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排序方式: 共有1467条查询结果,搜索用时 312 毫秒
101.
Bixue Xu Luca Unione Dr. Joao Sardinha Shaoping Wu Prof. Mélanie Ethève‐Quelquejeu Prof. Amelia Pilar Rauter Prof. Yves Blériot Dr. Yongmin Zhang Dr. Sonsoles Martín‐Santamaría Dr. Dolores Díaz Prof. Jesus Jiménez‐Barbero Prof. Matthieu Sollogoub 《Angewandte Chemie (International ed. in English)》2014,53(36):9597-9602
Molecular mimicry is an essential part of the development of drugs and molecular probes. In the chemical glycobiology field, although many glycomimetics have been developed in the past years, it has been considered that many failures in their use are related to the lack of the anomeric effects in these analogues. Additionally, the origin of the anomeric effects is still the subject of virulent scientific debates. Herein, by combining chemical synthesis, NMR methods, and theoretical calculations, we show that it is possible to restore the anomeric effect for an acetal when replacing one of the oxygen atoms by a CF2 group. This result provides key findings in chemical sciences. On the one hand, it strongly suggests the key relevance of the stereoelectronic component of the anomeric effect. On the other hand, the CF2 analogue adopts the natural glycoside conformation, which might provide new avenues for sugar‐based drug design. 相似文献
102.
Joanna Kolniak-Ostek Agnieszka Kita Joanna Miedzianka Lucia Andreu-Coll Pilar Legua Francisca Hernandez 《Molecules (Basel, Switzerland)》2020,25(23)
Opuntia ficus-indica (L.) Mill. is the Cactaceae plant with the greatest economic relevance in the world. It can be used for medicinal purposes, animal nutrition, production of biofuels and phytoremediation of soils. Due to its high content of bioactive compounds, the prickly pear has antioxidant, antimicrobial and anticancer properties. The aim of this study was to determine the polyphenolic, fatty acid and amino acid profile and characterize the antioxidant capacity of seeds of seven Spanish prickly pear cultivars. A total of 21 metabolites, mainly phenolic acids and flavonols, were identified using ultraperformance liquid chromatography photodiode detector quadrupole/time-of-flight mass spectrometry (UPLC-PDA-Q/TOF-MS). Significant differences were found in the phenolic concentrations of the investigated varieties. The highest amount of phenolic compounds (266.67 mg/kg dry matter) were found in the “Nopal espinoso” variety, while the “Fresa” variety was characterized by the lowest content (34.07 mg/kg DM) of these compounds. In vitro antioxidant capacity was positively correlated with the amount of polyphenols. The amino acid composition of protein contained in prickly pear seeds was influenced by the variety. Glutamic acid was the predominant amino acid followed by arginine, aspartic acid and leucine, independent of prickly pear variety. Overall, 13 different fatty acids were identified and assessed in prickly pear seeds. The dominant fatty acid was linoleic acid, with content varying between 57.72% “Nopal ovalado” and 63.11% “Nopal espinoso”. 相似文献
103.
Fertout Radia Imane Ghelamallah Madani Kacimi Soufi López Paloma Navarro Corberán Vicente Cortés 《Russian Journal of Applied Chemistry》2020,93(2):289-298
Russian Journal of Applied Chemistry - Nickel catalysts supported on γ–Al2O3 doped with La2O3 and alkaline earth oxides (MgO, CaO, and SrO) were investigated in the dry reforming of... 相似文献
104.
Rhea C. Garcellano John R. Cort Syed G. A. Moinuddin Scott G. Franzblau Rui Ma 《Natural product research》2020,34(8):1175-1179
AbstractCoronaridine (1) was isolated from the CH2Cl2 root extract of Tabernaemontana ternifolia. The structure of 1 was established from 1D- and 2D-NMR and HR-ESIMS experiments, and by comparison with reported spectroscopic data. To date, this is the first report of compound 1 from T. ternifolia, introduced as new Tabernaemontana species from Philippines in 2005 on the basis of morphological characters. Coronaridine, an iboga-type indole alkaloid, has been isolated from over 50 Tabernaemontana species and can thus be inferred as a chemotaxonomic marker of the genus. T. ternifolia has a distinct arrangement of leaves not known in the genus, but is variable in other genera. Its isolation from endemic T. ternifolia establishes its position in the genus and supports the claim that coronaridine is a chemical marker of the genus Tabernaemontana. Interestingly, coronaridine exhibited relatively weak activity against Mycobacterium tuberculosis H37Rv (MIC 82.64?μg/mL) (Rifampicin MIC 0.05?μg/mL). 相似文献
105.
