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排序方式: 共有329条查询结果,搜索用时 13 毫秒
321.
Francisco Marcellán M. Francisca Pérez-Valero Yamilet Quintana 《Journal of Mathematical Analysis and Applications》2015
The aim of this paper is to present some new results about the asymptotic behavior of the partial derivatives of the kernel polynomials associated with the Gamma distribution. We also show how these results can be used in order to obtain the inner relative asymptotics for certain Laguerre–Sobolev type polynomials. 相似文献
322.
A sensitive and specific method for the determination of valproic acid in plasma has been developed. After the proteins in the plasma have been precipitated with a saturated solution of ammonium sulfate in 1N HCl, the valproic acid, together with the internal standard, is extracted from the plasma with dichloromethane. An aliquot of the organic solution is taken for derivatization of the valproic acid and the internal standard with O-p-nitrobenzyl-N,N′-diisopropylisourea. Separation is carried out by HPLC using two chromatographic systems: an adsorption system with a μ Porasil column, hexane-chloroform (94:6) as mobile phase, and caproic acid as internal standard and a partition reverse phase system comprising a μ Bondapak TM/C18 column, acetonitrile/methanol/0.0035 M phosphate buffer (60:10:30), and caprylic acid as internal standard. UV detection is at 254 nm. This method, developed in both systems, permits the determination of plasma levels of valproic acid in the reported range of 50-100 μg/mL. With adequate sensitivity, specificity, precision, and accuracy. The plasma levels of valproic acid may be determined by this method without interference from the commonest antiepileptic drugs. Good correlation is obtained with the enzymatic immune analytic method: EMIT. 相似文献
323.
Raül Rigo-Bonnin Roser Juvany-Roig Elisabet Leiva-Badosa Joan Sabater-Riera Xosé L. Pérez-Fernández Paola Cárdenas-Campos Enric Sospedra-Martínez Helena Colom Pedro Alía 《Analytical and bioanalytical chemistry》2014,406(20):4997-5007
Meropenem is a broad-spectrum antibiotic, often used for the empirical treatment of infections in critically ill patients with acute kidney injury. Meropenem has clinically insignificant protein binding and, as a carbapenem antibiotic, shows time-dependent bacterial killing, meaning that the unbound or free antibiotic concentration in blood should be maintained above the minimal inhibitory concentration of the pathogen for at least 40 % of the dosing interval. We developed and validated simple chromatographic methods by ultra-performance liquid chromatography-tandem mass spectrometry to measure plasma, filtrate-dialysate, and urine concentrations of meropenem. Chromatographic separation was achieved using an Acquity® UPLC® BEHTM (2.1?×?100 mm id, 1.7 μm) reverse-phase C18 column, with a water/acetonitrile linear gradient containing 0.1 % formic acid at a 0.4-mL/min flow rate. Meropenem and its internal standard (ertapenem) were detected by electrospray ionization mass spectrometry in positive ion multiple reaction monitoring mode. The limits of quantification were 0.27, 0.24, and 1.22 mg/L, and linearity was observed between 0.27–150, 0.24–150, and 1.22–2,000 mg/L for plasma, filtrate-dialysate, and urine samples, respectively. Coefficients of variation and relative biases were less than 13.5 and 8.0 % for all biological fluids. Recovery values were greater than 68.3 %. Evaluation of the matrix effect showed ion suppression for meropenem and ertapenem. No carry-over was observed. The validated methods are useful for both therapeutic drug monitoring and pharmacokinetic studies. It could be applied to daily clinical laboratory practice to measure the concentration of meropenem in plasma, filtrate-dialysate, and urine. Figure
Meropenem chemical structures 相似文献
324.
325.
Andrew J. Smaligo Jason Wu Nikolas R. Burton Allison S. Hacker Dr. Aslam C. Shaikh Jason C. Quintana Ruoxi Wang Dr. Changmin Xie Prof. Dr. Ohyun Kwon 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(3):1227-1231
Reported herein is a one-pot protocol for the oxodealkenylative introduction of carbonyl functionalities into terpenes and terpene-derived compounds. This transformation proceeds by Criegee ozonolysis of an alkene, reductive cleavage of the resulting α-alkoxy hydroperoxide, trapping of the generated alkyl radical with 2,2,6,6-tetramethylpiperidin-1-yl (TEMPO), and subsequent oxidative fragmentation with MMPP. Using readily available starting materials from chiral pool, a variety of carbonyl-containing products have been accessed rapidly in good yields. 相似文献
326.
Alessandra Guglielmi Francesca Ieva Anna Maria Paganoni Fernardo A. Quintana 《Advances in Data Analysis and Classification》2018,12(2):399-423
We propose a Bayesian semiparametric regression model to represent mixed-type multiple outcomes concerning patients affected by Acute Myocardial Infarction. Our approach is motivated by data coming from the ST-Elevation Myocardial Infarction (STEMI) Archive, a multi-center observational prospective clinical study planned as part of the Strategic Program of Lombardy, Italy. We specifically consider a joint model for a variable measuring treatment time and in-hospital and 60-day survival indicators. One of our main motivations is to understand how the various hospitals differ in terms of the variety of information collected as part of the study. To do so we postulate a semiparametric random effects model that incorporates dependence on a location indicator that is used to explicitly differentiate among hospitals in or outside the city of Milano. The model is based on the two parameter Poisson-Dirichlet prior, also known as the Pitman-Yor process prior. We discuss the resulting posterior inference, including sensitivity analysis, and a comparison with the particular sub-model arising when a Dirichlet process prior is assumed. 相似文献
327.
Determination of acidic drugs in sewage water by gas chromatography-mass spectrometry as tert.-butyldimethylsilyl derivatives 总被引:1,自引:0,他引:1
Rodríguez I Quintana JB Carpinteiro J Carro AM Lorenzo RA Cela R 《Journal of chromatography. A》2003,985(1-2):265-274
A procedure is described for the determination of five acidic non-steroidal anti-inflammatory pharmaceuticals (ibuprofen, naproxen, ketoprofen, tolfenamic acid and diclofenac) in sewage water. The analytical method involves the concentration of water samples using a solid-phase extraction polymeric sorbent, functionalized with N-vinylpyrrolidone. Analytes were eluted with ethyl acetate. derivatized using N-methyl-N-(tert.-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) and analyzed by GC-MS. Influence of time, temperature and volume of MTBSTFA in the yield of the derivatization step were studied in detail using a factorial central composite design. Quantification limits of the analytical procedure for 500 ml of sewage water ranged from 20 to 50 ng/l. Recoveries from 90 to 115% were found for sewage water samples spiked with the studied compounds at the low ng/ml level. Results obtained for real samples show the presence of ibuprofen and naproxen in both influent and effluent of a sewage water treatment plant. 相似文献
328.
329.
A. Salmern-valverde J. G. Robles-Martínez J. García-serrano R. Gmez R. Ridaura M. Quintana A. Zehe 《Crystal Research and Technology》1997,32(5):717-722
The degree of charge transfer has been determined in six TTF-fluorene derivative charge transfer complexes, using IR and Raman vibrational spectroscopies. It has been found that changes of the intermolecular electronic distribution is strongly influenced by the presence of the dicyanomethylene group, by the increase of the nitro groups, as well as by the symmetry of the acceptor. 相似文献