ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
Filter
  • Theoretical, Physical and Computational Chemistry  (18)
  • Wiley-Blackwell  (18)
  • American Institute of Physics
  • 1
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 69 (1998), S. 629-637 
    ISSN: 0020-7608
    Schlagwort(e): Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: We introduce a new molecular theory beyond the Born-Oppenheimer approximation, where both electrons and nuclei are treated quantum mechanically and equivalently. First, we develop the coupled mean-field theory (CMFT) for both the electronic and nuclear fields. Then, to take into account the dynamic correlation between these particles, we develop a new molecular theory using the generator coordinate method (GCM) based upon the CMFT, which enables us to calculate the molecular eigenstate and eigenvalue directly. Finally, we apply this method to a water molecule and analyze the isotope effect on the vibrational frequency and the particle density.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 69: 629-637, 1998
    Zusätzliches Material: 2 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 2
    Digitale Medien
    Digitale Medien
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 18 (1997), S. 1971-1984 
    ISSN: 0192-8651
    Schlagwort(e): genetic algorithm ; peptide ; conformer ; enkephalin ; search ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Informatik
    Notizen: A genetic algorithm-driven search method (GAP1.0; Genetic Algorithm Peptide search, version 1.0) has been developed for the computational exploration of peptide conformational space. The suitability of a variety of genetic algorithm operators was evaluated through representative calculations on the pentapeptide [Met]-enkephalin (Tyr-Gly-Gly-Phe-Met). GAP1.0 was successful in efficiently elucidating backbone conformational features observed in the global minimum energy structure. Furthermore, the program readily identified the tremendous diversity among [Met]-enkephalin conformers under physiological conditions. It is concluded that GAP1.0 provides a useful extension to the current repertoire of conformational analysis techniques.   © 1997 John Wiley & Sons, Inc.   J Comput Chem 18: 1971-1984, 1997
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 3
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 261-272 
    ISSN: 0894-3230
    Schlagwort(e): 1-substituted 2-pyrrolidinones ; C=O stretching frequencies ; solvent effects ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: In an effort to model solute-solvent interactions, the C=O stretching frequencies of five 1-substituted 2-pyrrolidinones and four other carbonyl-containing compounds were measured for 30 common solvents. These were then correlated with four empirical parameter sets and one theoretical (computational) parameter set. While an empirical parameter set gave the best correlation equations, the theoretical parameter equations are physically and statistically significant. Solvent volume, polarizability and hydrogen bond donor acidity (capacity) terms are significant in the correlation equations. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 14 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 4
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 610-613 
    ISSN: 0894-3230
    Schlagwort(e): Conjugate addition ; α-carbonylcarbenes ; water ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: α-Carbonylcarbenes (2a-c) generated by UV photolysis of 2-diazophenylacetic acid (1a), its methyl ester (1b) and 4-diazo-3-isochromanone (1c) in aqueous solution undergo conjugate addition of water across the entire carbonylcarbene moiety to give enols (3a-c) of the corresponding α-hydroxycarbonyl compounds. These carbenes are long-lived, with microsecond lifetimes in aqueous solution. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 5
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 10 (1997), S. 669-674 
    ISSN: 0894-3230
    Schlagwort(e): azoles ; diiodine complexes ; basicity ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: ---The diiodine basicity (a soft Lewis basicity) of 15 azoles (imidazoles, pyrazoles and triazoles) was measured by means of the formation constant of the diiodine-azole complexes in heptane at 298 K. The preferred sites of diiodine fixation are the nitrogens N-3 in imidazoles, N-2 in pyrazoles and N-4 in 1,2,4-triazoles. The diiodine basicity decreases with (i) the number of ring nitrogens, (ii) benzofusion, (iii) field electron-withdrawing effects of substituents on N-1 and (iv) for pyrazoles only, steric effect of substituents on N-1. In imidazoles and 1,2,4-triazoles, the lengthening and branching of alkyl groups on N-1 increase significantly the basicity, and 1-(adamant-1-yl)imidazole is the most basic of the azoles studied. © 1997 John Wiley & Sons, Ltd.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 6
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 536-539 
    ISSN: 0894-3230
