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  • 1985-1989  (13)
  • 1980-1984  (25)
  • 1890-1899  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Investigation of the kinetic mechanism for the ion-assisted etching of GaAs in Cl2 using a modulated ion beam (1985)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 58 (1985), S. 4670-4678 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: There is increasing technological interest in using Cl2 and Cl-containing compounds in the dry plasma etching of III–V semiconductors. This paper presents a study of the ion-assisted etching of GaAs by Cl2 using a modulated ion beam technique to gain insight into the kinetic mechanism of this process. The etching rate increases with increasing ion energy (0.3–3 kV) and depends linearly on ion flux (1.0–10.0×1014 ions cm2 s). The etching rate increases with increasing Cl2 pressure up to a saturation limit near 2×10−6 Torr. This saturation limit is independent of the ion flux coincident on the surface within the range studied. The ion-enhanced etching rate decreases with increasing sample temperature over the range 300–500 K. Major etch products are AsCl3 and GaCl2 (and possibly GaCl), and the time dependence of the increase in these mass spectrometer signals following the initiation of the ion pulse is consistent with all of the products having a most probable translational energy of ∼0.14 eV. There is an additional delay in the appearance of the AsCl3 signal which roughly corresponds to a first order reaction with an associated time constant of 1.1 ms. One possible kinetic mechanism for the ion-enhanced etching is proposed which involves the surface reactions of Ga and AsCl with adsorbed chlorine. In this model, the ∼1 ms delay in the appearance of the AsCl3 is attributed to the lifetime of potential energy excitation caused by the ion.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.336241
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  • 2
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    Unknown
    The Interior of the Earth (1893)
    Boston, Mass., etc. : Periodicals Archive Online (PAO)
    The North American Review. 156 (1893:Jan./June) 439 
    Details
    ISSN: 0029-2397
    Topics: English, American Studies , History
    URL: http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&res_dat=xri:pao:&rft_dat=xri:pao:article:3197-1893-156-00-000009
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  • 3
    Electronic Resource
    Electronic Resource
    Buchbesprechungen (1981)
    Springer
    Helgoland marine research 34 (1981), S. 507-522 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01995922
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  • 4
    Electronic Resource
    Electronic Resource
    An intense cold core eddy in the North-East Atlantic (1986)
    [s.l.] : Nature Publishing Group
    Nature 319 (1986), S. 474-477 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Western basin cold core eddies are spawned from Gulf Stream meanders that intensify, grow into loops, and pinch off from the main stream to form rings of current that wander independently in the waters to the south and south-east of the Gulf Stream3. They are readily distinguishable from other ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/319474a0
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  • 5
    Electronic Resource
    Electronic Resource
    Net-building behaviour, tolerance and development of two caddisfly species from the river Rhine (Hydropsyche contubernalis and H. pellucidula) in relation to the oxygen content (1987)
    Springer
    Oecologia 73 (1987), S. 242-250 
    Details
    ISSN: 1432-1939
    Keywords: Net-building behaviour ; Development ; O2-deficiency tolerance ; Hydropsyche ; River Rhine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tolerance, growth and development of H. contubernalis and H. pellucidula were analyzed at different O2-concentrations to determine the species specific potency amplitude in relation to O2-concentration. In addition netbouilding behaviour was compared at different O2-concentrations and current velocities. Under anaerobic conditions slightly greater tolerance was observed in H. contubernalis than in H. pellucidula. But at a higher O2-concentration H. contubernalis showed a distinctly higher O2-deficiency tolerance than H. pellucidula in relation to net-building activity, growth and development. In addition, more than 50% of H. contubernalis instars built capture nets with regular meshes at an O2-saturation of only 30% (15°C). High growth rates were also found at 50% O2-saturation and more than half the larvae developed into imagos. In addition to diminished net-spinning activity the mean growth rate started to decrease at an O2-saturation of 70% to 38% and the development into an imago was not possible in H. pellucidula. Because H. contubernalis corresponds to a regulative type, being able to maintain a high level of netbuilding activity, growth rate and development over a wide range (50% to 100% O2-saturation). On the other hand H. pellucidula corresponds to a conform type, because physiological efficiency decreases rapidly with falling O2-concentration, so that development into an imago is no longer possible below 85% O2-saturation. Positive correlation between net-spinning activity and tested current velocity between 10 cm/s and 25 cm/s (15°C) was found in H. pellucidula. H. contubernalis showed no change in net-building activity, over this range of current velocity. H. contubernalis can be classified as an euryoecious species with a great potency amplitude in relation to O2-concentration and current velocity. The high tolerance to O2-deficiency conditions probably allowed the early recolonization of the Mittel-and Niederrhein when a distinct O2-deficit (mean 29%, max 56%) could still be measured. H. contubernalis can be considered a bioindicator of O2-deficiency situations. Undisturbed development of H. pellucidula in this section of the river requires a further improvement in O2-content.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377514
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  • 6
    Electronic Resource
