排序方式: 共有107条查询结果,搜索用时 31 毫秒
31.
Mara Tomassetti Michela Fanì Gianluca Bianchini Sandra Giuli Andrea Aramini Sandro Colagioia Giuseppe Nano Samuele Lillini 《Tetrahedron letters》2013
Chiral substituted phenylethyl-1H-tetrazoles were built-up from the corresponding carboxylic acid derivatives by a useful three-step synthesis. The procedure, that preserves the chiral center from racemization, was successfully applied to a selection of several hit compounds by conversion of the carboxylic acid moiety to the nitrile derivatives and subsequent reaction with trimethylstannyl azide, under microwave conditions. A useful application to the corresponding tetrazole analogue has been found also in the conversion of the aminoacidic moiety like (R)-N-Cbz-phenylglycine showing a wide potential synthetic application. 相似文献
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Bertoncini J Nazzi T Cabrera L Lorenzi C 《The Journal of the Acoustical Society of America》2011,129(5):2761-2764
Young deaf children using a cochlear implant develop speech abilities on the basis of speech temporal-envelope signals distributed over a limited number of frequency bands. A Headturn Preference Procedure was used to measure looking times in 6-month-old, normal-hearing infants during presentation of repeating or alternating sequences composed of different tokens of /aba/and /apa/ processed to retain envelope information below 64 Hz while degrading temporal fine structure cues. Infants attended longer to the alternating sequences, indicating that they perceive the voicing contrast on the basis of envelope cues alone in the absence of fine spectral and temporal structure information. 相似文献
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Samuele Giraudo 《Discrete Mathematics》2019,342(6):1624-1657
We introduce bud generating systems, which are used for combinatorial generation. They specify sets of various kinds of combinatorial objects, called languages. They can emulate context-free grammars, regular tree grammars, and synchronous grammars, allowing us to work with all these generating systems in a unified way. The theory of bud generating systems uses colored operads. Indeed, an object is generated by a bud generating system if it satisfies a certain equation in a colored operad. To compute the generating series of the languages of bud generating systems, we introduce formal power series on colored operads and several operations on these. Series on colored operads are crucial to express the languages specified by bud generating systems and allow us to enumerate combinatorial objects with respect to some statistics. Some examples of bud generating systems are constructed; in particular to specify some sorts of balanced trees and to obtain recursive formulas enumerating these. 相似文献
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Orazio A. Attanasi Lucia De Crescentini Paolino Filippone Samuele Lillini 《Tetrahedron letters》2007,48(14):2449-2451
New tetrahydro-3aH-cyclopenta[d][1,3]thiazolines and hexahydro-1,3-benzothiazolines were obtained in satisfactory yields by reaction of cycloalkenyl-1-diazenes with thioamides. These thiazolines were converted into unknown fused cycloalkyl-thiazoline-pyrazole systems. 相似文献
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Combination of the enantioselective properties of the two versatile gas-chromatographic chiral stationary phases (CSPs) octakis(3-O-butanoyl-2,6-di-O-n-pentyl)-gamma-CD (Lipodex E) 1 and L-valine-diamide-based CSP Chirasil-Val-C11 2 has been realized by doping the chiral polymer 2 with the nonpolymeric selector 1. The resulting mixed-mode CSP Chirasil-Val(gamma-Dex) 3 was found to have a greatly improved enantioselectivity toward proline and aspartic acid (as N-trifluoroacetyl ethyl or methyl esters) in comparison to the single-mode CSP 2. The presence of the CD selector in 3 extended the scope of gas-chromatographic enantioseparations achievable on 2 to underivatized alcohols, terpenes, and other chiral compounds that are exclusively enantioseparated on 1. 相似文献
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Lo Conte M Staderini S Marra A Sanchez-Navarro M Davis BG Dondoni A 《Chemical communications (Cambridge, England)》2011,47(39):11086-11088
The free-radical hydrothiolation of alkynes (thiol-yne coupling, TYC) unites two thiol fragments across the carbon-carbon triple bond to give a dithioether derivative with exclusive 1,2-addition; this reaction can be used for modification of peptides and proteins allowing glycoconjugation and fluorescent labeling. These results have implications not only as a flexible strategy for attaching two modifications at a single site in proteins but also for unanticipated side-reactions of reagents (such as cycloalkynes) used in other protein coupling reactions. 相似文献
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Samuele Giraudo 《Comptes Rendus Mathematique》2012,350(11-12):549-552
We study a functorial construction from the category of monoids to the category of set-operads and we give some combinatorial examples of applications. 相似文献
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Federica Aiello Gloria Uccello-Barretta Claudio Picchi Samuele Nazzi Alessandra Recchimurzo Federica Balzano 《Molecules (Basel, Switzerland)》2022,27(19)
The understanding of the interaction between non-steroidal anti-inflammatory drugs and human serum albumin plays a fundamental role in the development of new drugs and new therapeutic strategies. Several studies have been performed, nevertheless, the interaction phenomena are still not fully understood. In this work, high-field solution Nuclear Magnetic Resonance (NMR) spectroscopy was applied to compare the strength of the interaction of diclofenac sodium salt, ketorolac tris salt and flurbiprofen sodium salt toward albumin. To this aim, mono- and bi-selective relaxation rate measurements were performed by applying selective π-pulses at the selected frequencies and by following magnetization recovery. On the basis of the dependence of relaxation parameters on albumin concentration, normalized affinity indexes were calculated for several protons of the drugs. Affinity indexes for diclofenac were about five-fold higher in comparison with ketorolac and flurbiprofen. Aromatic moieties of the three drugs and methine protons at the chiral centers of ketorolac and flurbiprofen were more involved in the interaction with albumin. In conclusion, NMR spectroscopy allows not only for the comparison of drug-to-protein affinities but also points out the nature of the drug sites that are more extensively involved in the interaction. 相似文献