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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    The visual computer 1 (1985), S. 49-63 
    ISSN: 1432-2315
    Keywords: Molecular modelling ; Computer-assisted drug design (CADD) ; Graphics language ; Molecular computer graphics (MCG) ; Chemical information systems
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Molecular computer graphics (MCG) has become the indispensable complement of experimental chemical and biological tools and, in a way, will shape the evolution of these fields. This accelerated and popularized evolution takes root in the visual, even scenic, grasping of fundamental chemical concepts, perceived as veritable ideograms, which condense a vast amount of information with a few two- or threedimensional graphic symbols. With MCG one can carry out real computerized syntheses of chemical images. MCG is also an ideal tool through which to visualize the changes of a system as a function of time. This review article describes the potentials and advantages of structural MCG for visualizing the basic steps of important modelization concepts, particularly for handling on-line structures in information networks and in computer-assisted drug design (CADD) applications.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1612-1112
    Keywords: Alkenes ; Gas-solid chromatography ; Ion exchangers ; Alkene separation ; Selectivity ; Specific interactions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The gas chromatographic selectivity of K+, Zn2+, Ag+, Ni2+, and Cd2+ forms of a cation exchange packing have been determined for a set of 44 C2 to C8 alkenes. The retention characteristics of each ion are broken down into electronic (charge-transfer) and steric effects associated with the alkene sub-populations of each carbon number. Almost every pair of alkenes tested can be separated on at least one of these packings. Retention is much stronger on the ion exchangers than on metal-ion containing packings in gas-liquid chromatography, even with shorter columns and higher temperatures.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Chemical Kinetics 15 (1983), S. 855-866 
    ISSN: 0538-8066
    Keywords: Chemistry ; Physical Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A new couloamperometric apparatus has been designed to extend the range of this kinetic technique to the measurement of very high rate constants, 108M-1s-1, by using TFCR-EXSEL conditions (TFCR - very low reactant concentration; EXSEL - salt excess), which give half-lives of a few seconds for very fast second-order reactions. Very low faradaic currents, in the nanoampere range for halogens, corresponding to very low reactant concentrations of 10-8-10-9M, are measured selectively by compensating the eddy currents, principally the residual and the induced currents. When the electroactive species is bromine, the concentration is demonstrated to be linearly related to the limiting reduction current in the very low concentration range. The upper limit of this technique for bromination is at present 3 × 108M-1s-1. The method is applied to the kinetic study of highly reactive enol ethers EtO-C(R) = CH-R′, where R and R′ are H or Me. A value of 2.2 × 108M-1s-1 is obtained for kBr2, the rate constant for free bromine addition to EtO-CH = CH2, by extrapolating the kinetic bromide ion effects to [Br-] = 0. An α-methyl effect (kα-Me/kH)EtO of 15 is found; this is a small decrease in the methyl effect compared to the marked increase in the double bond reactivity. For the enol acetate MeCOO-CH = CH2, whose rate constant is 6 × 102M-1s-1, (kα-Me/kH)OCOMe is 21. The dependence of substituent effects on reactivity is discussed in terms of the Hammond effect on the transition state position and of charge delocalization by group G of olefins G-CH = CH2.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 14 (1983), S. 83-86 
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The time-resolved resonance Raman spectrum (excitation: 532 nm, 30 ns laser pulse; optical multichannel detection) of the short-lived species generated by UV flash irradiation of a benzooxazolinic spiropyran in toluene or benzene, has been obtained. The CW resonance Raman spectrum of a related permanent benzooxazolinic merocyanine closely resembles the spectrum of the transient species. A tentative assignment of the Raman bands is proposed in order to characterize the bonds directly involved in the π-electron delocalization of the merocyanines.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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