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101.
Valeeva F. G. Zakharov A. V. Voronin M. A. Zakharova L. Ya. Kudryavtseva L. A. Isaikina O. G. Kalinin A. A. Mamedov V. A. 《Russian Chemical Bulletin》2004,53(7):1563-1571
The data are presented on the synthesis of podands with terminal quinoxaline fragments of rings and their influence on both the micellization properties of cetyltrimethylammonium bromide in a water—DMF solution and kinetics of basic hydrolysis of O-p-nitrophenyl O-ethyl chloromethylphosphonate and O-p-nitrophenyl O-hexyl chloromethylphosphonate in the absence and presence of surfactants. The mechanism of the podand effect on the reaction rate depends on the structures of phosphonate and podand. 1,8-Bis(3-ethyl-1,2-dihydro-2-oxoquinoxalin-1-yl)-3,6-dioxaoctane inhibits the basic hydrolysis of the substrates to 3—4 times. In a micellar solution of the surfactant, an approximately 20-fold acceleration of the reaction rate constant is observed. The observed rate constant decreases when podand is added to a micellar solution. The catalytic effect of the polycomponent system is due to concentrating of the reactants. The micellar microenvironment can exert both positive and negative effects on the reactivity of phosphonates. 相似文献
102.
Zakharova L. Ya. Valeeva F. G. Ibragimova A. R. Kudryavtseva L. A. Valeev N. N. Didenko T. L. Kovalenko V. I. Konovalov A. I. 《Russian Chemical Bulletin》2002,51(12):2176-2182
The formation of mixed micelles in the surfactant cetyltrimethylammonium bromide—polyethylene glycol(9) monoalkanoate(14) binary system was shown. The stable lyomesophase involving monomers of both surfactants forms in the region of high surfactant concentrations in the temperature interval from 25 to 96 °C. In the binary micellar system, the alkaline hydrolysis of O-ethyl-O-p-nitrophenyl chloromethyl phosphonate is accelerated up to 30-fold compared with the reaction in water in the absence of a surfactant. The efficiency of catalysis depends on the molar ratio between both surfactants. The sign of the catalytic effect changes at high surfactant concentrations. 相似文献
103.
Zakharova L. Ya. Valeeva F. G. Kudryavtseva L. A. Zuev Yu. F. Idiatullin B. Z. 《Russian Journal of General Chemistry》2002,72(9):1367-1372
Solvolysis of p-nitrophenyl bis(chloromethyl)phosphinate is accelerated in the micellar system sodim dodecyl sulfate-ethylene glycol, since the reaction in the micellar pseudophase has increased activation entropy. Among metal salt catalysts, the highest activity is characteristic of La3
+ salts. 相似文献
104.
L. Ya. Zakharova F. G. Valeeva D. B. Kudryavtsev A. V. Bilalov A. Ya. Tret ‘yakova L. A. Kudryavtseva A. I. Konovalov V. P. Barabanov 《Russian Chemical Bulletin》2005,54(3):641-649
Concentration boundaries within which polymer—colloid structures exist in a sodium dodecyl sulfate—polyethyleneimine—water system were determined. The catalytic effect of this composition was found for the hydrolysis of phosphonic acid esters. The found acceleration of hydrolysis up to 25-fold is caused by reagent concentrating in a catalytic complex.__________Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 630–638, March, 2005. 相似文献
105.
L. Ya. Zakharova F. G. Valeeva A. R. Ibragimova V. M. Zakharov L. A. Kudryavtseva Yu. G. Elistratova A. R. Mustafina A. I. Konovalov S. N. Shtykov I. V. Bogomolova 《Colloid Journal》2007,69(6):718-725
It is found that a sodium dodecyl sulfate-Brij 35 binary mixture inhibits the alkaline hydrolysis of O-ethyl-O-p-nitrophenylchloromethylphosphonate. Tensiometric data and variations in cloud point suggest the synergistic effect of the above surfactants caused by the formation of mixed micelles. The method of solvatochromic probe E T(30) shows that the micropolarity of a medium rises at the sites of localization of substrates solubilized in micelles with an increase in ionic surfactant fraction in mixed aggregates. Variations in micellization properties, micropolarity, and surface potential with the composition of the binary mixture of the surfactants influence the catalytic properties of mixed micelles with respect to the examined reaction. 相似文献
106.
L. Ya. Zakharova A. R. Ibragimova F. G. Valeeva V. M. Zakharov L. A. Kudryavtseva A. I. Konovalov N. L. Zakharchenko Yu. F. Zuev 《Russian Chemical Bulletin》2005,54(6):1449-1457
A change in the reactivity of ethyl p-nitrophenyl chloromethylphosphonate in the sodium bis(2-ethylhexyl)sulfosuccinate-n-nonane-water system around the percolation threshold was found. Study of location sites of the reactants by NMR self-diffusion
and optical spectroscopy and modeling of the kinetic data in terms of the pseudophase approach demonstrated that below the
percolation threshold, the reaction occurs in the surface layer. The observed rate constant for substrate hydrolysis in a
microemulsion below the percolation threshold is described by the Arrhenius equation, like that in aqueous solutions. Above
the percolation threshold, the slope of the Arrhenius plot sharply changes, which is apparently due to a change in the reactant
location pattern and, hence, the microscopic properties of the medium in the region of their solubilization.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1407–1414, June, 2005. 相似文献
107.
108.
109.
In situ measurements of the magnetic susceptibility of ordered and disordered titanium monoxides TiOy in the temperature range from 300 to 1200 K have revealed that it depends on the size of crystals, their stoichiometry, and long-range order parameters. Analysis of the data for both the ordered and disordered TiOy has demonstrated that the dependence of the Van Vleck paramagnetism on the nanocrystal size is inversely proportional due to the breaking of symmetry of the local environment of titanium and oxygen atoms near the surface of nanocrystals. It has been found that the Van Vleck contribution from the atomic vacancy disorder in monoxide nanocrystals of superstoichiometric composition, as well as in the crystalline stoichiometric monoxide, is proportional to the deviation of the degree of long-range order from the maximum value. 相似文献
110.
Gainanova GA Vagapova GI Syakaev VV Ibragimova AR Valeeva FG Tudriy EV Galkina IV Kataeva ON Zakharova LY Latypov SK Konovalov AI 《Journal of colloid and interface science》2012,367(1):327-336
A systematic study of the aggregation behavior of alkyltriphenylphosphonium bromides (TPPB-n; n=8, 10, 12, 14, 16, 18; here n is the number of carbon atoms in alkyl groups) in aqueous solutions has been carried out and compared with trimethyl ammonium bromides (TMAB-n). Critical micelle concentrations (cmcs) of TPPB-n and TMAB-n decrease with the number of carbon atoms with the slope parameter of ca.0.3. The low cmcs and effective solubilization power toward Orange OT indicate high micellization capacity of phosphonium surfactants. The low counterion binding parameter β is revealed for TPPB-10 and TPPB-12, while high counterion binding of ≥80% is observed for high TPPB-n homologs. Values of the surface potential ψ calculated on the basis of pK(a) shifts of p-nitrophenols is similar for both series and monotonously increase with alkyl chain length. Several points indicate non-monotonic changes within TPPB-n series. There are peculiarities of the tensiometry and solubilization plots for high homologs and above mentioned increases in counterion binding on transiting from low to high molecular weight surfactants. Differences in aggregation behavior between TPPB and TMAB series and between low and high homologs can be due to the specific structural character of the TPP(+) cation, which is supported by X-ray data. 相似文献