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971.
Na3AZr(PO4)3 (A=Mg, Ni) phosphates were prepared at 750 °C by coprecipitation route. Their crystal structures have been refined at room temperature from X-ray powder diffraction data using Rietveld method. Li2.6Na0.4NiZr(PO4)3 was synthesized through ion exchange from the sodium analog. These materials belong to the Nasicon-type structure. Raman spectra of Na3AZr(PO4)3 (A=Mg, Ni) phosphates present broad peaks in favor of the statistical distribution in the sites around PO4 tetrahedra. Diffuse reflectance spectra indicate the presence of octahedrally coordinated Ni2+ ions. 相似文献
972.
Fathy Abdel‐Kader Amer Metwally Hammouda Bakr Fathy Abdel‐Wahab Abdel‐Aziz Sayed El‐Ahl 《Journal of heterocyclic chemistry》2008,45(6):1549-1569
This review presents a survey of the synthetic methods and reactions of 3‐pyrrolidinones I (R = H, alkyl, acyl, ester; R1 = H, alkyl, cyano, ester, etc). 3‐Pyrrolidinones are synthetically versatiles substrate, as they can be used for synthesis of a large variety of heterocyclic compounds, such as indoles and 5‐deazapteroic acid analogues and as a raw material for drug synthesis. The high reactivity of an active methylene group next to the carbonyl of the pyrrolidine ring is useful for various syntheses. 相似文献
973.
974.
975.
We wish to present herein a simple one-pot synthesis of 2,5-disubstituted oxazoles, starting from benzyl halides and acyl chlorides. The in situ formation of isocyanides, followed by the addition of an acyl chloride in the presence of a base leads to the desired oxazoles in good yields. 相似文献
976.
Kamal El Fahri 《Quaestiones Mathematicae》2016,39(4):487-496
We investigate Banach lattices on which each positive almost Dunford- Pettis operator is almost limited and conversely. 相似文献
977.
This paper aims to present a general framework of the quadratic spline functions to develop a numerical method for solving the nonlinear space fractional Fisher's equation. Using Von Neumann method, the proposed method is shown to be conditionally stable. Finally, a numerical example is given to verify the effectiveness of the proposed algorithm. The results reveal that the proposed approach is very effective, convenient, and quite accurate to such considered problems. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
978.
High-performance InGaAs/InGaAlAs multiple-quantum-well vertical-cavity surface-emitting lasers (VCSELs) with InGaAlAs/InP distributed Bragg reflectors are proposed for operation at the wavelength of . The lasers have good heat diffusion characteristic, large index contrast in DBRs, and weak temperature sensitivity. They could be fabricated either by metal-organic chemical vapor deposition (MOCVD) or by molecular beam epitaxy (MBE) growth. The laser light-current characteristics indicate that a suitable reflectivity of the DBR on the light output side in a laser makes its output power increase greatly and its lasing threshold current reduce significantly, and that a small VCSEL could output the power around its maximum for the output mirror at the reflectivity varying in a broader range than a large VCSEL does. 相似文献
979.
S. El‐Zanati O. Heden G. Seelinger P. Sissokho L. Spence C. Vanden Eynden 《组合设计杂志》2010,18(6):462-474
Let V = V(n, q) denote the vector space of dimension n over GF(q). A set of subspaces of V is called a partition of V if every nonzero vector in V is contained in exactly one subspace of V. Given a partition 𝒫 of V with exactly ai subspaces of dimension i for 1≤i≤n, we have , and we call the n‐tuple (an, an − 1, …, a1) the type of 𝒫. In this article we identify all 8‐tuples (a8, a7, …, a2, 0) that are the types of partitions of V(8, 2). © 2010 Wiley Periodicals, Inc. J Combin Designs 18: 462–474, 2010 相似文献
980.
A series of fused and spiro pyrazolones, isoxazolines, pyrimidines, β‐lactams, and thiazolidinones incorporating 4‐amino‐2‐methyl‐5,10‐dioxo‐1,5,10,11‐tetrahydrobenz[g]quinoline 3‐carbonitrile 1 and 4‐amino‐2‐methyl‐5,6,11‐trioxo‐1,4,4a,5,6,11,12,12a‐octahydro‐1,12‐diazanaphthacene 3‐carbonitrile 2. 7,8a‐c, 15,16a‐c, 19,20a‐d, 21,22a‐d , have been synthesised by cyclocondensation addition reaction and cycloaddition reaction of hydrazines, hydroxylamine, urea, thiourea, monochloroacetyl chloride and mercaptoacetic acid with the synthesised 15,16a‐c and 17,18a‐c . 相似文献