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91.
In this paper we describe the synthesis of a new series of substituted 2-(4-alkoxy or 4-acyloxyphenethyl)-phthalimide derivatives (4--11). in good yields (58--87%), exploring the remarkable fast O-alkylation or O-acylation of 2-(4-hydroxyphenethyl)-phthalimide (3) in dry media under microwave irradiation. 相似文献
92.
93.
P. Barreiro A. Moya E. Correa M. Ruiz-Altisent M. Fernández-Valle A. Peirs K. M. Wright B. P. Hills 《Applied magnetic resonance》2002,22(3):387-400
The potential of nuclear magnetic resonance (NMR) relaxometry for quantitative evaluation of apple mealiness has been investigated. The degree of “mealiness” was defined by several mechanical techniques, including penetration, compression and shear rupture as well as by the BRIX (soluble solids) and juiciness levels. These data were correlated with both magnetic resonance imaging (MRI) and NMR water proton transverse relaxation time measurements on a fruit-by-fruit basis. It was found that increasing mealiness caused a systematic increase in the transverse relaxation rate. The potential for rapid, on-line NMR/MRI detection of apple mealiness is discussed. 相似文献
94.
Mónica Silva Isabel Martins Filomena Barreiro Madalena Dias Alírio E. Rodrigues 《International Journal of Polymer Analysis and Characterization》2017,22(8):709-724
The synthesis of poly(urethane–urea) shells (PUU) using poly(ethylene glycols) of different molecular weights and methylene-bis(4-cyclohexylisocyanate) was performed for the microencapsulation of limonene, using a step-growth polymerization process. The obtained microcapsules were structurally characterized by dynamic light scattering, optical microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, and thermogravimetric analysis. The results showed that the core–shell microcapsules had spherical shape, a mean diameter in between 10 and 20?µm, and characteristic urethane-urea bonds. Furthermore, the molecular weight of polyol influences the entrapment efficiency, which ranged from 38 to 55%. The release data were analyzed by applying the Korsmeyer–Peppas model. 相似文献
95.
Fernando Barreiro 《Fortschritte der Physik》1986,34(8):503-604
The main features of the hadronic final states measured in e+e− annihilation at DORIS and PETRA energies are reviewed. Comparisons are made between data and QCD predictions. The importance of perturbative versus non-perturbative contributions is critically examined. 相似文献
96.
Carlos M. R. De Sant'anna Ricardo Bicca De Alencastro Carlos A. M. Fraga Eliezer J. Barreiro Joaquim Delphino Da Motta Neto 《International journal of quantum chemistry》1996,60(5):1069-1080
Platelet-activating factor (PAF) is an autacoid derived from cellular membrane phospholipids in response to chemical or physical stimuli. It has been identified as 1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphocholine; the alkyl group is composed of 16 or 18 carbon atoms in human cells. PAF can cause a series of pathophysiological effects, related to inflammatory and allergic diseases such as asthma, gastric ulcerations, transplant rejections, psoriasis, cerebral, renal, and myocardial ischemia. As PAF biological action is a result of interactions with specific receptors on target cells, several specific PAF receptor antagonists have been proposed for therapeutic control of the pathological states in which PAF is implicated. In this work we have calculated at AM1 level 16 conformations of a model (alkyl = octyl) of (R)-PAF. We have used these conformations and calculated structures of two hetrazepines (WEB 2086 and E 6123), FR 128998 and RP 59227, known antagonists of PAF activity currently under development, to test a recently proposed pharmacophore map. Our results suggest that the model is too rigid. Having this in mind, we used the pharmacophore model to evaluate the potential activity of a new series of proposed PAF receptor antagonists based on bicyclo[3.3.0]-2-oxaoctane. The results were used to decide which compounds should receive priority in synthesis. The synthetic results and pharmacological profiles of the new derivatives will be published elsewhere. © 1996 John Wiley & Sons, Inc. 相似文献
97.
Water-in-Oil-in-Water Double Emulsions as Protective Carriers for Sambucus nigra L. Coloring Systems
Liandra G. Teixeira Stephany Rezende ngela Fernandes Isabel P. Fernandes Lillian Barros Joo C. M. Barreira Fernanda V. Leimann Isabel C. F. R. Ferreira Maria-Filomena Barreiro 《Molecules (Basel, Switzerland)》2022,27(2)
The use of natural colorants is needed to overcome consumer concerns regarding synthetic food colorants′ safety. However, natural pigments have, in general, poor stability against environmental stresses such as temperature, ionic strength, moisture, light, and pH, among others. In this work, water-in-oil-in-water (W1/O/W2) emulsions were used as protective carriers to improve color stability of a hydrophilic Sambucus nigra L. extract against pH changes. The chemical system comprised water and corn oil as the aqueous and oil phases, respectively, and polyglycerol polyricinoleate (PGPR), Tween 80, and gum Arabic as stabilizers. The primary emulsion was prepared using a W1/O ratio of 40/60 (v/v). For the secondary emulsion, W1/O/W2, different (W1/O)/W2 ratios were tested with the 50/50 (v/v) formulation presenting the best stability, being selected as the coloring system to test in food matrices of different pH: natural yogurt (pH 4.65), rice drink (pH 6.01), cow milk (pH 6.47), and soy drink (pH 7.92). Compared to the direct use of the extract, the double emulsion solution gave rise to higher color stability with pH change and storage time, as corroborated by visual and statistical analysis. 相似文献
98.
99.
100.
The synthesis of a new 8-azaprostanoid is described, using 2-carboethoxycyclopentanone as starting material. 相似文献