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  • Engineering General  (5)
  • Cell & Developmental Biology  (3)
  • Organic Chemistry  (3)
  • 1990-1994  (11)
  • 1935-1939
  • 1991  (11)
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  • 1990-1994  (11)
  • 1935-1939
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  • 1
    Digitale Medien
    Digitale Medien
    Distribution of filamentous actin in and around spermatids and in spermatozoa of Australian conilurine rodents (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    Molecular Reproduction and Development 30 (1991), S. 369-384 
    Details
    ISSN: 1040-452X
    Schlagwort(e): F-actin ; Sperm head ; Australian rodents ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie
    Notizen: The distribution of filamentous actin around the maturing sperm head and in spermatozoa of four species of Australian conilurine rodents was investigated at the light and electron microscopic levels. Similar results were obtained for all the species studied. Mechanically isolated spermatids had NBD-phallacidin-positive longitudinal bands of fluorescence over the dorsolateral surface and, in late spermatids, bands of bright fluorescence passed perpendicularly from the dorsal convex to ventral concave surface. TEM observations indicated that these regions corresponded to filaments of ectoplasmic specializations and granular filamentous material around the tubulobulbar complexes, respectively. In testicular and cauda spermatozoa NBD-phallacidin fluorescent material was present in the two ventral processes that extended from the upper concave surface of the sperm head; also fainter material occurred along the concave border and as a dorsocaudal spur. Its distribution was identical for testicular and cauda spermatozoa. TEM of late spermatids showed that in the ventral process closest to the apical hook there were between 170 and 245 filaments, which attached to the inner surface of the postacrosomal dense lamina; in the more caudal ventral process about 70 filaments occurred. No filaments were, however, visible in the mature spermatozoon but, after immunocytochemical labelling for actin, deposition of gold particles was evident over ventral processes of both late spermatids and cauda spermatozoa. Within the female tract these ventral processes made contact with the zona matrix and were taken into the egg cytoplasm unchanged in morphology. The possible functional significance of the filamentous actin in these structures is discussed.
    Zusätzliches Material: 39 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/mrd.1080300412
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  • 2
    Digitale Medien
    Digitale Medien
    Transonic viscous-inviscid interaction by a finite element method (1991)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 13 (1991), S. 309-319 
    Details
    ISSN: 0271-2091
    Schlagwort(e): Viscous-inviscid interaction ; Shock wave-boundary layer interaction ; Boundary layers ; Finite element method for flow problems ; Zonal methods ; Choked viscous flows ; Stream function-vorticity formulation ; Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Notizen: A method is outlined for solving two-dimensional transonic viscous flow problems, in which the velocity vector is split into the gradient of a potential and a rotational component. The approach takes advantage of the fact that for high-Reynolds-number flows the viscous terms of the Navier-Stokes equations are important only in a thin shear layer and therefore solution of the full equations may not be needed everywhere. Most of the flow can be considered inviscid and, neglecting the entropy and vorticity effects, a potential model is a good approximation in the flow core. The rotational part of the flow can then be calculated by solution of the potential, streamfunction and vorticity transport equations. Implementation of the no-slip and no-penetration boundary conditions at the walls provides a simple mechanism for the interaction between the viscous and inviscid solutions and no extra coupling procedures are needed. Results are presented for turbulent transonic internal choked flows.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/fld.1650130304
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  • 3
    Digitale Medien
    Digitale Medien
    Finite element solution of the incompressible Navier-Stokes equations by a Helmholtz velocity decomposition (1991)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 13 (1991), S. 135-144 
    Details
    ISSN: 0271-2091
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Maschinenbau
    Notizen: Finite element solution methods for the incompressible Navier-Stokes equations in primitive variables form are presented. To provide the necessary coupling and enhance stability, a dissipation in the form of a pressure Laplacian is introduced into the continuity equation. The recasting of the problem in terms of pressure and an auxiliary velocity demonstrates how the error introduced by the pressure dissipation can be totally eliminated while retaining its stabilizing properties. The method can also be formally interpreted as a Helmholtz decomposition of the velocity vector.The governing equations are discretized by a Galerkin weighted residual method and, because of the modification to the continuity equation, equal interpolations for all the unknowns are permitted. Newton linearization is used and at each iteration the linear algebraic system is solved by a direct solver. Convergence of the algorithm is shown to be very rapid. Results are presented for two-dimensional flows in various geometries.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/fld.1650130202
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  • 4
    Digitale Medien
    Digitale Medien
    Solution of Helmholtz equation by Trefftz method (1991)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 32 (1991), S. 63-78 
    Details
    ISSN: 0029-5981
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Mathematik , Technik allgemein
    Notizen: The application of the Trefftz method for calculating wave forces on offshore structures is presented. Indirect and direct formulations using complete and non-singular systems of Trefftz functions for the Helmholtz equation are posed in this paper. An effective technique using different interpolation functions for the velocity potential and wave force are suggested to improve the computational accuracy of the wave force. The numerical examples show that the present method is highly efficient and accurate.
