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排序方式: 共有219条查询结果,搜索用时 15 毫秒
11.
Cecilia Rodríguez de Barbarín Sylvain Berns Blanca Njera Perla Elizondo 《Acta Crystallographica. Section C, Structural Chemistry》2007,63(10):o597-o599
Two salts of acyclic Schiff base cationic ligands, namely N,N′‐bis(2‐nitrobenzyl)propane‐1,3‐diammonium dichloride monohydrate, C17H22N4O42+·2Cl−·H2O, (I), and 2‐hydroxy‐N,N′‐bis(2‐nitrobenzyl)propane‐1,3‐diammonium dichloride, C17H22N4O52+·2Cl−, (II), were synthesized as precursors in order to obtain new acyclic and macrocyclic multidentate ligands and complexes. The cation conformations in compounds (I) and (II) are different in the solid state, although the cations are closely related chemically. Similarly, the hydrogen‐bonding networks involving ammonium cations, hydroxyl groups and chloride anions are also different. In the cation of compound (II), the hydroxyl group is disordered over two sets of sites, with occupancies of 0.785 (8) and 0.215 (8). 相似文献
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Chandrika Nanjappa Gopalpur Nagendrappa Pasura Subbaiah Sujan Ganapathy Shirur Dakappa Shruthi Sunil S. More 《合成通讯》2013,43(22):2529-2545
A new 2,2′-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS)-radical scavenging and antiproliferative agents of pyrrolo[1,2-a]quinoline derivatives have been synthesized. An efficient method for the synthesis of 14 novel diversified pyrrolo[1,2-a]quinoline derivatives has been described using 4-(1,3-dioxolan-2-yl)quinoline and different phenacyl bromides in acetone and followed by reacting with different acetylenes in dimethylformamide/K2CO3. The structure of the newly synthesized compounds was determined by infrared, 1H NMR, 13C NMR, mass spectrometry, and elemental analysis. The in vitro antioxidant activity revealed that among all the tested compounds 5n exhibited maximum scavenging activity with ABTS. Compound 5b has showed good antiproliferative activity as an inhibitor of epidermal growth factor receptor (EGFR) tyrosine kinase. 相似文献
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P. Prathap N. Revathi Y.P.V. Subbaiah K.T. Ramakrishna Reddy R.W. Miles 《Solid State Sciences》2009,11(1):224-232
Al-doped ZnS films were deposited using close-spaced evaporation of the powders synthesized by chemical precipitation method. The films were prepared for different Al concentrations in the range 0–10 at.% on glass substrates kept at 300 °C. The effect of Al-doping on ZnS composition, microstructure and optoelectronic properties of as-grown ZnS layers was determined using appropriate techniques. The films were polycrystalline and showed (111) preferred orientation for all the doping concentrations in spite of an additional phase of Al2S3 observed at higher dopant levels. The surface morphological studies indicated that the Al incorporation had a considerable effect on the surface roughness of the films. The optical measurements indicated that the optical energy band gap decreased slightly with the increase of dopant concentration without affecting the optical transmittance characteristics significantly. The electrical analysis indicated that the resistivity of the layers changed significantly with the doping concentration in the layers. The change of photoluminescence behaviour of the as-grown ZnS:Al films with dopant concentration was also studied. 相似文献
16.
Perla N. Peszkin J. M. Schultz J. S. Lin 《Journal of Polymer Science.Polymer Physics》1986,24(12):2617-2630
Small- and wide-angle X-ray scattering (SAXS and WAXS), shrinkage, and density experiments were performed on poly(butylene terephthalate) fibers which had been isothermally crystallized at different temperatures, and at constant tension, for times ranging from 100 to 1050 ms. A consistent correlation among WAXS, SAXS, and the kinetic results is demonstrated. Shrinkage results show that the crystallization process prevails over the chain-re-coiling process. Density measurements show that the rate of crystallization increases with temperature. Pinhole X-ray photos show that the orientation of the chains within the crystals remains constant with time and temperature. WAXS diffractometer scans show the development of wide-angle Bragg peaks. SAXS shows the development of small-angle Bragg peaks, as the annealing time is increased. The two-lobe arced pattern is the characteristic pattern. The value for long spacing ranged from 100 to 120 Å, increasing with temperature. 相似文献
17.
Sara Luisa Rodríguez De Luna Luis Ángel GarzaSylvain Bernès Perla ElizondoBlanca Nájera Nancy Pérez 《Polyhedron》2010
A series of mononuclear complexes based on lanthanide ions has been synthesized and X-ray characterized. The compounds [LnIIIL2(NO3)3(H2O)2] (Ln = La, Ce, Pr, Nd, Sm, Gd and Tm; L = 2,6-bis(2-formylphenoxymethyl)pyridine) are found to be isomorphous and isostructural. Ligand L systematically coordinates through one carbonyl functionality, and the resulting complexes are placed on a twofold axis in crystals belonging to C2/c space-group. Emission spectra for Ln = La, Pr, Nd revealed a correlation between the Ln–O coordination bond length and the photoluminescent properties of the complexes, in line with a Förster–Dexter mechanism for intramolecular energy transfer. Ligand L is therefore a suitable sensitizer for lanthanide ions. 相似文献
18.
Participating life insurance policies: an accurate and efficient parallel software for COTS clusters
In this paper we discuss the development of a parallel software for the numerical simulation of Participating Life Insurance
Policies in distributed environments. The main computational kernels in the mathematical models for the solution of the problem
are multidimensional integrals and stochastic differential equations. The former is solved by means of Monte Carlo method
combined with the Antithetic Variates variance reduction technique, while differential equations are approximated via a fully
implicit, positivity-preserving, Euler method. The parallelization strategy we adopted relies on the parallelization of Monte
Carlo algorithm. We implemented and tested the software on a PC Linux cluster. 相似文献
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Jacopo La Nasa Marco Zanaboni Daniele Uldanck Ilaria Degano Francesca Modugno Hartmut Kutzke Eva Storevik Tveit Biljana Topalova-Casadiego Maria Perla Colombini 《Analytica chimica acta》2015
Modern oil paints, introduced at the beginning of the 20th century, differ from those classically used in antiquity in their chemical and compositional features. The main ingredients were still traditional drying oils, often used in mixtures with less expensive oils and added with several classes of additives. Consequently, detailed lipid profiling, together with the study of lipid degradation processes, is essential for the knowledge and the conservation of paint materials used in modern and contemporary art. 相似文献