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41.
范宇航 孙丽萍 霍丽华 赵辉 Jean-Marc Bassat Aline Rougier Sbastien Fourcade Jean-Claude Grenier 《无机化学学报》2016,32(10):1730-1738
采用EDTA-柠檬酸法合成了中温固体氧化物燃料电池阴极材料Sr_(1.5)La_(0.5)Mn_(1-x)Co_xO_4(SLMCOx),并利用粉末X射线衍射(XRD)、X射线光电子能谱(XPS)以及电化学交流阻抗谱(EIS)进行表征。结果表明,该材料与Ce0.9Gd0.1O1.95(CGO)在1 200℃烧结12 h不发生化学反应。随着Co掺入量的增加,氧化物中Mn~(3+)和Co~(2+)含量增多,晶格氧含量降低,晶格畸变率增大。交流阻抗谱(EIS)测试结果显示,钴的掺杂明显降低电极的极化电阻,其中Sr_(1.5)La_(0.5)Mn_(0.7)Co_(0.3)O_4阴极在700℃空气中的极化电阻为0.62Ω·cm~2,明显小于Sr_(1.5)La_(0.5)MnO_4阴极在750℃的极化电阻(1.5Ω·cm~2),表明钴掺杂的Sr_(1.5)La_(0.5)Mn_(1-x)CoxO_4是一种潜在的IT-SOFC阴极材料。 相似文献
42.
Pd(dba)2[dba = dibenzylideneacetone]/PPh3-or Pd(PPh3)4-catalyzed cyclizations of acetoxy-dienes 2 → 3 and 10 → 11 gave 1-vinyl-2-methylidene-subsituted cyclopentances and cyclohexanes in high yield, consistent with a palladium-ene/β-elimination mechanism ( D → E → F , Scheme 2). The efficient and highly stereoselective cyclizations 7 → 7 and 8 → 9 illustrate intramolecular allylpalladium insertions into 1,2-dialkyl-, trialkyl-, trialkyl-, and cyclic alkenes followed by elimination of the exocyclic β–H giving 1,2-divinylcyclopentanes. These new olefin insertions proceed faster in AcOH (compared to THF) and occur preferentially cis relative to the Pd ( 13 → 14 → 15 ). 相似文献
43.
Strong ion-exchange centrifugal partition chromatography as an efficient method for the large-scale purification of glucosinolates 总被引:1,自引:0,他引:1
The glucosinolates sinalbin and glucoraphanin were purified by strong ion-exchange displacement centrifugal partition chromatography (SIXCPC). The optimized conditions involved the biphasic solvent system ethyl acetate/n-butanol/water (3:2:5, v/v), the lipophilic anion-exchanger Aliquat 336 (trioctylmethylammonium chloride, 160 and 408 mM) and a sodium iodide solution (80 and 272 mM) as displacer. Amounts as high as 2.4 g of sinalbin and 2.6g of glucoraphanin were obtained in one step in 2.5 and 3.5h respectively, starting from 12 and 25 g of mustard and broccoli seed aqueous extracts, using a laboratory scale CPC column (200 mL inner volume). 相似文献
44.
We discuss model-independent constraints on spin observables in exclusive and inclusive reactions, with special attention to the case of photoproduction. 相似文献
45.
We prove that for any positive real number
which is not an integer, the density of the integers
which are coprime to
, a result conjectured by Moser, Lambek and Erd Hs.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
46.
El Bakkari M McClenaghan N Vincent JM 《Journal of the American Chemical Society》2002,124(44):12942-12943
A new hydrocarbon/perfluorocarbon phase-switching strategy based on coordination of pyridyl-tagged molecules to a highly fluorinated dicopper-carboxylate complex possessing two accessible axial coordination sites is described. When a chloroform solution of the tetrapyridyl-substituted porphyrin 3 (0.1 mM, 2 mL) is layered on a perfluorodecalin solution of 2 (3.25 mM, 1.5 mL), complete extraction of the porphyrin into the fluorous phase is observed after 30 min of stirring. Quantitative release of both the porphyrin and 2 is achieved simply by adding excess THF to the biphasic system, the THF acting as a pyridine competing ligand. The recovered perfluorocarbon solution containing 2 can be reused for another complexation with the same efficiency. The scope of this approach is emphasized by the phase-switching of a dipyridyl-substituted fullerene, another example of a molecule for which solubilization in perfluorocarbons is very challenging. 相似文献
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50.
Luc Chapleau Jacques-A. Ferland Jean-Marc Rousseau 《European Journal of Operational Research》1985,20(1):48-57
This paper introduces a new approach for generating school bus routes in a dense urban area. First, a districting algorithm is used to determine clusters including appropriate numbers of students. Then, for each cluster, a route and the stops along this route are determined. Numerical results are reported and compared with those obtained previously. Although the algorithm has been developped and tested in a specific context, it could easily be extended to more general vehicle routing problems. 相似文献