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  • 1
    ISSN: 1432-1017
    Keywords: Fluorescent steroid probes ; steroid-protein interactions, energy alternation of n − π * and π − π * states (level crossing)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The physiologically important 3-keto-steroids are non-fluorescent or only weakly fluorescent in protic as well as in aprotic solvents. In contrast, the 4,6,8(14)-triene-3-one steroids are highly fluorescent in aqueous solution but they do not appreciably fluoresce in other solvents. Evidence is presented that the introduction of double bonds into the skeleton of the 3-keto-steroids leads to a decrease of the energy of the lowest π − π * state, bringing this level into the neighbourhood of the non-fluorescent n − π * state. As a consequence, for two states of approximately the same energy, relatively small perturbations such as those due to solvent interactions, protein binding and micelle formation, will then determine whether a system will fluoresce (π − π * state lowest) or not (n − π * state lowest). When the fluorescent 3-keto-steroids, having three conjugated double bonds, bind to proteins, the fluorescence intensity becomes almost zero, making these compounds useful as probes for steroid-protein interactions. This quenching of the fluorescence is explained by a decrease in energy of the n − π * state relative to the π − π * state of the steroids due to hydrophobic interactions with the proteins.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Chronic treatment of rats with reserpine, isoproterenol, or a combination of these two agents has been suggested as a means to produce an experimental animal model for the chronic exocrinopathy cystic fibrosis. The effect of these treatments on glycoconjugate distribution in rat submandibular gland acinar cells was investigated by quantitative lectin cytochemistry. Significant changes in wheat-germ agglutinin (WGA), soy bean agglutinin (SBA) and concanavalin A (Con A) binding sites in the mucus granules were observed, but peanut agglutinin (PNA) binding was not significantly affected. The quantitative changes in glycoconjugates in the acinar cells of the submandibular gland could be a possible explanation for the increased binding of calcium by the intracellular mucus noted in previous studies on these animal models.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1041
    Keywords: nicotine ; epinephrine ; cigarette smoking ; total forearm blood flow ; muscle blood flow ; plethysmography
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary In 9 healthy subjects the effect of smoking one cigarette (nicotine content 0.9 mg) on blood pressure, heart rate and total and muscle blood flow in the forearm was measured. Blood flow was measured by a new noninvasive plethysmographic method that simultaneously gives quantitative data about total and muscle blood flow. Smoking the cigarette did not significantly affect blood pressure or heart rate. Total blood flow in the forearm did not change but the flow to the muscle was increased and resistance in this vascular bed was decreased. The pattern of haemodynamic changes in the forearm indicates that epinephrine may be the mediator of the circulatory effects of nicotine.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1434-6036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The onset of EHD instabilities in nematic liquid crystals driven by parametric modulation is investigated starting with the one-dimensional linear model of Dubois-Violette. The superposition of a constant electric field with a dichotomous (stochastic or periodic) field as well as the superposition of two dichotomous stochastic fields (pregaussian noise) are considered in detail. The experimentally observed discontinuous behaviour of the threshold (direct transition towards chaos) above a critical strength of the driving field and the dependence of the threshold curve on the correlation time of the noise can be explained qualitatively. Experiments to complete the phase diagram are proposed.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-601X
    Keywords: 12.40.Aa ; 13.75.Gx
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The(q¯ q) creation and annihilation terms of the one-gluon-exchange Lagrangian are incorporated into the quark cluster model. A resonating group study of theπ N interaction within this extended model yields scattering phase shifts which are in qualitative agreement with experiment without any parameter adjustment.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A scanning laser acoustic microscope (SLAM) is described. The SLAM achieves a resolution of about 10 μm and is capable of imaging subsurface features at depths up to several millimeters, using appropriate reconstruction algorithms. The various components of the apparatus, both acousto-optical and electronic, are described. A major feature of the SLAM is a digital data-acquisition system capable of storing and processing the complex acoustic field in images with 256×256-pixel resolution. An array processor enables most floating-point operations to be completed in a few seconds. Examples of acoustic images obtained from a test sample are presented.
    Type of Medium: Electronic Resource
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  • 7
    Publication Date: 2013-08-31
    Description: The measurement system requirements to obtain accurate electrical performance measurements of amorphous silicon cells and modules were described. The progress achieved in modifying the Jet Propulsion Laboratory (JPL) system toward that objective were reviewed.
    Keywords: ENERGY PRODUCTION AND CONVERSION
    Type: Proceedings of the 26th Project Integration Meeting; p 491-496
    Format: application/pdf
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  • 8
    Electronic Resource
    Electronic Resource
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 1252-1260 
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Nine rotational transitions of v=0 X˜ 2B1 H2O+ have been measured by laser magnetic resonance. Optical combination differences have been combined with the LMR data in a weighted least-squares analysis using a Watson S-reduced rotational-fine structure Hamiltonian. Twenty-four molecular constants were simultaneously determined, including three hyperfine parameters and the axial components of both the anisotropic and rotational g tensors. The anisotropic g tensors are compared with their calculated values using the Curl relationship. An r0 structure was determined and is in good agreement with several ab initio results.
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  • 9
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Conclusion By the use of structural analogues of nicotine and cotinine as internal standards, the elimination of environmental sources of contamination and an exact clean-up procedure, we were able to develop a rapid and sensitive method which has acceptable accuracy and precision over the concentration range necessary in pharmacokinetic studies.
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  • 10
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The long-time (t=10–200 h) heat release $$\dot Q$$ from glasses, from organic materials, and from Nb-Ti-H (D) was measured at 30≤T≤70 mK. For Suprasil W glass, Dimethyl-Siloxan, Stycast 1266, Stycast 2850 FT, Vespel, and for Nb-Ti-H (D) with various Ti and D concentrations, we found $$\dot Q \sim t^{ - 1}$$ . Typical values are $$\dot Q$$ = 0.05 nW/g for the organic materials and for Nb-Ti-H (D) and $$\dot Q$$ = 0.005 nW/g for the glass att=100 h after cooldown from room temperature. For charging temperaturesT i 〈5 K, we find the predicted dependence $$\dot Q \sim t_i^2$$ (investigated for Suprasil W glass and for Nb-Ti-D). The observed time and temperature dependences agree with predictions of the conventional two-level tunneling model for amorphous materials even at these very long times. No heat release was observed for Teflon, graphite, and Al2O3.
    Type of Medium: Electronic Resource
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