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31.
Dietrich Flöβner 《Hydrobiologia》1984,108(3):259-263
A new species of Neodiaptomus, N. intermedius n. sp. is described and illustrated. It is compared with related species of the strigilipes — physalipus species group. 相似文献
32.
Albrecht Guhlmann Wolfgang Hagmann Dietrich Keppler 《Prostaglandins & other lipid mediators》1987,34(1)
N-Acetyl-leukotriene E4, the end product of leukotriene C4 metabolism in the mercapturic acid pathway, was rapidly eliminated from the blood circulation into the bile of rats. Part of the N-acethyl-leukotriene E4 secreted from bile into the intestine undewent enterohepatic circulation. Leukotriene absorption occurred from the small intestine and from the colon. Biliary and urinary excretion within 5.5 h amounted to 15 and 2%, respectively, of the intraduodenally administered N-acetyl- H leukotriene E4 in animals anesthetized with ketamine. HPLC analyses indicated that 35% of the biliary radioactivity corresponded to unchanged N-acetyl- H leukotriene E4, while 65% in bile and 100% in urine were polar metabolites. Enterohepatic circulation extends the biological half-life of N-acetyl-leukotriene E4. 相似文献
33.
34.
Ineffective erythropoiesis in acute human P. falciparum malaria 总被引:5,自引:0,他引:5
An analysis of erythroblast cell kinetics utilizing quantitative 14C-autoradiography has been performed in five cases of acute Plasmodium falciparum malaria prior to and, in four patients, 3 or 6 days after the onset of antimalarial therapy. Associated with no or only moderate anemia were changes of erythroblast morphology, a considerable shift in the frequency of red and white blood cell precursors in the bone marrow, and a reduced rate of erythroblast proliferation. There was a marked loss of polychromatic erythroblasts, which was smaller but still detectable during the therapeutic phase. The results provide some quantitative data on the extent of "parenchymal damage" of bone marrow and stress the impact of ineffective erythropoiesis and reduced rate of erythropoietic proliferation on the emergence of anemia in Plasmodium falciparum malaria. 相似文献
35.
Summary Reaction kinetic analysis of the electrical properties of the electrogenic Cl– pump inAcetabularia has been extended from steady-state to nonsteady-state conditions: electrical frequency responses of theAcetabularia membrane have been measured over the range from 1 Hz to 10 kHz at transmembrane potential differences across the plasmalemma (V
m
) between –70 and –240 mV using voltage-clamp techniques. The results are well described by an electrical equivalent circuit with three parallel limbs: a conventional membrane capacitancec
m
, a steadystate conductanceg
o
(predominantly of the pump pathway plus a minor passive ion conductance) and a conductanceg
s
in series with a capacitancec
p
which are peculiar to the temporal behavior of the pump. The absolute values and voltage sensitivities of these four elements have been determined:c
m
of about 8 mF m–2 turned out to be voltage insensitive; it is considered to be normal.g
o
is voltage sensitive and displays a peak of about 80 S m–2 around –180 mV. Voltage sensitivity ofg
s
could not be documented due to large scatter ofg
s
(around 80 S m–2).c
p
behaved voltage sensitive with a notch of about 20 mF m–2 around –180 mV, a peak of about 40 mF m–2 at –120 mV and vanishing at –70 mV. When these data are compared with the predictions of nonsteady-state electrical properties of charge transport systems (U.-P. Hansen, J. Tittor, D. Gradmann, 1983,J. Membrane Biol. in press), model A (redistribution of states within the reaction cycle) consistently provides magnitude and voltage sensitivity of the elementsg
o
,g
s
andc
p
of the equivalent circuit, when known kinetic parameters of the pump are used for the calculations. This analysis results in a density of pump elements in theAcetabularia plasmalemma of about 50 nmol m–2. The dominating rate constants for the redistribution of the individual states of the pump in the electric field turn out to be in the range of 500 sec–1, under normal conditions. 相似文献
36.
Dietrich Neumann 《Oecologia》1971,8(1):1-20
Zusammenfassung Die in der Gezeitenzone lebende Mücke Clunio marinus ist längs der europäischen Küstenlinie verbreitet. Die experimentell geprüften Stämme verschiedener geographischer Herkunft repräsentieren ökologische Rassen, die sich in der zeitlichen Programmierung ihrer Entwicklung unterscheiden. Es wurde die Kreuzbarkeit zwischen insgesamt 7 Stämmen geprüft.Zwischen einzelnen Stämmen wurde eine nicht-reziproke Kreuzungssterilität (abgekürzt n.r.St.) nachgewiesen, bei der jeweils in einer Kreuzungsrichtung fertile Nachkommen entstanden und in der reziproken Kreuzung Nachkommen fehlten.Die Vererbung der n.r.St. wurde zwischen 2 Stämmen benachbarter Rassen mit der Methode der wiederholten Rückkreuzung geprüft. Es ergab sich ein matrokliner Erbgang. Die Befunde werden mit entsprechenden Ergebnissen von Laven an Culex pipiens verglichen.Die populationsgenetischen Konsequenzen der n.r.St. werden in Hinblick auf die Elimination von Kreuzungstypen, Genfluß und reproduktive Isolation betrachtet. Für die Bedeutung der n.r.St. im Freiland werden 3 Hypothesen erörtert: 1. Begleiterscheinung der genetisch divergierenden Rassen, 2. in einer Richtung wirksamer Isolationsmechanismus zwischen benachbarten Rassen und 3. Speciation.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.
