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  • 1990-1994  (10)
  • 1970-1974  (9)
  • 1955-1959
  • 1990  (10)
  • 1970  (9)
Material
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  • 1990-1994  (10)
  • 1970-1974  (9)
  • 1955-1959
Year
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 68 (1990), S. 6520-6522 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Gold evaporated on air-cleaved (00.1) graphite was observed by scanning tunneling microscopy. Most individual gold islands were not stable during scanning; some islands even appeared to translate. These observations suggest that the interaction between the gold islands and the scanning tunneling microscope tip is stronger than that between the gold and the air-cleaved graphite substrate. Some gold islands were observed to be stable. It was deduced that stable islands at steps were located on the upper layer rather than on the lower layer. It is also deduced that the alignment of the elongated gold grains in the continuous film may be related to cleavage steps.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 56 (1990), S. 2396-2398 
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: An anomalously large periodicity has been observed in scanning tunneling microscope images of a (00.1) graphite sample. The unusual contrast has hexagonal symmetry, a periodicity of 7.7±0.2 nm and is superimposed on the usual a=0.246 nm atomic spacing of graphite. Current-voltage curves recorded in the scanning tunneling spectroscopy mode from the region showing the superperiodicity exhibit slightly more metallic behavior than those from neighboring normal regions. One possible explanation for the observed periodicity is that it is a rotational moiré pattern resulting from the overlap between a misoriented layer of graphite and the underlying graphite single crystal.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: —(1) The effects of aminooxyacetic acid, ouabain and Ca2+ on the compartmentation of amino acid metabolism have been studied in slices of brain incubated with sodium-[1-14C]acetate, l-[U-14C]glutamate and l-[U-14C]aspartate as tracer metabolites.(2) Aminooxyacetic acid (10-3 m) inhibited the labelling of aspartate from [14C]acetate and [14C]glutamate, as well as the incorporation of label from [14C]aspartate into glutamate and glutamine. It also inhibited the labelling of GABA from all three radioactive precursors, as would be anticipated if there was inhibition of several transaminases as well as glutamate decarboxylase. The RSA of glutamine labelled from [1-14C]acetate was increased. This finding indicated that the glutamate pool which is utilized for glutamine formation is associated with glutamate dehydrogenase, and this enzyme appears to be related to the ‘synthetic tricarboxylic acid cycle’. AOAA exerted its major inhibitory effects on the citric acid‘energy cycle’with which transaminases are associated.(3) Ouabain (10-5 m) inhibited the labelling of glutamine to a much greater extent than the labelling of glutamate from [1-14C]acetate. It also caused leakage of amino acids from the tissue into the medium. Its effect on the glutamate–glutamine system was interpreted to be a selective inhibition of the 'synthetic’citric acid cycle.(4) The omission of Ca2+ from the incubation medium was associated with formation of glutamine with RSA less than 1·0 when labelled from [U-14C]glutamate, [U-14C]aspartate and lower than normal when labelled from [1-14C]acetate.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: —(1) Compartmentation of the metabolism of amino acids in brain has been studied in slices of cerebral cortex incubated with sodium [1-14C]acetate, sodium [1-14C]-bicarbonate, [1-14C]GABA or l-[1-14C]glutamate and in samples of brain after injection in vivo of [1-14C]- or [3H]acetate.(2) The method of treatment of the slices (a) maintained in ice-cold medium prior to incubation; (b) preincubation at 37°C and transfer to fresh medium affected the metabolism of the added, labelled substrate, particularly its labelling of glutamine.(3) The specific activity of glutamine labelled from the above metabolites was greater than that of glutamic acid in experiments of 10–30 minutes duration, whether or not subjected to pretreatment in the cold.(4) Incubation in medium containing 27 mm-K+ was associated with a decrease in the relative specific activity (RSA) of glutamine, except for the increase when l-[1-14C]glutamate was the precursor.(5) The data have been discussed in terms of metabolic compartmentation and their consistency with the concept of the presence in brain of more than one citric acid cycle, one containing the relatively smaller pools of intermediates and associated with synthetic processes; the other containing the relatively larger pools of intermediates and functioning as a homeostatic buffer for energy metabolism.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    European journal of neuroscience 2 (1990), S. 0 
