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131.
水相金属有机化学   总被引:4,自引:0,他引:4  
邓道利  陆忠辉  吴可 《有机化学》1994,14(4):337-349
本文对近年来锡、锌、铋等介入下的水相金属有机化学作了综述。特别对水相Barbier 反应作了较详细的介绍, 同时也描述了一些典型的水相金属有机反应,如Immonium 阳离子的烷基化反应, α, β 不饱和化合物的共轭加成, 醇醛缩合反应及水溶性金属有机化合物的反应等。某些反应的机理也被讨论。  相似文献   
132.
Recent advances on the deoximation reactions are reviewed in this review. It was shown that catalytic deoximation with molecular oxygen as the mild oxidant should be the developing trend of the reaction.  相似文献   
133.
Zhong H  Li N  Zhao F  Li KA 《Talanta》2004,62(1):37-42
A new protein determination method by enhanced Rayleigh light scattering (RLS) technique has been developed. In acid condition (pH=3.60), RLS of 1,2-dihydroxyanthraquinone-3-sulfonate (Alizarin Red S) can be greatly enhanced by addition of proteins, resulting in two characteristic peaks, 360 and 505 nm, respectively. The new protein assay is based on the RLS enhancement and spectrum change. The optimum condition for the reaction was investigated. The linear range is 0.20-24.9 μg ml−1 for BSA and 0.20-15.5 μg ml−1 for HSA. The detection limits (S/N=3) are 9.59 ng ml−1 for BSA and 9.51 ng ml−1 for HSA. The results of determination for human serum samples were comparable to those obtained by Bradford method. The binding stoichiometry was determined.  相似文献   
134.
New symmetrical and asymmetrical triphenylene-containing discotic liquid crystals with two different peripheral alkyl chains, known as sym-TP(OC6H13)3(OR)3 and asym-TP(OC6H13)3(OR)3, were synthesized. Their thermotropic liquid crystal properties were investigated through polarizing optical microscopy (POM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD) analyses. The asyrranetdcal discogens are 2,6,11-rialkoxy-3,7,10-trihexyloxytriphenylenes, with the alkyl chain carbon numbers varying from 3-10, 12, and 14, while the symmetrical compounds are 2,6,10-trialkyloxy-3,7,11-trihexyloxytriphenylene. Two fluoroalkoxy substituted triphenylene discogens, 2,6,10-td(4,4,4-trifluorobutoxy)-3,7,11-trihexyloxytriphenylene and its asymmetrical isomer 2,6,11-tri(4,4,4-trifluorobutoxy)-3,7,10-trihexyloxytdphenylene were prepared. These two compounds show higher melting and clearing points than their alkoxy analogs, which implies that fluorophilic effect exists in the formation and stabilization of discotic columnar mesophase. The triphenylene derivatives TP(OC6H13)3(OR)3 with two different peripheral chains, symmetrically or asymmetrically attached on triphenylene cores, have lower melting points and clearing points than those of the higher symmetrical compounds TP(OR)6 with the same total chain carbon numbers. The mixed-chain-triphenylenes with longer alkoxy chains (n=9,10,12,14) show columnarmesophase at room temperature.  相似文献   
135.
Mesoporous titanium dioxide nanosized powder with high specific surface area and anatase wall was synthesized via hydrothermal process by using cetyltrimethylammonium bromide (CTAB) as surfactant-directing agent and pore-forming agent. The resulting materials were characterized by XRD, nitrogen adsorption, FESEM, TEM, and FT-IR spectroscopy. The as-synthesized mesoporous TiO2 nanoparticles have mean diameter of 17.6 nm with mean pore size of 2.1 nm. The specific surface area of the as-synthesized mesoporous nanosized TiO2 exceeded 430 m2/g and that of the samples after calcination at 600 degrees C still have 221.9 m2/g. The mesoporous TiO2 nanoparticles show significant activities on the oxidation of Rhodamine B (RB). The large surface area, small crystalline size, and well-crystallized anatase mesostructure can explain the high photocatalytic activity of mesoporous TiO2 nanoparticles calcined at 400 degrees C.  相似文献   
136.
