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Gas-phase derivatization of [C3H5]+ ions using tandem mass spectrometry methods A13C labelling study
Nguyen Kieu My Marita Schilling Helmut Schwarz 《Journal of mass spectrometry : JMS》1987,22(5):254-258
The study of specifically 13C-labelled precursors sheds further light on the gas-phase chemistry of allyl and 2-propenyl cations. It is demonstrated that both species are formed from allyl and 2-propenyl bromide upon 70 eV electron impact ionization without skeletal reorganization. Gas-phase derivatization of the [C3 H5]+ ions with benzene facilitates, as suggested and observed earlier, the distinction of the two isomers using collision-induced dissociation of the Wheland complexes (or isomers thereof). The 13C labelling data clearly demonstrate that 64% of allyl cations survive the derivatization while 36% isomerize to 2-phenylpropyl cations; the latter are also formed via the reaction of 2-propenyl cation with benzene, protonation of α-methylstyrene and water loss from protonated 2-phenyl-2-propanol, respectively. Unimolecular loss of C2H4 from protonated allylbenzene proceeds via two competing reaction channels: one involves heterolysis of 1-phenylpropyl cations (~30%); the major pathway (~70%), however, involves decomposition via propylene benzenium ions. 相似文献
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Thien Y Vu Prof. Anna Chrostowska Prof. Thi Kieu Xuan Huynh Prof. Saïd Khayar Prof. Alain Dargelos Katarzyna Justyna Dr. Beata Pasternak Prof. Stanisław Leśniak Prof. Curt Wentrup 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(44):14983-14988
Thermal reactions of N‐benzylidene‐ and N‐(2‐pyridylmethylidene)‐tert‐butylamines ( 5 and 13 ) under FVT conditions have been investigated. Unexpectedly, at 800 °C, compound 5 yields 1,2‐dimethylindole and 3‐methylisoquinoline. In the reaction of 13 at 800 °C, 3‐methylimidazo[1,5‐a]pyridine was obtained as the major product. Mechanisms of these reactions have been proposed on the basis of DFT calculations. Furthermore, UV‐photoelectron spectroscopy combined with FVT has been applied for direct monitoring and characterization of the thermolysis products in situ. 相似文献
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Monitoring and Quantifying the Passive Transport of Molecules Through Patch–Clamp Suspended Real and Model Cell Membranes 下载免费PDF全文
Dr. Pierluca Messina Dr. Frédéric Lemaître Prof. François Huet Dr. Kieu An Ngo Dr. Vincent Vivier Prof. Eric Labbé Dr. Olivier Buriez Prof. Christian Amatore 《Angewandte Chemie (International ed. in English)》2014,53(12):3192-3196
Transport of active molecules across biological membranes is a central issue for the success of many pharmaceutical strategies. Herein, we combine the patch–clamp principle with amperometric detection for monitoring fluxes of redox‐tagged molecular species across a suspended membrane patched from a macrophage. Solvent‐ and protein‐free lipid bilayers (DPhPC, DOPC, DOPG) patched from single‐wall GUV have been thoroughly investigated and the corresponding fluxes measurements quantified. The quality of the patches and their proper sealing were successfully characterized by electrochemical impedance spectroscopy. This procedure appears versatile and perfectly adequate to allow the investigation of transport and quantification of the transport properties through direct measurement of the coefficients of partition and diffusion of the compound in the membrane, thus offering insight on such important biological and pharmacological issues. 相似文献
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The authors describe a microreactor for performing a multiplexed polymerase chain reaction (PCR) which is operated with minimal accessories such as a single heater for gene amplification and a hand-held syringe for sample actuation. It was fabricated by wrapping a polytetrafluoroethylene (PTFE) tube around a rectangular poly(dimethylsiloxane) (PDMS) block having a predetermined thickness. The resulting portable microreactor was applied to PCR using a single heater because the rectangular PDMS block spatially segregated the upper and lower arrays of the PTFE tube. This warrants the adjustment of distinct temperatures inside the upper and lower tubes. A hand-held plastic syringe was connected to the inlet of the PTFE tube and used as a portable pump to achieve a homogeneous transport of a sample liquid inside the microreactor. The use of gas-impermeable PTFE prevents the formation of bubbles during thermal cycling. The microreactor was successfully applied to the amplification of typical DNA fragments of three foodborne pathogens in less than 30 min. In our perception, this method paves the way to the construction of a truly portable PCR chip that is applicable to rapid clinical diagnosis and the detection of foodborne pathogens. 相似文献
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A simple analytical system using disposable, open-tubular ion exchange clean-up precolumns coupled in-line to capillary electrophoresis for direct injection of biological samples is presented. The clean-up precolumns were prepared from fused silica capillaries by thermally initiated layer-by-layer polymerization of poly(butadiene-maleic acid) (PBMA) directly on the capillary wall. Typically, 6 cm long precolumns with 4-layers of PBMA were used for sample pretreatment. A robust and reproducible coupling between the precolumn (75 μm ID) and the analytical capillary (50 μm ID) was achieved using an inexpensive, commercially available low dead volume union. No extra dispersion of the analyte zones was observed. Proteins and other high molecular weight compounds from biological sample matrices were retained on the cation-exchanger sites of the precolumn, which eliminated their adsorption on analytical capillary walls and ensured stable electroosmotic flow and migration times of target analytes. Unretained small inorganic cations migrated freely into the analytical capillary for separation and detection. Applicability of the sample clean-up procedure was proved by determination of major inorganic cations in blood serum and plasma samples using capillary electrophoresis with contactless conductivity detection. Separations were performed in background electrolyte solution consisting of 15 mM L-arginine, 12.5 mM maleic acid, 3 mM 18-crown-6 at pH 5.5 and repeatabilities of migration times and peak areas were below 1.5% and 7.3%, respectively. Less than 1 μL of biological sample was required for injection. 相似文献
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This work is a continuation of [7]. In that paper, a sufficient condition was given on a real analytic fmlction g defined near 0 in C so that the algebra generated by z2 and g2 is dense in the space of continuous functions on D for all disks D close enough to the origin in C. By using the same methods and some ideas taken from the first named author's thesis we deal with the case where g is only of class C1 near 0. 相似文献
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In this first part a straight general wave-guide with a perfectly conducting outer wall and several dielectrics, excited by an electrically generally polarized matter is considered and the electromagnetic field is determined. 相似文献
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Differential Equations - We consider compact difference schemes of approximation order $$4+2 $$ on a three-point spatial stencil for the Klein–Gordon equations with constant and variable... 相似文献