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  • Articles: DFG German National Licenses  (18)
  • Computational Chemistry and Molecular Modeling  (14)
  • Cell & Developmental Biology  (4)
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  • Articles: DFG German National Licenses  (18)
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  • 1
    Electronic Resource
    Electronic Resource
    π-Orbital electron-energy contributions to chemical reaction heats, I. Reactions involving only linear molecules containing up to three first-row atoms (1980)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 17 (1980), S. 599-608 
    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: Ab initio calculations of various expectation energies have been made for the reactant and product species in six reactions that involve only small linear molecules. The reactions include fission by hydrogen, addition of hydrogen, exchange of triply bonded atoms, fluorination, and oxygen atom transfer. The change in total electronic energy is not invariably the result of changes in inner shell energy and outer shell σ- and π-electron energies simply augmenting each other, but in several cases there is a complex interplay of opposing effects. This approach gives a different insight into the energetic aspects of changes in bonding from that derived from the concept of shared electron pairs in σ and π bonds together with lone pairs in valence shells. Changes in π-electron energy are shown to be important in a reaction in which neither reactant nor product molecules contain π bonds in the usual chemical sense. While in a reaction in which there is a complete change in the nature of the triple bonds, and hence the π bonding, the change in π-electron energy makes a smaller contribution than either the change in inner shell or the outer shell σ-electron energies.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560170402
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Correlation energy contributions to reaction heats (1977)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 12 (1977), S. 61-81 
    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: New, more accurate, Hartree-Fock limit energies (EHF) for ethane and ethylene are obtained from SCF total molecular energie using Ermler and Kern's procedure. These results, together with EHF values for other small closed shell molecules, are employed to calculate correlation energy (Ec) contributions to reaction heats. Cancellation to within 98% of the total Ec involved, and often to more than 99%, is found for a wide variety of chemical reactions, which strongly suggests that there are systematic regularities in the contribution to Ec from the different kinds of electron pairs in the valence shell. Assuming trictly localized pairs occupying orbitals having strongly directional character, Ec for the valence shell is evaluated in terms of Ec per lone pair, Ec per X—H bond, and Ec per X/X shared pair for Ne and for molecules containing first row atoms, where X is C, N, O, and F.
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560120107
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Attractive-dominant and repulsive-dominant hydrocarbon reactions (1978)
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 13 (1978), S. 271-295 
    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 difference between the expectation values of the total electronic kinetic energy operator (ΔEK), and the operators accounting for the Coulombic interactions between the electrons and nuclei (ΔVen), between all pairs of electrons (ΔVee), and between all pairs of nuclei (ΔVnn) for the product and reactant species in a wide variety of hydrocarbon reactions are calculated using single determinant basis set data reported in the literature. Following Allen, their contributions to ΔET, the difference between the corresponding total molecular energies and thus the reaction heat, are grouped together as a repulsion energy term, ΔErep = ΔEK + ΔVee + ΔVnn, and an attraction energy term ΔEattr = ΔVen. For all but 2 of the 71 individual reactions considered in this paper, the experimental reaction heat at 0°K corrected for zero-point energy contributions, (ΔH00)zpe, is the result of near compensation between far larger ΔErep and ΔEattr terms, in sharp contrast to the much smaller ΔErep and ΔEattr terms which are characteristic of many molecular rotation processes. By matching the sign of (ΔH00)zpe with that of ΔErep or ΔEattr, as the case may be, the reactions are classified as attractive-dominant or repulsive-dominant (46 in the former class and 23 in the latter), a property which is independent of the direction in which the reaction is written. The sign and magnitude of ΔVee, ΔVnn, and ΔVen and reaction category are discussed in relation to the various kinds of structural change involved in going from reactants to products. For the vast majority of reactions, the numerical relationship ΔVee ≈ ΔVnn has been found to hold to within a few percent.
