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  • 1
    ISSN: 1520-6041
    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
    Journal of the American Chemical Society 85 (1963), S. 243-244 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 20 (1982), S. 0 
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: In the design of ground-water heat pump systems the quantitative analysis of heat transport and heat storage is of great interest. A unified finite element approach to the transient nonlinear heat transport and heat storage problem is presented. The theory presented includes nonlinear physical properties and boundary conditions, coupled conductive and convective heat flow, freezing (phase change), and time-dependent heat input and output. The given theory is applied to two problems. The first problem is a transient study during a few years of heat storage in saturated clay. A pure conductive theory is used due to the small amount of convective water flow in clay. The second problem deals with transient heat transport in an aquifer according to coupled conduction-convection theory on a one-dimensional model problem.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1520-6041
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Bradford : Emerald
    Engineering computations 20 (2003), S. 725-740 
    ISSN: 0264-4401
    Source: Emerald Fulltext Archive Database 1994-2005
    Topics: Technology
    Notes: A numerical model is presented for the computation of unsteady two-fluid interfaces in nonlinear porous media flow. The nonlinear Forchheimer equation is included in the Navier-Stokes equations for porous media flow. The model is based on capturing the interface on a fixed mesh domain. The zero level set of a pseudo-concentration function, which defines the interface between the two fluids, is governed by a time-dependent advection equation. The time-dependent Navier-Stokes equations and the advection equation are spatially discretized by the finite element (FE) method. The fully coupled implicit time integration scheme and the explicit forward Eulerian scheme are implemented for the advancement in time. The trapezoidal rule is applied to the fully implicit scheme, while the operator-splitting algorithm is used for the velocity-pressure segregation in the explicit scheme. The spatial and time discretizations are stabilized using FE stabilization techniques. Numerical examples of unsteady flow of two-fluid interfaces in an earth dam are investigated.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Structural chemistry 1 (1990), S. 151-157 
    ISSN: 1572-9001
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract MNDO calculations have been carried out on the reactions of the electron-rich germylene L2Ge [L=(H3Si)2N] with diazo compounds, as models for the experimentally observed reactions of L2Ge [L=(Me3Si)2N]. The most stable form of the 1∶1 adduct of L2Ge with N2C(COOMe)2 is found to have a cyclic configuration resulting from a strong intramolecular interaction between the oxygen of one of the carbonyl groups and the germanium atom. Protonation of this cyclic adduct occurs at nitrogen, giving an intermediate, addition to which of nucleophiles X− provides acyclic L2Ge(X)NHN(COOMe)2, as observed experimentally. Two similar cyclic adducts are formed between L2Ge and N2C(COCH3)(COOCH3), the most stable of which provides, after a proton shift, the observed 1,3,4,2-oxadiazagermine system $$L_2 $$ . Adduct formation between Me2Si=NSiMe3 and simple Lewis bases (H2O, NH3, THF, H2CO) is calculated to be strong, but the corresponding adducts of Me2Ge=NSiMe3 are very weak: much stronger adducts are predicted for L2GeNNC(COOMe)2.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 3986-3988 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 105 (1972), S. 1399-1402 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Hindered Rotation in Silyltriazenes1H n.m.r. spectroscopic investigations of the silyltriazene Ph - N = N - N(SiMe3)2 show hindered rotation of the amino group about the N - N-single bond similar to that shown for the organyltriazene Ph - N = N - NMe2. The decrease of the hindrance of rotation by substitution of the methyl groups in Ph - N = N - NMe2 by silyl groups is explained by the difference in electronic effects of the organyl and the silyl group.
    Notes: Im Silyltriazen Ph - N = N - N(SiMe3)2 läßt sich ähnlich wie im Organyltriazen Ph - N = N - NMe2 1H-NMR-spektroskopisch gehinderte Rotation der Aminogruppe um die N - N-Einfachbindung nachweisen. Die Abnahme der Rotationshinderung beim Übergang von Organyl- zu Silyltriazenen läßt sich durch unterschiedliche elektronische Effekte der Organyl- und Silylgruppen deuten.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 117 (1984), S. 2886-2899 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Partially Substituted Tetrazenes (Me3E)nN4H4 - n (E = Si, