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51.
52.
A high-performance liquid chromatographic method is presented for the simultaneous identification and quantification of six commonly prescribed phenothiazines. Single-step extraction was achieved from alkaline samples with heptane - isoamyl alcohol (98.5 + 1.5), using prochlorperazine as an internal standard. A Spherisorb CN column was used, with a mobile phase of acetonitrile - acetate buffer (95 + 5). Detection was carried out at 254 nm. 相似文献
53.
A. Mougin C. Dufour N. Maloufi K. Dumesnil Ph. Mangin 《The European Physical Journal B - Condensed Matter and Complex Systems》2001,19(2):289-296
Single crystal RFe2(110) films were grown by molecular beam epitaxy to a total thickness of 1000 ? at different substrate temperatures ranging
from 450
°
C to 660
°
C. The first stages of growth and the surface morphology of the deposited layers have been studied using Reflection High Energy
Electron Diffraction (RHEED) and Atomic Force Microscopy (AFM). The growth is first strained but further deposit induces the
formation of three-dimensional fully relaxed islands. Subsequently, the morphology of the RFe2(110) nanosystems evolves from anisotropic dots to a smooth surface, as a function of the preparation parameters, i.e. nominal thickness and substrate temperature. It also depends on the rare earth involved in the compound.
Received 29 June 2000 相似文献
54.
Because of the emergence of dried blood spots (DBS) as an attractive alternative to conventional venous plasma sampling in
many pharmaceutical companies and clinical laboratories, different analytical approaches have been developed to enable automated
handling of DBS samples without any pretreatment. Associated with selective and sensitive MS–MS detection, these procedures
give good results in the rapid identification and quantification of drugs (generally less than 3 min total run time), which
is desirable because of the high throughput requirements of analytical laboratories. The objective of this review is to describe
the analytical concepts of current direct DBS techniques and to present their advantages and disadvantages, with particular
focus on automation capacity and commercial availability. Finally, an overview of the different biomedical applications in
which these concepts could be of major interest will be presented. 相似文献
55.
56.
AM Cardoso SM Alexandre CM Barros AJ Correia NM Nibbering 《Rapid communications in mass spectrometry : RCM》1999,13(19):1885-1888
The collision-induced dissociation (CID) of deprotonated arylalkylamines of general formula R(1)C(6)H(4)CHR(2)CH(2)NR(3)(2) (where R(1) = H, OH, F or NO(2); R(2) = H or OH; R(3) = H or CH(3)) generated by negative chemical ionization with H(2)O and D(2)O as ionizing reagents, is discussed. The negative chemical ionization mass spectra show that, in the absence of a hydroxy group in the aromatic ring, deprotonation takes place at the benzylic position whereas the proton is lost from the OH group when present. The nitro compound forms only M(-.) ions. The CID spectra of the deprotonated molecules show that fragmentations are strongly dependent on the structural features of the molecules, namely the presence or absence of substituents in the aromatic ring or aliphatic chain. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
57.
Abstract Dielectric constant, spontaneous polarization and pyroelectric response measurements were performed on thin samples (e < 100 μm) of H-thiourea as a function of temperature and applied electric field. Along with previous data obtained by optical birefringence, X-ray and neutron diffraction techniques, the results put in evidence three features in the modulated region between the ferroelectric state and the paraelectric one. The tricritical point is determined for Etr ? 2075 V/mm and Ttr ? 192 K. 相似文献
58.
Magnetization in Fex Si1?x amorphous alloys was measured at high magnetic field up to 150 k0e. The experimental data show the existence of critical conditions for the occurence of magnetic order whose first stage is the appearance of giant moments in the 0.35 < × < 0.50 composition range. At larger iron concentration (x ? 0.5) a férromagnet behaviour arises from a percolation process. 相似文献
59.
AM Johnston CM Scrimgeour MO Henry LL Handley 《Rapid communications in mass spectrometry : RCM》1999,13(14):1531-1534
The conversion of nitrate (NO(3)(-)) to 1-phenylazo-2-naphthol (Sudan-1) has been examined as a method for natural abundance measurement of delta(15)N of NO(3)(-). The reaction results in dilution of NO(3)(-)-N with only one reagent-derived N and the product is readily concentrated from dilute samples by reverse phase chromatography. There is systematic isotopic fractionation during the reaction, but this can be allowed for by analysing known NO(3)(-) standards along with each sample set. Sudan-1 prepared from surface water samples containing approximately 50 &mgr;g NO(3)(-)-N can be analysed by automated continuous flow isotope ratio mass spectrometry with a precision of 0.2 per thousand (one standard deviation) and the accuracy is not affected by interference from other nitrogenous species in the sample or reagents. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
60.
B. Wyncke F. Brehat J. Mangin G. Marnier M. F. Ravet M. Metzger 《Phase Transitions》2013,86(2):179-183
The kinetic theory of overlapping phase transformations is a valuable tool in the characterization of diffusion-controlled precipitation reactions. Using this approach, one can obtain the kinetic parameters (n,?k) for simultaneous diffusion-controlled precipitation reactions, based on the knowledge of a specific macroscopic parameter, P(t), chosen to study the ongoing reaction. Both large and small process overlaps are considered. This methodology calculates the kinetic parameters for defined intervals of the fraction-transformed curve rather than for the entire curve. The approach used in this study permits an evaluation of which are the best protocols for the precipitate nucleation and growth rates during tempering reactions in low-alloy steel, whereas an analysis of the total combined transformations data set could lead to erroneous conclusions. 相似文献