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  • Articles  (4,049)
  • Analytical Chemistry and Spectroscopy  (3,123)
  • Computational Chemistry and Molecular Modeling  (818)
  • Industrial Chemistry
  • 1990-1994  (1,731)
  • 1980-1984  (1,276)
  • 1975-1979  (846)
  • 1965-1969  (196)
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  • Articles  (4,049)
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  • 1
    Electronic Resource
    Electronic Resource
    Electrophoric labelling of nucleosides for sensitive analysis by negative ion chemical ionization gas chromatography/mass spectrometry (1992)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 21 (1992), S. 441-450 
    Details
    ISSN: 1052-9306
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The formation and analytical utility of several electrophone derivatives of native and oxidatively modified nucleosides of deoxythymidine and deoxyguanosine were studied. Derivatives include the incorporation of trimethylsilyl, acetyl or perfluoroacyl groups together with pentafluorobenzyl. Acetylation followed by pentafluorobenzylation was the most favourable method. In general, the combined information from the electron impact, positive ion chemical ionization and negative ion chemical ionization spectra was well suited for structure elucidation purposes. The acetyl-pentafluorobenzyl derivative of deoxythymidine was prepared in quantitative yield and was very sensitive on analysis by gas chromatography negative ion chemical ionization. Injection of 0.45 fmol of 3′,5′-bis(O-acetyl)-3-pentafluorobenzyl-deoxythymidine, in multiple ion detection experiments, gave a response with a signal-to-noise ratio larger than 10.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bms.1200210905
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  • 2
    Electronic Resource
    Electronic Resource
    Mixed solvent matrices for fast atom bombardment mass spectrometry of (4,4′-Disubstituted-2,2′-bipyridine) tetracarbonylmetal complexes of molybdenum and tungsten (1984)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 19 (1984), S. 294-294 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210190608
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  • 3
    Electronic Resource
    Electronic Resource
    Etude en RMN du 13C de Mérocyanines Benzimidazoliniques (1978)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 11 (1978), S. 493-498 
    Details
    ISSN: 0030-4921
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A series of α-oxobenzimidazolinic merocyanines differently substituted on the ‘phenolate’ part and bearing a paraffinic chain on one heterocyclic nitrogen, has been studied by 13C NMR. Electron donating substituents bring about an increase of the electronic density on the 3 methine carbon and an increase of the alternation of electron density on the 3,4-dimethine bridge. A bathochromic shift of the lower energy electronic transition is also observed. Furthermore, the low field resonance of the 3 methine proton is probably due to a specific interaction between this proton and the ‘phenolate’ oxygen atom. This implies the existence of a favoured trans configuration for merocyanine dyes.
    Notes: Une série de mérocyanines α-oxo benzimidazoliniques diversement substituées sur la partie ‘phénolate’ et possédant une chaǐne grasse sur l'un des azotes hétérocycliques, a été étudiée en RMN du carbone- 13. Des substituants donneurs d'électrons provoquent une augmentation de la densité électronique sur le carbone méthinique C-3 et une augmentation de l'alternance de la distribution de charge sur le pont diméthinique 3,4. Corrélativement un déplacement bathochrome de la transition électronique de plus basse énergie est observé. Par ailleurs, l'apparition de la résonance à champ faible du proton méthinique H-3 semble due à une interaction spécifique intervenant entre ce proton et l'atome d'oxygène ‘phénolate’, ce qui suppose l'existence d'une configuration trans privilégiée pour les mérocyanines.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1270111004
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  • 4
    Electronic Resource
    Electronic Resource
    On the characterization of dihydro-oxazin-6-ones and N-acetylazetidin-2-ones by mass spectrometry (1977)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 12 (1977), S. 578-581 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mass spectrometry has been used in an attempt to resolve the ambiguity in the structures of the isomeric dihydro-oxazin-6-ones and N-acyl-azetidin-2-ones.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210120911
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  • 5
    Electronic Resource
    Electronic Resource
    Dependence of RHF properties of hydrogen and helium chains on the exchange lattice summations (1990)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 38 (1990), S. 593-606 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: An alternative configuration space scheme for ab initio polymer band structure calculations based on a Filon-type quadrature is proposed. This scheme avoids the explicit calculation and the storage of the “troublesome” Fourier transforms of the LCAO density matrix elements. Furthermore, the lattice sums (Coulomb and exchange) can be carried out up to infinity which removes the difficult problem of guessing limits to these summations. The potential of the proposed technique is illustrated by minimal basis set calculations on the infinite chains of H and He atoms.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560382458
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  • 6
    Electronic Resource
    Electronic Resource