Conformational characteristics of poly(vinylpyrrolidone). solvent-dependence of the chain dimensions
María Pilar Tarazona Enrique Saiz Ligia Gargallo Deodato Radic 《Macromolecular theory and simulations》1993,2(5):697-710
Conformational energies as function of rotational angles over two consecutive skeletal bonds for both meso and racemic diads of poly(Nvinyl-2-pyrrolidone) have been computed. The results of these calculations were used to formulate a statistical model that was then employed to calculate the unperturbed dimensions of this polymer. The conformational energies are sensitive to the Coulombic interactions, which are governed by the dielectric constant, of the solvent, and to the size of the solvent molecules. Consequently, the calculated values of the polymeric chain dimensions are strongly dependent on the nature of the solvent, as it was experimentally found before. 相似文献
106.
107.
Liquid chromatography with ultraviolet absorbance detection for the analysis of tetracycline residues in honey 总被引:5,自引:0,他引:5
Viñas P Balsalobre N López-Erroz C Hernández-Córdoba M 《Journal of chromatography. A》2004,1022(1-2):125-129
The separation of tetracyclines (TCs) using reversed-phase liquid chromatography (LC) is proposed. The use of an amide-based stationary phase prevents the interaction of tetracyclines with the residual silanol groups and thus avoids the appearance of tailed peaks. Detection was based on using an UV spectrophotometer and gradient elution with acetonitrile-oxalic acid as mobile phase permitted good separation of all the peaks. Specificity was demonstrated by the retention characteristics, UV spectra and peak purity index. Linearity, precision, recovery and sensitivity were satisfactory. The procedure was applied to the analysis of tetracycline residues (tetracycline, oxytetracycline (OTC), chlortetracycline (CTC), doxycycline (DC), minocycline (MINO) and methacycline (MTC)) in honey of different types. Extraction involved using a mild acidic solvent containing EDTA to release protein-bound or sugar-bound tetracyclines. For the clean-up step, solid phase extraction using phenyl cartridges was applied. Detection limits in the honey using the proposed procedure are between 15 and 30 ng g(-1), depending on the tetracycline. 相似文献
108.
Germán Bianchini Mónica Denham Ana Cortés Tomàs Margalef Emilio Luque 《Journal of computational science》2010,1(4):229-237
Several Data-Driven Methods have been developed to try to solve the input parameters uncertainty when considering problems like Wildfires Prediction. In general, these methods operate over a large number of input parameters, and consider the most recent known behavior of wildfires. The purpose of the methods is to find the parameter set that best describes the real situation under consideration. Therefore, it is presumed that the same set of values could be used to predict the immediate future.However, because this kind of prediction is based on a single set of parameters, for those parameters that present a dynamic behavior (e.g. wind direction and speed), the new optimized values are not adequate to make a prediction.In this paper we propose an alternative method developed in a new branch of Data-Driven Prediction, which we called Multiple Overlapping Solution. This method combines statistical concepts and HPC (High Performance Computing) to obtain a higher quality prediction. 相似文献
109.
Dendronized Anionic Gold Nanoparticles: Synthesis,Characterization, and Antiviral Activity 下载免费PDF全文
Cornelia E. Peña‐González Pilar García‐Broncano Prof. M. Francesca Ottaviani Dr. Michela Cangiotti Dr. Alberto Fattori Margarita Hierro‐Oliva Prof. M. Luisa González‐Martín Dr. Jorge Pérez‐Serrano Dr. Rafael Gómez Prof. M. Ángeles Muñoz‐Fernández Dr. Javier Sánchez‐Nieves Dr. F. Javier de la Mata 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(9):2987-2999
Anionic carbosilane dendrons decorated with sulfonate functions and one thiol moiety at the focal point have been used to synthesize water‐soluble gold nanoparticles (AuNPs) through the direct reaction of dendrons, gold precursor, and reducing agent in water, and also through a place‐exchange reaction. These nanoparticles have been characterized by NMR spectroscopy, TEM, thermogravimetric analysis, X‐ray photoelectron spectroscopy (XPS), UV/Vis spectroscopy, elemental analysis, and zeta‐potential measurements. The interacting ability of the anionic sulfonate functions was investigated by EPR spectroscopy with copper(II) as a probe. Different structures and conformations of the AuNPs modulate the availability of sulfonate and thiol groups for complexation by copper(II). Toxicity assays of AuNPs showed that those produced through direct reaction were less toxic than those obtained by ligand exchange. Inhibition of HIV‐1 infection was higher in the case of dendronized AuNPs than in dendrons. 相似文献
110.
Maria Caterina Fragnelli Pilar Hoyos Diego Romano Raffaela Gandolfi Andrés R. Alcántara Francesco Molinari 《Tetrahedron》2012,68(2):523-528
Water/organic solvent two-liquid-phase systems have been successfully applied in the synthesis of enantiomerically pure (S)-benzoin through two different methodologies catalysed by whole cells from the non-conventional yeast Pichia glucozyma: the stereoselective monoreduction of benzil and the deracemisation of benzoin. The presence of the organic solvent influences the redox systems implied in the reactions, avoiding the formation of the corresponding diols, increasing the enantioselectivity and allowing the easy isolation of the products in high yields and excellent enantiomeric excesses. The use of both strategies has been extended to the preparation of different chiral benzoin derivatives. 相似文献