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961.
Thermal Cyclization of Copper Carbenoid of α‐Dizao α‐Phosphorylacetate: Unexpected and Novel Access to Oxaphosphirane 下载免费PDF全文
Under the catalysis of Cu(OTf)2 in refluxing CH2Cl2, ethyl α‐dizao α‐(diethylphosphoryl)acetate was shown to undergo a new cyclization reaction to afford a pentacovalent oxaphosphirane product. The reaction is proposed to occur through the addition of the P=O double bond to the copper carbenoid, followed by the hydrolysis of the ylide intermediate. Our finding represents the first example on producing oxaphosphiranes from dizao phosphoryl compounds. On the other hand, the corresponding rhodium carbenoid displayed the different reactivity under the same thermal conditions, to produce the β‐propiolactone through the well‐recognized C‐H insertion pathway. 相似文献
962.
固体热载体热解淮南煤实验研究 总被引:3,自引:3,他引:3
自制处理量为1 kg煤的间歇式固体热载体热解装置,以淮南烟煤为原料,石英砂作热载体,对该煤进行热解特性评价实验。考察了热载体初始温度700 ℃~900 ℃、反应
4 min~16 min、煤粒径及热载体与煤的质量比5~9对热解产物产率和性质的影响。结果表明,提高热载体初始温度,气、液产率增加;延长反应时间和提高热载体比例,气体产率有所增加;热载体初始温度对热解气组成影响显著。提高热载体与煤的质量比和热载体初始温度,可以抑制半焦对热解反应器内壁的黏附。 相似文献
963.
化学发光酶免疫方法检测克伦特罗残留 总被引:11,自引:0,他引:11
建立了间接竞争化学发光酶免疫法(competitive indirect chemilumine scent enzyme immunoassy,ic-CLEIA)检测猪尿中残留克伦特罗(clenbuterol,CLB)的方法,并优化了竞争反应时间,Tween-20含量,PBS离子强度与pH4个参数。优化后的ic-CLEIA检出限可达0.01μg/L,检测范围为0.04~25.8μg/L,ED50为0.54μg/L;尿样检测的平均回收率为98%~120%,批内与批间相对标准偏差(variation of coefficent,CV)均小于10%。这些参数均优于目前广泛使用的ELISA方法,说明本CLEIA方法可替代ELISA法,用于实际尿样的检测。 相似文献
964.
965.
Jian-Ping Zou Sheng-Lian Luo Ming-Jun Li Xin-Hua Tang Qiu-Ju Xing Qiang Peng Guo-Cong Guo 《Polyhedron》2010
A series of lanthanide(III) complexes with chelidamic acid ligand, [Ln(C7H2NO5)·3H2O]n·nH2O (Ln = La (1), Y (2), Sm (3), and Nd (4)), [Gd2(C7H2NO5)3·4H2O]n·2nH2O (5) and [Ce(C7H2NO5)·1.5H2O]n (6), have been synthesized by hydrothermal method and structurally characterized by single-crystal X-ray diffraction. Complexes 1–4 are isostructural and possess 2D framework. Complex 5 contains two different Gd(III) ions linked through carboxylate group to form a 2D framework. Complex 6 exhibits a (44) topology 2D network. The variable-temperature magnetic properties of 3 and 5 have been investigated. Furthermore, the photoluminescent properties of 1, 2, 3, and 5 at room temperature were also studied. 相似文献
966.
A cationic quinine‐imide dye brilliant cresyl blue (BCB) and horseradish peroxidase (HRP) were co‐immobilized within ormosil on multiwalled carbon nanotubes modified glassy carbon electrode for the fabrication of highly sensitive and selective hydrogen peroxide biosensor. The presence of epoxy group in ormosil as organic moiety improves the mechanical strength and transparency of the film and amino group provides biocompatible microenvironment for the immobilization of enzyme. The presence of MWCNTs improved the conductivity of the nanocomposite film. The surface characterization of MWCNT modified ormosil nanocomposite film was performed with scanning electron microscopy (SEM) and atomic force microscopy (AFM). Cyclic voltammetry and amperometry measurements were used to study and optimize the performance of the resulting peroxide biosensor. The apparent Michaelis–Menten constant was determined to be 1.5 mM. The proposed H2O2 biosensor exhibited wide linear range from 3×10?7 to 1×10?4 M, and low detection limit 1×10?7 M (S/N=3) with fast response time <5 s. The probable interferences in bio‐matrix were selected to test the selectivity and no significant response was observed in the biosensor. This biosensor possessed good analytical performance and long term storage stability. 相似文献
967.
