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排序方式: 共有127条查询结果,搜索用时 31 毫秒
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Hydrophilic interaction chromatography combined with tandem-mass spectrometry to determine six aminoglycosides in serum 总被引:2,自引:0,他引:2
An ion-pair liquid chromatography-electrospray mass spectrometry (LC-ESI-MS) method with in vivo microdialysis for the determination of free-form amphetamine in rat brain has been developed. A microdialysis probe was surgically implanted into the striatum of the rat and artificial cerebrospinal fluid (aCSF) was used as the perfusion medium. Samples were collected and then analyzed off-line by LC-ESI-MS. A reversed phase C18 column was employed for LC separation. Trifluoroacetic acid (TFA) was added in the mobile phase (acetonitrile-water, 10:90, v/v) as an ion-pair reagent. The ion-pair process disguises the protonated amphetamine cations from the ESI-MS electric field as neutral molecules. Post-column addition of volatile organic acid was utilized to minimize TFA signal suppression effect on ESI-MS detection. More than six-fold enhancement of ESI-MS response was achieved by the post-column addition of propionic acid. Good linearity (0.01-1.00 microg/ml, r2 = 0.99) and detection limit (0.002 microg/ml) were determined. Good precision and accuracy were obtained. The applicability of this newly developed method was demonstrated by continuous monitoring of amphetamine concentrations in rat brain after a single 3.0 mg/kg i.p. administration. 相似文献
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EI Rodriguez Martinez CI Barriga-Paulino MI Zapata CC Chinchilla AM López-Jiménez CM Gómez 《BMC neuroscience》2012,13(1):104-23
ABSTRACT: BACKGROUND: The peri-adolescent period is a crucial developmental moment of transition from childhood to emergent adulthood. The present report analyses the differences in Power Spectrum (PS) of the Electroencephalogram (EEG) between late childhood (24 children between 8 and 13 years old) and young adulthood (24 young adults between 18 and 23 years old). RESULTS: The narrow band analysis of the Electroencephalogram was computed in the frequency range of 0--20 Hz. The analysis of mean and variance suggested that six frequency ranges presented a different rate of maturation at these ages, namely: low delta, delta-theta, low alpha, high alpha, low beta and high beta. For most of these bands the maturation seems to occur later in anterior sites than posterior sites. Correlational analysis showed a lower pattern of correlation between different frequencies in children than in young adults, suggesting a certain asynchrony in the maturation of different rhythms. The topographical analysis revealed similar topographies of the different rhythms in children and young adults. Principal Component Analysis (PCA) demonstrated the same internal structure for the Electroencephalogram of both age groups. Principal Component Analysis allowed to separate four subcomponents in the alpha range. All these subcomponents peaked at a lower frequency in children than in young adults. CONCLUSIONS: The present approaches complement and solve some of the incertitudes when the classical brain broad rhythm analysis is applied. Children have a higher absolute power than young adults for frequency ranges between 0-20 Hz, the correlation of Power Spectrum (PS) with age and the variance age comparison showed that there are six ranges of frequencies that can distinguish the level of EEG maturation in children and adults. The establishment of maturational order of different frequencies and its possible maturational interdependence would require a complete series including all the different ages. 相似文献
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Emilie Boulard Vivien Zibulski Luisa Oertel Dr. Philip Lienau Dr. Martina Schäfer Dr. Ursula Ganzer Dr. Ulrich Lücking 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(19):4378-4388
A short synthetic approach with broad scope to access five- to seven-membered cyclic sulfoximines in only two to three steps from readily available thiophenols is reported. Thus, simple building blocks were converted to complex molecular structures by a sequence of S-alkylation and one-pot sulfoximine formation, followed by intramolecular cyclization. Seventeen structurally diverse cyclic sulfoximines were prepared in high overall yields. In vitro evaluation of these underrepresented, three-dimensional, cyclic sulfoximines with respect to properties relevant to medicinal chemistry did not reveal any intrinsic flaw for application in drug discovery. 相似文献
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A. Burr F. M. Berberich Sprinkmeyer Diedrichs E. Ackermann C. Valencien E. Müller-Hössly G. Cornalba Wuyt Courtoy F. Bordas F. Touplain R. Sanfelici G. Knappe H. Durand W. Gero R. Eichloff H. Bleçkmann L. Mathieu L. Ferré W. D. Kooper E. Oertel A. Kling P. Roy L. Ronnet L. Vandam R. Ledent E. Comanducci T. Jona Tillmans und Schneehagen 《Fresenius' Journal of Analytical Chemistry》1920,59(5-6):266-273
Ohne Zusammenfassung 相似文献
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A. Burr F. M. Berberich Sprinkmeyer Diedrichs E. Ackermann C. Valencien E. Müller-Hössly G. Cornalba Wuyt Courtoy F. Bordas F. Touplain R. Sanfelici G. Knappe H. Durand W. Gero R. Eichloff H. Bleçkmann L. Mathieu L. Ferré W. D. Kooper E. Oertel A. Kling P. Roy L. Ronnet L. Vandam R. Ledent E. Comanducci T. Jona Tillmans Schneehagen 《Analytical and bioanalytical chemistry》1920,59(5-6):266-273
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An integral equation formulation for buoyancy-driven convection problems is developed and illustrated. Buoyancy-driven convection in a bounded cylindrical geometry with a free surface is studied for a range of aspect ratios and Nusselt numbers. The critical Rayleigh number, the nature of the cellular motion, and the heat transfer enhancement are computed using linear theory. Green's functions are used to convert the linear problem into linear Fredholm integral equations. Theorems are proved which establish the properties of the eigenvalues and eigenfunctions of the linear integral operator which appears in these equations. 相似文献
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Stanley M. Miller J. R. Giles C. P. Oertel 《Journal of Radioanalytical and Nuclear Chemistry》2009,279(2):487-491
Radium concentration was determined in 23 types of bottled mineral waters, commercially available in Romania. Using the Lucas
cells with the device Luk 3A, the radium concentration was determined directly, after the radon balanced with radium. From
these measurements, the corresponding annual effective ingestion dose was determined. 相似文献