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11.
12.
Pérez-Prieto J Galian RE Miranda MA Catalina F Martín-Vargas N López-Ortiz F 《Organic letters》2004,6(4):561-564
[reaction: see text] Several benzo[d]-1,2-oxaphosphole 2-oxides were examined as potential precursors of stabilized C-centered radicals. The transient absorption spectra obtained after laser flash photolysis in the presence of di-tert-butyl peroxide showed the features of benzylic radicals with formation and decay kinetics not significantly influenced by the presence of oxygen. In the case of compounds with two possible diastereomeric forms, the C-H bond of the trans-isomers [corrected] is more reactive toward hydrogen abstraction. 相似文献
13.
M. Valcárcel Mercedes Gallego Angel Ríos 《Fresenius' Journal of Analytical Chemistry》1998,362(1):58-66
The interfaces between low-pressure continuous sample treatment systems and high-level information instruments such as gas
chromatographs, capillary electrophoresis equipment and graphite furnace atomic spectroscopic instruments, which are characterized
by conventional discrete sample introduction devices, are presented. The present and future developments are discussed of
(directly) linking real samples and those analytical equipments with the main objective of avoiding or minimizing manually
implemented preliminary operations of the analytical process.
Received: 27 January 1998 / Revised: 5 March 1998 / Accepted: 7 March 1998 相似文献
14.
Masip I Pérez-Payá E Messeguer A 《Combinatorial chemistry & high throughput screening》2005,8(3):235-239
N-Alkylglycine oligomers (peptoids) constitute a family of non-natural peptidomimetics attractive for the early drug discovery process because of their physicochemical features, easy of adaptation to combinatorial chemistry approaches and their proteolytic stability. Consequently, peptoid libraries have found application for discovering hits against a wide diversity of pharmaceutical targets, among which different examples of antibacterials are found. In the present work, research efforts addressed towards the identification of peptoids as antibacterial agents are discussed. 相似文献
15.
Triolo A Russina O Hardacre C Nieuwenhuyzen M Gonzalez MA Grimm H 《The journal of physical chemistry. B》2005,109(46):22061-22066
A detailed investigation on the nature of the relaxation processes occurring in a typical room temperature ionic liquid (RTIL), namely, 1-butyl-3-methyl imidazolium hexafluorophosphate ([bmim][PF(6)]), is reported. The study was conducted using both elastic and inelastic neutron scattering over a wide temperature range from 10 to 400 K, accessing the dynamic features of both the liquid and glassy amorphous states. In this study, the inelastic fixed energy scan technique has been applied for the first time to this class of materials. Using this technique, the existence of two relaxation processes below the glass transition and a further diffusive process occurring above the glass-liquid transition are observed. The low temperature processes are associated with methyl group rotation and butyl chain relaxation in the glassy state and have been modeled in terms of two Debye-like, Arrhenius activated processes. The high temperature process has been modeled in terms of a Kohlraush-Williams-Watts relaxation, with a distinct Vogel-Fulcher-Tamman temperature dependence. These results provide novel information that will be useful in rationalizing the observed structural and dynamical behavior of RTILs in the amorphous state. 相似文献
16.
Photocyclization of 2-chloroacetyl-1,2,3,4,5,6-hexahydro-1, 5-methanoazocino[4,3-b]indole () takes place at the indole 4-position to give a 1 ,2 ,3 ,4 , 5 ,6-hexahydro-2 ,11-ethano-1 ,5-methanoazocino [4 , 3-6] indole system. Consequently, the method appears to be unsuitable for constructing the pyrrolidine ring of pentacyclic Strychnos indole alkaloids. 相似文献
17.
Elena Laukhina Vladislava Tkacheva Salavat Khasanov Leokadia Zorina Jordi Gómez-Segura Angel Pérez del Pino Jaume Veciana Vladimir Laukhin Concepció Rovira 《Chemphyschem》2006,7(4):920-923
Temperature has great impact on the structure and size of the linked crystallites of the conducting topmost layer formed at the surface of a polycarbonate film via the reaction BEDT-TTF+IBr [BEDT-TTF=bis(ethylenedithio)tetrathiafulvalene]. We show that fine temperature control permits formation of a semiconducting topmost layer of alpha'-(BEDT-TTF)(2)(I(x)Br(1-x))(3) crystallites with either micro- or nanometre size, a result that opens a route to miniaturized conducting plastic materials. 相似文献
18.
We describe the preparation of 1,4′-bipyrazolyls and 4-pyrazolylpyrimidines by the reaction of 2-pyrazolyl-3-dimethylamino acrylate and acrylonitrile with double nucleophilic reagents such as hydrazines, urea and guanidine. Reactions were performed under microwave irradiation in 5-60 min. This is a useful procedure for the preparation of valuable compounds with applications in medicinal and coordination chemistry. 相似文献
19.
Screening and analytical confirmation of sulfonamide residues in milk by capillary electrophoresis-mass spectrometry 总被引:1,自引:0,他引:1
A new methodology is proposed to automate the monitoring of sulfonamide residues in milk samples. It combines a screening unit for the total amount of sulfonamide with capillary electrophoresis-mass spectrometry (CE-MS) equipment for processing the samples containing a detectable level of sulfonamide. The screening unit consists of continuous-flow system (CFS) to precipitate the proteins connected on-line to the CE-MS equipment, in which a common characteristic ion of all sulfonamides was monitored with the MS detector by flushing the sample through the capillary. The confirmatory method is based on the purification and preconcentration of sulfonamides in a CFS unit and posterior analysis by CE-MS. The sample treatment unit was also on-line connected to the CE-MS equipment. In order to increase sensitivity, the flow rate of the sheath liquid was diminished from 0.5 to 0.2 microL.min(-1) by increasing the content in water from 0 to 50% and the formic acid from 0.5 to 1.5% in this liquid and by applying an overimposed pressure of 5 mbar during the electrophoretic separation. The method allowed the analysis of 30 samples per hour. 相似文献
20.
Angel Alberola Luis Calvo Teresa Rodríguez Rodríguez Carmen Saudo 《Journal of heterocyclic chemistry》1992,29(2):445-450
The reactivity of 3-methyl-5-phenylisoxazole against electrophilic compounds in the presence of different bases is studied. With n-BuLi, alkylated products at C-4 position and C-3 methyl group, and, in a few cases, dialkylated isoxazoles are obtained. When the reactions are carried out with LICA, the nature of the alkylated products depends on the alkyl halide used. By using LICA-TMEDA, as deprotonating system, regio-selective reaction at the C-3 methyl group is found. 相似文献