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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 14 (1976), S. 0 
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: The value of the electrical resistivity method as a quantitative indicator of ground-water resistivity, porosity and effective matrix resistivity is examined through the equivalence of these parameters as manifested in the surface-measured resistivity of heterogeneous water-saturated sands. It is demonstrated that, where there are unknown variations in porosity, the mapping of groundwater resistivity is most feasible at lower salinities and where porosity is relatively high. Porosity can be determined most exactly at lower values and where groundwater salinity is relatively high. Both these approaches become less efficient as matrix conduction increases. The mapping of effective matrix resistivity is best effected at lower values where this parameter can be approximately monitored against moderate variations in both porosity and ground-water resistivity. In general, however, where there are unknown and pronounced variations in any two of these parameters, the geoelectrical determination of the third can be so ambiguous that the uncertainty in the estimated value of this parameter can exceed the total range of values encountered in an entire formation.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Surveys in geophysics 2 (1975), S. 313-366 
    ISSN: 1573-0956
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Groundwater flow and storage in granular aquifers are much more amenable to analysis than in fissured reservoirs. The hydrological parameters used to describe the behaviour of a granular aquifer have been seen to be related to geophysical parameters in diverse water-bearing formations. This means that certain geophysical survey techniques are potentially useful as quantitative hydrogeological tools. Yet the study of these basic relationships and their subsequent field application have been disjointed and lacking in overal co-ordination. Consequently these quantitative hydrogeophysical procedures have not been applied to maximum advantage. The role of geophysics in quantitative studies of granular aquifers is reviewed in terms of the prediction of effective porosity and intergranular permeability from geophysical measurement. The potential usefulness of these methods manifests itself through the degree of correlation between hydrological and geophysical parameters observed from laboratory studies, borehole logging investigations or field survey data. Their application is exemplified through an ordered series of hydrogeophysical case histories. It is contended that the potential of geophysical methods in quantitative studies of this kind has by no means been fully exploited.
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  • 3
    ISSN: 1434-193X
    Keywords: Indiumallyl compounds ; Vinylcyclopropanes ; α,β-Unsaturated carbonyl compounds ; Diastereoselectivity ; Dibenzylideneacetone ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Allylindium reagents, prepared from excess allylic halide (Br or I) and indium metal, react with α,β-unsaturated ketones and aldehydes to give, after aerobic acidic workup, homoallyl-substituted vinylcyclopropanes. This process was explored and developed after a chance discovery arising from a side reaction in an attempted Pd-catalysed process. The structure of the cyclopropane arising from the reaction of bis(p-chlorobenzylidine)acetone was confirmed by X-ray crystallography. Whilst bis-α,β-unsaturated ketones give rise to a single homoallylcyclopropane species, α,β-unsaturated ketones and aldehydes give diastereomeric mixtures whose relative stereochemistry were assigned by NOE experiments. Crotylindium reagents react with good to perfect regioselectivity to afford tetrasubstituted cyclopropanes but prenylindium reagents fail to generate the analogous pentasubstituted rings.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1434-193X
    Keywords: Indium ; Vinylcyclopropanes ; Ring closing metathesis ; Norcarenes ; Kinetic diastereoselection ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: ---Homoallyl-substituted vinyl cyclopropanes 1a-c, which are readily prepared by reaction of allylindium reagents with α,β-unsaturated ketones and aldehydes, undergo Ru-catalysed RCM reactions with Grubbs catalyst to give [4.1.0]bicyclooct-2-ene (norcarene) type bicyclic products. Noncyclisable ‘trans’ homoallyl-substituted vinyl cyclopropanes 1b and 1c are separated from their ‘cis’ diastereomers by RCM to 5b and 5c - but only with moderate efficiency due to a competing homo-cross metathesis (‘dimerisation’) to give 7b and 7c, respectively. However, the four diastereomers of the (homoallyl)distyrylcyclopropane 14a obtained from indium-mediated reaction of dibenzylideneacetone and crotyl bromide undergo remarkable kinetic diastereoselection in their RCM reactions to give a 4,7-dimethyl[4.1.0]bicyclohept-2-ene-type product 15a. This process allows recovery of a single diastereomer (〉 95%) of 14a without dimerisation being a significant side reaction. Furthermore, the RCM product 15a is obtained rich in one diastereomer (ca. 90%). The kinetic diastereoselection and lack of dimerisation can be rationalised by considering developing transannular interactions and a pseudo-A1,3 strain model.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Publication Date: 2017-07-04
