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  • 1
    Electronic Resource
    Electronic Resource
    Unoccupied electronic structure of phthalocyanine films (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 93 (1990), S. 6859-6864 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The unoccupied molecular orbitals of metal-free phthalocyanine (H2PC), nickel-phthalocyanine (NiPC), and copper-phthalocyanine (CuPC) adsorbed on single crystal surfaces have been studied by inverse photoemission spectroscopy (IPES) and near-edge x-ray absorption spectroscopy (NEXAFS). The features observed in the experimental data are assigned by reference to molecular orbital calculations. Carbon and nitrogen 1s NEXAFS measurements of NiPC adsorbed on Cu(110) surface indicates that the phthalocyanine molecular planes are parallel to the surface. X-ray absorption data recorded at the Ni LIII and LII edges show that the unoccupied Ni 3d level is located in the plane of the phthalocyanine rings.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.458918
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  • 2
    Electronic Resource
    Electronic Resource
    In vitro studies of the submerged angiospermRuppia maritima: Auxin and cytokinin effects on plant growth and development (1991)
    Springer
    Marine biology 110 (1991), S. 1-6 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Axenic tissue cultures ofRuppia maritima L. were established and propagated clonally in vitro from terminal rhizome segments collected from Tampa Bay, Florida, USA. Cultures were maintained in a base medium consisting of synthetic seawater supplemented with half-strength Murashige and Skoog salts and 1% sucrose at pH 5.6. The effects of five cytokins [6-furfurylaminopurine (kinetin), 6-benzylaminopurine (BAP), 2-isopentyladenine (2iP), 6-(4-hydroxy-3-methyl-but-2-enylamino) purine (zeatin), andn-phenyl-n′-1,2,3-thidiazol-5′yl urea (thidiazuron)] and one auxin [napthalene acetic acid (NAA)] on explant growth and development were investigated. Cytokinin additions resulted in a 3- to 4-fold increase in nodal production, branching, and biomass ofR. maritima after 12 wk in culture. Cultures responded in a dose-dependent manner to 2iP but exhibited broad dose-response curves to kinetin, BAP, zeatin, and thidiazuron. NAA addition resulted in increased leaf and internodal lengths, but reduced the number of leaves per node and the rhizome biomass. The addition of NAA almost completely suppressed root growth in media without cytokinins and had an antagonistic effect on nodal production and branching in cytokinin-supplemented media.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01313085
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  • 3
    Electronic Resource
    Electronic Resource
    Hydrodynamics, diffusion-boundary layers and photosynthesis of the seagrasses Thalassia testudinum and Cymodocea nodosa (1994)
    Springer
    Marine biology 118 (1994), S. 767-776 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Photosynthetic rates of aquatic plants frequently increase with increasing current velocities. This is presumably due to a reduction in the thickness of the diffusion boundary-layer which allows for a higher carbon availability on the plant surface. Blades of the seagrasses Thalassia testudinum and Cymodocea nodosa exposed to different current velocities under controlled laboratory conditions, showed increased photosynthetic rates with increasing flow only at low current velocities (expressed as blade friction velocities, u *). Carbon saturation of photosynthetic processes occurred at a relatively low u * level (0.25 cm s-1) for T. testudinum collected from a calm environment compared to C. nodosa (0.64 cm s-1) collected from a surf zone. No further enhancement of photosynthetic rates was observed at higher u * levels, suggesting limitations in carbon diffusion through the boundary layer below critical u * levels and possible limitations in carbon fixation by the enzymatic system at higher u * levels. These results, as well as those of previous theoretical studies, assumed the flow on the immediate seagrass-blade surface to be hydrodynamically smooth. The presence of epiphytes and attached debris causes the surface of in situ seagrass blades to be exposed to flows ranging from smooth to rough-turbulent. As a consequence, the boundary-layer thickness on moderately epiphytized blades under medium to high flow-conditions is not continuous, but fluctuates in time and space, enhancing carbon transport. In situ u * levels measured directly on blades of seagrasses indicate that T. testudinum and C. nodosa can be exposed to conditions under which the boundary layer limits photosynthesis during short periods of time (milliseconds) during low-energy events. As waves cause the thickness of the diffusion boundary-layer to fluctuate constantly, carbon-limiting conditions do not persist for prolonged periods.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00347527
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  • 4
    Electronic Resource
    Electronic Resource
    Euklidische Normalisatoren für trikline und monokline Raumgruppen bei spezieller Metrik des Translationengitters (1990)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 46 (1990), S. 826-831 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A listing of the Euclidean normalizers for triclinic and monoclinic space groups having translation lattices with specialized metric is given. These normalizers have not been included in previous tabulations. For convenience, in the case of monoclinic space groups, only the second setting (c-axis unique) is considered and the metric of the cells is restricted within certain limits which warrant that all specialized cases and all cell choices according to International Tables for Crystallography [(1987) Dordrecht: Kluwer] are included.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767390007085
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  • 5
    Electronic Resource
    Electronic Resource
