排序方式: 共有63条查询结果,搜索用时 15 毫秒
31.
Wan Li Xiangfeng Chen Y.-L. Elaine Wong Y.-L. Winnie Hung Ze Wang Liulin Deng T.-W. Dominic Chan 《Analytica chimica acta》2016
In this work, sorbent-attached membrane funnel-based spray ionization mass spectrometry was explored for quantitative analysis of anti-diabetic drugs spiked in human plasma. C18-attached membrane funnel was fabricated for in situ extraction and clean-up to alleviate matrix suppression effect in the ionization process. Repaglinide was used as a target analyte of anti-diabetic drugs. Under optimal working conditions, good linearity (R2 > 0.99) was obtained in the concentration range of 1–100 ng mL−1. The method detection limit of target drugs spiked in the human plasma was around 0.30 ng mL−1. Through the application of an isotope-labeled internal standard, the signal fluctuation caused by residual background matrices was largely alleviated and the precision of measurement (RSD) was below 15%. The recovery of repaglinide for 5, 25, and 100 ng mL−1 of spiked human plasma matrixes ranged from 87% to 112%. The developed method was successfully applied to determine repaglinide in plasma volunteers who orally received a dose of drug association. Our results demonstrated that membrane funnel-based spray is a simple and sensitive method for rapid screening analysis of complex biological samples. 相似文献
32.
Eriksson KL Chow WW Puglia C Bäckvall JE Göthelid E Oscarsson S 《Langmuir : the ACS journal of surfaces and colloids》2010,26(21):16349-16354
With the aim of extending the usefulness of an existing biomimetic catalytic system, cobalt porphyrin catalytic units with thiol linkers were heterogenized via chemical grafting to silicon wafers and utilized for the catalytic oxidation of hydroquinone to p-benzoquinone. Atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were used to analyze the morphology and composition of the heterogeneous catalyst. The results of the catalytic oxidation of hydroquinone obtained with porphyrins grafted on silicon were compared with those obtained earlier with the same catalyst in homogeneous phase and immobilized on gold. It was found that the catalysis could run over 400 h, without showing any sign of deactivation. The measured catalytic activity is at least 10 times higher than that measured under homogeneous conditions, but also 10 times lower than that observed with the catalytic unit immobilized on gold. The reasons of this discrepancy are discussed in term of substrate influence and overlayer organization. The silicon-immobilized catalyst has potential as an advanced functional material with applications in oxidative heterogeneous catalysis of organic reactions, as it combines long-term relatively high activity with low cost. 相似文献
33.
FAN Caiyun JIA Hongmei Deuther-Conrad Winnie Brust Peter Steinbach J?rg & LIU Boli . Key Laboratory of Radiopharmaceuticals 《中国科学B辑(英文版)》2006,(2)
Sigma (σ) receptors are a distinct class of proteinsexisting in at least two subtypes termed σ1 and σ2[1].They are expressed in the central nervous system, en-docrine, immune and certain peripheral tissues andmay play an important role in regulating an… 相似文献
34.
We describe the structure and operation of a micro/nanofluidic device in which individual metaphase chromosomes can be isolated and processed without being displaced during exchange of reagents. The change in chromosome morphology as a result of introducing protease into the device was observed by time-lapse imaging; pressure-driven flow was then used to shunt the chromosomal DNA package into a nanoslit. A long linear DNA strand (>1.3 Mbp) was seen to stretch out from the DNA package and along the length of the nanoslit. Delivery of DNA in its native metaphase chromosome package as well as the microfluidic environment prevented DNA from shearing and will be important for preparing ultra-long lengths of DNA for nanofluidic analysis. 相似文献
35.
In this paper we study various groups of ideal classes of number fields containing integral ideals of equal norms and the distribution of integral ideals in such groups. 相似文献
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Biao Gao Frank K. Hwang Wen-Ching Winnie Li Uriel G. Rothblum 《Mathematical Programming》1999,85(2):335-362
Received March 1996 / Revised version received April 5, 1998
Published online January 20, 1999 相似文献
39.
Winnie W. Yin Mingda Wang Alan G. Marshall Edward B. Ledford 《Journal of the American Society for Mass Spectrometry》1992,3(3):188-197
The Penning ion trap, consisting of hyperbolically curved electrodes arranged as an unbroken ring electrode capped by two end electrodes whose interelectrode axis lies along the direction of an applied static magnetic field, has long been used for single-ion trapping. More recently, it has been used in “parametric” mode for ion cyclotron resonance (lCR) detection of off-axis ions. In this article, we describe and test a Penning trap whose ring electrode has been cut into four equal quadrants for conventional dipolar ICR excitation (on one pair of opposed ring quadrants) and dipolar ICR detection (on the other pair). In direct comparisons to a cubic trap, the present hyperbolic trap offers somewhat improved ICR mass spectral peak shape, higher mass resolving power, and comparable frequency shift as a function of trapping voltage. Mass measurement accuracy over a wide mass range is improved twofold and mass discrimination is somewhat worse than for a cubic trap. The relative advantages of parametric, dipolar, and quadrupole modes are briefly discussed in comparison to screened and unscreened cubic traps. 相似文献
40.
Ming-Hsuan Kang Wen-Ching Winnie Li Chian-Jen Wang 《Israel Journal of Mathematics》2010,177(1):335-348
The zeta function attached to a finite complex X
Γ arising from the Bruhat-Tits building for PGL3(F) was studied in [KL], where a closed form expression was obtained by a combinatorial argument. This identity can be rephrased
using operators on vertices, edges, and directed chambers of X
Γ. In this paper we re-establish the zeta identity from a different aspect by analyzing the eigenvalues of these operators
using representation theory. As a byproduct, we obtain equivalent criteria for a Ramanujan complex in terms of the eigenvalues
of the operators on vertices, edges, and directed chambers, respectively. 相似文献