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排序方式: 共有125条查询结果,搜索用时 343 毫秒
51.
Dr. Hui Liu Dr. Davide Audisio Lucie Plougastel Elodie Decuypere David‐Alexandre Buisson Dr. Oleksandr Koniev Dr. Sergii Kolodych Dr. Alain Wagner Dr. Mourad Elhabiri Anna Krzyczmonik Dr. Sarita Forsback Prof. Olof Solin Prof. Véronique Gouverneur Dr. Frédéric Taran 《Angewandte Chemie (International ed. in English)》2016,55(39):12073-12077
We report the synthesis and reactivity of 4‐fluorosydnones, a unique class of mesoionic dipoles displaying exquisite reactivity towards both copper‐catalyzed and strain‐promoted cycloaddition reactions with alkynes. Synthetic access to these new mesoionic compounds was granted by electrophilic fluorination of σ‐sydnone PdII precursors in the presence of Selectfluor. Their reactions with terminal and cyclic alkynes were found to proceed very rapidly and selectively, affording 5‐fluoro‐1,4‐pyrazoles with bimolecular rate constants up to 104 m ?1 s?1, surpassing those documented in the literature with cycloalkynes. Kinetic studies were carried out to unravel the mechanism of the reaction, and the value of 4‐fluorosydnones was further highlighted by successful radiolabeling with [18F]Selectfluor. 相似文献
52.
Cover Picture: Diffusion of Oligonucleotides from within Iron‐Cross‐Linked,Polyelectrolyte‐Modified Alginate Beads: A Model System for Drug Release (ChemPhysChem 7/2016)
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53.
Rudiuk S Franceschi-Messant S Chouini-Lalanne N Perez E Rico-Lattes I 《Langmuir : the ACS journal of surfaces and colloids》2008,24(16):8452-8457
The natural packaging of DNA in the cell by histones provides a particular environment affecting its sensitivity to oxidative damage. In this work, we used the complexation of DNA by cationic surfactants to modulate the conformation, the dynamics, and the environment of the double helix. Photo-oxidative damage initiated by benzophenone as the photosensitizer on a plasmid DNA complexed by dodecyltrimethylammonium chloride (DTAC), tetradecyltrimethylammonium chloride (TTAC), cetyltrimethyammonium chloride (CTAC) and bromide (CTAB) was detected by agarose gel electrophoresis. By fluorescent titration in the presence of ethidium bromide (EB) and agarose gel electrophoresis, we experimentally confirmed the complexation diagrams with a critical aggregation concentration on DNA matrix (CAC DNA) delimiting two regions of complexation, according to the DNA-phosphate concentration. The study of the photo-oxidative damage shows, for the first time, a direct correlation between the DNA complexation by these surfactants and the efficiency of DNA cleavage, with a maximum corresponding to the CAC DNA for DTAC and CTAC, and to DNA neutralization for CTAC and CTAB. The localization of a photosensitizer having low water solubility, such as benzophenone, inside the hydrophobic domains formed by the surfactant aggregated on DNA, locally increases the photoinduced cleavage by the free radical oxygen species generated. The inefficiency of a water-soluble quencher of hydroxyl radicals, such as mannitol, confirmed this phenomenon. The detection of photo-oxidative damage constitutes a new tool for investigating DNA complexation by cationic surfactants. Moreover, highlighting the drastically increased sensitivity of a complexed DNA to photo-oxidative damage is of crucial importance for the biological use of surfactants as nonviral gene delivery systems. 相似文献
54.
Chiral 1,3,2‐Diazaphospholenes as Catalytic Molecular Hydrides for Enantioselective Conjugate Reductions
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Dr. Solène Miaskiewicz John H. Reed Dr. Pavel A. Donets Dr. Caio C. Oliveira Prof. Dr. Nicolai Cramer 《Angewandte Chemie (International ed. in English)》2018,57(15):4039-4042
Secondary 1,3,2‐diazaphospholenes have a polarized P?H bond and are emerging as molecular hydrides. Herein, a class of chiral, conformationally restricted methoxy‐1,3,2‐diazaphospholene catalysts is reported. We demonstrate their catalytic potential in asymmetric 1,4‐reductions of α,β‐unsaturated carbonyl derivatives, including enones, acyl pyrroles, and amides, which proceeded in enantioselectivities of up to 95.5:4.5 e.r. 相似文献
55.
Bridging β‐Cyclodextrin Prevents Self‐Inclusion,Promotes Supramolecular Polymerization,and Promotes Cooperative Interaction with Nucleic Acids
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Dr. Pierre Evenou Dr. Julien Rossignol Dr. Gaëlle Pembouong Adélie Gothland Dr. Dmitri Colesnic Dr. Renaud Barbeyron Dr. Sergii Rudiuk Prof. Anne‐Geneviève Marcelin Dr. Mickaël Ménand Prof. Damien Baigl Prof. Vincent Calvez Dr. Laurent Bouteiller Prof. Matthieu Sollogoub 《Angewandte Chemie (International ed. in English)》2018,57(26):7753-7758
56.
Serhii O. Kokhan Andriy V. Tymtsunik Stephan L. Grage Sergii Afonin Oleg Babii Marina Berditsch Alexander V. Strizhak Dmytro Bandak Maxim O. Platonov Igor V. Komarov Anne S. Ulrich Pavel K. Mykhailiuk 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2016,128(47):15008-15012
A conformationally restricted monofluorinated α‐amino acid, (3‐fluorobicyclo[1.1.1]pentyl)glycine (F‐Bpg), was designed as a label for the structural analysis of membrane‐bound peptides by solid‐state 19F NMR spectroscopy. The compound was synthesized and validated as a 19F label for replacing natural aliphatic α‐amino acids. Calculations suggested that F‐Bpg is similar to Leu/Ile in terms of size and lipophilicity. The 19F NMR label was incorporated into the membrane‐active antimicrobial peptide PGLa and provided information on the structure of the peptide in a lipid bilayer. 相似文献
57.
It has been found that the Cl− and Br− anions change the microstructure of their hydration shells in the temperature range 30–35 °C. The effect was observed for
simple salt solutions and ternary systems with different organic compounds. Probably this effect can be responsible for the
thermoregulation of warm-blooded animals. 相似文献
58.
A. V. Butenko A. I. Govorov E. D. Donets E. E. Donets D. E. Donets K. A. Levterov V. A. Monchinsky G. V. Trubnikov V. V. Fimushkin 《Physics of Particles and Nuclei Letters》2012,9(4-5):398-405
The Nuclotron Injection Facility is intended to be used to inject beams of light and heavy ions with the charge-to-mass ratio q/A ?? 1/3 and energy 5 MeV/u and protons with the energy 20 MeV into the Nuclotron. The main directions in the upgrading of the laser source of light-element ions and the KRION heavyion source, the development of the new high-intensity source of polarized ions, and the preinjector updating plan are described. 相似文献
59.
Physics of the Solid State - A decrease in the longitudinal-transverse exciton splitting in a wide GaAs/AlGaAs quantum well (QW) in a homogeneous electric field has been theoretically considered.... 相似文献