Library

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
    Springer
    Experimental brain research 37 (1979), S. 581-593 
    ISSN: 1432-1106
    Keywords: Vestibular nuclei ; Alert monkey ; Vestibular stimulation ; Optokinetic stimulation ; Nystagmus suppression
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Single neurons were recorded in the vestibular nuclei of monkeys trained to suppress nystagmus by visual fixation during vestibular or optokinetic stimulation. During optokinetic nystagmus vestibular nuclei neurons exhibit frequency changes. With the suppression of optokinetic nystagmus this neuronal activity on average is attenuated by 40% at stimulus velocities of 40 °/s. At a stimulus velocity of 5 °/s responses are, under both conditions, close to threshold. For steps in velocity, suppression of vestibular nystagmus shortens the time constants of the decay of neuronal activity from 15–35 s to 5–9 s, while the amplitude of the response remains unchanged. The results are discussed in relation to current models of visual-vestibular interaction. These models use a feedback mechanism which normally operates during vestibular and optokinetic nystagmus. Nystagmus suppression interrupts this feedback loop.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 199 (1963), S. 918-919 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Our laboratory has been investigating the evolution of the hmoglobin molecule among the Primates. We recently received an opportunity to study the hmoglobin of two East African elephant shrews, Petrodromus sultani and Rhynchocyon chry-sopygus, species of Macroscelididae. Blood was obtained by heart ...
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 197 (1963), S. 1018-1019 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1. A typical starch gel of galago haemoglobins. The right-hand part is a photograph of the half of the gel stained with benzidine. The left-hand part is a diagram of the other half of the same gel after it was stained with amido-black. All samples except sample No. 5 are from galagos. Sample ...
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Archives of Biochemistry and Biophysics 133 (1969), S. 164-170 
    ISSN: 0003-9861
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 5
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 201 (1964), S. 510-511 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Fig. 1. Starch-gel electrophoretogram of plasma proteins from: (1) human, haptoglobin type 2-1, transferrin type CC; (2) elephant; and (3) hyrax. A is a photograph of half of the gel stained with benzidine; B is a diagram of benzidine-positive bands in A; C is a photograph of half of the gel ...
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    International Journal of Biochemistry 1 (1970), S. 322-326 
    ISSN: 0020-711X
    Keywords: Haemoglobin ; Papio sphinx haemoglobins ; mandrill haemoglobins ; multiple haemoglobins ; primate haemoglobin
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 1432-2013
    Keywords: Retina ; Receptive Fields ; Sinusoidal Stimulation ; Summation of Excitation and Inhibition ; Retina ; Receptive Felder ; Sinuslichtreizung ; Summation von Erregung und Hemmung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung 1. Aktionspotentiale von Fasern des Tractus opticus von hell adaptierten Katzen wurden stereotaktisch registriert. Die Antwort von on-Zentrum-Neuronen mit rezeptiven Feldern im Bereiche der Area centralis und paracentralis wurden registriert, die Daten mit einem Digitalrechner quantitativ analysiert. Zwei kleine Lichtpunkte von 0,22° Durchmesser und 0,15° horizontaler Distanz wurden in das rezeptive Feldzentrum projiziert, ihre Leuchtdichte sinusförmig variiert (0,5–35 Hz). Der Phasenwinkel ϕ zwischen den beiden Lichtreizen wurde in 8 Stufen zwischen 0 und 360° variiert. 2. Durch die Änderung von ϕ konnten excitatorische Prozesse (on), die von einem Reiz ausgelöst wurden, mit inhibitorischen Prozessen (off), die der andere Reiz hervorrief, überlagert werden. Die neuronale Antwort (mittlere Impulsrate $$\bar R$$ , maximale ImpulsrateR max) war von cos ϕ/2 abhängig (Gl. 4 und 6). Die mittlere neuronale Aktivierung war dazu von der Sinusfrequenz abhängig, jedoch änderte sich die relative Beziehung zwischen cos ϕ/2 und $$\bar R$$ bzw.R max nicht mit der Reizfrequenz zwischen 2 und 20 Hz. 3. Aus diesen Befunden kann geschlossen werden, daß on-excitatorische und off-inhibitorische Prozesse, die aus dem rezeptiven Feldzentrum ausgelöst werden, bis zu 20 Hz linear summiert werden. Mit diesem Verfahren kann der Amplituden-und Phasenfrequenzgang der off-Inhibition indirekt gemessen werden; er weicht nicht signifikant vom Amplituden- und Phasenfrequenzgang der on-Excitation ab, solange die Sinusfrequenz unter 15–20 Hz liegt. Die Stärke der off-Inhibition in diesem Frequenzbereich ist proportional (aber nicht notwendigerweise gleich) der Stärke der on-Excitation durch den gleichen Lichtreiz. Im Gegensatz zu der linearen Summation von on-Erregung und off-Hemmung im RF-Zentrum ist die Summation der Excitation innerhalb des RF-Zentrums im gleichen Frequenzbereich nicht linear. Diese Nichtlinearität ist in Gl. (4) und (6) durch den Gewichtsfaktorb gekennzeichnet. 4. Bei Reizfrequenzen über 20 Hz ändern sich die Phasenbeziehungen zwischen on-Excitation und off-Inhibition. Die Interaktion in diesem Frequenzbereich hängt von der Sinusfrequenz ab und kann nicht mehr durch ein einfaches lineares Modell beschrieben werden. Nahe der kritischen Flimmerfrequenz sind vermutlich Schwellenmechanismen der hauptsächliche Faktor für die nicht lineare Summation von on-Excitation und off-inhibition.
