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  • 1
    Electronic Resource
    Electronic Resource
    Molecular scattering from surfaces: theoretical methods and results (1987)
    s.l. : American Chemical Society
    Chemical reviews 87 (1987), S. 29-79 
    Details
    ISSN: 1520-6890
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/cr00077a003
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  • 2
    Electronic Resource
    Electronic Resource
    Insulinsekretion in vitro (1966)
    Springer
    Diabetologia 2 (1966), S. 269-276 
    Details
    ISSN: 1432-0428
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Le diazoxide, dérivé des thiazides et sans effet diurétique, dont l'action hyperglycémiante est connue depuis longtemps, empêche la sécrétion d'insuline stimulée par le glucose, du pancréas isolé du rat, du lapin et du cochon-nain in vitro. La concentration la plus faible nécessaire pour l'inhibition de la sécrétion d'insuline correspond aux doses thérapeutiques. Le tolbutamide abolit l'inhibition par le diazoxide. 5 préparations de thiazides employées comme diurétiques auxquelles on a attribué une action diabétogéne n'avaient pas d'influence sur la sécrétion d'insuline du pancréas isolé du lapin.-Nos recherches démontrent que l'inhibition de la sécrétion d'insuline doit être une des causes essentielles de l'hyperglycémie provoquée par le diazoxide. En même temps, elles sont en contradiction avec l'opinion que cette inhibition de la sécrétion soit seulement la conséquence d'une libération d'adrénaline stimulée par le diazoxide.
    Abstract: Zusammenfassung Das nichtdiuretisch wirkende Thiazidderivat Diazoxide, dessen hyperglykämische Wirkung seit langem bekannt ist, hemmt in vitro die mit Glucose stimulierte Insulinabgabe des isolierten Pankreas der Ratte, des Kaninchens und des Zwergschweins.-Die für die Hemmung der Insulinabgabe notwendige Konzentration (ab 5μg/ml) des Diazoxide liegt in einem Bereich, der auch bei der Gabe therapeutisch wirksamer Dosen erreicht wird. Tolbutamid hebt die Hemmwirkung des Diazoxide auf. Fünf Thiazidpräparate, die als Diuretika Verwendung finden und denen ebenfalls eine sogenannte diabetogene Nebenwirkung zugeschrieben wird, hatten keinen Einfluβ auf die Insulinabgabe des isolierten Kaninchenpankreas.-Unsere Untersuchungen zeigen, daß die Hemmung der Insulinsekretion eine wesentliche Teilursache der Diazoxide-Hyperglykämie sein muß. Sie sprechen gleichzeitig gegen die Ansicht, die Sekretionshemmung sei nur Folge einer durch Diazoxide gesteigerten Adrenalinfreisetzung.
    Notes: Summary The nondiuretic, hyperglycemia-producing thiazide derivative Diazoxide, inhibits the glucose-stimulated insulin release from the isolated pancreas of the rat, the rabbit, and the miniature pigin vitro. Tolbutamide prevents the inhibitory Diazoxide effect. The lowest concentrations of Diazoxide (5μg/ml) necessary for the inhibition of insulin release are in the same range as therapeutic doses. Five thiazide preparations, commonly used as diuretics and known for their possible so-called diabetogenic side effect, did not have any influence on the insulin release from the isolated rabbit pancreas. The results of our experiments indicate an inhibition of insulin secretion as an important etiological factor in the mechanism of Diazoxide-hyperglyeemia. They do not corroborate those observations that show the inhibition of insulin secretion to be induced by a Diazoxide-mediated epinephrine release.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01268185
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  • 3
    Electronic Resource
    Electronic Resource
    Streptozotocin diabetes in the pregnant rat induces cardiovascular dysfunction in adult offspring (1999)
    Springer
    Diabetologia 42 (1999), S. 81-89 
    Details
    ISSN: 1432-0428
    Keywords: Keywords Insulin dependent diabetes ; rat offspring ; vascular function ; endothelium ; streptozotocin.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Severe diabetes in pregnant rats produces persistent metabolic consequences in adult offspring. This study investigated whether diabetes in pregnant rats could also lead to cardiovascular abnormalities in the adult offspring. Blood pressure, heart rate and in vitro vascular reactivity of small arteries were evaluated in female adult offspring of control rats and of rats rendered diabetic with streptozotocin. Rise in blood pressures were similar in both groups of offspring but heart rate was lower in the diabetic offspring (p 〈 0.05). The rise in blood pressure associated with infusion of a nitric oxide synthase inhibitor was similar in both groups, but the associated decrease in heart rate was more pronounced in diabetic offspring (p 〈 0.01). Small mesenteric arteries from this group showed enhanced sensitivity to noradrenaline (p 〈 0.05) and abnormal endothelium-dependent relaxation to acetylcholine (p 〈 0.01) and bradykinin (p 〈 0.05). Reduction in acetylcholine induced relaxation, reflected reduced synthesis of nitric oxide or a cyclooxygenase product and was not attributable to an endothelium-derived hyperpolarizing factor. Sensitivity to exogenous nitric oxide was normal. A subgroup of pups born to diabetic dams were suckled by control maternal dams and a subgroup of those born to controls by diabetic dams. Suckling was an important determinant of impaired growth; offspring of diabetic rats suckled by their own mother and those of control rats by diabetic dams showed impaired growth rates whereas growth of offspring of diabetic rats suckled by control dams paralleled those of control rats suckled by their own mother. [Diabetologia (1999) 42: 81–89]
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001250051117
