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991.
992.
Agnieszka Wieckowska Renata Bilewicz Aleksandra Misicka Marek Pietraszkiewicz Krzysztof Bajdor Lucjan Piela 《Chemical physics letters》2001,350(5-6):447-452
Two newly synthesised 21-amino acid peptides substituted with ferrocene groups preserve the helical structure of the peptide and behave as multi-centre donor systems with six electroactive reversible redox centres per molecule. The formal potential of the hexaferrocene compound is slightly less positive than that of its single centre analogue. 相似文献
993.
Agnieszka Tarasiska 《Mathematical Methods in the Applied Sciences》2006,29(11):1215-1236
The article is devoted to describe asymptotics in the heat convection problem for a micropolar fluid in two dimensions. We show the existence and the uniqueness of global in time solutions and then prove the existence of a global attractor for considered model. Next, the Hausdorff dimension of the global attractor is estimated. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
994.
Andrzej Gzella Maria D. Rozwadowska Agnieszka Sulima 《Acta Crystallographica. Section C, Structural Chemistry》2001,57(12):1454-1456
The structures of two racemic thiazolino[2,3-a]isoquinolinone S-oxides, i.e. 8,9-dimethoxy-2,3,5,6-tetrahydro-10bH-thiazolo[2,3-a]isoquinolin-3-one 1-oxide [C13H15NO4S, (IIa)] and 8,9-dimethoxy-10b-methyl-2,3,5,6-tetrahydro-10bH-thiazolo[2,3-a]isoquinolin-3-one 1-oxide [C14H17NO4S, (IIb)], are described. The thiazolinone ring in (IIa) exists in an envelope conformation, while in (IIb), it assumes a half-chair conformation. In (IIa) and (IIb), the six-membered heterocyclic ring adopts an envelope conformation. The O atom at sulfur is oriented in a pseudo-axial position, whereas the H atom in (IIa) and the methyl group in (IIb), linked to the stereogenic C centre, occupy a bisectional position with respect to the partially saturated pyridine ring and a pseudo-axial position with respect to the thiazolinone ring. In both structures, the S=O group and the substituent at the stereogenic C centre are trans with respect to one another. Intermolecular C—H⋯O hydrogen bonds are observed in the crystal lattice of (IIa) and (IIb). 相似文献
995.
Agnieszka Iwan Bozena Kaczmarczyk Janusz Kasperczyk Jan Jurusik Henryk Janeczek Danuta Sek Zbigniew mazurak 《Journal of polymer science. Part A, Polymer chemistry》2006,44(19):5645-5660
New luminescent materials—aromatic polyketanils (PKs) containing p‐phenylene and biphenylene linkages in the backbone and electron‐donating, side‐group substitutions—were synthesized via melt polycondensation with the goal of studying the interactions between the polymer chains (PKs), primary dopant [1,2‐(di‐2‐ethylhexyl)ester of 4‐sulfophthalic acid (PSA)], and secondary dopant [m‐cresol (MC)] with 1H NMR, 13C NMR, Fourier transform infrared (FTIR), ultraviolet–visible, and photoluminescence measurements. Spectral changes were observed for the PKs after primary and secondary doping, and they supported ionic‐ and hydrogen‐bond formation between the PKs and the PSA and MC, respectively. This specific interaction of the dopant with the host polymer influenced the PK properties, and the following observations were made: (1) HOMO/LUMO energy gap of the protonated PKs; (2) bathochromic/hypsochromic photoluminescence shifts observed after protonation with PSA; (3) a downfield chemical shift of the labile proton in the protonating agent OH group in the 1H NMR spectra of the protonated polymers; (4) a protonation decrease in the intensity of the C?N stretching band in the FTIR spectrum; and (5) a spherulite‐like morphology, detected by atomic force microscopy and polarized optical microscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5645–5660, 2006 相似文献
996.
Grzegorz Schroeder Nataliya Lyapchenko Piotr Przybylski Bogumil Brzezinski Tomasz Kozik Agnieszka Burzynska Pawe Kafarski 《Journal of Molecular Structure》2005,750(1-3):142-151
Four N-(2-pyridyl)aminomethyldiphoshonic acids have been synthesized and the formation of the complexes between them and alkali cations were studied by the electrospray ionization mass spectrometry (ESI MS). The ESI spectra have evidenced formation of various types of complexes of the acids and monovalent cations, directly related to the formation of respective mono- and disalts of the acids. The main fragmentation path of the acids and their complexes is realized by the elimination of H2O or H3PO3 molecules. The structures of the acids and their complexes with monovalent cations have been calculated by the PM5 method. The structure and the stabilization role of the intramolecular hydrogen bonds for the complexes are discussed. 相似文献
997.
Agnieszka Adamczyk-Woźniak Izabela Madura Aldrik H. Velders Andrzej Sporzyński 《Tetrahedron letters》2010,51(47):6181-6185
In the reaction of 2-formylphenylboronic acid with secondary amines different products are formed depending on the structure of the amines. For aliphatic amines the reaction proceeds with the formation of 3-amino-substituted benzoxaboroles or with the formation of complexed boroxins. A crystal structure of the benzoxaborole with a thiomorpholinyl substituent was determined. 相似文献
998.
Agnieszka Hryniewicka 《Journal of organometallic chemistry》2010,695(9):1265-1270
A synthesis of new Hoveyda-Grubbs-type catalyst with chromenyl ligand was described herein. The new catalyst was tested in model RCM and CM reactions. The catalyst proved to be quite efficient. It showed activity comparable or superior to that of commercially available Grubbs second-generation complexes. 相似文献
999.
New derivatives of 2-(1-amino-1-phenylmethyl)-1,3,4-oxadiazole and 1,2,4-triazin-6-one were synthesised in the reactions of optically active α-aminocarboxylic acid hydrazides and triethyl orthoesters in xylene. The electronic and steric effects of substituents at the α position influencing the formation of five- or six-membered products are discussed. 相似文献
1000.
Agnieszka Plis Janusz Lasek Agnieszka Skawińska Marcin Kopczyński 《Chemical Papers》2014,68(7):879-889
Posidonia oceanica (PO) is a marine plant endemic to the Mediterranean basin, forming extensive grasslands. Onshore residues represent a major environmental, economic, social and hygienic problem in all coastal zones of the Mediterranean basin due to the great disturbance they cause to bathers and beachfront populations. This work sought to evaluate the thermo-chemical properties of PO in pyrolysis and thermo-oxidative degradation processes. The investigations were carried out using a thermogravimetric analyser (TGA) coupled to a quadrupole mass spectrometer (MS) and an infrared spectrometer (FTIR). In addition, proximate, ultimate, diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and biodegradability analyses were carried out on PO. The biodegradability analysis confirmed that residues of PO were a biodegradable material. Accordingly, the application of PO as a feedstock for combustion/co-combustion or biorefining is recommended. 相似文献