微量锌(Ⅱ)的实验条件。在本实验条件下,Zn(Ⅱ)与钙黄绿素蓝生成1:1的配合物使钙黄绿素蓝的荧光增强,最大激发波长和最大发射波长分别为353nm和440nm。 相似文献
95.
Tae Oan Ahn Jung Ho Kim Jong Chan Lee Han Mo Jeong Jong-Yoon Park 《Journal of polymer science. Part A, Polymer chemistry》1993,31(2):435-441
A macro-azoinitiator containing polyarylate segment and azo group was prepared by the solution polycondensation of azobiscyanopentanoyl chloride and hydroxy-terminated polyarylates having viscosity-average molecular weights of 6200, 8100, and 12 400. These macro-azoinitiators were used in the radical polymerization of styrene to synthesize polyarylate-polystyrene block copolymers. Thermal properties measured by the differential scanning calorimetry indicated the phase separated morphology of the block copolymers except at low molecular weight of the block constituents. © 1993 John Wiley & Sons, Inc. 相似文献
96.
97.
Amide-water mixtures are studied by all-atom molecular dynamics (MD) simulations and the relative temperature-dependent NMR experiment. The weak C-H...O contacts are found in the amide-water systems theoretically and experimentally. The statistical results of the average numbers of hydrogen bonds indicate that the methyl groups in amide molecules represent different capabilities in forming the weak C-H...O contacts. The statistics also imply that the C-H...O contacts are more obvious in the amide-rich region than those in the water-rich region. The temperature-dependent NMR spectra are also adopted to investigate the weak C-H...O contacts in the amide-water systems. The relative chemical shifts of the methyl groups are in good agreement with the MD simulations. 相似文献
98.
99.
基团的电子效应与单取代苯对位1H、13C的化学位移*韩长日冯娇杨钟照平(海南师范学院化学系海口571158)关键词1H的化学位移13C的化学位移基团电负性共轭效应引言在1H、13C核磁共振谱中,化学位移值的大小主要取决于屏蔽作用的大小,而屏蔽作用的大... 相似文献
100.
The development of highly active and stable reversible oxygen electrocatalysts is crucial for improving the efficiency of metal-air battery devices. Herein, an efficient liquid exfoliation strategy was designed for producing silk-like FeS2/NiS2 hybrid nanocrystals with enhanced reversible oxygen catalytic performance that displayed excellent properties for Zn-air batteries. Because of the unique silk-like morphology and interface nanocrystal structure, they can catalyze the oxygen evolution reaction (OER) efficiently with a low overpotential of 233 mV at j = 10 mA cm?2. This is an improvement from the recently reported catalysts in 1.0 M KOH. Meanwhile, the oxygen reduction reaction (ORR) activity of the silk-like FeS2/NiS2 hybrid nanocrystals showed an onset potential of 911 mV and a half-wave potential of 640 mV. In addition, the reversible oxygen electrode activity of the silk-like FeS2/NiS2 hybrid nanocrystals was calculated to be 0.823 V, based on the potential of the OER and ORR. Further, the homemade rechargeable Zn-air batteries using FeS2/NiS2 hybrid nanocrystals as the air-cathode displayed a high open-circuit voltage of 1.25 V for more than 17 h and an excellent rechargeable performance for 25 h. The solid Zn-air batteries exhibited an excellent rechargeable performance for 15 h. This study provided a new method for designing interface nanocrystals with a unique morphology for efficient multifunctional electrocatalysts in electrochemical reactions and renewable energy devices. 相似文献