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排序方式: 共有183条查询结果,搜索用时 7 毫秒
41.
Gerald Platzer Moriz Mayer Andreas Beier Sven Brüschweiler Julian E. Fuchs Harald Engelhardt Leonhard Geist Gerd Bader Julia Schrghuber Roman Lichtenecker Bernhard Wolkerstorfer Dirk Kessler Darryl B. McConnell Robert Konrat 《Angewandte Chemie (International ed. in English)》2020,59(35):14861-14868
While CH–π interactions with target proteins are crucial determinants for the affinity of arguably every drug molecule, no method exists to directly measure the strength of individual CH–π interactions in drug–protein complexes. Herein, we present a fast and reliable methodology called PI (π interactions) by NMR, which can differentiate the strength of protein–ligand CH–π interactions in solution. By combining selective amino‐acid side‐chain labeling with 1H‐13C NMR, we are able to identify specific protein protons of side‐chains engaged in CH–π interactions with aromatic ring systems of a ligand, based solely on 1H chemical‐shift values of the interacting protein aromatic ring protons. The information encoded in the chemical shifts induced by such interactions serves as a proxy for the strength of each individual CH–π interaction. PI by NMR changes the paradigm by which chemists can optimize the potency of drug candidates: direct determination of individual π interactions rather than averaged measures of all interactions. 相似文献
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Sensors: Highly Selective SAM–Nanowire Hybrid NO2 Sensor: Insight into Charge Transfer Dynamics and Alignment of Frontier Molecular Orbitals (Adv. Funct. Mater. 5/2014) 下载免费PDF全文
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A novel interface adapter has been designed to provide a new way of directly coupling a nano-liquid chromatograph to an electron ionization mass spectrometer. It connects the transfer capillary coming from the liquid chromatograph to the ionization chamber and can be easily screwed into the ion source. Liquid coming from the column passes through the heated adapter flow path and is vaporized. A continuous flow of new liquid pushes the vapor into the ionization chamber where it is ionized and continues on to the mass analyzer. The advantages of the new adapter are reduced ice formation inside the ion source and less clogging of the transfer capillary. Improvements achieved are demonstrated on the basis of caffeine and steroid analysis. The limits of detection of selected steroids are compared with and without the adapter. The adapter improves the detection limit of the system by a factor of 2 and precision from ≤15% to ≤9% relative standard deviation. No derivatization procedure is necessary before the analysis of small polar compounds. The resulting spectra are reproducible, easily interpretable, and database searchable. The new method is robust, delivers reproducible results, and provides a highly efficient alternative to existing methods in the field of pharmaceutical analysis. 相似文献
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Prof. Dr. Jürgen Evers Christiane Herzog Leonhard Möckl Christoph von Plotho Peter Stallhofer Rudolf Staudigl 《Chemie in Unserer Zeit》2016,50(6):410-419
Cars, television, mobile phones, digital cameras, cash machines: Daily life is strongly affected by microchips produced from high purity silicon single crystals via thin wafers. Most of these single crystals are prepared by a process invented by the German‐Polish scientist Jan Czochralski in 1916 in the “Kabelwerk Oberspree (KWO)” of the “Allgemeine Elektricitätsgesellschaft (AEG)” in Berlin‐Oberschöneweide. Czochralski discovered the famous method to pull single crystals by accident: Deep in thought, he dipped his pen not into an ink pot but into a crucible with liquid tin, both standing next to one another on his desk. Quickly he pulled his pen out and observed a thin thread of tin emerging from the tip. After etching, the thread was identified as a single crystal of tin. This observation is probably one of the most important technical inventions of the first half of the 20th century. In 1917, he left the AEG in Berlin and worked in the metal research laboratory, later belonging to the “Metallgesellschaft”, in Frankfurt/Main. Until today, wafers of high‐purity silicon are prepared by the Czochralski method. Silicon wafers with 200 mm diameter were produced in 1990, 300 mm wafers in 2001. The production of wafers with 450 mm diameter was expected for 2016. Siltronic produced in 2009 the first dislocation‐free silicon single crystal with 450 mm diameter, and other companies followed. However, until now, the 450 mm technology is not standard. This is due to a combination of very high investment costs needed to establish the 450 mm technology and very low prices of microchips. 相似文献
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The addition vs. deprotonation ratio in the reaction of nitriles with n-PrMgBr is increased by complexation of the Grignard reagent with LiClO4. For nitriles having moderately labile α-hydrogen atoms the deprotonation reaction is almost completely suppressed; but for nitriles having very labile α-hydrogen atoms (CH3 CN, PhCH2CN) yields in ketones are increased from 2 to 10–20%. 相似文献
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