排序方式: 共有17条查询结果,搜索用时 15 毫秒
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Experimental results concerning the interaction between a variety of nanocrystalline metals (gold, silver, nickel and chromium) and both crystalline polymer [poly-DCH (1,6-di (N-carbazolyl)-2,4-hexadiene)] and amorphous carbon substrates, are presented and analyzed. Attention is focused on aspects of the interaction that concern interfacial bonding, its correlation with the cohesive energies of the various metals and the energy of the interfaces. Experimental contributions include qualitative estimates of the magnitude of interfacial energies for the crystalline polymer/metal and amorphous carbon/metal interfaces and a direct measurement of the interfacial energies for gold and silver nanocrystals deposited on the amorphous carbon substrate. The sequence of interfacial energy values for the polymer/metal and amorphous carbon/metal systems is also determined. The interfacial energies for both the poly-DCH and amorphous carbon substrates decreases in the order silver, gold, nickel, and chromium, as expected from cohesive energy, melting point and surface energy data for these elements. The crystalline polymer/metal interfaces were examined for the presence of orientation relationships using selected area diffraction and optical diffractometry of high-resolution TEM images. No orientation relationships were found for any of the polymer/metal combinations spanning a large range of metal reactivities. Lack of atomic matching or some as yet unknown surface condition on the polymer may be responsible for this effect. 相似文献
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Miroslawa Kolowska-Gawiejnowicz 《Mathematical Logic Quarterly》1999,45(1):51-58
We present a labelled version of Lambek Calculus without unit, and we use it to prove a completeness theorem for Lambek Calculus with respect to some relational semantics. 相似文献
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Miroslawa Kolowska-Gawiejnowicz 《Mathematical Logic Quarterly》1997,43(1):60-72
We prove a representation theorem for (abstract) residuated algebras: each residuated algebra is isomorphically embeddable into a powerset residuated algebra. As a consequence, we obtain a completeness theorem for the Generalized Lambek Calculus. We use a Labelled Deductive System which generalizes the one used by Buszkowski [4] and Pankrat'ev [17] in completeness theorems for the Lambek Calculus. 相似文献
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Miroslawa Jańczak 《Journal of Number Theory》2010,130(3):580-585
We call a set A of positive integers an asymptotic basis of order h if every sufficiently large integer n can be written as a sum of h elements of A. If no proper subset of A is an asymptotic basis of order h, then A is a minimal asymptotic basis of that order. Erd?s and Nathanson showed that for every h?2 there exists a minimal asymptotic basis A of order h with d(A)=1/h, where d(A) denotes the density of A. Erd?s and Nathanson asked whether it is possible to strengthen their result by deciding on the existence of a minimal asymptotic bases of order h?2 such that A(k)=k/h+O(1). Moreover, they asked if there exists a minimal asymptotic basis with lim sup(ai+1−ai)=3. In this paper we answer these questions in the affirmative by constructing a minimal asymptotic basis A of order 2 fulfilling a very restrictive condition
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Mieczyslaw Maciejewski Miroslawa Panasiewicz Danuta Jarminska 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5):701-718
Products of hydrolysis and condensation of organosilicon monomers in the presence of [btilde]-cyclodextrin (cycloheptaamylose [btilde]-CD) were studied by IR, NMR, MS, and x-ray methods. It was established that when an aqueous solution of [btilde]-CD is treated with dimethyldichlorosilane (DMDCS), diphenyldichlorosilane (DFDCS), methylphenyldichlorosilane (MFDCS), or with a mixture of the DMDCS and DFDCS, crystalline compounds of cyclodextrin with appropriate siloxane oligomers, are formed: /3-CD-MSO (69% yield by weight), [btilde] -CD-FSO (6.0% yield by weight), [btilde]-CD-MFSO (16%) yield by weight), [btilde]-CD-(MSO + FSO) (22–63% yield by weight). The content of the obtained products showed: [btilde]-CD:MSO = 1 mole of [btilde]-CD:2 (CH3)2SiO elements; [btilde]-CD:FSO = 1 mole of [btilde]-CD:0.57 mole of (C6H5)2SiO; [btilde]-CD:MFSO = 1 mole of [btilde]-CD:0.87 mole of (CH3) (C6H5)SiO. Contents of [btilde]-CD′ (MSO + FSO) depend on the starting monomer mixture. It is suggested that nonchemical bonds between [btilde]-CD molecules and siloxane elements occur. The topological structure of the obtained substances is analyzed. Analogous compounds are not formed with methyltrichlorosilane, triphenylchlorosilane, diethoxydichlorosilane, dimethyldimethoxysilane, dimethyl -diacetoxysilane, or silica tetrachloride. Compounds with [btilde]-cyclodextrin are not formed from already formed siloxane oligomers. In the processes described above, linear dextrins show a total lack of activity. Methylsiloxanes bound with [btilde]-CD have a cyclic structure, while phenyl ones probably have a linear structure. 相似文献
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Ito H Nishida Y Yamazaki M Nakahara K Michalska-Hartwich M Furmanowa M Leistner E Yoshida T 《Chemical & pharmaceutical bulletin》2004,52(10):1262-1264
We established callus cultures of the monocotyledonous plants Kniphofia foliosa and K. tuckii (Asphodelaceae), which produce the anthraquinone derivatives chrysophanol and its glycosides. The minor product chrysophanol 8-O-beta-gentiobioside was fully characterized by spectroscopic analysis and synthesis. 相似文献
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Titration with dithiooxamide in potassium hydrogenphthalate medium (pH 5–6) is suitable for the determination of mercury in concentrations above 0.05 ppm. The precision in the range 0.05–1.0 ppm Hg is ? 4%. Significant amounts of sulphate, nitrate, Zn2+, Cd2+ and Pb2+ and small amounts of Ni2+, Co2+ and Al3+ can be tolerated, but Fe3+, Cu2+ and Ag+ interfere. 相似文献
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Jacek Sonicki Tadeusz Jagodziski Miroslawa Krlikowska 《Journal of heterocyclic chemistry》1999,36(4):1033-1041
Several thiocarbamoyl derivatives of cannabinoids were obtained in the collidine-catalysed condensation of 2,4-dihydroxybenzothioamides with citral and citronellal. The thioamide function was found to change the regioselective preferences of the reaction as compared with the known cannabinoid syntheses from hydroxyacetophenones. The experimental results and theoretical (FMO theory) considerations made it possible to advance the reaction mechanism. Convenient methods were developed for the synthesis of the starting 2,4-dihydroxybenzothioamides from resorcinol and isothiocyanates in the presence of the boron trifluoride/acetic acid 1:2 complex or aluminum chloride in nitromethane. 相似文献