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R Bonfiglio RC King TV Olah K Merkle 《Rapid communications in mass spectrometry : RCM》1999,13(12):1175-1185
A post-column infusion system was developed in order to analyze suppression of electrospray ionization (ESI) tandem mass spectrometry response in the presence of endogenous plasma interferences. By enabling direct detection of these interfering components, this experimental system was used to analyze the ability of several common extraction procedures to remove endogenous plasma components that cause changes in the ESI response of model drug substances. Methyl-t-butyl ether (MTBE) liquid-liquid, Oasis and Empore solid-phase, and acetonitrile (ACN) protein precipitation sample preparation methods were tested using the post-column infusion system. In all cases, ACN protein precipitation samples showed the greatest amount of ESI response suppression while liquid-liquid extracts demonstrated the least. In addition, the three test compounds, phenacetin, caffeine, and a representative Merck compound, demonstrated that ESI response suppression is compound dependent. Suppression was greatest with caffeine, the most polar analyte, and the smallest for the Merck compound, the least polar analyte. Copyright 1999 John Wiley & Sons, Ltd. 相似文献
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王建功 《纯粹数学与应用数学》1993,9(1):79-86
T.Sheil-Small[1]讨论了阶梯函数的Fourier级数。本文对[1]中所涉及到一些阶梯函数的性质进行了详细讨论,并给出了详细证明。 相似文献
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林苏榕 《数学物理学报(A辑)》1998,(Z1)
该文研究极限方程在部分边界上为退缩椭圆型(椭圆-抛物)的一类六阶椭圆型方程混合边值问题的奇摄动,在适当的假设下,应用改进了的多重尺度法,求得其解包括边界层和套层在内除了半圆域的两个角点外,在整个半圆域中有任意阶的一致有效的渐近展开式. 相似文献
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For a relation A (C × D), where C,D are two finite sets, and an ordering σ of C we construct a matroid M(σ) on the set D. For the relation A with the incidence matrix  we also define a geometrical basis with respect to F, where F is a subset of the set of all circuits of the column matroid on Â. Geometrical bases are certain bases of this column matroid. We establish connections between the bases of matroids M(σ) and the geometrical bases of A with respect to F. These connections give a combinatorial way of constructing bases of the column matroid on  using a subset F of its circuits.
We also consider a matroid M and the incidence relation between what we call the extended circuits of M and the bases of M. Applying the technique above we obtain the matroids M(σ) on the set of bases of the matroid M. In case of the incidence relation between vertices and edges of a graph this technique yields a unique matroid, the usual matroid of the graph.
Some particular relations are considered: a class of relations with a certain property (the T-property) and the relation of inclusion of chambers in simplices in an affine point configuration. 相似文献
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Shashwati Sen DK Aswal Ajay Singh TV Chandrasekhar Rao KP Muthe JC Vyas LC Gupta SK Gupta VC Sahni 《Pramana》2002,58(5-6):867-870
The MgB2 superconductor, synthesized using solid-state and liquid-phase sintering methods, have been characterized for various properties.
The upper critical field, irreversibility line and critical current density have been determined using magnetization data.
The current-voltage characteristics recorded under an applied magnetic field revealed the existence of vortex glass transition.
The surface analysis using X-ray photoelectron spectroscopy shows that MgB2 is sensitive to atmospheric degradation. 相似文献
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增加光子奇偶q相干态的高阶压缩效应 总被引:8,自引:3,他引:5
通过数值计算研究了增加光子奇q相干态aq+m|α>qo和增加光子偶q相干态aq+m|α>qe的高阶压缩效应.结果表明:当q较小时,态aq+m|α>qo和aq+m|α>qe都能呈现出强烈的奇次方阶压缩效应,但无偶次方阶压缩效应,而且奇次方阶压缩随m的增大而增强.当m=0时aq+m|α>qo和aq+m|α>qe为光场振幅偶次幂的最小测不准态,但当m≠0时它们不是光场振幅偶次幂的最小测不准态. 相似文献
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