    Schlagwort(e): enzyme design ; enzyme mechanism ; genetic engineering ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Aspartate aminotransferase (AATase) and aminocyclopropane carboxylate synthase (ACC synthase) are pyridoxal phosphate (PLP)-dependent enzymes whose common junction of mechanistic divergence is after the formation of a Cα carbanion from the amino acid substrate bound to PLP as a Schiff base (aldimine). AATase catalyzes the reversible interconversion of α-amino acids and α-keto acids, while ACC synthase effects the irreversible decomposition of S-adenosylmethionine (SAM) to 1-aminocyclopropane-1-carboxylate (ACC) and 5′-methylthioadenosine (MTA). ACC is subsequently converted to ethylene, the plant ripening and senescence hormone, by ACC oxidase, the next enzyme in the pathway. AATase and ACC synthase exhibit many similar phenomenological characteristics that result from different detailed mechanistic origins. The kcat/KM versus pH profiles for both enzymes are similar (AATase, acidic pKa = 6.9, basic pKa = 9.6; ACC synthase, acidic pKa = 7.5, basic pKa = 8.9); however the acidic pKa of AATase reflects the ionization of an enzyme proton from the internal Schiff base, and the basic one is that of the α-amino group of the substrate, while the opposite situation obtains for ACC synthase, i.e. the apparent pKa of 7.4 is due to the α-amino group of SAM, whereas that of 9 reflects the Schiff base pKa. The mechanistic imperative underlying this reversal is dictated by the reaction mechanism and the low pKa of the α-amino group of SAM. The low pKa of SAM requires that the enzyme pKa be moved upward in order to have sufficient quantities of the reacting species at neutral pH. It is shown by viscosity variation experiments with wild-type and active site mutant controls of both enzymes that the reaction of SAM with ACC synthase is 100% diffusion controlled (kcat/KM = 1.2 × 106 l mol-1 s-1) while the corresponding reaction for the combination of L-aspartate with AATase is insensitive to viscosity, and is therefore chemically not diffusion limited. Tyr225 (AATase) or Tyr233 (ACC synthase) forms a hydrogen bond with the PLP in both enzymes, but that formed with the former enzyme is stronger and accounts for the lower pKa of the Schiff base. © 1998 John Wiley & Sons, Ltd.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 7
    Digitale Medien
    Digitale Medien
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 9 (1996), S. 361-370 
    ISSN: 0894-3230
    Schlagwort(e): Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie , Physik
    Notizen: Acetylenic alcohols - ynols - and acetylenic amines - ynamines - have been generated in aqueous solution by flash phololytic decarbonylation of hydroxy- and aminocyclopropenones and their chemistry has been examined in that medium. This has revealed a remarkably strong acid-strengthening effect of the acetylenic group, which ab initio molecular orbital calculations suggest results from a combination of destabilizing inductive effects on the initial state and stabilizing resonance effects on the final state of the acid ionization reaction.
    Zusätzliches Material: 8 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 8
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 66 (1998), S. 301-307 
    ISSN: 0020-7608
    Schlagwort(e): LaC3n+ ; structure ; vibrational frequency ; density functional theory ; Gaussian 92/DFT ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: LaC3n+ (n=0, 1, 2) clusters have been studied using B3LYP (Becke 3-parameter-Lee-Yang-Parr) density functional method. The basis set is Dunning/Huzinaga valence double zeta for carbon and [2s2p2d] for lanthanum, denoted LANL1DZ. Four isomers are presented for each cluster; two of them are edge binding isomers with C2v symmetry, the other two are linear chains with C∞v symmetry. Meanwhile, two spin states for each isomer, that is, singlet and triplet for LaC3+, doublet and quartet for LaC3 and LaC32+, respectively, are also considered. Geometries, vibrational frequencies, infrared intensities, and other quantities are reported and discussed. The results indicate that at some spin states; the C2v symmetry isomers are the dominant structures, while for the other spin states, linear isomers are energetically favored.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 66: 301-307, 1998
    Zusätzliches Material: 1 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 9
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 63 (1997), S. 393-401 
    ISSN: 0020-7608
    Schlagwort(e): Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Heteroatomic cages (BN/2NN/2) with borons and nitrogens fully replacing alternant sets of carbons in cages are built graph-theoretically and investigated via the semiempirical MNDO Hamiltonian. The comparison with their parent carbon cages CN is made in terms both of electronic and of geometric changes. Infinite classes first of octahedral symmetry and second of hexagonal-bipyramidal symmetry fullerenoid cages are considered in detail. The difference in the electronegativities for boron and nitrogen implies the opening of HOMO-LUMO gaps for alternant BN clusters. In general, the borons prefer planar geometry (sp2 hybridization) while the nitrogens prefer pyramidalization (sp3 hybridization). © 1997 John Wiley & Sons, Inc.
    Zusätzliches Material: 6 Ill.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
  • 10
    Digitale Medien
    Digitale Medien
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 65 (1997), S. 377-377 
    ISSN: 0020-7608
    Schlagwort(e): Chemistry ; Theoretical, Physical and Computational Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: No abstract.
    Materialart: Digitale Medien
    Standort Signatur Erwartet Verfügbarkeit
    BibTip Andere fanden auch interessant ...
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...