Juan Peng Lily Zu Weihai Fang Lingyun Huang Yaru Wang Dacheng He 《Journal of mass spectrometry : JMS》2010,45(6):627-634
An understanding of the dissociation of penetratin is important for improving its metabolic stability and cargo‐delivery efficiency. In this study, we describe the selective cleavage of the K15–K16 amide bond of penetratin under the low‐energy collision‐induced dissociation condition in mass spectrometry. A variety of penetratin substitutes have been studied in which key basic amino acids have been substituted within the sequence. The calculated structure indicates that an α‐helix structure prevents the fragmentation of the central peptide domain and the side chain of lysine is involved in the proton translocation process. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
968.
A method was developed for the determination of silver ion (Ag) by combining dispersive liquid-liquid microextraction preconcentration with graphite furnace atomic absorption spectrometry. Diethyldithiocarbamate was used as a chelating agent, and carbon tetrachloride and methanol as extraction and dispersive solvent. Factors influencing the extraction efficiency of Ag and its subsequent determination were studied and optimized. The detection limit is 12 ng L?1 (3 s) with an enrichment factor of 132, and the relative standard deviation is 3.5% (n?=?7, at 1.0 ng mL?1). The method was successfully applied to the determination of trace amounts of Ag in water samples. 相似文献
969.
Yan Li Peng Wang Xin Wang Ming Cao YunSheng Xia Chun Cao MeiGui Liu ChangQing Zhu 《Mikrochimica acta》2010,169(1-2):65-71
A method for determination of vitamin B1 has been developed that is based on the enhancement effect of vitamin B1 on the luminescence of water-soluble CdTe nanorods modified with thioglycolic acid and cysteine. The effect of variables including the size of the nanorods on the enhancement of luminescence have been investigated. A preliminary mechanistic study showed that the passivating action of vitamin B1 on the surface of the CdTe nanorods is likely to be responsible for the enhancement. Interferences by shortwave fluorescence are effectively eliminated because measurements are performed in the near-infrared. Due to the near-infrared measurement character, the fluorescence interference of vitamin B2 can be effectively eliminated. Under the optimum conditions, the extent of luminescence enhancement is proportional to the concentration of vitamin B1 in the range from 0.1 to 3.0 μmol L?1 and the detection limit is 0.03 μmol L?1. The relative standard deviation for 2.0 μmol L?1 vitamin B1 is 1.3% (n?=?6). The method is highly sensitive and selective, avoids the sample treatment needed in other procedures, and can be applied to the determination of vitamin B1 in real samples with satisfactory results. 相似文献
970.
FDU-15-SO3H, a solid acid material prepared from the sulfonation of FDU-15 mesoporous polymer, has been demonstrated to serve as an efficient catalyst in the esterification of palmitic acid with methanol as well as in the transesterification of fatty acid-edible oil mixture. FDU-15-SO3H achieved an acid conversion of 99.0% when the esterification was carried out at 343 K with a methanol/palmitic acid molar ratio of 6:1 and 5 wt% catalyst loading. It was capable of giving 99.0% yield of fatty acid methyl esters (FAME) when the transesterification of soybean oil was performed at 413 K and the methanol/oil weight ratio of 1:1. FDU-15-SO3H was further applied to the transesterification/esterification of the oil mixtures with a varying ratio of soybean oil to palmitic acid, which simulated the feedstock with a high content of free fatty acids. The yield of FAME reached 95% for the oil mixtures containing 30 wt% palmitic acid. This indicated the sulfonated mesopolymer was a potential catalyst for clean synthesis of fuel alternative of biodiesel from the waste oil without further purification. 相似文献