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  • Springer  (71)
  • 1995-1999  (22)
  • 1990-1994  (30)
  • 1975-1979  (19)
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  • 1
    Electronic Resource
    Electronic Resource
    A comparison of carbon-specific respiration rates in gelatinous and non-gelatinous zooplankton: A search for general rules in zooplankton metabolism (1992)
    Springer
    Helgoland marine research 46 (1992), S. 377-388 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Using 470 data from the literature the dry weight-specific respiration rates of gelatinous zooplankton (cnidarians, ctenophores and salps) and non-gelatinous zooplankton (mainly crustacea) were converted to carbon-specific values. The resulting carbon-specific respiration rates showed no significant differences between the two groups of zooplankton, indicating similar oxygen requirements per gram of carbon biomass. From this finding, it can be suggested that the differences in the rates of oxygen consumption measured in the two types of zooplankton in the sea can be explained by the carbon biomass ratio between gelatinous and non-gelatinous zooplankton. Furthermore, the low rate of metabolism of gelatinous species compared with that of non-gelatinous animals of the same volume can be attributed predominantly to the relatively low organic matter content in the former. It is recommended that all weight-specific metabolism rates be expressed using carbon as body mass unit (e.g. mg O2 gC−1 d−1) which enables more accurate comparisons between individuals exhibiting different dry weight/carbon ratios.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02367205
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  • 2
    Electronic Resource
    Electronic Resource
    A comparison of summer nutrient data obtained in Königshafen Bay (North Sea, German Bight) during two investigation periods: 1979–1983 and 1990–1992 (1994)
    Springer
    Helgoland marine research 48 (1994), S. 173-182 
    Details
    ISSN: 1438-3888
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A comparison of summer nutrients obtained during the investigation periods 1979–1983 and 1990–1992 was made, to elucidate whether or not changes have occurred in Königshafen Bay during the last decade. In both the flood current as well as in the ebb current, concentrations of silicate, phosphate, nitrite and nitrate have decreased. Ammonia, however, has increased by a factor of two in the flood current waters, but was similar in both investigation periods in the ebb current waters. In addition, a significant increase of salinity has been observed. The differences between flood and ebb current median nutrient concentrations suggest that the bay was a source of nutrients during the 1979–1983 period, exporting large amounts of silicate, nitrite and ammonia with the ebb current. Today, the bay appears to be more a sink than a source of nutrients. Export rates of silicate and nitrite are greatly reduced and phosphate and ammonia are imported nowadays. Nitrate fluxes were in balance during both periods. Reasons for the observed changes are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02367034
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  • 3
    Electronic Resource
    Electronic Resource
    Low molecular weight, polymeric, and covalently bound cobalt(II)-phthalocyanines for the oxidation of mercaptans (1991)
    Springer
    Journal of inorganic and organometallic polymers and materials 1 (1991), S. 115-130 
    Details
    ISSN: 1572-8870
    Keywords: Phthalocyanine-cobalt complexes ; catalyst ; thiol oxidation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Cobalt(II)-phthalocyanines in different environments are investigated as catalysts for the oxidation of thiols. Water-soluble low molecular weight 2,9,10,23-tetracarboxyphthalocyanine (1b) and polymeric phthalocyanine (2b) with carboxylic end groups are prepared. Compound1b is covalently bound at linear and cross-linked poly(chloromethylstyrene) in the presence of pyridine to obtain the water-soluble polymers (3a, b) and gel-type polymers (4a, b). Covalent binding of1b to surface modified silica was also realized. Low molecular weight and polymeric phthalocyanines (1a, 2a) are synthesized on silica, alumina, and charcoal. In addition,1a is encapsulated in the interior of NaX zeolite. All materials are efficient catalysts for the oxidation of 2-mercaptoethanol. The mechanism employing water-soluble catalysts is discussed in the direction of a mononuclear complex coordinating dioxygen and thiol. Heterogeneous catalysts containing1a and2a on the carriers show enhanced activity with increasing dispersion. The proposed mechanism considers different reaction sites for the coordination of O2 and thiol.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00701033
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  • 4
    Electronic Resource
    Electronic Resource
    Die norditalienische Erdbebenserie vom Mai 1976 (1976)
    Springer
    Naturwissenschaften 63 (1976), S. 430-430 
    Details
    ISSN: 1432-1904
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00599412
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  • 5
    Electronic Resource
    Electronic Resource
    NICMOS/HST Post-Perihelion Images of Comet Hale-Bopp in Outburst (1997)
    Springer
    Earth, moon and planets 78 (1997), S. 243-249 
    Details
    ISSN: 1573-0794
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Near-infrared images of comet Hale-Bopp (C/1995 O1) were obtained from NICMOS/HST on UT August 27–28, 1997, when the comet emerged from the 50 degree solar elongation limit at 2.99 AU from Earth. Diffraction-limited images were obtained with camera 2 filters centered at 1.87, 1.90, 2.04 and 2.22 μm with ∼0.2″ resolution (0.076″/pixel; 165 km/pixel). Over the 1.7-hour baseline of observation, a recent (〈7 hours) outburst is seen in the form of an expanding spiral arm with a projected expansion velocity of ∼80 m/s. Other asymmetric features include a jet emanating from the nucleus and several static linear features. Comparisons of the flux distribution in the 2.04 and 2.22 μm filters indicate that the region near the nucleus exhibits a slight, ∼3%, water ice absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006209302147
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  • 6
    Electronic Resource
    Electronic Resource
    Velocity measurements in a precessing jet flow using a three dimensional LDA system (1997)
    Springer