Herrn Professor Dr. Gerhard Krause zu seinem 65. Geburtstag. 相似文献
Summary The intertidal midge Clunio marinus is distributed along the European coast-line. Stocks from distinct locations differ in the programming of their emergence time. They represent ecological races. The crossability between 7 stocks was examined.Between some stocks a non-reciprocal cross sterility has been found, characterized by fertile hybrids in one cross direction, and no offspring in the reciprocal crosses.The cross Jean xSan was fertile, while the cross San xJean was sterile. After three backcrosses of the hybrid females to San males, the sterility in the reciprocal crosses with San females had not been changed. The maternal inheritance of this non-reciprocal sterility is compared with similar studies in Culex pipiens by Laven.According to aspects of population genetics, the non-reciprocal cross sterility is considered in view of elimination of crossing types, of gene flow and reproductive isolation. With regard to the significance of the non-reciprocal cross sterility in the field, three hypotheses are discussed: 1. by-product of evolutionary divergence in ecological races, 2. unilateral reproductive isolation which blocks the gene flow between adjacent populations only in one direction, and 3. speciation.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft.
Herrn Professor Dr. Gerhard Krause zu seinem 65. Geburtstag. 相似文献
37.
Dietrich Fürnkranz 《Plant Systematics and Evolution》1969,117(2):157-162
Zusammenfassung Diploidie, reliktäres Vorkommen und ziemlich genaue Übereinstimmung des Areals mit paläogeographischen Landkarten des Mittelmeergebietes und der östlich angrenzenden Länder weisen die kurzschnäbeligenTaraxaca als alte Typen — wahrscheinlich Tertiärrelikte — aus. Ein engerer Zusammenhang der übrigen, offenbar meist polyploiden mediterranenTaraxaca mit den alten Typen sowie dieser beiden mit den mittel- und nordeuropäischenTaraxacum-Arten scheint nicht gegeben zu sein.
Summary Diploidy, relic occurence and rather exact correspondence of their areals with paleogeographic maps of the mediterranean area and of adjacent territories mark the shortly rostratedTaraxaca as ancient types, probably relics. These ancient types are neither closely related to the younger mediterranean polyploids, nor to the middle- and north-europeanTaraxacum species, just as nearer connections between the young mediterranean types and the young middle- and north-europeanTaraxacum species are not probable.相似文献
38.
39.
Novel heparin degradation products. Isolation and characterization of novel disaccharides and oligosaccharides produced from heparin by bacterial degradation 总被引:5,自引:3,他引:2 下载免费PDF全文
Carl P. Dietrich 《The Biochemical journal》1968,108(4):647-654
1. Heparin was degraded by enzymes of adapted Flavobacterium heparinum. Several degradation products were separated by combined Sephadex-gel filtration and paper chromatography, and chemically analysed. 2. These products were identified as glucosamine 2,6-disulphate, saturated disaccharides constituted of uronic acid and glucosamine and containing two and three sulphate residues, and tetra- and hexa-saccharides with the same basic disaccharide units. 3. The implications of these findings with respect to the present knowledge of heparin structure and its enzymic degradation are discussed. 相似文献
40.
Dietrich Harder 《Radiation and environmental biophysics》1968,5(2):157-164
Zusammenfassung Beim Einbringen eines gasgefüllten Hohlraums in ein elektronenbestrahltes, festes oder flüssiges Material erhöht sich die Teilchenflußdichte im Volumenbereich des Hohlraums infolge geringerer Elektronenstreuung durch das Gas. Die im Gas erzeugte Ionisation übertrifft daher den Wert, der dem ungestörten Strahlungsfeld vor Einbringen des Hohlraums entspricht. Nach der Theorie der Kleinwinkel-Vielfachstreuung wird der zusätzliche im Gasvolumen liegende Weg von Elektronen und die daraus resultierende zusätzliche Ionisation für verschiedene Hohlraumformen berechnet. Die abgeleiteten Gesetzmäßigkeiten ermöglichen ein quantitatives Verständnis der von anderen Autoren experimentell beobachteten Streueffekte und die Abschätzung von Fehlereinflüssen der Vielfachstreuung bei luftgefüllten Ionisationskammern in der Elektronendosimetrie.
Meinem LehrerBoris Rajewsky zum 75. Geburtstag gewidmet.
Herrn Dr. H.-J.Schopka sei für eine Diskussion über die theoretische Bedeutung des Streueffektes herzlich gedankt. 相似文献
The effect of multiple electron scattering on the ionization in gas- filled cavities
Summary If a gas-filled cavity is inserted into an electron-irradiated solid or liquid material, the fluence of electrons within the volume now occupied by the cavity is increased due to the weakness of scattering from the gas. The amount of ionization produced in the gas therefore oversteps the amount corresponding to the undisturbed radiation field that was present prior to the insertion of the cavity. The additional track length of electrons within the cavity and the additional ionization resulting from it are calculated from the theory of small angle multiple scattering. The regularities derived in this way are used to understand the magnitude of the scattering effects observed by other authors and to estimate the experimental errors of gas-filled ionization chambers in electron dosimetry introduced by multiple scattering.
Meinem LehrerBoris Rajewsky zum 75. Geburtstag gewidmet.
Herrn Dr. H.-J.Schopka sei für eine Diskussion über die theoretische Bedeutung des Streueffektes herzlich gedankt. 相似文献