排序方式: 共有65条查询结果,搜索用时 15 毫秒
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Reda M. Fikry Nabila A. Ismael Adel A. El-Bahnasawy Aymen A. Sayed El-Ahl 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):1227-1236
Several new 2-arylidinoamino-4-(3-coumaryl)thiazole derivatives were synthesized via the reaction of 2-amino-4-(coumaryl)thiazole with aromatic aldehydes and other reagents. Structural elucidations were based on elementary analysis and spectral data studies. 相似文献
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Eleonora Truzzi Mohamed Aymen Chaouch Gaia Rossi Lorenzo Tagliazucchi Davide Bertelli Stefania Benvenuti 《Molecules (Basel, Switzerland)》2022,27(5)
The main focus of the current research was the characterization of the by-products from the steam distillation of Lavandula angustifolia Mill. (LA) and Lavandula x intermedia Emeric ex Loisel (LI) aerial parts, as they are important sources of bioactive compounds suitable for several applications in the food, cosmetic, and pharmaceutical industries. The oil-exhausted biomasses were extracted and the total polyphenol and flavonoid contents were, respectively, 19.22 ± 4.16 and 1.56 ± 0.21 mg/g for LA extract and 17.06 ± 3.31 and 1.41 ± 0.10 mg/g for LI extract. The qualitative analysis by liquid chromatography-electrospray tandem mass spectrometry (HPLC-ESI-MS) revealed that both the extracts were rich in phenolic acids and glycosylated flavonoids. The extracts exhibited radical scavenging, chelating, reducing activities, and inhibitory capacities on acetylcholinesterase and tyrosinase. The IC50 values against acetylcholinesterase and tyrosinase were, respectively, 5.35 ± 0.47 and 5.26 ± 0.02 mg/mL for LA, and 6.67 ± 0.12 and 6.56 ± 0.16 mg/mL for LI extracts. In conclusion, the oil-exhausted biomasses demonstrated to represent important sources of bioactive compounds, suitable for several applications in the food, cosmetic, and pharmaceutical industries. 相似文献
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Two synthetic protocols leading to novel γ-aminophosphonate and phosphine oxide derivatives, by reductive amination of γ-phosphonylketones, are reported. The first method involved a two-step procedure. Imine intermediates were first isolated from the p-toluenesulfonic acid-catalyzed reaction of primary amines with γ-ketophosphonates and phosphine oxides, then reduced with NaBH4 in refluxing ethanol. The second method consists of a one-pot procedure which includes the condensation of γ-ketophosphonates and phosphine oxides with primary amines, in the presence of molecular sieves, followed by reduction with NaBH4. These methods offer significant advantages over prior reports, such as efficiency, generality, and good yields. Furthermore, they are green protocols avoiding hazardous hydrides and solvents. 相似文献
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Olfa Labidi Rose-Noëlle Vannier Jean-Pierre Wignacourt 《Journal of solid state chemistry》2008,181(9):2268-2273
Reinvestigation of PbBiOXO4 (X=V, P, As) thermal behaviour revealed a phase transition for V- and P-compounds, but no transition for the As-compound. As shown by single-crystal X-ray diffraction and high-resolution neutron powder diffraction, α-PbBiOVO4 transforms to β-PbBiOVO4 at 550 °C. The two PbBiOPO4 varieties are isomorph to the vanadate forms, while PbBiOAsO4 adopts the β-type structure whatever the temperature. PbBiP1−xOAsxO4 and PbBiV1−xOMxO4 (M=As, P, Cr, Mn) solid solutions display both triclinic and monoclinic domains, and the α→β transition temperature is a function of the substitution rate. The ionic conductivity of these compounds was investigated by impedance spectroscopy. The analysis of free space in the β-PbBiOVO4 structure allows to propose a one-dimensional oxygen diffusion pathway along [010] when the temperature increases. 相似文献
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In this research article, we work with the notion of the measures of noncompactness in order to establish some results concerning the essential pseudospectra of closed, densely defined linear operators in the Banach space. We start by giving a refinement of the definition of the essential pseudospectra by means of the measure of noncompactness, and we give sufficient conditions on the perturbed operator to have its invariance. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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Let ? n be the (2n + 1)-dimensional Heisenberg group, and let T n be the n-dimensional torus acting on ? n by automorphisms. In this paper, we describe the space of admissible coadjoint orbits of the Heisenberg motion group G n = T n ? ? n and we determine the topology of this space. We show that the bijection between the unitary dual ? n of G n and its admissible coadjoint orbit space is a homeomorphism. 相似文献
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Mashhour Al-Ali Bani-Ata Christoph Hering Anni Neumann Aymen Rawashdeh 《Journal of Geometry》2007,86(1-2):1-5
The purpose of this paper is to prove the existence of semifields of order q
4 for any odd prime power q = pr, q > 3, admitting a free automorphism group isomorphic to Z
2 × Z
2. 相似文献
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Olfa Labidi Florence Porcher Rose-Noëlle Vannier 《Journal of solid state chemistry》2008,181(9):2260-2267
Reinvestigation of PbBiOVO4 thermal behaviour revealed a phase transition. As shown by single-crystal X-ray diffraction and high-resolution neutron powder diffraction, α-PbBiOVO4 transforms to β-PbBiOVO4 at 550 °C. At 25 °C, α-PbBiOVO4 is triclinic, S.G. P-1, Z=2, with a=5.6088(3), b=7.1109(3), c=7.2978(3) Å, α=108.957(2), β=111.889(2), and γ=94.833(2)°. Above 550 °C, β-PbBiOVO4 is monoclinic, S.G. C2/m, Z=4, with a=13.61(1), b=5.64(1), c=7.18(1) Å, and β=113.75(1)°. Both structures are built upon (O2Bi2Pb2)∞ chains parallel to the [100] direction in the α polymorph and [001] in the β-polymorph. These chains are undulated in α and linear in β. In both structures, VO4 tetrahedra are organized in two sets of rows parallel to (O2Bi2Pb2)∞ chains, thus building layers of (OBiPb) sandwiched by two layers of VO4 oriented head to tail; VO4 displays different orientations in α- and β-PbBiOVO4. 相似文献