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  • Engineering General  (4)
  • Organic Chemistry  (4)
  • Cell & Developmental Biology
  • 1990-1994  (10)
  • 1935-1939
  • 1990  (10)
Collection
Keywords
Publisher
Years
  • 1990-1994  (10)
  • 1935-1939
Year
  • 1
    Electronic Resource
    Electronic Resource
    Morphological changes in the oocyte and its surrounding vestments during in vivo fertilization in the dasyurid marsupial sminthopsis crassicaudata (1990)
    New York, NY : Wiley-Blackwell
    Journal of Morphology 204 (1990), S. 177-196 
    Details
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This light and transmission electron microscopical study shows that the first polar body is given off before ovulation and that part of its cell membrane and that of the surrounding oocyte have long microvilli at the time of its ejection. Several layers of cumulus cells initially surround the secondary oocyte and first polar body, but the ovulated oocytes in the oviducts in the process of being fertilized do not have cumulus cells around them. Partly expelled second polar bodies occur in the oviduct; they are elongated structures that lack organelles and have electron-dense nuclei. A small fertilization cone appears to form around the sperm tail at the time of sperm entry into the egg and an incorporation cone develops around the sperm head in the egg cytoplasm. In three fertilized eggs a small hole was seen in the zona, which was presumably formed by the spermatozoon during penetration. Cortical granules, present in ovarian oocytes, are not seen in fertilized tubal or uterine eggs; release of their contents probably reduces the chances of polyspermy, although at least one polyspermic fertilized egg was seen and several other fertilized eggs had spermatozoa within the zona pellucida. In the zygote the pronuclei come to lie close together, but there was no evidence of fusion. A “yolk mass,” which becomes eccentric before ovulation, is extruded by the time the two-cell embryos are formed, but many vacuoles remain in the non-yolky pole of the egg. A shell membrane of variable thickness is present around all uterine eggs but its origin remains undetermined.
    Additional Material: 51 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jmor.1052040207
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  • 2
    Electronic Resource
    Electronic Resource
    Finite element solution of the Navier-Stokes equations by a velocity-vorticity method (1990)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 11 (1990), S. 661-675 
    Details
    ISSN: 0271-2091
    Keywords: Finite elements ; Navier-Stokes ; Velocity-vorticity ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A velocity-vorticity formulation of the Navier-Stokes equations is presented as an alternative to the primitive variables approach. The velocity components and the vorticity are solved for in a fully coupled manner using a Newton method. No artificial viscosity is required in this formulation. The pressure is updated by a method allowing natural imposition of boundary conditions. Incompressible and subsonic results are presented for two-dimensional laminar internal flows up to high Reynolds numbers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650110511
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  • 3
    Electronic Resource
    Electronic Resource
    Application of the Trefftz method in plane elasticity problems (1990)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 30 (1990), S. 1147-1161 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: Direct and indirect approximations using sets of non-singular, complete Trefftz functions, i.e. the complete systems of solutions, have been successfully applied to harmonic problems.1 In this paper, the procedure is applied to a more complex situation - plane elasticity problems.The examples show that the present method can avoid the difficulties relating to singular integration and has good accuracy compared with traditional boundary elements.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620300605
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  • 4
    Electronic Resource
    Electronic Resource
    Finite element solution of the Navier-Stokes equations by a velocity-vorticity method (1990)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 10 (1990), S. 461-475 
    Details
    ISSN: 0271-2091
    Keywords: Finite elements ; Navier-Stokes ; Velocity-vorticity ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A velocity-vorticity formulation of the Navier-Stokes equations is presented as an alternative to the primitive variables approach. The velocity components and the vorticity are solved for in a fully coupled manner using a Newton method. No artificial viscosity is required in this formulation. The pressure is updated by a method allowing natural imposition of boundary conditions. Incompressible and subsonic results are presented for two-dimensional laminar internal flows up to high Reynolds numbers.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650100408
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  • 5
    Electronic Resource
    Electronic Resource
    Mycoplasma contamination alters 2′-deoxyadenosine metabolism in deoxycoformycin-treated mouse leukemia cells (1990)
    New York, N.Y. : Wiley-Blackwell
    Journal of Cellular Biochemistry 43 (1990), S. 161-172 
    Details
    ISSN: 0730-2312
    Keywords: deoxyadenosine metabolism ; adenosine phosphorylase ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Deoxycoformycin-treated P388 and L1210 mouse leukemia cells salvage 2′-deoxyadenosine from the medium only inefficiently, because deoxyadenosine deamination is blocked and its phosphorylation is limited by feedback controls. Mycoplasma contamination at a level that had no significant effect on the growth of the cells increased the salvage of deoxyadenosine 〉10 fold over a 90 min period of incubation at 37°C, but in this case deoxyadenosine was mainly incorporated into ribonucleotides and RNA via adenine formed from deoxyadenosine by mycoplasma adenosine phosphorylase. Deoxyadenosine was an efficient substrate for this enzyme, in contrast to 2′, 3′-dideoxyadenosine which was not phosphorolyzed. Mycoplasma infection was confirmed by the presence of uracil phosphoribosyltransferase activity and by culture isolation. The contaminant has been identified as Mycoplasma orale. Mycoplasma infection had no effect on the deamination and phosphorylation of deoxyadenosine and adenosine, on the salvage of hypoxanthine and adenine, or on the degradation of dAMP and dATP by the cells or on their acid and alkaline phosphatase activities.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jcb.240430207