    Notes: Summary 1. Action potentials of single, myelinated optic tract fibers were recorded stereotactically in light-adapted cats (pentobarbital anaesthesia, Curarine-Flaxedil immobilisation). The response of on-center neurons whose receptive fields were within a radius of 15 degrees around the area centralis were measured and quantitatively analyzed by means of a digital computer. Two small light spots of 0.22 degree diameter and 0.15 degree horizontal distance were projected to the RF-center. The luminance of the light spots was varied sinusoidally in time (0.5 to 35 cps) and the phase angle ϕ between the two sinusoidal stimuli changed in 8 steps between 0 and 360 degrees. 2. With a gradual change in ϕ on-excitatory periods elicited by one stimulus could be superimposed on off-inhibitory periods elicited by the other light stimulus and vice versa. The neuronal response (average impulse rate $$\bar R$$ , maximal impulse rateR max) depended on cos ϕ/2 (eqs. 4 and 6). The average neuronal activation further depended on the stimulus frequency; the relative relationship between cos ϕ/2 and the neuronal activation, however, was independent of the stimulus frequency between 2 and 20 cps. 3. From these findings one can draw the conclusion that on-excitatory and off-inhibitory events interacting at the ganglion cell membrane elicited from the RF-center are summed linearly up to 20 cps. The amplitude and the frequency properties of the off-inhibition does not deviate significantly from the frequency characteristics of the on-excitation up to 15–20 cps. The amount of inhibition during the off-periods in this frequency range is proportional but not necessarily equal to the amount of excitation during the on-periods. In contrast to the linear summation of inhibition and excitation elicited from the RF-center, the summation of excitation within the RF-center in the same frequency range is non-linear. This non-linearity is represented in eqs. (4) and (6) by the weighting factorb. 4. At stimulus frequencies above 20 cps the phase relation between on-excitation and off-inhibition changes. The interaction in this frequency range is dependent on the frequency and can no longer be described by a simple linear model. Near the critical flicker frequency, threshold mechanisms are one possible cause of nonlinearity for the interaction of excitation and inhibition.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Symmetrical carbonates were formed when the corresponding carbonochloridates containing electron-withdrawing groups were converted with tertiary amines in dry solvents at room temperature. 5-Norbornene-2,3-dicarboximido carbonochloridate (1) and bis(5-norbornene-2,3-dicarboximido) carbonate (5) were used for acylation of OH groups in polymers in the presence of tertiary amines under anhydrous conditions. The influence of the amounts of 1 and 5, the kind and amount of amines, the organic solvent, the reaction time and temperature on the yield of the active carbonate 7 was investigated using bead cellulose as polymer. The reaction based on the catalysis by strongly nucleophilic amines such as 4-dimethylaminopyridine (DMAP) was optimized for preparation of acylated polymers. The formation of cross-linking and cyclic carbonates 9 and 10, respectively, was observed as a side reaction. It was shown that carbonates 9 and 10 can also be obtained as the main products of acylation. The preparation of 9 was also carried out by treating 7 with an excess of DMAP. Examples are presented for the transesterification of 7 with compounds containing OH groups. The acylated polymers were characterized by a specific titration method, UV/VIS and IR spectroscopy. The mechanism of the DMAP-catalyzed acylation of polymers is discussed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 9
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Biochemistry 33 (1994), S. 4449-4453 
    ISSN: 1520-4995
    Source: ACS Legacy Archives
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...