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  • 1
    ISSN: 1436-5073
    Keywords: nitrofurazone ; 3-methylbenzothiazolin-2-one hydrazone ; 2-thiobarbituric acid ; isonicotinic acid hydrazide ; metol ; spectrophotometry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Four simple and sensitive visible spectrophotometric methods (A-D) for the determination of nitrofurazone in bulk samples and pharmaceutical formulations are described. They are based on the formation of colored species by treating either its reduction product with 3-methylbenzothiazolin-2-one hydrazone in the presence of ferric chloride (method A: λmax 600 nm) or its hydrolysis product with thiobarbituric acid (method B: λmax 520 nm, 440 nm) or barbituric acid (method C: λmax 400 nm) or by oxidizing it with excess N-bromosuccinimide and determining the consumed NBS using metol-isonicotinic acid hydrazide (method D: λmax 620 nm).
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Il nuovo cimento della Società Italiana di Fisica 14 (1992), S. 253-260 
    ISSN: 0392-6737
    Keywords: Dielectric thin films
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary Polyacrylamide polymer films of thickness 4.15 μm were prepared by isothermal immersion technique. The dielectric capacitance and dielectric loss of the films were studied as functions of frequency and temperature in the range 100 Hz|10 MHz and (300|450)K, respectively. Two dielectric loss peaks were observed in the dielectric loss spectra and were identified as β and α peaks. The β peak was attributed to the reorientation of dipoles and the α-peak was attributed to the deformations accompanied by large changes in the directions or locations of the dipoles.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-203X
    Keywords: Epidermis ; monolayer culture ; morphogenesis ; somatic embryos
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Somatic embroys and subsequent plant regeneration were obtained from isolated leaf epidermis of Gaillardia picta. Abaxial and adaxial epidermal peels (monolayer) from 45 days old aseptic seedlings were isolated and segments measuring 5 mm x 3 mm were cultured on B5 basal medium supplemented with various growth regulators such as naphthaleneacetic acid or indolebutyric acid and benzylaminopurine or kinetin. Within 12 h of culture the epidermal cells showed receding of cytoplasm from the walls. After 48 h of incubation 3 or 4 localized zones, each consisting of 3–8 cells that accumulated cytoplasm and stained densely, were observed. Mitotic divisions occurred in these zones on day 3 of culture and localized masses of callus were observed in 95% of the cultures after 10 days. In another 5 days, the callus differentiated somatic embryos or roots, depending on the growth regulators and their concentration in the medium.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Reaction kinetics and catalysis letters 48 (1992), S. 519-528 
    ISSN: 1588-2837
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Abstract Кинетика и механизм восстановления таллия(III) пере-кисью водорода исследовали в среде одномолярной пер-хпорной кислоты. Реакция имеет первый порядок по тал-лию (III) и второй порядок по перекиси водорода. На-блюдается отрицательный катализ по отношению к водо-родным и хлоридным ионам. Бромидный ион катализирует реакцию при низких концентрациях. Не наблюдалось ка-кое-либо влияние ионной силы на скорость реакции. Предложен вероятный механизм реакции, откуда вытека-ет следующее уравнение скорости: Скороств=−[T1(III)]/dt=kK[T1(III)][H2O2]2/[H+], где К-константа равновесия комплекса таллия(III) с перекисью водорода и к-константа скорости реакции между комплексом и перекисью водорода. Полученные с помощью ЭВМ величины EA и ΔS# равны 44,8±6,5 кДж/моль и −107,8±22,1 Дж/К·моль, соответственно.
    Notes: Abstract The kinetics and mechanism of reduction of thallium(III) by hydrogen peroxide has been studied in 1.0 mol dm−3 perchloric acid medium. The reaction is first order with respect to thallium(III) and second order with respect to hydrogen peroxide. A negative hydrogen ion and chloride ion catalysis is observed. Bromide ion is found to catalyze the reaction in low concentration. There is no effect of ionic strength on the rate of the reaction. A plausible mechanistic pathway for the reaction is suggested which leads to the following rate law: Rate=−d[T1(III)]/dt=kK[T1(III)][H2O2]2/[H+] where K is the formation constant of the complex between thallium(III) and hydrogen peroxide and k is the rate constant of the reaction between that complex and hydrogen peroxide. The computed values of Ea and ΔS# are 44.8±6.5 kJ mol−1 and −107.8±22.2 JK−1 mol−1, respectively.
