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排序方式: 共有1449条查询结果,搜索用时 109 毫秒
1.
Marco Reichel Mara Egenhöfer Burkhard Krumm Konstantin Karaghiosoff 《无机化学与普通化学杂志》2020,646(6):328-331
Fluoromethylating agents are a highly studied and controversely discussed class of compounds. New fluoromethyl pseudohalides FCH2N3, FCH2SCN, and FCH2SeCN were prepared for the first time and their physical and spectroscopic properties investigated. Their synthesis is performed conveniently by fluoromethylation of the respective silver or potassium pseudohalogenides with fluoroiodomethane. 相似文献
2.
Multiple orthogonal polynomials generalize standard orthogonal polynomials by requiring orthogonality with respect to several inner products. This paper discusses an application to the approximation of matrix functions and presents quadrature rules that generalize the anti-Gauss rules proposed by Laurie. 相似文献
3.
Jan Matthias Peschel Liên Sabrina Reichel Tim Hoffmann Christoph Enzensperger Ulrich Sigmar Schubert Anja Traeger Michael Gottschaldt 《Macromolecular bioscience》2023,23(12):2300135
Branched poly(ethylene imine) (bPEI) is frequently used in RNA interference (RNAi) experiments as a cationic polymer for the delivery of small interfering RNA (siRNA) because of its ability to form stable polyplexes that facilitate siRNA uptake. However, the use of bPEI in gene delivery is limited by its cytotoxicity and a need for target specificity. In this work, bPEI is modified with d- fructose to improve biocompatibility and target breast cancer cells through the overexpressed GLUT5 transporter. Fructose-substituted bPEI (Fru−bPEI) is accessible in three steps starting from commercially available protected fructopyranosides and bPEI. Several polymers with varying molecular weights, degrees of substitution, and linker positions on d- fructose (C1 and C3) are synthesized and characterized with NMR spectroscopy, size exclusion chromatography, and elemental analysis. In vitro biological screenings show significantly reduced cytotoxicity of 10 kDa bPEI after fructose functionalization, specific uptake of siRNA polyplexes, and targeted knockdown of green fluorescent protein (GFP) in triple-negative breast cancer cells (MDA-MB-231) compared to noncancer cells (HEK293T). 相似文献
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Locked by Design: A Conformationally Constrained Transglutaminase Tag Enables Efficient Site‐Specific Conjugation 下载免费PDF全文
Dr. Vanessa Siegmund Dr. Stefan Schmelz Stephan Dickgiesser Jan Beck Aileen Ebenig Heiko Fittler Dr. Holm Frauendorf Dr. Birgit Piater Dr. Ulrich A. K. Betz Dr. Olga Avrutina Dr. Andrea Scrima Prof. Dr. Hans‐Lothar Fuchsbauer Prof. Dr. Harald Kolmar 《Angewandte Chemie (International ed. in English)》2015,54(45):13420-13424
Based on the crystal structure of a natural protein substrate for microbial transglutaminase, an enzyme that catalyzes protein crosslinking, a recognition motif for site‐specific conjugation was rationally designed. Conformationally locked by an intramolecular disulfide bond, this structural mimic of a native conjugation site ensured efficient conjugation of a reporter cargo to the therapeutic monoclonal antibody cetuximab without erosion of its binding properties. 相似文献
6.
Novel Osmium‐based Coordination Complexes as Photosensitizers for Panchromatic Photodynamic Therapy 下载免费PDF全文
Savo Lazic Pavel Kaspler Ge Shi Susan Monro Tariq Sainuddin Sarah Forward Kamola Kasimova Robie Hennigar Arkady Mandel Sherri McFarland Lothar Lilge 《Photochemistry and photobiology》2017,93(5):1248-1258
Cancer remains a major global malaise requiring the advent of new, efficient and low‐cost treatments. Photodynamic therapy, which combines a photosensitizer and photons to produce cytotoxic reactive oxygen species, has been established as an effective cancer treatment but has yet to become mainstream. One of the main limitations has been the paucity of photosensitizers that are effective over a wide range of wavelengths, can exert their cytotoxic effects in hypoxia, are easily synthesized and produce few if any side effects. To address these shortfalls, three new osmium‐based photosensitizers (TLD1822, TLD1824 and TLD1829) were synthesized and their photophysical and photobiological attributes determined. These photosensitizers are panchromatic (i.e. black absorbers), activatable from 200 to 900 nm and have strong resistance to photobleaching. In vitro studies show photodynamic therapy efficacy with both red and near‐infrared light in normoxic and hypoxic conditions, which translated to good in vivo efficacy of TLD1829 in a subcutaneous murine colon cancer model. 相似文献
7.
Sandra Grebenteuch Clemens Kanzler Stefan Klaußnitzer Lothar W. Kroh Sascha Rohn 《Molecules (Basel, Switzerland)》2021,26(4)
Lipid oxidation and the resulting volatile organic compounds are the main reasons for a loss of food quality. In addition to typical compounds, such as alkanes, aldehydes and alcohols, methyl ketones like heptan-2-one, are repeatedly described as aroma-active substances in various foods. However, it is not yet clear from which precursors methyl ketones are formed and what influence amino compounds have on the formation mechanism. In this study, the formation of methyl ketones in selected food-relevant fats and oils, as well as in model systems with linoleic acid or pure secondary degradation products (alka-2,4-dienals, alken-2-als, hexanal, and 2-butyloct-2-enal), has been investigated. Elevated temperatures were chosen for simulating processing conditions such as baking, frying, or deep-frying. Up to seven methyl ketones in milk fat, vegetable oils, and selected model systems have been determined using static headspace gas chromatography-mass spectrometry (GC-MS). This study showed that methyl ketones are tertiary lipid oxidation products, as they are derived from secondary degradation products such as deca-2,4-dienal and oct-2-enal. The study further showed that the position of the double bond in the precursor compound determines the chain length of the methyl ketone and that amino compounds promote the formation of methyl ketones to a different degree. These compounds influence the profile of the products formed. As food naturally contains lipids as well as amino compounds, the proposed pathways are relevant for the formation of aroma-active methyl ketones in food. 相似文献
8.
Vast subterranean caverns may be used for hot water storage in distinct heating schemes; such caverns can be annular, with a central pillar. This paper considers the quasi-steady solution of the heat conduction equation for this geometry with periodic temperature variations 相似文献
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10.
A minimal model for studying properties of the mode-coupling type instability in friction induced oscillations 总被引:2,自引:0,他引:2
Norbert Hoffmann Michael Fischer Ralph Allgaier Lothar Gaul 《Mechanics Research Communications》2002,29(4)
A minimal two degree of freedom model is used to clarify from an intuitive perspective the physical mechanisms underlying the mode-coupling instability of self-excited friction induced oscillations. It is shown that simultaneous out-of-phase oscillations of friction force and displacement tangential to the friction force may lead to energy transfer from the frictional system to vibrational energy. Also it is shown that the friction force acts like a cross-coupling force linking motion normal to the contact surface to motion parallel to it and that a necessary condition for the onset of instability is that these friction-induced cross-coupling forces balance the corresponding structural cross-coupling forces of the system. Finally the origin and the role of phase shifts between oscillations normal and parallel to the contact surface is clarified with respect to the mode-coupling instability. It may be expected that the intuitive picture gained will be of considerable help for practical design purposes. 相似文献