    Experiments in fluids 23 (1997), S. 89-98 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  The turbulent, three dimensional and time dependent flow field of a precessing jet is investigated. In the present case the jet precession is generated by mechanically rotating a round jet inclined relative to the axis of rotation. A conditional flow visualisation technique is used to complement three dimensional laser Doppler velocity data, time-averaged and phase-averaged at the frequency of precession. The conditional phase-averaging technique enables phase-averaged velocity contours and vectors to be obtained which reveal flow patterns and structures within the flow field. Time-averaging of the velocity data shows that these structures are significant in that they generate a reverse flow (recirculation) region between the jet and its spinning axis. They are found also to cause a rapid decay of the mean velocity. The characteristics of the precessing jet found here are compared with previous investigations of the same flow and with investigations of other turbulent jets.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050089
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  • 7
    Electronic Resource
    Electronic Resource
    Velocity and Reynolds stresses in a precessing jet flow (1997)
    Springer
    Experiments in fluids 22 (1997), S. 489-495 
    Details
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  A novel fluid mixing device, described elsewhere, has been shown to have a dramatic effect on the combustion characteristics of a fuel jet. The main features of the flow are the deflection of the jet between 30° and 60° from the nozzle axis and its precession about that axis. Many of the factors governing the nozzle instabilities which drive the mixing in the external field are imprecisely defined. It is the aim of the present paper to examine, in isolation from the nozzle instabilities, the influence of precession on a deflected jet as it proceeds downstream from the nozzle exit. The fluid dynamically driven phenomena within the nozzle which cause the precession are in the present investigation replaced by a mechanical rotation of a nozzle from which is emerging a jet which is orientated at an angle from the nozzle axis. By this means the effect of precession on the deflected jet can be investigated independently of the phenomena which cause the precession. The experimental data reported here has been obtained from measurements made using a miniature, rapid response four-hole “Cobra” pitot probe in the field of the precessing jet. Phase-averaged three dimensional velocity components identify the large scale motions and overall flow patterns. The measured Reynolds stresses complement the velocity data and are found to be compatible with the higher entrainment rates of the jet found in earlier investigations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003480050076
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  • 8
    Electronic Resource
    Electronic Resource
    Advances in control-volume-based finite-element methods for compressible flows (1994)
    Springer
    Computational mechanics 14 (1994), S. 431-446 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Recent developments in the application of a control-volume-based finite-element method, that has proven successful in solving incompressible flow problems, to the solution of compressible flow problems are presented. The finite Element Differential Scheme (FIELDS) is demonstrated to retain the pressure checker boarding problem for the case of Euler flow under certain conditions of flow. The source of this is investigated and remedies are provided that surmount this problem for all flows including Euler flows. Success is demonstrated for incompressible flow and a formulation is provided for extension to compressible flows. One dimensional testing on a supersonic converging-diverging nozzle exhibits extremely high accuracy of flow prediction including both shock strength and sharpness of resolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00377597
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  • 9
    Electronic Resource
    Electronic Resource
    A comparison of carbon based ammonia excretion rates between gelatinous and non-gelatinous zooplankton: Implications and consequences (1990)
    Springer
    Marine biology 106 (1990), S. 219-225 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract About 560 literature data on weight-specific ammonia excretion rates of gelatinous zooplankton (cnidarians, ctenophores and salps) and non-gelatinous zooplankton (mainly crustacea) were converted to carbon based units to enabel a better comparison between both groups. If carbon is used as body-mass unit ammonia excretion rates of gelatinous zooplankton are in the same range as values obtained for other zooplankton taxa, indicating a similar nitrogen output per unit of organic matter in both groups. These results suggest nutrient regeneration potential to be the same in gelatinous and non-gelatinous zooplankton, and that nutrient regeneration within the pelagic system depends more upon the carbon biomass ratio between gelatinous and other zooplankton than on physiological differences.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01314803
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  • 10
    Electronic Resource
    Electronic Resource
    Zooplankton standing stock and community size structure within the epipelagic zone: a comparison between the central Red Sea and the Gulf of Aden (1994)
    Springer
    Marine biology 119 (1994), S. 191-198 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Standing stock and size composition of the zooplankton comunity (〉100 μm) were studied in four depth strata of the upper 200 m of the water column during a “Meteor” cruise to the central Red Sea and Gulf of Aden in spring 1987. The central Red Sea was divided into a northern area of higher salinity and a less saline southern part. Both areas exhibited significant differences in zooplankton abundance and standing stock. The latter increased by the ratio 1:2:3 from the northern central Red Sea to its southern part and further south to the Gulf of Aden. For size structure analysis samples were fractionated into three size classes (100 to 300, 300 to 500, 500 to 5000 μm). In the central Red Sea the smallest size was dominant whereas in the Gulf of Aden the largest size fraction played a greater relative role than in the central Red Sea. This shift in size structure of the zooplankton community from the Red Sea to the Gulf of Aden is apparently primarily related to ecosystem difference between both areas, leading to a change in species composition. In addition, size reduction of individual species common to both seas may be of some significance in the extreme environment of the Red Sea.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00349556
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