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  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Inorganic chemistry 12 (1973), S. 2714-2718 
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Inorganic chemistry 13 (1974), S. 719-723 
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    The @journal of organic chemistry 28 (1963), S. 1935-1936 
    ISSN: 1520-6904
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0487
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Description / Table of Contents: Übersicht Es werden die Umrisse des Rechenprogrammes PROFI beschrieben, welches zwei- oder dreidimensionale nichtlineare magnetostatische Felder, lineare elektrostatische oder stationäre elektrische Felder, stationäre nichtlineare zweidimensionale Wirbelstromfelder und stationäre Temperaturfelder berechnet. Das Programm benutzt die Methode der finiten Differenzen. Die Rechnungen können wahlweise in einem von fünf verschiedenen Koordinatensystemen ausgeführt werden, von denen zwei dreidimensional sind. Die Benutzung des Programmes wird durch Hilfsprogramme zur Aufbereitung der Eingabedaten, zur Analyse der Ergebnisse und zur Datenverwaltung erleichtert.
    Notes: Contents The paper describes the outlines of the computer program PROFI (program for calculation of fields) which calculates 2- or 3-dimensional nonlinear magnetostatic fields, linear electrostatic or stationary electric fields, stationary nonlinear 2-dimensional eddy-current fields and stationary temperature distributions. The program uses the finite difference method. The calculations may be carried out in one of five different coordinate systems, two of them being 3-dimensional. A set of service programs for preparing the input data, analysing the results, data handling etc. simplifies the use of the program.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Annals of hematology 16 (1968), S. 351-376 
    ISSN: 1432-0584
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Summary The purpose of this study was to take stock. It produced the following points of view: a) For a series of diseases the relationship to the ABO-blood-group-system has been prooved with such a high degree of probability that additional repetitions of the respective studies with the same method are superfluous. b) However, even here the mechanism is still so uncertain that studies utilizing additional and promoting points of view are desperately needed. Regarding the individual points of view one should be guided by the available working hypotheses on the cause of the relationships. c) If new working hypotheses are to be developed one should consider, as far as possible, that relationships exist to many and quite different diseases. Thus hypotheses which explained more than a single correlation would contribute considerably to the solution of the problem. d) There is a number of suspicious findings whose confirmation in a largertest series has not been carried out as yet. e) Some negative findings, for example congenital malformations, clearly show that the positive findings are not simulated by errors in the selection of the controls, since the controls were selected in the same manner. The ‘reserve est’ that is, the proof that in healthy old persons especially group 0 occurs much more frequently, also points in the same direction.
    Notes: Zusammenfassung Absicht der vorliegenden Untersuchung war eine Bestandsaufnahme. Sie hat folgende Gesichtspunkte ergeben: a) Für eine Reihe von Krankheiten ist eine Beziehung zu dem ABO-Blutgruppensystem mit so hoher Wahrscheinlichkeit erwiesen, daß weitere Wiederholungen entsprechender Untersuchungen mit der gleichen Methode überflüssig sind. b) Dagegen ist auch hier der Mechanismus noch so unklar, daß Untersuchungen unter Heranziehung zusätzlicher weiterführender Gesichtspunkte dringend nottun. Für diese Gesichtspunkte im einzelnen sollte man sich von den vorliegenden Arbeitshypothesen über die Ursache der Beziehungen leiten lassen. c) Wenn man neue Arbeitshypothesen entwickeln will, so sollte dabei nach Möglichkeit berücksichtigt werden, daß Beziehungen zu vielen, sehr verschiedenen Krankheiten bestehen; so hätten Hypothesen einen heuristischen Vorteil, wenn sie nicht nur eine einzige Korrelation erklärten. d) Es ist eine Reihe von verdächtigen Befunden bekannt, deren Nachprüfung an größerem Zahlenmaterial noch aussteht. e) Bestimmte negative Befunde, z. B. bei angeborenen Mißbildungen zeigen deutlich, daß die positiven Befunde nicht durch Fehler in der Auswahl der Kontrollen vorgetäuscht sind, da hier die Kontrollen in gleicher Weise ausgewählt wurden. In die gleiche Richtung weist auch die “Gegenprobe”, d. h. der Nachweis, daß unter gesunden Greisen besonders die Gruppe O erheblich vermehrt vorkommt.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular evolution 4 (1975), S. 201-247 
    ISSN: 1432-1432
    Keywords: Crossing over ; Unequal Crossing over ; Gene Duplication ; Selection Relaxation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The population genetics of unequal crossing over was examined for an infinite population with random mating. The following cases were considered: 1. There is an initial portion of duplicated genes which offer the opportunity for unequal crossing over, but the primary event leading to the duplication does not occur any more (model 1a). 2. This primary event occurs with a certain (small) probability (model 1b). For both possibilities the long-term consequences for the distribution of “alleles” (i.e. the single gene, the duplicated gene, the triplicated gene etc.) were considered with the following additional assumptions: 1. No selection. 2. Selection with maximum fitness for an optimum “allele length” (i.e. number of gene repeats). 