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Komarek Karel Safarikova Mirka Hubka Tomas Safarik Ivo Kandelova Martina Kujalova Hana 《Chromatographia》2009,70(1-2):133-142
An LC-DAD-ESI-MS(2) method was developed for simultaneous analysis of major chemical constituents in Shexiang Baoxin Pill (SBP), an important multiherbal formula in traditional Chinese medicine widely used for treating cardiovascular diseases. The chromatographic separation was performed on a Symmetry C18 column (5 μm, 250 × 4.6 mm), whilst water with 0.5% formic acid and acetonitrile were used as mobile phase. On the basis of the characteristic UV absorption profile, the information of molecular weight and structure provided by ESI-MS(2), 57 constituents from moschus, radix rhizoma ginseng, calculus bovis, cortex cinnamomi, styrax and venenum bufonis, were detected and 47 of them were identified in this study. The method can be the basis for the quality control of SBP. 相似文献
224.
Matt Rammo Dr. Aleksander Trummal Dr. Merle Uudsemaa Juri Pahapill Katrin Petritsenko Dr. Meelis-Mait Sildoja Dr. Charles W. Stark Dr. Sigrid Selberg Prof. Ivo Leito Kirsti Palmi Dr. Jasper Adamson Prof. Aleksander Rebane 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(8):e202103707
Lipophilic fluorophores are widely implemented in nonlinear microscopy; however, few existing membrane-specific probes combine the high brightness of two-photon excited fluorescence (2PEF) with pH sensitivity. Herein we describe four novel two-photon excited fluorophores, based on a coumarin 151 core structure, where lipophilicity is induced by a covalently attached phosphazene moiety. Changing the environmental acidity using trifluoromethanesulfonic (triflic) acid leads to profound changes in the linear fluorescence and 2PEF characteristics, due to chromophores’ switching between neutral- and protonated forms. We characterize this dependence by measuring the two-photon absorption (2PA) spectra over the region λ2PA=550–1000 nm, observing 2PA cross sections of σ2PA=10–20 GM, with an associated 2PEF brightness of 10–13 GM, in neutral solutions of both acetonitrile and n-octanol. Although quantum chemical modelling and NMR measurements show that, at high chromophore concentrations, protonation may be accompanied by a dimerization process, these dimers likely do not form at the lower concentrations used in optical spectroscopy. 相似文献
225.
Jan Holec Dr. Jiří Rybáček Dr. Jaroslav Vacek Dr. Manfred Karras Dr. Lucie Bednárová Dr. Miloš Buděšínský Michaela Slušná Dr. Petr Holý Prof. Bernd Schmidt Dr. Irena G. Stará Dr. Ivo Starý 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(49):11494-11502
Racemic and highly enantioenriched 3-methoxycarbonyl, 3-carboxy, and 3-hydroxymethyl derivatives of dibenzo[6]helicene were prepared. The Langmuir layers of these helicenes were formed at the air–water interface and transferred onto solid substrates to afford Langmuir–Blodgett films, which were then studied by ambient atomic force microscopy and (chir)optical spectroscopy. Significant differences were found in the behaviour of the Langmuir layers as well as in the morphology, UV/Vis, electronic circular dichroism (ECD), and fluorescence spectra of the Langmuir–Blodgett thin films depending on the molecular chirality and nature of the polar group. The experimental results were supported by molecular dynamics simulations. 相似文献
226.
Queueing Systems - We study systems with two classes of impatient customers who differ across the classes in their distribution of service times and patience times. The customers are served on a... 相似文献
227.
This paper presents a very effective numerical method for the solution of the two-compartmental pharmacokinetic model for oral drug administration. This model consists of a set of two fractional order differential equations which connect the two compartments. The first compartment represents the gut while the second compartment corresponds to the drug concentration in the target tissue. For ease of computation, the numerical solution is also created as a Matlab function. 相似文献
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Joanna Znaleziona Pavlína Ginterová Jan Petr Peter Ondra Ivo Válka Juraj Ševčík Jan Chrastina Vítězslav Maier 《Analytica chimica acta》2015
Synthetic cannabinoids have gained popularity due to their easy accessibility and psychoactive effects. Furthermore, they cannot be detected in urine by routine drug monitoring. The wide range of active ingredients in analyzed matrices hinders the development of a standard analytical method for their determination. Moreover, their possible side effects are not well known which increases the danger. 相似文献
230.
Ivo A. Hümmelgen 《Journal of Solid State Electrochemistry》2017,21(7):1977-1985
The application of electrochemical methods for the preparation of organic semiconductors for transistors, thermoelectric elements, and photovoltaic devices is briefly reviewed and discussed. Emphasis is given to the properties and material characteristics required for these applications, indicating niches where the use of electrochemical techniques is or could be advantageous. 相似文献