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  • 4
    Electronic Resource
    Electronic Resource
    Ingestion of natural particulate organic matter and subsequent assimilation, respiration and growth by tropical lagoon zooplankton (1979)
    Springer
    Marine biology 52 (1979), S. 33-43 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Rates of ingestion of natural particulate organic matter and subsequent assimilation and respiration by zooplankton at Enewetak Atoll lagoon (Marshall Islands) were measured using a flow-through system. Maximum daily ingestion rates of carbon and nitrogen, expressed as a percentage of the body content, were 79 and 37%, respectively, for the large copepod Undinula vulgaris; 112 and 65%, respectively, for a group of mixed small copepods; and 61 and 34%, respectively, for the pteropod Creseis acicula. Daily metabolic carbon losses, expressed as above, were 63% for U. vulgaris, 88% for the small copepods, and 50% for C. acicula. Assimilation efficiences of carbon and nitrogen ranged from about 86 to 91%. The above rates are generally higher than in previous reports for similar sized zooplankton in temperate waters, while the daily growth increments, expressed as a percentage of the body carbon content (4.8% for U. vulgaris, 8.6% for the small copepods, and 2.6% for C. acicula), are comparable. It appears that the high rates of ingestion and assimilation of organic matter are compensated by high metabolic losses. These results indicate that at least for carbon, tropical zooplankton may have low growth efficiencies ranging from 4 to 9%.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00386855
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  • 5
    Electronic Resource
    Electronic Resource
    Dynamics of molecular reactions in solids: Photodissociation of F2 in crystalline Ar (1990)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 92 (1990), S. 3551-3558 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Classical molecular dynamics simulations of F2 photodissociation in a host Ar crystal are presented. At temperature T=12 K, the photodissociation yield shows a sharp threshold for an excess energy of ∼0.6 eV, and it reaches nearly unity for excess energies above 2 eV. For a given excess energy, the quantum yield at 4 K is higher than a 12 K, and is predicted to remain finite even at 0 K. The transition state for photofragment exit from the reagent cage is found to be located in well-defined windows in the unit cell of the surrounding solid. The quantum yields (or photodissociation probabilities) are extremely high, especially at low T, in comparison with the values found in previous studies, e.g., for Cl2 in Xe and in Ar. Indeed, for high excess energy the near-unit quantum yields indicate the virtual absence of an inhibiting cage effect on the reaction. The anomalous behavior of F2 in Ar is attributed to the short effective range of the repulsive F/Ar interaction, which enables the F atom to exit the cage and migrate in the crystal. It is also due in part to the F/Ar attractive potential, which is found strong enough to focus and stabilize the migration of the F product in "channels'' within the lattice, following photolysis. Classical trajectories show long-range migration of the product atoms, of the scale of 30 A(ring), following the initial impulse provided by the photodissociation. This is the first system for which such long-range impulse-induced migration was found. The results of the simulations are analyzed focusing on the role of the initial state of F2 in the crystal, on the final sites occupied by the product atoms, and on the migration dynamics. Implications of the results for mechanisms of reactions in solids are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457864
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  • 6
    Electronic Resource
    Electronic Resource
    Erratum: Dynamics of energy flow for CH overtone excitations: Theoretical and experimental studies of CH3C ≡ CH [J. Chem. Phys. 88, 7434 (1988)] (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 89 (1988), S. 6557-6557 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.455736
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  • 7
    Electronic Resource
    Electronic Resource
    Vibrational states and structure of Ar3: The role of three-body forces (1991)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 94 (1991), S. 6728-6736 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Vibrational energies and eigenfunctions of Ar3, including some pertaining to highly excited states, are computed, and insights into their dynamical and structural properties are obtained. The method used employs the vibrational self-consistent-field (SCF) theory in hyperspherical coordinates as a first approximation. Exact results are obtained by configuration interaction, using the SCF states as an efficient basis. A focal point of the study is the effect of three-body potentials on the vibrational spectrum. Axilrod–Teller and other three-body potentials are used to examine this. It is found that the effect of three-body forces on the spectrum is substantial, and larger than effects due to uncertainties in the presently known two-body Ar–Ar potentials. This suggests that experimental spectroscopy of Ar3 may be used to determine reliable three-body forces among Ar atoms. It is also shown that the three-body double-dipole–quadrupole interaction, while less important than the Axilrod–Teller one, has a significant effect on the vibrational spectrum. Finally, a detailed analysis is made of the Ar–Ar distance distributions in the various states, of the structural distributions of Ar3, and of the properties of the wave functions. We find that the wave functions show well-ordered nodal patterns even for the highly excited large-amplitude states. Thus, these states do not correspond qualitatively to "liquid-like'' behavior of the cluster.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.460249