Dextran-Fe3O4 hybrid clusters were fabricated by coprecipitating ferric and ferrous ions in the presence of dextran, and after characterization of these clusters combined with calculation based on classical nucleation theory, a structure model of these hybrid clusters was proposed. The hybrid cluster was believed including small Fe3O4 nanoparticles and dextran which acted as both nucleating agent and stabilizer, so that exist in both the inside of magnetite nanoparticles and the periphery of the hybrid clusters. Besides, the effects of WCD (weightiron cation:weightdextran) and molecular weight of dextran on the size, morphology and magnetic property of clusters were also investigated in this paper. It was found that the variation of WCD and molecular weight of dextran have great effect on the size of the hybrid clusters, but have almost no effect on the size of the Fe3O4 nanoparticles. The characterization of magnetic property demonstrated that the Fe3O4 nanoparticles are of a single domain and the saturation magnetization was affected by the size of dextran-Fe3O4 hybrid clusters.  相似文献   
137.
超临界苯类溶剂对聚苯乙烯降解的影响   总被引:2,自引:0,他引:2  
在高压间歇反应器中,温度340~370℃,以苯、甲苯、乙苯和对二甲苯为超临界溶剂研究了聚苯乙烯(PS)的降解特性.苯类物质是聚苯乙烯的优良溶剂,在超临界条件下其优异的传质、传热性能使聚苯乙烯快速降解.聚苯乙烯在不同超临界溶剂中降解转化率相近,而降解产物组成差别很大,分析了不同超临界溶剂对聚苯乙烯降解过程的影响.结果表明超临界甲苯对降解过程影响最小,苯乙烯收率最高.聚苯乙烯降解过程中,高分子链断裂和解聚同时进行,结合连续分布理论建立了聚苯乙烯降解的动力学模型,得到在超临界甲苯中聚苯乙烯链端解聚活化能为138.4 kJ.mol-1.  相似文献   
138.
A quantitative analysis method for penicillins including ampicillin (AmP), benzyl penicillin (BP), oxacillin (OA) and amoxycillin (AmO) is proposed that makes use of the totally internally reflected resonance light scattering (TIR-RLS) signal from the penicillin at the H2O/CCl4 interface in the presence of cetyltrimethylammonium bromide (CTMAB), and enables the pharmacokinetics of penicillin taken orally and excreted through urine to be monitored. Penicillin is coadsorbed with CTMAB at the H2O/CCl4 interface in neutral solution, resulting in the formation of ion associates that display greatly enhanced TIR-RLS signals (maximum at 368–372 nm). This enhanced TIR-RLS intensity was found to be proportional to the penicillin concentration over the range 0.2×10–6 to 2.2×10–6 mol L–1, with limits of determination (3) of 5.0×10–8 to 7.0×10–8 mol L–1. Pharmacokinetics studies performed using the present method show that the excretion of orally-taken ampicillin through urine has a half-time of 1.05 h and an excremental quantum over 8 h of 49.3%, respectively.  相似文献   
139.
具无限时滞的非自治捕食者-食饵系统的持久性   总被引:16,自引:0,他引:16  
王克 《数学学报》1997,40(3):321-332
本文采用新的方法研究了具无限时滞的非自治、非卷积的捕食者-食饵系统的持久性问题,得到了新的、有趣的结果。本文的结果包含已知的结果作为特例.  相似文献   
140.
The synthesis of amphiphilic aggregation-induced emission(AIE) dyes based organic nanoparticles has recently attracted increasing attention in the biomedical fields. These AIE dyes based nanoparticles could effectively overcome the aggregation caused quenching effect of conventional organic dyes, making them promising candidates for fabrication of ultrabright organic luminescent nanomaterials. In this work, AIE-active luminescent polymeric nanoparticles(4-NH_2-PEG-TPE-E LPNs) were facilely fabricated through Michael addition reaction between tetraphenylethene acrylate(TPE-E) and 4-arm-poly(ethylene glycol)-amine(4-NH_2-PEG) in rather mild ambient. The 4-NH_2-PEG can not only endow these AIE-active LPNs good water dispersibility, but also provide functional groups for further conjugation reaction. The size, morphology and luminescent properties of 4-NH_2-PEG-TPE-E LPNs were characterized by a series of techniques in detail. Results suggested that these AIE-active LPNs showed spherical morphology with diameter about 100–200 nm. The obtained 4-NH_2-PEG-TPE-E LPNs display high water dispersibility and strong fluorescence intensity because of their self assembly and AIE properties of TPE-E.Biological evaluation results demonstrated that 4-NH_2-PEG-TPE-E LPNs showed negative toxicity toward cancer cells and good fluorescent imaging performance. All of these features make 4-NH_2-PEG-TPE-E LPNs promising candidates for biological imaging and therapeutic applications.  相似文献   
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