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  • 1965-1969  (11)
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  • 1
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterosesquifulvalene mit Schwefel oder Sauerstoff als Heteroatom lassen sich z.B. durch Kondensation von Cyclopentadienen und Thiopyronen bzw. Pyronen mit Acetanhydrid herstellen. N-haltige Heterosesquifulvalene sind aus diesen durch O,N-Austausch zugänglich. Der Grundzustand aller dieser Verbindungen wird vorwiegend durch die unpolare Grenzformel bestimmt.
    Additional Material: 2 Ill.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 0570-0833
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 0570-0833
    Keywords: Sesquifulvalenes ; Fulvalene ; Heterocycles ; Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Heterosesquifulvalenes containing sulfur or oxygen as hetero atom may be prepared, e.g., by condensation of cyclopentadienes with thiopyrones or pyrones in acetic anhydride. Heterosesquifulvalenes containing nitrogen can be obtained from the oxygen compounds by O,N-exchange. The ground state of all these compounds is determined mainly by the nonpolar resonance formula.
    Additional Material: 1 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Cell & tissue research 93 (1968), S. 525-529 
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die Doppelbrechung der Cornealinse und der Rhabdomere im Facettenauge von Calliphora erythrocephala (MEIG.) wurde untersucht. Der Gangunterschied wurde in Schnitten parallel zur Ommatidienachse gemessen. Die Differenz der Brechungsindices — die Doppelbrechung — zwischen dem außerordentlichen und dem ordentlichen Strahl ist (n e − n o) = 0,0012. Die Cornealinse ist ein einachsig, negativ doppelbrechender Kristall. Die optische Achse verläuft parallel zur Ommenachse. Die Kristallkegel und die Rhabdomerenkappen sind isotrop. Die Rhabdomere selbst sind anisotrop. Der Gangunterschied in den Sehstäben 1–6 (50 nm) scheint größer zu sein als im siebenten Rhabdomer (18 nm). Die Rhabdomere der siebenten und achten Sehzelle liegen jedoch genau hintereinander in einer Achse und dieTubuli sind zueinander senkrecht orientiert. Polarisationsoptisch gesehen liegen die beiden Sehstäbe in Subtraktionsstellung. Die Doppelbrechung der Rhabdomere ist (n e − n o) = − 0,0004.
    Notes: Summary The birefringency of the corneal lens and of the rhabdomeres in the compound eye of Calliphora erythrocephala (MEIG.) was investigated. The phase difference was measured in sections parallel to the axis of the ommatidium. The difference of the refractive indices — the birefringency — between the extraordinary and the ordinary beam is (n e − n o) = −0,0012. The corneal lens is a negative birefringent crystal. Its optical axis runs parallel to the axis of the ommatidium. The crystalline cones and the extracellular distal processes of the rhabdomeres are isotropic. The rhabdomeres are anisotropic. The phase difference along the rhabdomeres No. 1–6 (50 nm) seems to be higher than in the seventh (18 nm). As rhabdomere No. 8 is situated beneath rhabdomere No. 7 and the tubules of these two rhabdomeres are perpendicularly orientated, the phase differences are partially cancelled. The birefringency of the rhabdomeres is (n e − n o) = −0,0004.
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    ISSN: 0044-8249
    Keywords: Chemistry ; General Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 62 (1969), S. 61-74 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Die optischen Eigenschaften des Ommatidiums im Facettenauge des Leuchtkäferchens Phausis splendidula L. wurden untersucht. 1. Der dioptrische Apparat, bestehend aus Cornealinse und Processus corneae, setzt sich aus Schichten unterschiedlicher optischer Dichte zusammen. Die höchste Brechzahl wurde in der Mitte der Linse und des Pseudoconus gefunden (n e=1,520; Abb. 4a). Die optische Dichte nimmt zu den Rändern hin ab (n e=1,356). Die Cornealinse ist eine homogene, sphärische Linse; der Pseudoconus ist ein Linsenzylinder (Abb. 5). 2. Der Brechungsindex des Conus (n e=1,349) ist höher als der der Pigmentzellen (n e=1,340). Der Conus wirkt als Lichtleiter; der Winkel der Totalreflexion αT beträgt 83,4°. Die optische Dichte der proximalen Rhabdome beträgt n e=1,351. 3. In das Ommatidium einfallende Parallelstrahlen laufen zu einem Punkt der Brennebene, die innerhalb des Pseudoconus liegt, und verlassen diesen wieder als parallele Strahlen (Abb. 5). Exners Theorie über den Strahlenverlauf im dioptrischen Apparat konnte bestätigt werden. Der Öffnungswinkel des einzelnen Ommatidiums ergibt sich zu 8°. 4. Da die Coni als Lichtleiter wirken und auch, in dunkel-adaptierten Augen nicht das gesamte Irispigment zwischen die Pseudoconi wandert (Horridge, 1968), ist es fraglich, ob eine Superposition der von mehreren Ommen entworfenen Bilder überhaupt möglich ist.
    Notes: Summary The optical properties of the ommatidium in the compound eye of the firefly Phausis splendidula L. were investigated. 1. The dioptric apparatus — corneal lens and processus corneae — is composed of layers with different optical density. The highest refractive index is found in the centre of the lens and of the pseudocone (n e=1.520; Kg. 4a). The optical density decreases to the peripheral zone (n e=1.356). The corneal lens is a homogeneous spherical lens, the pseudocone is a lens cylinder (Fig. 5). 2. The refractive index of the cone is n e=1.349, and that of the pigment cells is n e=1.340. The cone acts as a wave guide, the angle of total reflection αT is 83.4°. The optical density of the proximal rhabdoms (Fig. 1) is n e=1.351. 3. Parallel rays entering the facet of an ommatidium converge to one point in the focal plane which lies inside the pseudocone. They leave the process of the corneal lens again as parallel rays (Fig. 5). The way of light beams through the dioptric apparatus corresponds to the theory of Exner (1891). The width of the visual field of a single ommatidium is about 8°. 4. The coni act as wave guides, the whole irispigment does not migrate between the pseudoconi in the dark-adapted eye (Horridge, 1968). Light leaving an ommatidium is captured by the pigment. For these reasons it is uncertain whether a superposition of several pictures, each formed by one ommatidium, occurs.
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