    Zusätzliches Material: 7 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nme.1620320105
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  • 5
    Digitale Medien
    Digitale Medien
    Na+-dependent, active nucleoside transport in S49 mouse lymphoma cells and loss in AE-1 mutant deficient in facilitated nucleoside transport (1991)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 46 (1991), S. 54-59 
    Details
    ISSN: 0730-2312
    Schlagwort(e): Na+/nucleoside cotransport ; AE-1 nucleoside transport mutant ; S49 mouse lymphoma cells ; Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Chemie und Pharmazie , Medizin
    Notizen: S49 murine lymphoma cells were examined for expression of various nucleoside transport systems using a non-metabolized nucleoside, formycin B, as substrate. Nitrobenzylthioinosine (NBTI)-sensitive, facilitated transport was the primary nucleoside transport system of the cells. The cells also expressed very low levels of NBTI-resistant, facilitated nucleoside transport as well as of Na+-dependent, concentrative formycin B transport. Concentrative transport was specific for uridine and purine nucleosides, just as the concentrative nucleoside transporters of other mouse and rat cells. A nucleoside transport mutant of S49 cells, AE-1, lacked both the NBTI-sensitive, facilitated and Na+-dependent, concentrative formycin B transport activity, but Na+-dependent, concentrative transport of α-aminoisobutyrate was not affected.
    Zusätzliches Material: 5 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jcb.240460109
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  • 6
    Digitale Medien
    Digitale Medien
    Ultrastructure of free neuromasts of Bathygobius fuscus (gobiidae) and canal neuromasts of Apogon cyanosoma (apogonidae) (1991)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 209 (1991), S. 111-120 
    Details
    ISSN: 0362-2525
    Schlagwort(e): Life and Medical Sciences ; Cell & Developmental Biology
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Biologie , Medizin
    Notizen: Light and electron microscopic observations were made on the lateral line organs of the free neuromasts of the goby Bathygobius fuscus and the canal neuromasts of the cardinal fish Apogon cyanosoma. As in other lateral line systems, each neuromast consists of hair cells, supporting cells and mantle supporting cells, the whole being covered by a cupula. In B. fuscus the free neuromasts are mounted on papillae and have hair cells with stereocilia up to 2.5 μm long and a single kinocilium at least 25 μm long. Each neuromast is covered by a vane-like cupula that can be divided into two regions. The central region over the sensory area contains columns of myelin-like figures. These figures are absent from the outer region covering the mantle. The canal neuromasts of A. cyanosoma are diamond-shaped with up to 1,500 hair cells. The cupula is unusual in having a channel that lies over the sensory region. The hair cells have up to 45 stereocilia, the tallest reaching 2.5 μm, and a kinocilium at least 5 μm long. Tip links are shown for the first time between rows of stereocilia of the hair cells of lateral line neuromasts. The presence of tip links has now been demonstrated for all acousticolateral hair cell systems.
    Zusätzliches Material: 4 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jmor.1052090109
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  • 7
    Digitale Medien
    Digitale Medien
    Pyryliumverbindungen. 45 [1]. 4-Aroyl-fluorene aus 2,4,6-Triaryl-pyryliumsalzen und Indan-1-on via 2-(5-Oxo-pent-2-en-1-yliden)-indan-1-one (1991)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 717-726 
    Details
    ISSN: 0021-8383
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Pyrylium Compounds. 45. 4-Aroyl-fluorenes from 2,4,6-Triaryl-pyrylium Salts and Indan-1-one via 2-(5-Oxo-pent-2-en-1-yliden)-indan-1-ones2,4,6-Triarylpyrylium salts 1 react with indan-1-one in the presence of an appropriate buffer system (e.g. piperidine acetate, triethylamine/acetic acid, triethylamine or sodium acetate) to yield the 2-(1,3,5-triaryl-5-oxo-pent-2-en-1-yliden)-indan-1-ones 2. For the reaction medium aliphatic alcohols (methanol, ethanol), dipolar aprotic solvents (acetonitrile) or chlorinated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride) can be used. On treating 2 with sodium methanolate in methanol, a cyclization reaction occurs giving rise to the 4-aroyl-1,3-diaryl-fluorenes 3. As by-products 1,3-diaryl-fluorenes 8 (e.g. 1,3-diphenyl-fluorene) are formed. - I.r., n.m.r. and u.v. spectroscopic data of the novel compounds 2 and 3 are reported.