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  • 6
    Electronic Resource
    Electronic Resource
    Tetrazolverbindungen. 5. Synthese und Umaminierung von Enaminoketonen der Tetrazolreihe (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 977-994 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Tetrazole Compounds. 5. Synthesis and Transamination of Enamino Ketones of the Tetrazole SeriesTetrazole-5-acetaldehyde enamines 5 react with aliphatic and aromatic carboxylic acid chlorides in the presence of an auxiliary base (e.g. pyridine or triethylamine) to give tetrazolylsubstituted enamino ketones 6. The latter can be modified by acid-catalyzed transamination with secondary aliphatic amines (e.g. diethylamine, pyrrolidine, piperidine, morpholine, hexamethylene imine) yielding 5-(1-acyl-2-dialkylamino-vinyl)-1-aryl-1 H-tetrazoles 7. The analogue transamination of 6 with primary alkyl, aralkyl, and aryl amines results in corresponding secondary enamino ketones 8, which exist in solution as an equilibrium mixture of the Z and E form. Acylation of secondary tetrazole-5-acetaldehyde enamines 9 does not lead to 8, but to the isomeric N-acyl derivatives 10. - Characteristic 1H-n.m.r., u.v., and i.r. spectroscopic data of the novel products are reported.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320615
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  • 7
    Electronic Resource
    Electronic Resource
    Substituierte 2-Amino-thiazole aus α-Thiocyanato-acetophenonen und DialkylaminenHerrn Prof. Dr. K. Gewald mit den besten Wünschen zum 60. Geburtstag gewidmet (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 453-460 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituted 2-Amino-thiazoles from α-Thiocyanato-acetophenones and Dialkylaminesα-Thiocyanato-acetophenones 1 react with dialkylammonium salts of weak acids (acetates, propionates, benzoates) to give 2-dialkylamino-4-aryl-thiazoles 4. As reaction medium aliphatic alcohols (methanol, ethanol), dipolar-aprotic solvents (acetonitrile, dimethylformamide, dimethyl sulphoxide) or chlorinated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride) can be used. In comparison to known methods for the preparation of the thiazoles 4 the synthesis via α-thiocyanato-acetophenones 1 has the advantage of the simpler accessible starting compounds. - I.r., u.v., n.m.r. and mass spectroscopic data of the thiazoles 4 are reported.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320405
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  • 8
    Electronic Resource
    Electronic Resource
    2-Dialkylamino-thiazolin-4-one aus α-Thiocyanato-carbonsäurederivatenHerrn Prof. Dr. G. Zimmermann mit den besten Wünschen zum 60. Geburtstag gewidmet (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 540-546 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 2-Dialkylamino-thiazolin-4-ones from α-Thiocyanato-carboxylic Acid Derivativesα-Thiocyanato-acetic acid esters 1a-c or amide 1d react with dialkylamine salts of weak acids to give 2-dialkylamino-thiazolin-4-ones 2a-f. The reaction can be performed using aliphatic alcohols, dipolar aprotic solvents or halogenated hydrocarbons as reaction medium or by heating the educts at 90°C without any solvent. According to the latter method, the 5-substituted thiazolinones 2g, h are obtained from α-thiocyanatopropionic acid ethyl ester (1d) or α-thiocyanato-phenylacetic acid ethyl ester (1e) and dimethylamine acetate. - I.r., u.v. and n.m.r. data of the thiazolinones 2 are reported.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320419
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  • 9
    Electronic Resource
    Electronic Resource
    Substituierte N,N′-Bis(thiazol-2-yl)-diaminoalkane aus α-Thiocyanato-acetophenonen und N,N′-Dialkyl-diamino-alkanen (1990)
    New York, NY : Wiley-Blackwell
    Journal für Praktische Chemie/Chemiker-Zeitung 332 (1990), S. 723-730 
    Details
    ISSN: 0021-8383
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Substituted N,N′-Bis(thiazol-2-yl)-diaminoalkanes from α-Thiocyanato-acetophenones and N,N′-Dialkyl-diaminoalkanesα-Thiocyanato-acetophenones 1 react with N,N′-dialkyl-diaminoalkanes 2 in the presence of an appropriate weak acid (acetic acid, propionic acid, benzoic acid) to give the hitherto unknown N,N′-dialkyl-N,N′-bis(4-aryl-thiazol-2-yl)-diaminoalkanes 3. As reaction medium aliphatic alcohols (ethanol, methanol), halogenated hydrocarbons (methylene chloride, chloroform, carbon tetrachloride) or dipolar-aprotic solvents (acetonitrile, dimethylformamide) can be used. - I.r., u.v., n.m.r. and mass spectroscopic data of the novel bisthiazoles 3 are reported.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/prac.19903320522
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  • 10
    Electronic Resource
    Electronic Resource
    A numerical integration scheme for finite element method based on symbolic manipulation (1990)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 29 (1990), S. 1539-1549 
    Details
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: This paper is concerned with the improvement of the efficiency and accuracy of the usual numerical integration procedures for the finite element method. A modified numerical integration scheme based on both the symbolic manipulation system and the numerical integration formula is proposed. Its efficiency for the integration of complicated rational or irrational expressions is demonstrated through several numerical examples. To verify its effectiveness in the calculation of the finite element stiffness matrix, a simple numerical example is also presented.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/nme.1620290711
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