ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

X
feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Haloaldehyde polymers. 55. Diastereomeric bromal unimers: synthesis, characterization, and absolute configuration (1992)
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 2319-2323 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00035a006
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 2
    Electronic Resource
    Electronic Resource
    The petrogenesis of Merensky Reef potholes at the Western Platinum Mine, Bushveld Complex: Sr-isotopic evidence for synmagmatic deformation (1999)
    Springer
    Mineralium deposita 34 (1999), S. 335-347 
    Details
    ISSN: 1432-1866
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Potholes represent areas where the normally planar PGE-rich Merensky Reef of the upper Critical Zone of the Bushveld Complex transgresses its footwall, such geometric relationships being unusual in layered intrusions. The recognition of vertical dykes of Merensky pyroxenite in the footwall suggests downward collapse of crystal mush into pull-apart sites resulting from tensional deformation due to the loading effects of major new magma additions. In contrast, crosscutting anorthosite veins display physical and isotopic evidence of upward emplacement. The Merensky Reef and its footwall have distinct initial Sr-isotope ratios (R 0 〉 0.7066 and 〈0.7066, respectively), which may be used to constrain these processes related to pothole formation. Merensky Reef in potholes (R 0 = 0.7069−0.7078) shows no isotopic evidence of assimilation of, or reaction with, footwall material. Discrete, discordant replacement bodies of anorthosite extend from the footwall lithologies to cross-cut the Merensky Reef and its hanging wall. The initial Sr-isotope ratio in these replaced rocks is totally reset to footwall values (R 0 = 0.7066), and immediately adjacent stratiform lithologies are slightly modified towards footwall values. In contrast, Neptunian pyroxenitic (Merensky) dykes cross-cutting the footwall lithologies, with a large surface area to volume ratio, and low Sr content, do not display footwall-like Sr-isotope initial-ratios (R 0 = 0.7077), and thus show no evidence for assimilation of or reaction with footwall material. Furthermore, pegmatoidal replacement pyroxenite (“replacement pegmatoid”), at the base of the Merensky Reef within potholes, has a high initial-ratio (R 0 〉 0.7071), and so models of pervasive metasomatism by footwall material are not applicable. This isotopic evidence indicates that there was no active interaction of footwall material with the overlying magma during, or after, the formation of Merensky Reef potholes, a basic tenet of existing pothole formation hypotheses involving footwall mass-transfer. In contrast, the isotopic data are entirely consistent with an extensional model for pothole formation, with the more radiogenic Merensky magma migrating laterally to fill extensional zones in the footwall layers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s001260050208
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Discordant ultramafic pegmatoidal pipes in the Bushveld Complex (2000)
    Springer
    Contributions to mineralogy and petrology 140 (2000), S. 119-133 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Discordant ultramafic pipes cut most of the layered sequence of the Bushveld Complex. We have studied one pipe in detail, the Tweefontein pipe, which cuts the Critical Zone, eastern Bushveld Complex, because it is well-exposed in a new road cutting. Field relations suggest that these pipes were emplaced while the layered rocks were extremely hot and incapable of brittle failure. The existence of displaced chromitite and anorthosite fragments in this discordant body is suggestive of an intrusive magmatic, rather than metasomatic, mode of emplacement. Initial Sr isotopic ratios of plagioclase from the pipe are in the range 0.7073 to 0.7079, which contrast with typical ratios of 0.7055 to 0.7065 for the Critical Zone, and 〉0.708 for Main Zone. These data preclude an origin for the pipe as residual magmas from the adjacent layered rocks. The compositions of, and extensive exsolution in, pyroxenes in the pipe indicate temperatures of formation comparable to those of the layered sequence itself, and that they underwent slow cooling comparable to the surrounding layered rocks, such that they both have similar closure temperatures. Preferential replacement of leuconoritic layers suggests a temperature of emplacement in excess of the plagioclase–pyroxene cotectic temperature. The per mil δ18O difference between plagioclase and pyroxene (Δplag–px) for samples from within the pipes ranges from 0.4 to 1.0, and averages 0.7 (for nine pairs), compared to Δplag–px of 0.4 to 0.6 for host rocks, again consistent with magmatic temperatures of formation. Oxygen isotope ratios for plagioclase and pyroxene in the pipes and layered host rocks are comparable, and preclude a significant fluid contribution from metamorphosed sediments in the floor of the Bushveld Complex in the formation of the primary mineralogy. The presence of hornblende, and occasional higher Δplag–px values than in the normal layered sequence rocks suggest lower temperature equilibration in the pipe, probably in the presence of a fluid. Higher absolute δ18O values for both minerals in a few of the pipe and host samples suggest reaction with a later fluid. These discordant ultramafic pipes are considered to form by emplacement of magma batches, which are Sr-isotopically distinct from those which produced the adjacent layered rocks of the Bushveld Complex, but were nevertheless extremely closely related in time to the main intrusive events. Dissolution of host rocks, rather than purely mechanical dilation, provided the space for pipe emplacement. However, the pipe may have acted ultimately as a channelway for low-temperature hydrothermal fluids related to later faulting in the immediate vicinity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004100000175
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 4
    Electronic Resource
    Electronic Resource
    Cyclic nucleotide levels in the perfused rat heart subjected to hypoxia (1977)
    Springer
    Cellular and molecular life sciences 33 (1977), S. 215-217 
    Details
    ISSN: 1420-9071
