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排序方式: 共有160条查询结果,搜索用时 193 毫秒
91.
Warwood S Mohammed S Cristea IM Evans C Whetton AD Gaskell SJ 《Rapid communications in mass spectrometry : RCM》2006,20(21):3245-3256
The application of guanidination chemistry, the conversion of lysine into homoarginine residues, is used to illustrate several important general considerations relating to the use of differential isotope labelling for relative quantification in proteomics. The derivatisation procedure has been optimised for automation using a liquid handling station designed for proteomics. Automated application of the procedure to the analysis of in-gel tryptic digests of multiple spots from the two-dimensional gel electrophoretic (2DE) analysis of proteins from the FDCP-mix cell line shows near-universal improvement in protein identification as a result of derivatisation. This chemistry has been extended for relative quantification, applicable to matrix-assisted laser desorption/ionisation mass spectrometry (MALDI-MS) and also tandem mass spectrometry (MS/MS). It provides a robust method for the quantitative comparison of two samples that have been separated by 2DE. A peptide pair may display poor detection during MS analysis, causing their reliable relative quantification to be difficult. In such circumstances, the additional selectivity of detection provided by MS/MS can substantiate identification and allow relative quantification of these species via product ion signal ratios. 相似文献
92.
Periodica Mathematica Hungarica - This paper continues our investigation of Rényi-type continued fractions studied in Lascu and Sebe (A dependence with complete connections approach to... 相似文献
93.
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96.
Marian Romeo Calin Alexandru Erminiu Druker Ileana Radulescu 《Journal of Radioanalytical and Nuclear Chemistry》2013,295(1):283-288
This paper presents a method for efficiency calibration of a measuring alpha–beta system PROTEAN ORTEC, MPC-2000-DP, using standard radioactive sources. The system is used to measure gross alpha–beta activity concentrations in environmental samples. The calculated efficiencies of detection were subsequently introduced in the system for two working geometries: measuring geometry—gross alpha–beta $ \varepsilon_{\alpha }^{g} $ = 31,37 ± 0.25 (%)—the alpha efficiency and $ \varepsilon_{\beta }^{g} $ = 44.94 ± 0.69 (%)—the beta efficiency, where the spillover factor is $ X_{\text{talk}}^{g} $ = 25.59 ± 0.50 (%) and measuring geometry up alpha–beta $ \varepsilon_{\alpha }^{u} $ = 36.23 ± 0.29 (%)—the alpha efficiency and $ \varepsilon_{\beta }^{u} $ = 48.53 ± 0.74 (%)—the beta efficiency, where the spillover factor is $ X_{\text{talk}}^{u} $ = 31.08 ± 0.60 (%). 相似文献
97.
Valeria Di Bussolo Ileana FrauLorenzo Checchia Lucilla FaveroMauro Pineschi Gloria Uccello-BarrettaFederica Balzano Graziella RoselliGabriele Renzi Paolo Crotti 《Tetrahedron》2011,67(25):4696-4709
The new racemic diastereoisomeric epoxides 6α and 6β, the carba analogs of the corresponding d-galactal- and d-allal-derived allyl epoxides have been synthesized and their regio- and stereoselective behavior examined in addition reactions with model O-, C-, N-, and S-nucleophiles. The results have indicated that epoxide 6β has a pronounced tendency toward anti-1,2-addition, whereas epoxide 6α shows interesting levels of syn- and/or anti-1,4-addition processes. A chiral recognition process found with epoxide 6β, turned out to be consistently reduced in epoxide 6α. All the results have been rationalized on the basis of conformational, steric, and stereoelectronic effects. 相似文献
98.
Carmen Limban Alexandru V. Missir Ileana C. Chirita George M. Nitulescu Miron T. Caproiu Mariana C. Chifiriuc Anca M. Israil 《Chemical Papers》2011,65(1):60-69
New acylthiourea derivatives, 2-((4-ethylphenoxy)methyl)-N-(phenylcarbamothioyl)benzamides, were tested by qualitative and quantitative methods on various bacterial and fungal strains
and proved to be active at low concentrations against Gram-positive and Gram-negative bacteria as well as fungi. These compounds
were prepared by the reaction of 2-((4-ethylphenoxy)methyl)benzoyl isothiocyanate with various primary aromatic amines, and
were characterised by melting point and solubility. The structures were identified by elemental analysis, 1H and 13C NMR, and IR spectral data. The level of antimicrobial activity of the new 2-((4-ethylphenoxy)methyl)benzoylthiourea derivatives
was dependent on the type, number and position of the substituent on the phenyl group attached to thiourea nitrogen. The iodine
and nitro substituents favoured the antimicrobial activity against the Gram-negative bacterial strains, while the highest
inhibitory effect against Gram-positive and fungal strains was exhibited by compounds with electron-donating substituents
such as the methyl and ethyl groups. 相似文献
99.
Macwan JS Ionita IA Dostalek M Akhlaghi F 《Analytical and bioanalytical chemistry》2011,400(2):423-433
The aim of the proposed work was to develop and validate a simple and sensitive assay for the analysis of atorvastatin (ATV)
acid, ortho- and para-hydroxy-ATV, ATV lactone, and ortho- and para-hydroxy-ATV lactone in human plasma using liquid chromatography-tandem mass spectrometry. All six analytes and corresponding
deuterium (d5)-labeled internal standards were extracted from 50 μL of human plasma by protein precipitation. The chromatographic
separation of analytes was achieved using a Zorbax-SB Phenyl column (2.1 mm × 100 mm, 3.5 μm). The mobile phase consisted
of a gradient mixture of 0.1% v/v glacial acetic acid in 10% v/v methanol in water (solvent A) and 40% v/v methanol in acetonitrile (solvent B). All analytes including ortho- and para-hydroxy metabolites were baseline-separated within 7.0 min using a flow rate of 0.35 mL/min. Mass spectrometry detection was
carried out in positive electrospray ionization mode, with multiple-reaction monitoring scan. The calibration curves for all
analytes were linear (R
2 ≥ 0.9975, n = 3) over the concentration range of 0.05–100 ng/mL and with lower limit of quantitation of 0.05 ng/mL. Mean extraction recoveries
ranged between 88.6–111%. Intra- and inter-run mean percent accuracy were between 85–115% and percent imprecision was ≤ 15%.
Stability studies revealed that ATV acid and lactone forms were stable in plasma during bench top (6 h on ice-water slurry),
at the end of three successive freeze and thaw cycles and at −80 °C for 3 months. The method was successfully applied in a
clinical study to determine concentrations of ATV and its metabolites over 12 h post-dose in patients receiving atorvastatin. 相似文献
100.
Mihaela Vlassa George Borodi Gabriela Blăniţa Ileana Cojocaru Mircea Vlassa Cristian Silvestru 《Central European Journal of Chemistry》2011,9(2):224-231
Reaction of [CuII(cyclam)](ClO4)2 or [NiII(cyclam)](ClO4)2 in DMF with aqueous 4-hydroxy-3-(4-sulfonato-1-naphthylazo)naphthalen-1-sulfonate disodium salt (carmoisine) yielded coordination
polymers {[CuII(cyclam)](carmoisine dianion)(H2O)5}n and powder {[NiII(cyclam)](carmoisine dianion)}n, respectively (cyclam = 1,4,8,11-tetrazacyclotetradecane). They were characterized by powder X-ray diffraction, IR, Raman
spectrometry and TGA. 相似文献