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  • 5
    Publication Date: 1992-05-01
    Print ISSN: 0026-3672
    Electronic ISSN: 1436-5073
    Topics: Chemistry and Pharmacology
    Published by Springer
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Circuits, systems and signal processing 11 (1992), S. 377-385 
    ISSN: 1531-5878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Fast progressive reconstruction (FPR) of images based on discrete Fourier transform (DFT) and Walsh-Hadamard transform (WHT) has been developed by Takikawa [3]. This technique is now extended to the discrete cosine transform (DCT). The quality of reconstructed images during the intermediate stages based on these transforms is analyzed. This comparison is both subjective and objective. The feasibility of the DCT in this FPR scheme is discussed.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Stochastic environmental research and risk assessment 6 (1992), S. 270-288 
    ISSN: 1436-3259
    Keywords: Periodicities ; hydraulic cycle ; spectral methods
    Source: Springer Online Journal Archives 1860-2000
    Topics: Architecture, Civil Engineering, Surveying , Energy, Environment Protection, Nuclear Power Engineering , Geography , Geosciences
    Notes: Abstract Periodicites in hydrologic data are frequently estimated and studied. In some cases the periodic components are subtracted from the data to obtain the stochastic components. In other cases the physical reasons for the occurrence of these periodicities are investigated. Apart from the annual cycle in the hydrologic data, periods corresponding to the 11 year sunspot cycle, the Hale cycle and others have been detected. The conclusions from most of these studies depend on the reliability and robustness of the methods used to detect these periodicities. Several spectral analysis methods have been proposed to investigate periodicities in time series data. Several of these have been compared to each other. The methods by Siddiqui and Wang and by Damsleth and Spjotvoll, which are stepwise procedures of spectrum estimation, have not been evaluated. Two of the methods of spectral analysis proposed by Siddiqui and Wang and by Damsleth and Spjotvoll are investigated in this study by using generated and observed data. Siddiqui and Wang's method is found to be superior to the Damsleth and Spjotvoll's method.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 55 (1992), S. 35-47 
    ISSN: 1436-4646
    Keywords: Perfect matrices ; balanced matrices
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this paper we define wheel matrices and characterize some properties of matrices that are perfect but not balanced. A consequence of our results is that if a matrixA is perfect then we can construct a polynomial number of submatricesA I,⋯,A n ofA such thatA is balanced if and only if all the submatricesA 1,⋯,A n ofA are perfect. This implies that if the problem of testing perfection is polynomially solvable, then so is the problem of testing balancedness.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical programming 55 (1992), S. 129-168 
    ISSN: 1436-4646
    Keywords: Polyhedral combinatorics ; integrality of polytopes ; decomposition
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract Claude Berge defines a (0, 1) matrix A to be linear ifA does not contain a 2 × 2 submatrix of all ones.A(0, 1) matrixA is balanced ifA does not contain a square submatrix of odd order with two ones per row and column. The contraction of a rowi of a matrix consists of the removal of rowi and all the columns that have a 1 in the entry corresponding to rowi. In this paper we show that if a linear balanced matrixA does not belong to a subclass of totally unimodular matrices, thenA orA T contains a rowi such that the submatrix obtained by contracting rowi has a block-diagonal structure.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Optical and quantum electronics 24 (1992), S. 825-832 
    ISSN: 1572-817X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
    Notes: Abstract We report for the first time the determination of the real part of the third order nonlinear susceptibilitiesχ (3) (−ω, ω, 0, 0) in the isotropic phase of two nematic liquid crystalsp-(ethoxybenzylidine)-p-butylaniline (EBBA) andp-(methoxybenzylidene)-p-butylaniline (MBBA) from electrooptic Kerr effect experiments. The highest value ofχ (3) observed near nematic-to-isotropic transition temperature, at 632.8 nm is found to be 1.067×10−20 m2V−2 for EBBA and 6.602×10−20 m2V−2 for MBBA.
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