    Electronic Resource
    Movement of thallium(I)-ions across the epithelium of intestinal segments in vitro of rats (1982)
    Springer
    Naunyn-Schmiedeberg's archives of pharmacology 321 (1982), S. 157-163 
    Details
    ISSN: 1432-1912
    Keywords: Tl+-ions ; Excretion ; Mucosal epithelium ; Small intestine ; Large intestine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary 1. The movement of Tl+-ions was investigated on both isolated non blood-perfused jejunal and ileal segments as well as on stripped colon segments in vitro of rats. 2. After having administered radioactively labeled 204Tl-(Tl2SO4) on either the mucosal or the serosal side of these preparations only, a preferential direction of the movement of Tl+-ions from the serosal to the mucosal side was observed. In jejunal segments, the 204Tl-radioactivity at the mucosal side reached a concentration equilibrium with the concentration administered at the serosal side of the preparations. In colon segments a concentration gradient of more than 2 was established between the mucosal and the serosal side. In ileal segments the concentration of 204Tl-radioactivity in the mucosal fluid reached roughly 80% of that administered at the serosal side. 3. The amount taken up into the intestinal tissue is much higher after having administered the 204Tl-radioactivity from the serosal side than from the mucosal side. This holds true for jejunal ileal, and colonic segments. 4. In equilibrium experiments of non-everted colonic segments which were incubated on either side with the same 204Tl-concentrations the net transfer of 204Tl was determined directly. After a delay of 60 min the net transfer of 204Tl follows the rapid uptake into the intestinal tissue. 5. The net transfer as well as the tissue content of 204Tl decreases with increasing concentrations. From concentrations of 204Tl-ions of 5×10-5M on, no concentration gradient between the mucosal and the serosal side could be established. 6. The net transfer of 204Tl depends highly on temperature. At 29°C a diminished concentration gradient of the 204Tl between the mucosal and the serosal fluid was observed. At 25°C no concentration gradient could be established. The content of 204Tl in tissue, however, was not affected by this decrease of temperature. 7. The net transfer of 204Tl is nearly doubled by an increase of the K+-concentration at the mucosal side from 4.5 (normal) up to 72 mM, whereas the change of the 204Tl-content in tissue was statistically not significant. A decrease, however, of the net transfer of 204Tl is the consequence of an increased K+-concentration at the serosal side. In these segments the 204Tl content in tissue is decreased by 16% at the highest concentration of K+-ions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00518485
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  • 7
    Electronic Resource
    Electronic Resource
    Neuere Veröffentlichungen (1981)
    Springer
    Ocean dynamics 34 (1981), S. 38-40 
    Details
    ISSN: 1616-7228
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02227004
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  • 8
    Electronic Resource
    Electronic Resource
    Quantitative fluorimetrische Bestimmung von Thiabendazol mittels Dünnschicht-Chromatographie im Vergleich zur Gas-Chromatographie (1984)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 318 (1984), S. 276-277 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00528606
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  • 9
    Electronic Resource
    Electronic Resource
    Electrical properties of adamantylphosphaethyne AdC≡P (1986)
    Springer
    Russian chemical bulletin 35 (1986), S. 1541-1541 
    Details
    ISSN: 1573-9171
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00954852
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  • 10
    Electronic Resource
    Electronic Resource
    Molekül- und Kristallstruktur des 1,4-Bis[tris(tetrahydrofuran)lithium]-octaphenyltetrasilans (1989)
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 572 (1989), S. 63-74 
    Details
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Molecular and Crystal Structure of 1,4-Bis[tris(tetrahydrofuran)lithium]-octaphenyltetrasilane1,4-Dilithium-octaphenyltetrasilane prepared from octaphenyl-cyclo-tetrasilane and lithium in tetrahydrofuran (THF) [4], can be isolated from tetrahydrofuran/n-pentane as an adduct with six molecules of tetrahydrofuran per formula unit. The orange-red compound crystallizes in the triclinic space group P1 {a = 1159.6(3); b = 1268.4(2); c = 1367.8(3) pm; α = 92,23(2)° β = 113.79(2)° γ = 111.62(2)° at -5 ± 3°C; Z = 1}. An x-ray structure determination (Rw = 0.046) shows the existence of a centrosymmetric molecule with an extended planar Li—Si4—Li unit; either lithium atom is bound to silicon and to the oxygen atoms of three molecules of tetrahydrofuran. Characteristic bond lengths and angles are: Li—Si 271; Si—Si 241 and 243; Si—C 190 to 192 pm; Li—Si—Si 126°; Si—Si—Si 127°. 29Si and 7Li n.m.r. measurements at low temperatures indicate the presence of three different adducts.
    Notes: Das aus Octaphenyl-cyclo-tetrasilan und Lithium in Tetrahydrofuran (THF) dargestellte, orangerote 1,4-Dilithium-octaphenyltetrasilan [4] kristallisiert aus Tetrahydrofuran/n-Pentan als Addukt mit sechs Molekülen Tetrahydrofuran triklin in der Raumgruppe P1. Die Verbindung weist folgende, bei -5 ± 3°C bestimmte Parameter der Elementarzelle auf: a = 1159,6(3); b = 1268,4(2); c = 1367,8(3) pm; α = 92,23(2)°; β = 113,79(2)° γ = 111,62(2)°; Z = 1. Nach den Ergebnissen einer Röntgenstrukturanalyse (Rw = 0,046) liegt ein zentrosymmetrisches Molekül mit gestrecktem, planarem Li—Si4—Li-Gerüst vor; jedes Lithium ist an Silicium und die Sauerstoffatome aus drei Tetrahydrofuran-Molekülen gebunden. Charakteristische Bindungslängen und -winkel sind: Li—Si 271; Si—Si 241 und 243; Si—C 190 bis 192 pm; Li—Si—Si 126°; Si—Si—Si 127°. 29Si- und 7Li-Kernresonanz-Messungen bei tiefen Temperaturen ergeben in Lösung drei unterschiedliche Addukte.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/zaac.19895720108
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