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  • 2000-2004  (4)
  • 1995-1999  (8)
  • 1920-1924  (1)
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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Stable transfection of the human neuroblastoma cell line SH-SY5Y with the human 5-hydroxytryptamine2A (5-HT2A) or 5-HT2C receptor cDNA produced cell lines demonstrating ligand affinities that correlated closely with those for the corresponding endogenous receptors in human frontal cortex and choroid plexus, respectively. Stimulation of the recombinant receptors by 5-HT induced phosphoinositide hydrolysis with higher potency but lower efficacy at the 5-HT2C receptor (pEC50 = 7.80 ± 0.06) compared with the 5-HT2A receptor (pEC50 = 7.30 ± 0.08). Activation of the 5-HT2A receptor caused a transient fourfold increase in intracellular Ca2+ concentration. Whole-cell recordings of cells clamped at −50 mV demonstrated a small inward current (2 pA) in response to 10 µM 5-HT for both receptors. There were no differences in potency or efficacy of phosphoinositide hydrolysis among four hallucinogenic [d-lysergic acid diethylamide (LSD), 1-(4-iodo-2,5-dimethoxyphenyl)-2-aminopropane (DOI), 5-methoxy-N,N-dimethyltryptamine, and mescaline] and three nonhallucinogenic drugs (m-chlorophenylpiperazine, quipazine, and ergotamine). Comparison of equipotent doses producing 20% of the maximal response induced by 5-HT revealed selective activation of the 5-HT2A receptor by LSD and to a lesser degree by DOI, mescaline, and ergotamine. Quipazine and 5-methoxy-N,N-dimethyltryptamine were relatively nonselective, whereas m-chlorophenylpiperazine selectively activated the 5-HT2C receptor. It is unlikely therefore that hallucinosis is mediated primarily by activity at the 5-HT2C receptor, whereas activity at the 5-HT2A receptor may represent an important but not unique mechanism associated with hallucinogenic drug action.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 69 (1996), S. 3854-3856 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Electron paramagnetic resonance measurements have been made on samples of float zone silicon, implanted with 1015 Er/cm2. One sample was coimplanted with oxygen to give an impurity concentration of 1020 O/cm3 and 1019 Er/cm3. In this coimplanted sample, sharp lines are observed which are identified as arising from a single spin 1/2 Er3+ center having a g tensor exhibiting monoclinic C1h symmetry. The principal g values and tilt angle are g1=0.80, g2=5.45, g3=12.60, and τ=2.6°. In the absence of O, the sharp lines are not observed. No Er3+ cubic centers were detected in either sample. Possible structures for the center are discussed. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Chemical reviews 22 (1922), S. 281-310 
    ISSN: 1520-6890
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 347-349 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effects of electrical current stressing on the field emission characteristics of hydrogenated amorphous carbon (a-C:H) thin films are reported. In these a-C:H films an initial conditioning treatment of the film is often required before the onset of stable emission and only after several voltage cycles do the values of the threshold field tend to converge. By stressing of the film by applying a predetermined current through the film, the initial conditioning treatment can be removed and stable and reproducible emission observed. Retesting of the current stressed films shows that the films remain fully conditioned provided a sufficiently high stress current was initially used. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2339-2341 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The observation of electron emission from amorphous carbon thin films at low applied electric fields is explained in terms of an enhancement of the field brought about by dielectric inhomogeneities within the film. These inhomogeneities originate from the differences between conductive, spatially localized sp2 C clusters surrounded by a more insulating sp3 matrix. By a more complete understanding of the concentration and distribution of the clusters, a generic model for field emission from amorphous carbon thin films can be developed. Extensions of this model to explain the emission properties of carbon nanotubes and carbon nanocomposite materials are also presented. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 77 (2000), S. 2006-2008 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The influence of the concentration and size of sp2 carbon clusters on the field emission properties of hydrogenated amorphous carbon thin films is investigated. In combination with electron paramagnetic resonance and optical measurements, it is shown that the trend in the threshold field for emission for films deposited under certain conditions can be explained in terms of improvements in the connectivity between sp2 clusters. These clusters are believed to be located near the Fermi level, and the connectivity is primarily determined by the cluster size and concentration, which in turn is determined by the choice of deposition conditions. Details of the appropriate emission mechanisms for different types of deposited carbon films are discussed. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Recent reports of ∼30 wt% of sulphate within saline sediments on Mars—probably occurring in hydrated form—suggest a role for sulphates in accounting for equatorial H2O observed in a global survey by the Odyssey spacecraft. Among salt hydrates likely to be ...