    Zusätzliches Material: 3 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/prac.19913330506
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  • 8
    Digitale Medien
    Digitale Medien
    Pyryliumverbindungen. 46. 4-Aroyl-fluoren-9-one durch Ringtransformation von 2,4,6-Triaryl-pyryliumsalzen mit Indan-1,3-dion (1991)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 333 (1991), S. 727-732 
    Details
    ISSN: 0021-8383
    Schlagwort(e): Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: Pyrylium Compounds. 46. 4-Aroyl-fluoren-9-ones by Ring Transformation of 2,4,6-Triarylpyrylium Salts with Indan-1,3-dioneThe ring transformation of 2,4,6-triarylpyrylium salts 1 with indan-1,3-dione in the presence of a condensing agent such as piperidine acetate, triethylamine/acetic acid, triethylamine or sodium acetate leads to 4-aroyl-1,3-diaryl-fluoren-9-ones 6. As reaction medium aliphatic alcohols (methanol, ethanol), dipolar aprotic solvents (acetonitrile, dimethylformamide) or chlorinated hydrocarbons (methylene chloride, chloroform) can be used. The structure of the novel compounds 6 was confirmed by spectroscopic methods as well as by independent synthesis of the fluorenone 6a.
    Zusätzliches Material: 1 Tab.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/prac.19913330507
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  • 9
    Digitale Medien
    Digitale Medien
    Novel photocycloadditions of electron-deficient nitrones to 2-methyl-2-butene (1991)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1991 (1991), S. 513-517 
    Details
    ISSN: 0170-2041
    Schlagwort(e): Nitrones, electron-deficient ; Oxaziridines ; Dipolarophiles ; [3+2]Photocycloadditions ; Oxazolidines ; Chemistry ; Organic Chemistry
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Chemie und Pharmazie
    Notizen: In Order to decrease the ground state reactivity and increase their potential for [3+2] cycloadditions, cyano- and methoxy-carbonyl-substituted nitrones 1a and 1b, respectively, were prepared and irradiated in the presence of electron-rich alkenes such as 2 to afford the corresponding oxazolidines in which th oxygen atom becomes attached to the least substituted terminus of the olefin and nitrogen attaches to the more highly substituted counterpart. While the oxazolidines 12a and 12b obtained from 1b, via the intermediacy of oxaziridine(s) 15 and subsequent N—O bond scission, are isolated and characterized, the oxazolidin(s) 18 formed bny cyclization of 1a are more labile and may undergo ionization to the stabilized oxazolinium ion 19 followed by nucleophilic attack by cyanide ion with accompanying ring opening to afford 6. A sequential diradical mechanism is proposed to rationalize the formation of the observed photoproducts 5 and 6.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/jlac.199119910194
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  • 10
    Digitale Medien
    Digitale Medien
    Implementation of hierarchical single surface δ0 and δ1 models in finite element procedure (1991)
    New York, NY [u.a.] : Wiley-Blackwell
    International Journal for Numerical and Analytical Methods in Geomechanics 15 (1991), S. 649-680 
    Details
    ISSN: 0363-9061
    Schlagwort(e): Engineering ; Engineering General
    Quelle: Wiley InterScience Backfile Collection 1832-2000
    Thema: Architektur, Bauingenieurwesen, Vermessung , Geologie und Paläontologie
    Notizen: Hierarchical single surface (HISS) δ0 and δ1 models are briefly discussed. An algorithm for the implementation of δ0 and δ1 models in a finite element code and the associated subroutines, written in FORTRAN 77, are presented. The algorithm is general and can be adopted for other computer codes with minor changes. Detailed steps and subroutines are included for easy implementation of the models in specific codes. Two example problems are also presented to enable the user to verify the implementation.
    Zusätzliches Material: 9 Ill.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1002/nag.1610150904
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