排序方式: 共有13条查询结果,搜索用时 15 毫秒
1.
2.
Empar Fos Francisco Bosc David Maulen Germane Carganico 《Journal of heterocyclic chemistry》1993,30(2):473-476
The synthesis of the new dihydropyridine diethyl 1,4-dihydro-4-(imidazo[1,5-α]pyridin-8-yl)-2,6-dimethyl-pyridine-3,5-dicarboxylate ( 1 ) is described. After many attempts to prepare the key intermediate aldehyde 2a by different approaches, this compound has been obtained in good yields from methyl 2-cyano-3-pyridinecar-boxylate ( 10 ). A three-step procedure involving reduction to the amine, formylation with concomitant cyclization and reduction of the ester group was used. 相似文献
3.
A quantitative analytical imaging approach for determining the nickel content of metallic meteorites is proposed. The approach uses a digital image of a series of standard solutions of the nickel-dimethylglyoxime coloured chelate and a meteorite sample solution subjected to the same treatment as the nickel standards for quantitation. The image is processed with suitable software to assign a colour-dependent numerical value (analytical signal) to each standard. Such a value is directly proportional to the analyte concentration, which facilitates construction of a calibration graph where the value for the unknown sample can be interpolated to calculate the nickel content of the meteorite. The results thus obtained were validated by comparison with the official, ISO-endorsed spectrophotometric method for nickel.The proposed method is fairly simple and inexpensive; in fact, it uses a commercially available digital camera as measuring instrument and the images it provides are processed with highly user-friendly public domain software (specifically, ImageJ, developed by the National Institutes of Health and freely available for download on the Internet).In a scenario dominated by increasingly sophisticated and expensive equipment, the proposed method provides a cost-effective alternative based on simple, robust hardware that is affordable and can be readily accessed worldwide. This can be especially advantageous for countries were available resources for analytical equipment investments are scant. The proposed method is essentially an adaptation of classical chemical analysis to current, straightforward, robust, cost-effective instrumentation. 相似文献
4.
Stepwise syntheses of difluoroazoles , , and have been performed. The JFF coupling constants are reported for the first time. Surprisingly, no coupling between F4 and F5 is observed. 相似文献
5.
M. L. Garcí a J. Pascual L. Borr s J. A. Andreu E. Fos D. Maule n G. Carganico F. Arcamone 《Tetrahedron》1991,47(48):10023-10034
A series of new glycerophospholipids, bearing a short-chain carboxylic acid in position sn-1 and phosphocholine or phosphoserine in postion sn-3 of glycerol, have been prepared in good overall yields. Compound 11, 1-0-(6-carboxyhexyl)-sn-glycero-3-phosphoserine, a strict analog of the structure proposed for modulator, has been synthesized in a stereoselective way from (R)-1,2-isopropylideneglycerol 1. 相似文献
6.
Gómez-Taylor Corominas B Antón Fos GM Garcı́a Mateo JV Lahuerta Zamora L Martı́nez Calatayud J 《Talanta》2003,60(2-3):623-628
A paper from this laboratory 'J. Anal. Chem. 73 (2001) 4301' was recently published and dealing with the first attempt to apply molecular connectivity calculations to predict a chemical property with analytical usefulness; namely, the chemiluminescent behaviour of substances when react with common strong oxidants in liquid phase. In the present work, the usefulness of molecular topology on the search for new chemiluminescent compounds is clearly demonstrated. The proposed discriminant equation, represented a success of 92.7% in the prediction. The present paper is the further step from the cited paper; it is dealing on the application of molecular connectivity calculations (former discriminant equation 'J. Anal. Chem. 73 (2001) 4301') to predict the chemiluminescent behaviour of phenols and polyphenols when they react with common oxidants in liquid phase. A number of phenols and polyphenols (close to 100) were theoretically studied by means of the discriminant equation 'J. Anal. Chem. 73 (2001) 4301', being some of them predicted as chemiluminescent with a high probability. These theoretical predictions have been empirically checked through a continuous flow manifold. A number of 33 compounds, selected between those which chemiluminescent behaviour was predicted, were assayed. A success of 100% over the theoretical predictions was obtained. 相似文献
7.
J. Escoriaza M. C. Dios-Viéitez I. F. Trocóniz M. J. Renedo D. Fos 《Chromatographia》1997,44(3-4):169-171
Summary A sensitive method was developed for the determination of temazepam in plasma using capillary gas chromatography. After the
extraction into dichloromethane-pentane (1∶1), temazepam was quantitated as its O-trimethylsilyl derivative on a capillary
column with a63Ni electron capture detector using prazepam as internal standard. The detector response was found to be linear in the concentration
range 0.031 to 8 μg mL−1. The detection limit was about 3.5 ng mL−1. The intraday and inter-day coefficients of variation were below 9%. The method was used to determine the pharmacokinetic
profile of temazepam in rats after intravenous administration. 相似文献
8.
Lucas R Vengut-Climent E Gómez-Pinto I Aviñó A Eritja R González C Morales JC 《Chemical communications (Cambridge, England)》2012,48(24):2991-2993
Mono- and disaccharides have been shown to stack on top of DNA duplexes stabilizing sequences with terminal C-G base pairs. Here we present an apolar version of glucose and cellobiose as new capping agents that stack on DNA increasing considerably its stability with respect to their natural polyhydroxylated mono- and disaccharide DNA conjugates. 相似文献
9.
Dr. Irene Gómez‐Pinto Empar Vengut‐Climent Dr. Ricardo Lucas Dr. Anna Aviñó Prof. Dr. Ramón Eritja Prof. Dr. Carlos González Dr. Juan Carlos Morales 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(6):1920-1927
Quadruplex DNA structures are attracting an enormous interest in many areas of chemistry, ranging from chemical biology, supramolecular chemistry to nanoscience. We have prepared carbohydrate–DNA conjugates containing the oligonucleotide sequences of G‐quadruplexes (thrombin binding aptamer (TBA) and human telomere (TEL)), measured their thermal stability and studied their structure in solution by using NMR and molecular dynamics. The solution structure of a fucose–TBA conjugate shows stacking interactions between the carbohydrate and the DNA G‐tetrad in addition to hydrogen bonding and hydrophobic contacts. We have also shown that attaching carbohydrates at the 5′‐end of a quadruplex telomeric sequence can alter its folding topology. These results suggest the possibility of modulating the folding of the G‐quadruplex by linking carbohydrates and have clear implications in molecular recognition and the design of new G‐quadruplex ligands. 相似文献
10.
Empar Fos Liset Borrs Maria Gasull David Maulen Germano Carganico 《Journal of heterocyclic chemistry》1992,29(1):203-208
Four series of potential PAF-antagonists in which the isoxazole nucleus is condensed with a polyhydrogenated five- or six-carbon ring were prepared. The synthesis of the compounds 3-aryl-4,5,6,7-tetrahydrobenz[c]isoxazoles 1 , 3-arylcyclopent[c]isoxazoles 2 , 3-aryl-4,5,6,7-tetrahydrobenz[d]isoxazoles 3 , and 3-arylcyclopent[d]isoxazoles 4 , required an extensive optimization and comparison of the methods available in the literature. 相似文献