3. For model 1a, selection with general advantage of longer alleles over shorter ones was also examined. The results are briefly the following: In model 1a under assumption 1 the distribution of allele length tends with increasing generation number to a stationary state which depends on the initial allele distribution (i.e. on the initial frequency of the duplicated gene) but not on the frequency, P, of unequal crossing over; the stationary frequencies of the alleles decrease with increasing allele length. Under assumption 2 there is likewise a stationary allele distribution, but this depends on P as on the strength of selection and not on the initial allele distribution; it is concentrated more or less tightly around the optimal allele length. Under assumption 3 no stationary state seems to be reached: the mean and the standard deviation of the allele distribution increase steadily with the generation number. In model 1b under assumption 1, with certainty no stationary distribution exists. Under assumption 2 the situation is the same as that in model 1a; the stationary distribution of allele length is identical with that in model 1a for the same P and same selection strength, quite independent of the probability of the primary event. The results were discussed with respect to empirical examples in which unequal crossing over is expected to be important, for example human haptoglobins, immune globulin determining cistrons, and nucleolus organizer regions. The consequences of selection relaxation were considered.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Human genetics 〈Berlin〉 82 (1989), S. 308-312 
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary It has been suggested that the mitochondrial DNA (mtDNA) of all present-day human beings stems exclusively from one woman who lived about 200000 years ago in Africa; examination of the problem by the mathematical theory of random walks supposedly renders alternatives very unlikely. However, a statistical argument first used by Fisher indicates that this hypothesis is untenable, at least if the assumptions made by previous workers are accepted. All present-day mtDNA might go back to one individual, especially if small populations and population bottlenecks with very small numbers of reproducing individuals are assumed; nevertheless, this phase in the evolution of Homo sapiens probably dates back considerably more than 200000 years.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The arrangement of centromeres, cluster formation and association with the nucleolus and the nuclear membrane were characterized in human lymphocytes during the course of interphase in a cell-phase-dependent manner. We evaluated 3 893 cell nuclei categorized by five parameters. The centromeres were visualized by means of indirect immunofluorescent labeling with anti-centromere antibodies (ACA) contained in serum of patients with CREST syndrome. The cell nuclei were classified as G0, G1, S, G2, Gl1′ and early S′ phase by comparing microscopically identified groups of cell nuclei with flow cytometric determination of cell cycle stage of synchronized and unsynchronized lymphocyte cell cultures. Based on a discrimination analysis, a program was devised that calculated the probability for any cell nucleus belonging to the G0, G1, S, G2, G1′ and early S′ phase using only two microscopic parameters. Various characteristics were determined in the G0, S, and G2 stages. A transition stage to S phase within G1 was detected. This stage shows centromere arrangements not repeated in later cell cycles and which develop from the dissolution of centromere clusters in the periphery of the nucleus during G0 and G1. S phase exhibits various non-random centromere arrangements and associations of centromeres with the nucleolus. G1′ and early S′ phase of the second cell cycle display no characteristic centromere arrangement. The duplication of centromeres in G2 is asynchronous in two phases. For all cell phases a test for random distribution of the centromeres in the cell nucleus was performed. There is a distinct tendency for centromeres to be in a peripheral position during Go and G1; this tendency becomes weaker in S phase. Although the visual impression is a seemingly random distribution of centromeres in G2 and G1′ statistical analysis still demonstrates a significant deviation from random distribution in favor of a peripheral location. Only the early S phase of the second cell cycle shows no significant deviation from a random distribution.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract The dual center surround organization of retinal and geniculate neurons in two antagonistic subsystems B and D, having on-center or off-center receptive fields and signalling brightness or darkness respectively, has been studied by local light increments and decrements. Intensity response functions obtained by the introduction and withdrawal of small center spots either brighter or darker than a common homogeneous field are similar in a given neuron, but the phasic responses are stronger in on-center neurons than in off-center neurons. Center size increments and decrements, however, lead to equal excitations in the B- and D-system, respectively, provided that both luminance steps start from the same level and are of equal size on a linear scale. Decrementing and incrementing the surrounding luminance of the same optimal center spots lead to equal surround responses in the two subsystems if the two luminance steps terminate at the same level. This lateral activation is elicited by light decrement in the B-system and by light increment in the D-system. Center and surround responses within a given subsystem are of comparable amplitude, but generally slightly stronger responses are elicited by optimal center increments (decrements) than by the equivalent surround decrements (increments) which lead to the same spatial contrast for B-(D-) neurons. The symmetry relations between the B- and D-system and the equivalence relations between center and surround in each subsystem hold for retinal and geniculate neurons. The difference between center and surround response latencies is about 9 ms in both subsystems at the retinal and 14 ms at the geniculate level. Stimulus response functions of on- and off-center neurons are unified on the basis of linear relative luminance scales.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Biological cybernetics 64 (1990), S. 135-140 
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract Peaks in more than 5000 spike train correlograms, obtained from monkey striate cortex, were measured. Earlier work had shown qualitatively that there are frequent prominent peaks having widths in a range around 50 ms, and narrower peaks less than about 7 ms wide. Here we demonstrate that the distribution of peak widths shows a dichotomy.
    Type of Medium: Electronic Resource
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