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of environmental contamination and toxicology 62 (1999), S. 608-615 
    ISSN: 1432-0800
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Medicine
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 119 (1995), S. 155-165 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract  A thermodynamic formulation of hydrous Mg-cordierite (Mg2Al4Si5O18⋅nH2O) has been obtained by application of calorimetric and X-ray diffraction data for hydrous cordierite to the results of hydrothermal syntheses. The data include measurements of the molar heat capacity and enthalpy of hydration and the molar volume. The synthesis data are consistent with a thermodynamic formulation in which H2O mixes ideally on a single crystallographic site in hydrous cordierite. The standard molar Gibbs free energy of hydration is −9.5±1.0 kJ/mol (an average of 61 syntheses). The standard molar entropy of hydration derived from this value is −108±3 J/mol-K. An equation providing the H2O content of cordierite as a function of temperature and fugacity of H2O is as follows (n moles of H2O per formula unit, n〈1): n=f  V H2 O/(f V H2 O+exp[−3.8389−5025.2(1T−1298.15) −ln(T298.15)−(298.15T−1)] ) Application of this formulation to the breakdown reaction of Mg-cordierite to an assemblage of pyrope-sillimanite-quartz±H2O shows that cordierite is stabilized by 3 to 3.5 kbar under H2O-saturated conditions. The thermodynamic properties of H2O in cordierite are similar to those of liquid water, with a standard molar enthalpy and Gibbs free energy of hydration that are the same (within experimental uncertainty) as the enthalpy and Gibbs free energy of vaporization. By contrast, most zeolites have Gibbs free energies of hydration two to four times more negative than the corresponding value for the vaporization of water.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 119 (1995), S. 155-165 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract A thermodynamic formulation of hydrous Mg-cordierite (Mg2Al4Si5O18·nH2O) has been obtained by application of calorimetric and X-ray diffraction data for hydrous cordierite to the results of hydrothermal syntheses. The data include measurements of the molar heat capacity and enthalpy of hydration and the molar volume. The synthesis data are consistent with a thermodynamic formulation in which H2O mixes ideally on a single crystallographic site in hydrous cordierite. The standard molar Gibbs free energy of hydration is-9.5±1.0 kJ/mol (an average of 61 syntheses). The standard molar entropy of hydration derived from this value is-108±3 J/mol-K. An equation providing the H2O content of cordierite as a function of temperature and fugacity of H2O is as follows (n moles of H2O per formula unit, n〈1): $$\begin{gathered}n = {{f_{{\text{ H}}_{\text{2}} O}^{\text{V}} } \mathord{\left/{\vphantom {{f_{{\text{ H}}_{\text{2}} O}^{\text{V}} } {\left( {f_{{\text{ H}}_{\text{2}} O}^{\text{V}} + {\text{exp}}\left[ { - {\text{3}}{\text{.8389}} - 5025.2\left( {\frac{1}{T} - \frac{1}{{298.15}}} \right)} \right.} \right.}}} \right.\kern-\nulldelimiterspace} {\left( {f_{{\text{ H}}_{\text{2}} O}^{\text{V}} + {\text{exp}}\left[ { - {\text{3}}{\text{.8389}} - 5025.2\left( {\frac{1}{T} - \frac{1}{{298.15}}} \right)} \right.} \right.}} \hfill \\{\text{ }}\left. {\left. { - {\text{ln}}\left( {\frac{T}{{{\text{298}}{\text{.15}}}}} \right) - \left( {\frac{{298.15}}{T} - 1} \right)} \right]} \right) \hfill \\\end{gathered}$$ Application of this formulation to the breakdown reaction of Mg-cordierite to an assemblage of pyrope-sillimanite-quartz±H2O shows that cordierite is stabilized by 3 to 3.5 kbar under H2O-saturated conditions. The thermodynamic properties of H2O in cordierite are similar to those of liquid water, with a standard molar enthalpy and Gibbs free energy of hydration that are the same (within experimental uncertainty) as the enthalpy and Gibbs free energy of vaporization. By contrast, most zeolites have Gibbs free energies of hydration two to four times more negative than the corresponding value for the vaporization of water.
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