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: The autoradiographic localization of radiolabelled taurine taken up in the rat substantia nigra in vivo together with conditions of release of the [3H]taurine taken up into brain slices were studied to determine whether they are consistent with the hypothesis that taurine may act as a neurotransmitter in the striatonigral pathway.At the light microscopic level the main cellular elements that became radiolabelled following the injection of [3H]taurine into the substantia nigra could be identified as glial cells. Electron microscope autoradiography confirmed that a subpopulation of glial cells including astrocytes, pericytes, and oligodendrocytes were radiolabelled and that neuronal perikarya were not radiolabelled. In addition, axonal elements including both terminal and preterminal boutons were found to have silver grains overlying them and were thus considered to be radiolabelled. This was supported by a quantitative analysis of the distribution of the silver grains; whereas glial elements had a significantly higher number of grains associated with them than with any other structure, axonal elements had a significantly greater number of grains than dendritic structures.Release of the preloaded [3H]taurine from superfused slices of substantia nigra occurred in response to veratridine, was calcium-dependent and was sensitive to inhibition by high magnesium concentrations or tetrodotoxin. Following the destruction of neurons in the striatum by ibotenic acid injections, although the weight of the ipsilateral substantia nigra was reduced, the uptake of [3H]taurine was not altered. In contrast to this, the veratridine-stimulated release was markedly attenuated, implying that the destruction of striatal neurons causes the loss of sites in the substantia nigra from which exogenous taurine is released.These results add further support to previous suggestions that taurine might act as a neurotransmitter or neuromodulator in the striatonigral pathway.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Results are presented on an investigation of photons produced in multihadronic final states frome + e − annihilation at 35 GeV and 44 GeV center of mass energies. Scalling violation between 14 and 44 GeV is observed in inclusive photon spectra. Comparing inclusive π0 spectra with charged pion spectra it is found that the average π0 multiplicity exceeds the charged pion multiplicity scaled by factor of 0.5 by (16±5)% and (21±7)% at 35 and 44 GeV respectively. The excess can be attributed to isospin violating decays of hadrons. The η multiplicity is found to be 〈n η〈=0.64±0.09±0.06 at 35 GeV. With a significance of three standard deviations a signal from quark bremsstrahlung is observed. The measured charge asymmetry in hadronic final states, due to the interference between initial and final state radiation, ofA=−0.141±0.041 is in accord with QED expectations. An interference effect in the azimuth angle distribution of charged jets around the photon direction is observed for the first time.
    Type of Medium: Electronic Resource
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  • 7
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    Minneapolis : Periodicals Archive Online (PAO)
    Philosophical Studies. 21:1/2 (1970:Jan./Feb.) 
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Contributions to mineralogy and petrology 25 (1970), S. 203-224 
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract New analyses show that Tertiary tholeiitic basalts from the Baffin Bay area have generally primitive characteristics. Comparison of the bulk chemical compositions of the basalts with material of known phase relations suggests that these basalts have properties intermediate between investigated natural and synthetic compositions. A discrete group of these basalts coincides in projection with the composition of the liquid produced by the partial melting of garnet periodotite at 30 kb. The compositions in this group are believed to be parental to the other rocks in the province principally through a mechanism of olivine fractionation. Eclogite fractionation is invoked to account for the chemical differences between the two suites of basalts in Baffin Bay.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1912
    Keywords: 5-HT4 ; 5-HT3 ; Desensitization ; 5-Methoxytryptamine ; 2-Methyl-5-HT
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Agonist-induced desensitization has been utilized to discriminate and independently “isolate” the neuronal excitatory receptors to 5-hydroxytryptamine (5-HT) in the guinea pig ileum (5-HT3 and putative 5-HT4 receptors). Electrically stimulated longitudinal muscle myenteric plexus preparations, and non-stimulated segments of whole ileum were used. Exposure to 5-methoxytryptamine (10 μmol/l) inhibited completely responses to 5-HT at the putative 5-HT4 receptor without affecting 5-HT3-mediated responses. Conversely, exposure to 2-methyl-5-HT (10 μmol/l) inhibited completely responses to 5-HT at the 5-HT3 receptor without affecting putative 5-HT4-mediated responses. The inhibition with 5-methoxytryptamine and 2-methyl-5-HT, either alone or in combination, appeared selective as responses to KCI, DMPP, carbachol, histamine, and substance P were unaffected or only very slightly modified. Furthermore, the pA2 values for ICS 205–930 at the putative 5-HT4 (pA2 = 6.2 to 6.5) and 5-HT3 (pA2 = 7.6 to 8.1) receptors (estimated in the presence of 2-methyl-5HT and 5-methoxytryptamine, respectively) were consistent with those estimated in the absence of desensitization. 5-Methoxytryptamine, but not 2-methyl-5-HT, suppressed completely but reversibly the concentration-effect curve to renzapride, suggesting that responses to this agent are mediated exclusively via agonism at the putative 5-HT4 receptor. It is concluded that 5-methoxytryptamine and 2-methyl-5-HT can be utilized as selective probes to discriminate the putative 5-HT4 receptor from the 5-HT3 receptor in guinea pig ileum. This finding is of importance as no selective antagonist exists for the putative 5-HT4 receptor. Furthermore, the presently described method of agonist-induced desensitization and 5-HT receptor discrimination may be useful for the identification and characterization of the putative 5-HT4 receptor in other tissues and species.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Philosophical studies 21 (1970), S. 25-28 
    ISSN: 1573-0883
    Source: Springer Online Journal Archives 1860-2000
    Topics: Philosophy
    Type of Medium: Electronic Resource
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