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  • 1
    ISSN: 0947-3440
    Keywords: Natural products ; Biomimetic synthesis ; Palmarumycins ; Phenol oxidation ; CD quantumchemical calculations ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first “open chain” representative of the palmarumycins, the biaryl ether 1, was isolated from Coniothyrium palmarum. Phenol oxidation of 1 with silver oxide as a model for a biosynthetic step yielded 4 with the usual spiroacetal structure of the palmarumycins. The absolute (S)-configuration of 4 (and thus of 1) was determined by quantumchemical CD calculations.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 11 (1999), S. 2583-2597 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A general asymptotic theory for two-layer, frontal geostrophic (FG) models including the effects of planetary sphericity and variable bottom topography is developed. In addition to the standard β-plane approximation, an additional baroclinic correction associated with planetary sphericity, the Veronis effect, enters into the leading-order dynamics of FG models. The Veronis effect depends on the variation of the longitudinal metric as the transformation to Cartesian coordinates is made. The Veronis effect becomes significant at mid to high latitudes for the long length scales associated with FG models which are larger than the internal Rossby radius of deformation. The inclusion of variable bottom topography results in an asymmetry between the dynamics of surface and bottom-trapped currents. Variable bottom topography enters the equations in a similar, but not identical, manner to the β effect. The asymmetry between the dynamics of surface-intensified and bottom-intensified FG currents over sloping topography occurs due to the fact that topography stabilizes surface flows while it destabilizes bottom flows. Physically, the asymmetry arises because sloping topography provides a stabilizing background vorticity gradient for surface-intensified flows. However, for the bottom-intensified flow of a relatively dense water mass, the presence of a sloping bottom allows the continual release of gravitational potential energy as the center of mass of the dense water "slides" down the sloping bottom and is thus a destabilizing rather than a stabilizing effect. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Physics of Fluids 11 (1999), S. 235-237 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Experiments show that the evolution of Stokes waves can lead to significant growth of transverse standing wave oscillations across the tank at a large distance from the wave maker. The peak power intensity of narrow-banded transverse standing waves can reach a similar level as that of the collinear waves, and a significant downshift is observed for the transverse waves. Dissipation may be less important for the downshift than previously anticipated. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The position response of blade monitors is mainly determined by their spectral sensitivity for low energy photoelectrons. For insertion devices with high energy first harmonics, the signals are contaminated by the light from the upstream and downstream bending magnets. A blade monitor design using energy selective detection of the photoelectrons from the blades will be presented. This way the background signals from the dipoles can be supressed and only position information from the insertion device beam can be obtained. A simulation code and experimental results at BESSY I will be presented. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The extension of a continuous scan high spectral resolution (0.006 cm−1) Fourier transform spectrometer for time-resolved Fourier transform spectroscopy with a temporal resolution in the ns regime is described. The time resolution is achieved by synchronizing a laser/transient digitizer system with the interferometer. The realization of the data acquisition and the experimental setup are described. Examples of time-resolved measurements are given. Detector limited temporal resolution of 〈10 ns is shown by recording scattered light from a pulsed dye laser. Spectral resolution of 〈0.5 cm−1 is demonstrated by observing the fluorescence of electronically excited CH radicals produced in the multi photon dissociation of CHBr3. The signal-to-noise behavior of time-resolved Fourier transform apparatus is investigated as a function of spectral (0.1–4.0 cm−1 unapodized) and time resolution and of the intensity of the detected light. © 1998 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of neurochemistry 72 (1999), S. 0 
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Interleukin (IL)-18 (interferon-δ-inducing factor or IL-1δ) belongs structurally to the IL-1 cytokine family and shares biological properties with IL-12. Expression, intracellular signaling, and functional relevance of IL-18 within the CNS are mostly unknown. We show that IL-18 protein is synthesized within mouse brain, preferentially during early postnatal stages, and that microglial cells but not astrocytes are a potential source. IL-18 is produced by cultured microglia on exposure to lipopolysaccharide (LPS). Microglia also express major components of the IL-1/IL-18 receptor system. On IL-18 stimulation, microglial IL-1 receptor-associated kinase (IRAK) can be coprecipitated with tumor necrosis factor (TNF) receptor-associated factor 6 (TRAF6) but not with IL-1 receptor type I, indicating that IRAK recruits TRAF6 during IL-18 signaling. IL-18 inhibits the LPS-induced release of IL-12 and attenuates that of TNF-α, whereas the production of IL-6 and macrophage inflammatory protein-1 a is only marginally affected. IL-18 may play a role during CNS development and can be produced by activated microglia, thus probably contributing to immune and inflammatory processes in the brain.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Oxford UK : Blackwell Science Ltd
    Grass and forage science 54 (1999), S. 0 
    ISSN: 1365-2494
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: White clover (Trifolium repens L.) is an important stoloniferous pasture legume in the Great Lakes region of the United States, but it often has limited persistence. Researchers in New Zealand and Wales have found that in spring, compared with other seasons, white clover plants have reduced branching complexity and have the fewest buds that produce leaves. They therefore suggested that in spring the plants are most vulnerable to grazing and climatic stress.Because of severe winter and cool, wet spring weather in New York State, it was hypothesized that white clover plants would also be of low branching complexity, smaller and have low axillary bud activity in spring compared with later in the grazing season. To test this, growth of white clover was monitored in an orchard grass (Dactylis glomerata L.)/white clover pasture in New York that was rotationally grazed with dairy cows during the 1993 and 1994 grazing seasons.Three sets of plants were sampled. The first set consisted of forty random plants sampled before each grazing event. Stolon branching order, number of each stolon branching type and area the plant occupied were determined. Approximately each month before one grazing event, a separate set of 32 random plants was measured in the field to determine the area they occupied; these plants were then removed to the laboratory for the measurement of stolon order, number of each stolon type, stolon lengths, total number of growing points, number of taproots and adventitious roots, root position and above-ground dry matter. Once a month, 12 additional plants were removed to measure axillary bud activity at each node.Leaf development from nodes tended to increase from spring to summer. However, the stolon branching order of white clover plants was not simpler in spring compared with summer or autumn. In 1994 during and after a dry and hot period, white clover plants were smaller, of lower stolon branching order and had fewer roots. Climate and associated soil organism activity appear to explain the different white clover growth patterns observed in New York and New Zealand. Severe winters in New York limit earthworm activity and stolon burial, which is important in contributing to stolon/plant breakdown in New Zealand. During the years of this study in New York, a hot and dry period had the most negative effect on the growth pattern of white clover.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 1906-1908 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Carbon nanotubes dispersed in ethanol are aligned by an electric field. Due to the orientation of these elongated particles, the dispersion exhibits anisotropic behavior. Transmission experiments show rotation of the linear polarization of an incident laser beam. Alignment and relaxation times and the influence of the magnitude of the electric field have been measured. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 2129-2131 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Near-field scanning optical microscopy (NSOM) has been utilized to study the behavior of liquid crystals at room temperature. The material, 4′-octyl-4-biphenylcarbonitrile (8cb) was studied at the air–liquid interface. The NSOM probe is shown to take an active role in modifying, and subsequently reading, the liquid crystal with about 65 nm resolution. The optical modification is proven to be independent of topographic modification. Results indicate potential technological uses in data storage and displays. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
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