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1.
    
A novel PtSnNa/ZSM-5 monolithic catalyst was designed and synthesized for the propane dehydrogenation reaction, which was a significant transformation in industry. Experimental results showed that although the propane conversion and the propylene selectivity gradually fell down along with the reaction time, the descent speed of the PtSnNa/ZSM-5 monolithic catalyst was slower than that of the granule catalyst and the propane conversion and propylene selectivity of the reaction with monolithic catalyst still remained at a high level after 12 hr. The monolithic catalyst had regular pore structure that facilitated the separation of the product from the catalyst and reduced the limitation on internal and external diffusion and mass transfer, and led to the high catalytic activity and stability. The catalyst could be easily fabricated and was of highly industrial application potential.  相似文献   
2.
This work exploited a sequential injection lab-on-valve (LOV) system for the determination of cadmium by anodic stripping voltammetry (ASV). A miniaturized electrochemical flow cell (EFC) was fabricated in LOV, in which a nafion coated bismuth film electrode was used as working electrode. The cadmium was electrodeposited on the electrode surface in bismuth solution, and measured with the subsequential stripping scan. Under optimal conditions, the proposed system responded linearly to cadmium concentrations in a range 2.0-100.0 μg L−1. The detection limit of this method was found to be 0.88 μg L−1. By loading a sample volume of 800 μL, a sampling frequency of 22 determinations h−1 was achieved. The repeatability expressed as relative standard derivation (R.S.D.) was 3.65% for 20 μg L−1 cadmium (n = 11). The established method was applied to analysis of trace cadmium in environmental water samples and the spiked recoveries were satisfactory.  相似文献   
3.
Journal of Inclusion Phenomena and Macrocyclic Chemistry - The combination of the electron donor and acceptor into a donor–acceptor system can transform the intermolecular charge transfer...  相似文献   
4.
运用电容法研究卵磷脂/氨基酸/H2O胶束和囊泡体系结构与性质.卵磷脂的临界胶束浓度和囊泡生成浓度可由体系电容-卵磷脂浓度关系曲线求得.随着卵磷脂浓度增加,体系电容增加,卵磷脂由胶束形成囊泡.随着氨基酸浓度增加,胶束、囊泡半径增大,体系电容减小.氨基酸能促进卵磷脂形成胶束和囊泡,使得卵磷脂临界胶束浓度和囊泡生成浓度减小,其影响的强弱顺序为组氨酸色氨酸垌甘氨酸.  相似文献   
5.
6.
Great efforts have been devoted to the developing of simple, efficient and stable heterogeneous catalysts for the styrene epoxidation reaction (SER). Metal oxides can be of industrial importance by offering an economic and green route for selectively converting styrene into styrene oxide (SO). Herein, by treating the pristine porous 2D Co3O4 sheets with NaBH4 solution, a novel hierarchical structure, i.e., 0D Co3O4 nanoparticles decorated on 2D porous Co3O4 sheets, was obtained. This simple solution reduction strategy not only realizes the morphology evolution, but also induces the modification of the valence states of metal ions and the simultaneous generation of surface oxygen vacancies. The hierarchical 0D/2D Co3O4 hybrids rich in oxygen vacancies (OV-Co3O4) exhibit a much better SER performance than the Co3O4 sheets (P-Co3O4), with the yield of SO more than doubled. The excellent catalytic performance of the OV-Co3O4 can be ascribed to the synergistic effects regarding the hierarchical porous structure, the modification of surface chemical composition and the creation of surface oxygen vacancies.  相似文献   
7.
In the paper we consider a closed Riemannian manifold M with a time-dependent Riemannian metric g ij (t) evolving by ? t g ij  = ?2S ij , where S ij is a symmetric two-tensor on (M,g(t)). We prove some differential Harnack inequalities for positive solutions of heat equations with potentials on (M,g(t)). Some applications of these inequalities will be obtained.  相似文献   
8.
    
A redox-relay migratory hydroarylation of isomeric mixtures of olefins with arylboronic acids catalyzed by nickel complexes bearing diamine ligands is described. A range of structurally diverse 1,1-diarylalkanes, including those containing a 1,1-diarylated quaternary carbon, were obtained in excellent yields and with high regioselectivity. Preliminary experimental evidence supports the proposed non-dissociated chainwalking of aryl-nickel(II)-hydride species along the alkyl chain of alkenes before selective reductive elimination at a benzylic position. A catalyst loading as low as 0.5 mol % proved to be sufficient in large-scale synthesis while retaining high reactivity, highlighting the practical value of this transformation.  相似文献   
9.
The effect of high-energy radiation on Acid Red 1 (AR1) azo-dye solution was investigated by UV–Vis spectroscopy and chemical oxygen demand (COD) measurements. Doses in the order of 10 kGy cause complete decolouration of the 10−3–10−4 mol dm−3 solutions; however, for complete mineralization doses higher by 1–2 order of magnitude are needed. Hydrated electrons and H atom are more effective in fading reaction, while the OH radicals have higher efficiency in mineralization. The HO2/O2•− radical–radical anion pair is rather inefficient in fading reaction.  相似文献   
10.
Qu Q  Hu X  Zhu X  Gao S  Xu Q  Wang Y  Wang X 《Journal of separation science》2004,27(14):1229-1232
This paper introducesa novel method for packing Capillary Electrochromatography Columns (CEC). Using vacuum packing methodology, silica particles as small as 1 microm were successfully packed into the capillary columns with 75 microm inner diameter. The columns are verystable and show no noticeable loss in efficiency after 200 sample injections. The performance of these vacuum packed capillary columns was evaluated with a mixture of aromatic and non-aromatic compounds. A 24 cm long capillary column can produce peak efficiencies of around 45,000 plates for benzene.  相似文献   
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