    Ladder operators for central potential wave functions from the algebraic representation of orthogonal polynomials (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 155-164 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A general algebraic procedure that yields to raising and lowering operators for the solutions of second-order differential equations is presented. The method is illustrated by applying it to the differential equations of Hermite and Laguerre polynomials. Taking advantage of the algebraic representation of these polynomials, the ladder operators for harmonic oscillator and hydrogen atom wavefunctions are straightforwardly deduced without resorting to specialized factorizations. The proposed algebraic approach can be extended to the determination of new sets of ladder operators that could be used in the calculation of matrix elements in specific applications.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560400818
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  • 7
    Electronic Resource
    Electronic Resource
    An Ab Initio computational scheme for polymeric chains with fully converged coulomb and exchange lattice sums (1991)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 40 (1991), S. 603-618 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The restricted Hartree-Fock formalism applied to quasi one-dimensional translational systems embodies slowly convergent Coulomb and exchange lattice summations. In this contribution, an algorithm based on a Filon like quadrature procedure to carry out the k-space integration of density matrix elements is analyzed and its efficiency is illustrated by its application to the linear chains of hydrogen molecules. It allows the computation of Coulomb and exchange lattice sums to their asymptotic limit, and renders obsolete the empirical procedure of guessing the number of interactions to be included in the calculations.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560400854
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  • 8
    Electronic Resource
    Electronic Resource
    Alternative approach to the factorization method (1992)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 44 (1992), S. 171-179 
    Details
    ISSN: 0020-7608
    Keywords: Computational Chemistry and Molecular Modeling ; Atomic, Molecular and Optical Physics
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A procedure to obtain the operational solutions of second order differential equations related with Sturm-Liouville problems is presented. The method is based on the commutation relation between the ladder operators themselves, with a certain structure, and the position and momentum operators. Even though the creation and annihilation operators, derived by the proposed approach, factorize as expected the corresponding differential equation, the method does not use, as original premise factoring, the differential relation under consideration. That is, the displayed procedure is quite different, simple, and direct when compared with other procedures such as the factorization method of Infeld and Hull. To illustrate the above, the usefulness of the proposed procedure is shown by finding the ladder operators associated to the quantum numbers n and I for various potential wave functions. © 1992 John Wiley & Sons, Inc.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560440816
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  • 9
    Electronic Resource
    Electronic Resource
    Azo compounds for free radical crosslinking of polysiloxane stationary phases (1983)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 6 (1983), S. 371-374 
    Details
    ISSN: 0935-6304
    Keywords: Free radical crosslinking ; Capillary gas chromatography ; Azo compounds ; Nonextractable Polysiloxane stationary phases ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: There has been much effort spent in recent years developing the technology for free radical crosslinking of polysiloxane polymers to prepare capillary columns coated with thermally stable and nonextractable stationary phases. Organic peroxides have been used extensively as the free radical initiators for the in situ polymerization of the stationary phases. However, these peroxides adversely affect the phase polarity and column activity. Seven azo compounds were studied for crosslinking efficiency. Azo compounds can be used as free radical initiators to prepare nonextractable stationary phases without the adverse effects caused by peroxides.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240060705
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  • 10
    Electronic Resource
    Electronic Resource
    Identification of Diels-Alder regioisomers by mass spectrometry coupled with theoretical calculations (1993)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 28 (1993), S. 752-758 
    Details
    ISSN: 0030-493X
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Differences in the mass spectra of Diels-Alder cyclohexene regioisomers are explained with the aid of a simple model based on the relative stability differences of the open-chain structures resulting from the alternative cleavage of the C(1)-C(2) and the C(5)-C(6) bonds of the 1-substituted cyclohexene ring. Theoretical SCF-MO calculations at a semi-empirical level proved to be useful tools for determining the relative stabilities of these open-chain radical cation structures and hence in the interpretation of mass spectra and the correct assignment of regioisomer structures from these spectra.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/oms.1210280705
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