    Additional Material: 15 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/qua.560130303
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The wrist joint of two-toed sloths and its relevance to brachiating adaptations in the hominoidea (1979)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 162 (1979), S. 413-424 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Two-toed sloths have evolved a wrist complex that includes the following traits: (1) diminution and distal migration of the pisiform, with a loss of contact with the ulna; (2) reduction of the distal end of the ulna to a styloid process; and (3) extremely reduced contact between the ulna and triquetrum. These traits were proposed by Lewis ('65, '74) to be indicative of brachiating habits and to be a unique adaptation of the Hominoidea. Cartmill and Milton ('77) recently found a similar complex in the wrists of the lorisines. Very similar adaptations of the wrist among the Hominoidea, lorisines, and two-toed sloths clearly refute contentions of Lewis and strengthen the hypothesis of Cartmill and Milton that the traits common to those animals are due to similar slow, cautious, but acrobatic locomotion.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051620308
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  • 5
    Electronic Resource
    Electronic Resource
    Foot of two-toed sloths: Its anatomy and potential uses relative to size of support (1981)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 170 (1981), S. 357-372 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Feet of two-toed sloths (Choloepus) are long, narrow, hook-like appendages with only three functional digits, numbers II, III, and IV; Rays I and V are represented by metatarsals. Proximal phalanges of complete digits are little more than proximal and distal articulating surfaces. All interphalangeal joints are restricted, by interlocking surfaces, to flexion and extension. Ankle and transverse tarsal joints, however, allow extreme flexion and inversion of foot. Powerful digital flexion is augmented by several muscles from extensor compartment of leg. Intrinsic foot musculature is reduced to flexors and extensors but these, with the exception of lumbricals, are large and well developed. Choloepus uses its feet much like hooks with distal phalanges and covering claws forming the “hook” element. These hook-like appendages are seemingly best suited for supports less than 50 mm in diameter suggesting that two-toed sloths may prefer supports of this size in their natural habitat.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051700307
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  • 6
    Electronic Resource
    Electronic Resource
    The hand of two -toed sloths (Choloepus): Its anatomy and potential uses relative to size of support (1981)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 169 (1981), S. 1-19 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Hands of two-toed sloths (Choloepus) are long, narrow, hook-like apparatuses with only two functional digits (II and III); rays I and IV are represented only by metacarpals. The proximal phalanges of digits II and III are shortened to essentially proximal and distal articulating surfaces, and all but distal interphalangeal joints of these digits are restricted by interlocking surfaces to minimal ranges of flexion and extension. Several intercarpal joints and the wrist joint, however, allow wide ranges of movement in several axes. Wide excursion at the wrist is permitted by an extremely lax joint capsule, the manner of insertion of several prime movers of the carpus, and the reduced participation of the ulna in the wrist joint. Several extrinsic digital muscles, particularly extensors, are absent and others have unusual actions. Intrinsic musculature consists primarily of mm. interossei and m. extensor digitorum brevis, although other, inconstant muscles do occur. Hands of Choloepus are used as flexible hooks on supports less than 52 mm in diameter and as fixed grapnels on larger supports. In both cases, distal phalanges (and covering claws) form the “hook” element. Whereas bare volar pads seem to be adjunctive on supports smaller than 52 mm in diameter, they are essential on those larger than 65 mm. Two-toed sloths may prefer supports 50 mm in diameter or smaller. The potential importance of vines as supports is discussed.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1051690102
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  • 7
    Electronic Resource
    Electronic Resource
    True cholinesterases with pronounced resistance to eserine (1946)
    Philadelphia : Wiley-Blackwell
    Journal of Cellular and Comparative Physiology 27 (1946), S. 69-85 
    Details
    ISSN: 0095-9898
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcp.1030270202
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  • 8
    Electronic Resource
    Electronic Resource
    The effect of including polarization functions on the geometrical parameters calculated for pyridine (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 7 (1986), S. 153-157 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: Geometrical parameters for pyridine have been calculated using the 6-31G, 6-31G*(5D), 6-31G**(6D), and 6-31G(2 × 6D) basis sets. Comparisons are made with a microwave substitution structure and with results of other ab initio calculations reported in the literature. Particular attention is paid to the influence of polarization functions on the magnitude of the ring angle, 〈C6N1C2, which is analogous to the ipso angle in monosubstituted benzene derivatives.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540070208
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  • 9
    Electronic Resource
    Electronic Resource
    An ab initio study of the influence of substituents and intramolecular hydrogen bonding on the carbonyl bond length and stretching force constant. I. Monosubstituted carbonyl compounds (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 2 (1981), S. 30-37 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The C=O bond length and fC=O,C=O, the corresponding harmonic stretching force constant, are calculated ab initio using the 4-31G basis set (augmented by polarization functions on the sulfur and chlorine) with full geometry optimization for the monosubstituted carbonyl compounds RCHO, where R = H, CHO, CH=CH2, CO2H, CH=CHOH, OH, OC(=O)OH, OOH, S—H, Li, F, Cl, and NH2. Straight-line relationships are found in plots of ln[fC=O,C=O] vs. ln[rC=O] for the series of compounds in which carbon atoms and oxygen atoms are bonded directly to the carbonyl carbon, in accordance with the empirical expression f = C′/rn. The slopes and intercepts give n = 7.62 and 6.47, C′ = 62.6 and 48.6, for the lines with carbon and oxygen as the atom bonded directly to the carbonyl carbon, respectively. The point for formaldehyde lies very close to the C line, whereas the points for SH, Li, F, Cl, and NH2 lie closer to the O line.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540020107
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    Paper (German National Licenses)
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  • 10
    Electronic Resource
    Electronic Resource
    An ab initio study of the geometry, harmonic and anharmonic force fields, and fundamental vibrational frequencies of cis- and trans- thiolformic acid (1980)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 1 (1980), S. 167-177 
    Details
    ISSN: 0192-8651
    Keywords: Computational Chemistry and Molecular Modeling ; Biochemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: The geometry, harmonic and anharmonic force fields, and fundamental vibrational frequencies of cis- and trans-thiolformic acid are studied ab initio in the 4-31G basis set. An extensive comparison is made between changes in diagonal and off-diagonal quadratic and cubic force constants and diagonal stretching quartic constants in going from the chain to the ring structure in thiolformic acid and formic acid. The changes in the force constants are indicative of a much weaker interaction in the trans conformer between S—H and O=C, compared with O-H and O=C, in keeping with the weaker hydrogenbonding property of the S—H group in general.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcc.540010209
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