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排序方式: 共有193条查询结果,搜索用时 15 毫秒
41.
Tin Thanh Le 《Tetrahedron》2010,66(46):8893-8898
Starting from isosorbide and isomannide, two by-products from the starch industry, a family of chiral functionalized β-aminoalcohols presenting a THF ring has been synthesized as potential ligands for hydrogen transfer reduction of prochiral ketones. Under optimal conditions, more than 70% ee with an excellent conversion were obtained for the HTR of the acetophenone. 相似文献
42.
Rosemarie Philipp Olaf Hanebeck Sebastian Hein Wolfram Bremser Tin Win Irene Nehls 《Accreditation and quality assurance》2010,15(3):141-146
The Federal Institute for Materials Research and Testing (BAM), Germany, has issued a series of large volume ethanol in water
certified reference materials (CRMs), primarily developed for the calibration of evidential breath alcohol analyzers in Germany.
The certified parameter is the ethanol mass concentration at 20 °C. When used in a wet bath simulator, the solutions deliver
gas samples that meet the requirements set by the Organization of Legal Metrology for calibration of breathalyzers. The materials
were prepared gravimetrically by spiking of ethanol into water in single 5 L units. A complete uncertainty budget for the
preparation process has been established. The purity of the commercial ethanol stock solution was identified to be the main
source of uncertainty. For stability and homogeneity measurements and for the verification of the gravimetric mass concentration
of the CRMs, a robust high-precision gas chromatography, with flame-ionization detection method for ethanol determination
in aqueous samples was developed and validated. The good performance of this method has been demonstrated in several international
comparisons organized by the Consultative Committee for Amount of Substance—Metrology in Chemistry at the International Bureau
of Weights and Measures. 相似文献
43.
Pelosi C. Tombari E. Wurm F. R. Tiné M. R. 《Journal of Thermal Analysis and Calorimetry》2022,147(22):12631-12639
Journal of Thermal Analysis and Calorimetry - Protein-polymer conjugates are a promising class of biohybrids. In this work, the dynamics of a set of biodegradable conjugates myoglobin-poly(ethyl... 相似文献
44.
45.
研究了水溶性钯-膦配合物PdCl2(TPPTS)2催化1-己烯加氢反应,考察了两相催化体系中添加表面活性剂CTAB,膦配体TPPTS,以及溶液pH值等对反应的影响,证明了1-己烯加氢反应中有一诱导期.反应中涉及两种催化活性物种.一种是由PdCl2(TPPTS)2还原生成的低氧化态催化物种,它在一定的CTAB浓度下,可以保持相当的稳定性.另一种是被TPPTS或H2还原形成的钯黑.根据PdCl2和TPPTS反应过程的31PNMR研究,对PdCl2(TPPTS)2分子中Pd被还原和TPPTS被氧化提出了解释 相似文献
46.
An experimental investigation of cold storage in an encapsulated thermal storage tank 总被引:5,自引:0,他引:5
Sih-Li Chen Chin-Lung Chen Chun-Chuh Tin Tzong-Shing Lee Ming-Chun Ke 《Experimental Thermal and Fluid Science》2000,23(3-4):133-144
This paper experimentally investigates the thermal performance and the pressure drop of an encapsulated thermal storage tank during the charging process. A polyvinyl chloride (PVC) hollow cylinder is used as the thermal storage tank. The cylindrical capsules inside the thermal storage tank utilize water added with nucleation agents as the phase change material (PCM), and the coolant is the aqueous solution of ethylene glycol. A series of experiments were carried out to investigate the effects of the inlet coolant temperature and coolant flow rate on nucleation of capsules, heat transfer and pressure drop of the tank. The results indicate that cool energy can be fully stored in the form of latent heat when the inlet coolant temperature is set below the temperature with 100% nucleation probability. The lower the inlet coolant temperature and the larger the coolant flow rate, the more efficient the storage tank. A correlation for the pressure drop of coolant during a charging process is also developed. 相似文献
47.
Inside Cover: Covalent Immobilization of Polyoxotungstate on Alumina and Its Catalytic Generation of Sulfoxides (Chem. Eur. J. 32/2016) 下载免费PDF全文
48.
49.
Covalent Immobilization of Polyoxotungstate on Alumina and Its Catalytic Generation of Sulfoxides 下载免费PDF全文
Lanlan Hong Pyaesone Win Xuan Zhang Dr. Wei Chen Dr. Haralampos N. Miras Prof. Yu‐Fei Song 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(32):11232-11238
The structural and chemical stabilities of immobilized polyoxometalate (POM)‐containing catalysts are crucial factors for their industrial application. An alumina supported POM catalyst is prepared by using a facile condensation reaction between the trilacunary POM Na12[α‐P2W15O56] ? 24 H2O (P2W15) and the hydroxy groups on the surface of γ‐Al2O3 spheres under acidic conditions. The heterogeneous catalyst P2W15?Al2O3 is characterized by a wide variety of techniques and shows excellent stability and highly efficient reactivity and selectivity for the oxygenation of thioethers to sulfoxides, which are a very useful intermediate in organic synthesis and the industrial preparation of drugs. Furthermore, P2W15?Al2O3 can be recycled and reused at least ten times without any observable loss of its catalytic efficiency, mainly due to the covalent immobilization and high dispersion of P2W15 on the γ‐Al2O3 surface. 相似文献
50.
Films were prepared from mixtures of copolymers of 4-nitro-4'- [N- methylacryloyloxyethyl,N'-ethyl] amino azobenzene with glycidyl methacrylate (chromophore content: 6 mol%) andcopolymers containing anhydride units, which was obtained by the reaction of 4-nitro-4'-[N-hydroxyethyl, N'-ethyl] amino azobenzene with polymethacryloyl chloride (chromophorecontent: 25 mol %). During thermal poling process the anhydride reacts with the epoxygroup and the resulting crosslinked network structure will stabilize the second harmonicgeneration in the poled film. The second harmonic generation of the poled film shows amaximum with the variation of composition, this is presumed to be due to the effects of theincreasing of concentration, orientation order as well as orientation stability of chromophoregroups during crosslinking. 相似文献