    Triply periodic minimal balance surfaces: a correction (1993)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 49 (1993), S. 209-210 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: In previous papers, 15 families of minimal balance surfaces that can be generated with the aid of disc-like surface patches were noted. Recently, it has become apparent that the inherent symmetry of two of these families, the C(S) surfaces and the Y surfaces, is higher than the symmetry used for their generation. As a consequence, C(S) surfaces are in fact P surfaces and Y surfaces are in fact D surfaces.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767392007591
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  • 6
    Electronic Resource
    Electronic Resource
    Lattice complexes with at most one comprehensive complex (1995)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 51 (1995), S. 586-587 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: Most lattice complexes with less than three degrees of freedom are contained as limiting complexes within several comprehensive complexes corresponding to general Wyckoff positions. There exist, however, 21 exceptional cases: 3 lattice complexes without any and 18 lattice complexes with exactly one such comprehensive complex each. They are listed together with their comprehensive complexes. This information may be used to restrict geometrical investigations of all point configurations to general positions of space groups.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767394013681
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  • 7
    Electronic Resource
    Electronic Resource
    Flat points of minimal balance surfaces (1990)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 46 (1990), S. 33-40 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: The symmetry conditions for flat points of minimal surfaces have been studied in relation to the order β of points on such surfaces. Using symmetry aspects, a set of rules for the derivation of fiat points have been developed. By means of these rules the flat points for the 45 families of minimal balance surfaces known so far have been determined. As a check for completeness the relation between the genus of a minimal surface and the orders of its flat points has been used.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S010876738900927X
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  • 8
    Electronic Resource
    Electronic Resource
    Minimal surfaces with self-intersections along straight lines. I. Derivation and properties (1999)
    [S.l.] : International Union of Crystallography (IUCr)
    Acta crystallographica 55 (1999), S. 58-64 
    Details
    ISSN: 1600-5724
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Notes: A special kind of three-periodic minimal surface has been studied, namely surfaces that are generated from disc-like-spanned skew polygons and that intersect themselves exclusively along straight lines. A new procedure for their derivation is introduced in this paper. Several properties of each such surface may be deduced from its generating polygon: the full symmetry group of the surface, its orientability, the symmetry group of the oriented surface, the pattern of self-intersections, the branch points of the surface, the symmetry and periodicity of the spatial subunits demarcated by the surface, and the Euler characteristics both of the surface and of the spatial subunits. The corresponding procedures are described and illustrated by examples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1107/S0108767398007521
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  • 9
    Electronic Resource
    Electronic Resource
    Determination of kinetic models by the use of pattern recognition methods (1991)
    Springer
    Journal of thermal analysis and calorimetry 37 (1991), S. 1915-1916 
    Details
    ISSN: 1572-8943
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01912222
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  • 10
    Electronic Resource
    Electronic Resource
    The ‘Theorem of common kinetic runs’ in homogeneous non-isothermal reaction kinetics (1992)
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 1653-1669 
    Details
    ISSN: 1572-8943
    Keywords: experiments in solution ; kinetic models ; linear temperature program ; numerical integration
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die kinetischen Eigenschaften der homogenen Zweistufen-Modelle wurden durch die Auswertung von 2500 Kurven systematisch untersucht, die durch Computer-simulationen für linear ansteigende Temperatur erhalten und mit zahlreichen Experimenten verglichen wurden. Für Methoden, bei denen jede Teilrate zu ihrem Beitrag zum derivativen Gesamtsignal proportional ist, wurde gefunden, daß aus der Halbwertsbreite und dem Formfaktor der Kurven verhaltenstypische Sätze dreier, von der Reaktionsordnung abhängiger Parameter ermittelt werden können, die bestimmten Intervallen der Startkonzentration zugeordnet sind. Solche thermoanalytischen Muster stimmen mit denen, die aus den Verteilungslisten einiger Tausend DTA- und UV-Experimente erhalten wurden, überein und werden für die 21 wichtigsten Zweistufen-Modelle aufgeführt. Sie sind praktisch unabhängig von den Aktivierungsdaten und den methodenspezifischen Proportionalitätsfaktoren; deshalb erlauben sie die direkte Identifizierung des Reaktionsmodells.
    Notes: Abstract The kinetic features of the fundamental homogeneous two-reaction models for linearly increasing temperature have been studied systematically by the analysis of 2500 signal curves (organized in 250 series), obtained from computer simulations and compared with numerous TA experiments. For methods based on a proportionality between the particular reaction rates and their contribution to the derivative overall signal, it has been found that characteristicbehaviour sets of three order-dependent parameters which refer to definite intervals of the starting concentration in series, can be extracted from the halfwidth and shape index of the curves. Such thermoanalytical patterns agree with those obtained from the distribution lists of some thousand DTA- and UV-experiments. They are presented for the 21 most important two-step model and almost independent of the activation data and of the method-dependent proportionality factors. Therefore, they allow for the direct kinetic identification of the complex reaction involved.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01979362
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