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Isolated rat hearts were subjected to hypoxic perfusion on a recirculating Langendorff apparatus. Following a 30-min-period of aerobic stabilization the hearts were perfused for 30 min with media equilibrated with 84% N2, 12% O2 and 4% CO2. At the end of the hypoxic period myocardial concentrations of cyclic AMP and cyclic GMP were determined by radioimmunoassay. Exposure to hypoxia resulted in a significant increase in cyclic AMP (p〈0.01) and a decrease in cyclic GMP (p〈0.05) as compared to hearts perfused for 60 min with media gassed with 96% O2, 4% CO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02124074
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 5
    Electronic Resource
    Electronic Resource
    Source-area determination of elephant ivory by isotopic analysis (1990)
    [s.l.] : Nature Publishing Group
    Nature 346 (1990), S. 744-746 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] For this pilot project, we obtained ivory and/or bone specimens from more than 100 adult elephants, collected by wildlife conservation officers or the police in over 20 identifiable game refuge areas in 10 African countries (Fig. 1). Collagen was extracted from the bone or dentine samples and ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/346744a0
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 6
    Electronic Resource
    Electronic Resource
    Significance of 87 Sr/ 86 Sr ratios in the Merensky cyclic unit of the Bushveld Complex (1982)
    [s.l.] : Nature Publishing Group
    Nature 298 (1982), S. 53-55 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] In the Bushveld Complex the PGE-bearing Merensky pegmatoid is part of the Merensky cyclic unit which occurs at the base of the main zone (subdivision after Willemse6?Fig. 1). Above the Merensky unit lies the lithologically similar Bastard cyclic unit. Both these units consist of a basal layer of ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/298053a0
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 7
    Electronic Resource
    Electronic Resource
    Photosynthetic characteristic of South African sclerophylls (1983)
    Springer
    Oecologia 58 (1983), S. 398-401 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Sclerophyll shrubs of the South African mountain fynbos have leaves similar in structural and physiological properties to leaves from evergreen shrubs of other mediterranean-climate regions. These leaves have relatively low photosynthetic capacities (〈14 μmol CO2 m−2 s−1), and are light saturated at relatively low photon irradiances (〈1.0 mmol m−2 s−1). They have broad temperature responses of photosynthesis, moderate water-use efficiencies (∼0.003 mol CO2/mol H2O), high specific weights (∼200 g m−2) and low nitrogen contents (∼10 mg g−1).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385242
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 8
    Electronic Resource
    Electronic Resource
    Plant species diversity in cape fynbos: Gamma and delta diversity (1980)
    Springer
    Plant ecology 41 (1980), S. 85-93 
    Details
    ISSN: 1573-5052
    Keywords: Fynbos ; Plant species diversity ; Sclerophyllous shrublands ; South Africa ; Species-area relations ; Species diversity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This paper reports the number of plant species on circumscribed fynbos areas (gamma diversity), ranging in size from 0.27 km2 (a site with 364 species) to 471 km2 (2351 species). The composition of the floras of four of these sites was analysed to measure delta diversity, the change in flora from one site to the next. Maximum gamma diversity values fitted a species-area curve log S=2.69+0.25 log A. Gamma diversity is apparently higher than in any of the world's biogeographic zones except perhaps the tropical rain forest, and in other South African sites of areas around 1.0 km2, which have about as many species. High delta diversities are reflected in differences between fynbos floras of 50 to 70 %, in spite of relative proximity; this degree of diversity is apparently unmatched anywhere. The results support the conventional view that fynbos plant diversity is partly a consequence of the peculiar geography of the zone, and of palaeo-climatic change, which have favoured geographic speciation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00121419
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 9
    Electronic Resource
    Electronic Resource
    Pflanzensoziologische Studie der Fynbosvegetation am Kap der guten Hoffnung (1972)
    Springer
    Plant ecology 24 (1972), S. 71-89 
    Details
    ISSN: 1573-5052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Summary TheBraun-Blanquet phytosociological method was tested in the complex Fynbos (Macchia) vegetation of the Cape of Good Hope, South Africa. In Swartboschkloof Nature Reserve the Fynbos, riverine scrub and forest vegetation was classified preliminarily into eight communities, which are described floristically and related to habitat. The results hold promise, and the possibilities of classifying the Cape Fynbos in a formal phytosociological system are discussed.
    Notes: Zusammenfassung Im Swartboschkloof-Naturschutzgebiet am Kap der Guten Hoffnung wurden pflanzensoziologische Methoden ausprobiert und ergaben eine vorläufige Klassifikation der dortigen Fynbos-(Macchia), Flußsaum- und Wald vegetation. Acht Gesellschaften sind floristisch beschrieben und mit Standortfaktoren korreliert worden. Die Ergebnisse sind vielversprechend, und die Möglichkeiten einer Klassifikation der kapländischen Fynbos-Vegetation in ein formelles pflanzensoziologisches System werden diskutiert.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02387392
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
  • 10
    Electronic Resource
    Electronic Resource
    A DSC study of curative interactions. I. The interaction of ZnO, sulfur, and stearic acid (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 42 (1991), S. 2643-2649 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The interaction between combinations of sulfur, stearic acid, and ZnO were studied by differential scanning calorimetry in the absence of rubber. The only reaction observed was between ZnO and stearic acid. A small amount of zinc stearate formed as soon as the stearic acid melted, but the solid product blocked further reaction, which was only completed at 154°C. Water played a major role in the reaction, and in the presence of water, the reaction went to completion at lower temperatures. Sulfur, too, affected the temperature of the ZnO/stearic acid reaction. The preparation of zinc stearate by a number of routes was investigated.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1991.070421002
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
    Paper (German National Licenses)
    Fulltext
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...