    Description: The amalgamation of the Central Asian Orogenic Belt in the southwestern Tian Shan in Tajikistan is represented by tectono-magmatic-metamorphic processes that accompanied late Paleozoic ocean closure and collision between the Karakum–Tarim and Kazakh–Kyrgyz terranes. Integrated U-Pb geochronology, thermobarometry, pseudosection modelling, and Hf geochemistry constrain the timing and petro-tectonic nature of these processes. The Gissar batholith and the Garm massif represent an eastward, along-strike increase in paleodepth from upper-batholith (~21–7 km) to arc-root (~36–19 km) levels of the Andean–syn-collisional Gissar arc, which developed from ~323–288 Ma in two stages: (i) Andean, I-type granitoid magmatism from ~323–306 Ma due to northward subduction of the Gissar back-arc ocean basin under the Gissar microcontinent, which was immediately followed by: (ii) syn-collisional, I–S-type granitoid magmatism in the Gissar batholith and the Garm massif from ~304–288 Ma due to northward subduction/underthrusting of Karakum marginal-continental crust under the Gissar microcontinent. A rapid isotopic pull-up from ~288–286 Ma signals the onset of juvenile, alkaline-syenitic, post-collisional magmatism by ~280 Ma, which was driven by delamination of the Gissar arclogite root and consequent convective asthenospheric upwelling. Whereas M–HT/LP prograde metamorphism in the Garm massif (650–750 °C / 6–7 kbar) from ~310–288 Ma was associated with subduction-magma inundation and crustal thickening, HT/LP heating and decompression to peak-metamorphic temperatures (~800–820 °C / 6–4 kbar) at ~288 ± 6 Ma was driven by the transmission of a post-collisional, mantle-derived heat wave through the Garm-massif crust.
    Print ISSN: 0278-7407
    Electronic ISSN: 1944-9194
    Topics: Geosciences
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 6
    Publication Date: 1975-07-01
    Description: Groundwater flow and storage in granular aquifers are much more amenable to analysis than in fissured reservoirs. The hydrological parameters used to describe the behaviour of a granular aquifer have been seen to be related to geophysical parameters in diverse water-bearing formations. This means that certain geophysical survey techniques are potentially useful as quantitative hydrogeological tools. Yet the study of these basic relationships and their subsequent field application have been disjointed and lacking in overal co-ordination. Consequently these quantitative hydrogeophysical procedures have not been applied to maximum advantage. The role of geophysics in quantitative studies of granular aquifers is reviewed in terms of the prediction of effective porosity and intergranular permeability from geophysical measurement. The potential usefulness of these methods manifests itself through the degree of correlation between hydrological and geophysical parameters observed from laboratory studies, borehole logging investigations or field survey data. Their application is exemplified through an ordered series of hydrogeophysical case histories. It is contended that the potential of geophysical methods in quantitative studies of this kind has by no means been fully exploited. ©1975 Reidel Publishing Company
    Print ISSN: 0169-3298
    Electronic ISSN: 1573-0956
    Topics: Geosciences , Physics
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  • 7
    Publication Date: 1988-12-01
    Description: The well logging activity of the Ocean Drilling Programme, which deploys the most technically advanced suite of downhole measurements available for routine use, is providing new opportunities for advancement in marine geoscience. Particular examples are cited of the application of wireline data to problems associated with global environmental changes, crust/ mantle interactions, crustal fluid circulation in the context of a global geochemical budget, lithospheric stress and deformation, and evolutionary processes in oceanic communities. Further technological developments will expand the scientific role of downhole measurements still further, especially in terms of the integration of geophysical data at different scales of measurement, and the interpretation of these data in accordance with; global scientific themes. Copyright © 1988, Wiley Blackwell. All rights reserved
    Print ISSN: 0950-091X
    Electronic ISSN: 1365-2117
    Topics: Geosciences
    Published by Wiley
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  • 8
    Publication Date: 1989-09-01
    Print ISSN: 0950-091X
    Electronic ISSN: 1365-2117
    Topics: Geosciences
    Published by Wiley
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