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排序方式: 共有209条查询结果,搜索用时 171 毫秒
161.
Rezeda A. Ishkaeva Ilyas S. Nizamov Dmitriy S. Blokhin Elizaveta A. Urakova Vladimir V. Klochkov Ilnar D. Nizamov Bulat I. Gareev Diana V. Salakhieva Timur I. Abdullin 《Molecules (Basel, Switzerland)》2021,26(10)
Phosphorus species are potent modulators of physicochemical and bioactive properties of peptide compounds. O,O-diorganyl dithiophoshoric acids (DTP) form bioactive salts with nitrogen-containing biomolecules; however, their potential as a peptide modifier is poorly known. We synthesized amphiphilic ammonium salts of O,O-dimenthyl DTP with glutathione, a vital tripeptide with antioxidant, protective and regulatory functions. DTP moiety imparted radical scavenging activity to oxidized glutathione (GSSG), modulated the activity of reduced glutathione (GSH) and profoundly improved adsorption and electrooxidation of both glutathione salts on graphene oxide modified electrode. According to NMR spectroscopy and GC–MS, the dithiophosphates persisted against immediate dissociation in an aqueous solution accompanied by hydrolysis of DTP moiety into phosphoric acid, menthol and hydrogen sulfide as well as in situ thiol-disulfide conversions in peptide moieties due to the oxidation of GSH and reduction of GSSG. The thiol content available in dissolved GSH dithiophosphate was more stable during air oxidation compared with free GSH. GSH and the dithiophosphates, unlike DTP, caused a thiol-dependent reduction of MTS tetrazolium salt. The results for the first time suggest O,O-dimenthyl DTP as a redox modifier for glutathione, which releases hydrogen sulfide and induces biorelevant redox conversions of thiol/disulfide groups. 相似文献
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163.
Damir A. Safin Dr. Felix D. Sokolov Timur R. Gimadiev Vasiliy V. Brusko Maria G. Babashkina Dinara R. Chubukaeva Dmitriy B. Krivolapov Igor A. Litvinov 《无机化学与普通化学杂志》2008,634(5):967-971
Reaction of the potassium salt of N‐thiophosphorylthiourea tBuNHC(S)NHP(S)(OiPr)2 ( HL ) with ZnII, CdII, NiII and CoII in aqueous EtOH leads to complexes of common formula M(L‐S,S′)2 ( ML2 ). Complexes were investigated by IR, UV‐Vis, 1H and 31P{1H} NMR spectroscopy and microanalysis The structure of complex NiL2 was investigated by single crystal X‐ray diffraction analysis. The nickel(II) ion has a squre‐planar environment, S4, with two anionic ligands involving 1,5‐S,S′‐coordination mode. The ligands are bound in a trans configuration. 相似文献
164.
Timur Ashirov Thamon Puangsamlee Alexandra Robles Patrick W. Fritz Krzysztof Piech Ognjen Š. Miljanić Ali Coskun 《Helvetica chimica acta》2023,106(8):e202300072
The development of porous materials is of great interest for the capture of CO2 from various emission sources, which is essential to mitigate its detrimental environmental impact. In this direction, porous organic polymers (POPs) have emerged as prime candidates owing to their structural tunability, physiochemical stability and high surface areas. In an effort to transfer an intrinsic property of a cyclotetrabenzoin-derived macrocycle – its high CO2 affinity – into porous networks, herein we report the synthesis of three-dimensional (3D) macrocycle-based POPs through the polycondensation of an octaketone macrocycle with phenazine-2,3,7,8-tetraamine hydrochloride. This polycondensation was performed under ionothermal conditions, using a eutectic salt mixture in the temperature range of 200 to 300 °C. The resulting polymers, named 3D-mmPOPs, showed reaction temperature-dependent surface areas and gas uptake properties. 3D-mmPOP-250 synthesized at 250 °C exhibited a surface area of 752 m2 g−1 and high microporosity originating from the macrocyclic units, thus resulting in an excellent CO2 binding enthalpy of 40.6 kJ mol−1 and CO2 uptake capacity of 3.51 mmol g−1 at 273 K, 1.1 bar. 相似文献
165.
