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21.
Marian Mikolajczyk Slawomir Grzejszczak Katarzyna Korbacz 《Tetrahedron letters》1981,22(32):3097-3100
A convenient synthesis of vinylphosphonates which involves addition of elemental selenium to phosphonate carbanions followed by alkylation and selenoxide elimination is described. A general approach to 1,4-dicarbonyl systems based on diethyl α-methylthiovinylphosphonate is also reported. 相似文献
22.
The lipophilicity of some antiarrhythmic and antihypertensive active 1-[2-hydroxy- or 1-[2-acetoxy-3-(4-aryl-1-piperazinyl)propyl]pyrrolidin-2-one derivatives (1-12) has been investigated. Their lipophilicity (R(MO) and log k') was determined by reversed-phase thin-layer chromatography and reversed-phase high-performance liquid chromatography with mixtures of acetonitrile and Tris buffer as mobile phases. The partition coefficients of compounds 1-12 (log P(ScilogP)) were also calculated with the ScilogP program. Comparison of R(MO), log k' and calculated log D(7.0 ScilogP) values enabled calculation of clog D(7.0 TLC) and clog D(7.0 HPLC) values. Preliminary quantitative structure-activity relationship studies indicated that for active compounds there is a dependence between affinity for alpha(2)-adrenoceptors and their clog D(7.0 HPLC) values. 相似文献
23.
Katarzyna Kaszyńska Ewa Banachowicz Genowefa Ślósarek Adrian Morawiec Iwona Gawrońska Jan Barciszewski 《Journal of solution chemistry》2002,31(12):987-993
We analyze the structure of napin (BngNAP1), a storage protein (m.w. 14.5 kDa) from Brassica napus. On the basis of the results of 1H NMR spectroscopy and dynamic light scattering (DLS) studies, the overall shape and secondary structure of the molecule are estimated. 相似文献
24.
Ewa Bulska Katarzyna Wróbel Adam Hulanicki 《Fresenius' Journal of Analytical Chemistry》1992,342(9):740-743
Summary The optimal conditions for the determination of aluminium and chromium in blood serum are proposed. Several sample pretreatment procedures for the purpose are compared. The best results are obtained by sample dilution with nitric acid (0.1 mol/l) and addition of Mg(NO3)2 as modifier with a magnesium concentration of 0.2 mg/ml. This procedure has been used for studying the intestinal intake of aluminium by patients after oral administration of aluminium compounds. 相似文献
25.
Surface properties of the binary mixed systems of alkylpyridinium halides and sodium alkylsulfonates 总被引:1,自引:0,他引:1
Danuta Gralczyk Katarzyna H
c Pawe
Wydro 《Colloids and surfaces. A, Physicochemical and engineering aspects》2003,220(1-3):55-60
Surface properties of the binary mixed systems of decyl- and dodecylpyridinium chloride or bromide and sodium pentyl- and heptylsulfonate have been investigated. The surface tension of solutions of equimolar mixtures of surfactants and individual surfactants was measured, and the composition of mixed monolayers and surface interaction parameter β were calculated with the regular solution theory. Our results indicate that the properties of mixed films depend on both ionic strength and the kind of added inorganic electrolyte. With the increase of inorganic electrolyte concentration, the content of more surface active ions in the adsorption films enhances and is the highest in the presence of NaI and the smallest when solutions contain NaCl. Mutual interactions in mixed adsorbed films were found to be attractive. However, the strength of interaction weakens with the increase of ionic strength and depends on the kind of inorganic ions in the order: Cl−>Br−>I−. 相似文献
26.
Magdalena Kurdziel Elżbieta Szczepaniec-Cięciak Barbara Dąbrowska Wojciech Nitek Katarzyna Paliś Edyta Ślusarska 《Journal of solution chemistry》2003,32(7):601-615
The solubilities of solid 2,3-dimethylbutane and cyclopentene in liquid argon at a temperature of 87.3 K and in liquid nitrogen at 77.4 K have been measured by the filtration method. The hydrocarbon contents in solutions were determined using gas chromatography. GC–MS was used to identify impurities in solutes. The experimental value of the mole fraction solubility of solid 2,3-dimethyl-butane in liquid argon at 87.3 K is (8.26 ± 1.60) × 10–6 and (2.77 ± 0.94) × 10–8 in liquid nitrogen at 77.4 K. The experimental value of the mole fraction solubility of solid cyclopentene in liquid argon at 87.3 K is (5.11 ± 0.44) × 10–6 and (4.60 ± 0.76) × 10–8 in liquid nitrogen at 77.4 K. The Preston–Prausnitz method was used for calculation of the solubilities of solid hydrocarbons in liquid argon in the temperature range 84.0–110.0 K and in liquid nitrogen from 64.0 to 90.0 K. The solvent–solute interaction parameters l
12 were also calculated. At 90.0 K liquid argon is a better solvent for investigated solid hydrocarbons than is liquid nitrogen. 相似文献
27.
Katarzyna Guzow Mariusz Szabelski Jerzy Karolczak Wiesaw Wiczk 《Journal of photochemistry and photobiology. A, Chemistry》2005,170(3):215-223
The photophysical properties of N-Boc-3-[2-(9-anthryl)benzoxazol-5-yl]-l-alanine methyl ester (BoxAnt) and N-Boc-3-[2-[4-(9′-(10′-butyl)anthryl)phenyl]benzoxazol-5-yl]-l-alanine methyl ester (BoxPhAnt) were studied in a series of solvents. Their absorption spectra are less sensitive to the solvent polarity than the corresponding fluorescence spectra which show a pronounced solvatochromic effect leading to large Stokes shifts. Using an efficient solvatochromic method, based on the empirical solvent polarity parameter , a large change of the dipole moment on excitation for BoxPhAnt has been found. From an analysis of the solvatochromic behaviour of the absorption and fluorescence spectra in terms of bulk solvent polarity functions, f(r, n) and g(n), a larger excited-state dipole moment (about 8 D, ψ = 56) was obtained for BoxPhAnt than for BoxAnt (about 3 D, ψ = 0). Both applied methods gave similar values of the excited-state dipole moments for both compounds studied. 相似文献
28.
Janina Lulek Maurycy Opielewicz Katarzyna Szyrwińska Bart?omiej Milanowski 《Analytica chimica acta》2005,540(1):25-31
The database of the relative retention times (RRTs) of polychlorinated biphenyls (PCBs) reported in literature was used to calculate the retention indices (RIs) of all 209 PCB congeners on temperature programmed capillary column Rtx-5. Calculation of retention indices was based on reference series of seven congeners (PCB IUPAC Nos. 18, 52, 101, 143, 185, 203 and 206) that exhibit linear relative retention time behaviour as a function of chlorine number. The calculated indices were compared to those determined in our laboratory as well as to those obtained by other authors. The proposed indices system was applied for identification individual congeners in mixture of Aroclors 1242:1254:1260, using only reference series of PCBs. 相似文献
29.
30.
A simple optical method for quantitative comparison of the effectiveness of epoxy cure accelerators, used for speeding up the crosslinking process of epoxy resins with cyclic anhydrides, is described. Fluorescent molecular probes and a miniature fiber optic spectrometer have been applied for measurement of the cure kinetics of a model epoxy resin/anhydride composition in the presence of various cure accelerators. A quantitative index of accelerator performance has been determined for several of the most common accelerators. 相似文献