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  • 8
    Electronic Resource
    Electronic Resource
    Vibrational states of very floppy clusters: Approximate separability and the choice of good curvilinear coordinates for XeHe2, I2He (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 1813-1823 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A study is made of the vibrational energy levels and the corresponding oscillation dynamics of the clusters Xe4He2, Xe3He2, and I24He. XeHe2 is a representative of the "three ball'' clusters, while I2He is a prototype of the "stick and ball'' systems. The treatment is based on the vibrational self-consistent field (SCF) method, which introduces an approximate separation of the modes involved. Success of the method depends on an adequate choice of the coordinates that are being mutually separated. We use physical arguments, based on mass ratios and potential function considerations, as well as comparative SCF calculations in different coordinate systems, to determine the appropriate modes for each system. Numerically exact results are also obtained by configuration interaction (CI) calculations using a basis of SCF states. The SCF and CI calculations include all modes and employ realistic potentials. Several states that are both rotationally and vibrationally excited are also calculated. The main conclusions are: (1) Hyperspherical coordinates are the best modes for XeHe2; ellipsoidal coordinates are best for I2He. In each case, the "good modes'' SCF gives energies in remarkable agreement with the exact (CI) ones. (2) XeHe2 resembles a quantum liquid drop: Even in the ground state, it is delocalized over and between the (two) classical equilibrium structures. (3) Structural distributions, rather than rigid geometry, are essential for the description of such floppy clusters. The single-mode SCF wave functions offer a highly accurate description of the structural distributions. (4) There is a sequence of bound, excited rotational states of I2He in which the He precesses around the I2 axis. The amplitude of the I2He bending vibrations are very large (θA〈20°), but none of the bound states involves a full rotational motion around the I2 stick (with angular momentum normal to the axis). The SCF method with the "good coordinates'' proposed here is expected to yield results of similar high accuracy for any cluster of the "three balls'' or "stick and ball'' types.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.457086
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  • 9
    Electronic Resource
    Electronic Resource
    Cross sections for He scattering from surface imperfections: Vacancies and CO adsorbates on Pt(111) (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 3722-3731 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Total cross sections for He scattering from isolated imperfections on surfaces are calculated using the Sudden approximation, and in some cases also by a numerically exact, time-dependent quantum-mechanical wave packet method. Systems studied include: CO adsorbates on Pt(111); mono-, di-, and trivacancies on Pt(111). The main results are: (1) the incidence angle and energy dependence of the cross section for He/[Pt(111)+CO] are very sensitive to the CO distance from the Pt plane. Interactions with the adsorbate image have little effect on the cross section. (2) The cross sections for clusters of vacancies are given within 10% or better, by the geometric sum of the monovacancy cross sections, the latter being treated as circles centered at each monovacancy. (3) The dependence of the cross section on the energy is sufficiently sensitive to distinguish between the "electron density hole'' and "electron density hump'' models for vacancies and vacancy clusters. (4) The Sudden approximation compares well with the exact quantum-mechanical results at typical experimental energies, when the incidence angle is not too far from the normal. These results indicate that experimental measurements of He scattering cross sections as a function of energy and incidence angle, combined with Sudden or wave packet scattering calculations, can provide detailed information on surface defects and their interactions with gas-phase atoms.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454712
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  • 10
    Electronic Resource
    Electronic Resource
    Exact time-dependent quantum mechanical dissociation dynamics of I2He: Comparison of exact time-dependent quantum calculation with the quantum time-dependent self-consistent field (TDSCF) approximation (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 87 (1987), S. 2760-2765 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The vibrational predissociation dynamics of a collinear model of the I2(v)He cluster is studied by numerically exact time-dependent quantum mechanics, and by the time-dependent self-consistent field (TDSCF) approximation. The time evolution for the initial excitation levels v=5, 11, 22 is explored. Excellent agreement is found between the TDSCF and the exact evolution of the wave packet; in particular the approximation reproduces well the dephasing events in the dynamics, and the measurable predissociation lifetimes. The results are very encouraging as to the applicability of quantum TDSCF as a quantitative tool in the study of van der Waals predissociation dynamics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.453063
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