We treat the problems of phase-contrast image formation, deterministic phase retrieval and aberration balancing, in the imaging of weak objects using two-dimensional shift-invariant linear imaging systems. Three classes of model sample are considered: weak phase objects, weak phase-amplitude objects and single-material weak phase-amplitude objects. For each class of sample we show how the various aberration coefficients, which characterise a given imaging system, contribute to the structure of the associated phase-contrast image. The corresponding inverse problem, of obtaining a closed-form expression for the input wave-field given one or more aberrated phase-contrast images of the same, is then examined. Two sample applications are considered: analyser-crystal phase-contrast imaging of weak objects using hard X-rays, and Zernike-type phase-contrast imaging. We close with a discussion of how coherent and incoherent aberrations may be “balanced” against one another, briefly mentioning the applications of this idea to both “deblur by defocus” and proximity-corrected X-ray lithography. 相似文献
166.
Timur T. Sadykov Roman S. Syakaev Anastasia N. Andriianova Akhat G. Mustafin 《国际化学动力学杂志》2024,56(2):81-95
This study reports the effect of substituents in the ortho position of polyaniline on the adsorption capacity to remove the anionic dye methyl orange (MO) from an aqueous solution. The aim of this study is the synthesis of polyaniline (PANI) and its derivatives, poly-o-methylaniline (poly-o-toluidine, POT) and poly-o-methoxyaniline (poly-o-anisidine, POA) for the adsorption removal of MO dye. All polymers were obtained by oxidative polymerization of the corresponding monomers and characterized by scanning electron microscopy (SEM) and infrared spectroscopy (IR). The average particle size of the polymer was about 200 nm. The effect of various parameters such as pH, temperature, adsorption time and initial concentration was analyzed. It was found that the adsorption capacity for dye removal increases from 50.68 to 222.56 mg g−1 for PANI, from 16.89 to 66.57 mg g−1 for POT, and from 97.26 to 532.54 mg g−1 for POA with an increase in the initial dye concentration from 5 up to 50 mg L−1. For all polymers, the equilibrium state of MO adsorption was reached in 50 min. The results showed that MO adsorption on PANI, POT, and POA is well described by a pseudo second order kinetic model. Isothermal studies have shown that adsorption is in good agreement with the Langmuir isotherm model, as evidenced by higher values of correlation coefficients. Based on the data of thermodynamic studies, it was concluded that MO adsorption on PANI, POT, and POA is spontaneous and endothermic. 相似文献
167.
Damir A. Safin Maria G. Babashkina Timur R. Gimadiev Michael Bolte Marina V. Pinus Dmitriy B. Krivolapov Igor A. Litvinov 《Polyhedron》2008
Reaction of O,O’-diisopropylthiophosphoric acid isothiocyanate (iPrO)2P(S)NCS with diethyl 4-aminobenzylphosphonate (EtO)2P(O)CH2C6H4-4-NH2 leads to the new N-thiophosphorylated thiourea (EtO)2P(O)CH2C6H4-4-[NHC(S)NHP(S)(OiPr)2] (HL). Reaction of the potassium salt of HL with Zn(II), Cd(II) and Co(II) in aqueous EtOH leads to complexes of formula M(L-S,S’)2 (ML2). Heteroligand copper(I) complex of HL and triphenylphosphine was prepared by the reaction of the potassium salt KL and Cu(PPh3)3I. Copper in complex Cu(PPh3)L is bound by one PPh3 and one SCNPS fragment of the chelating ligand. Compounds obtained were investigated by IR, UV–Vis, 1H and 31P{1H} NMR spectroscopy, and microanalysis. The structures of HL and Cu(PPh3)L were investigated by single crystal X-ray diffraction analysis. 相似文献
168.
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170.
Timur Oikhberg 《Proceedings of the American Mathematical Society》1999,127(12):3659-3669
We give a characterization of operators on a separable Hilbert space of norm less than one that can be represented as products of orthogonal projections and give an estimate on the number of factors. We also describe the norm closure of the set of all products of orthogonal projections.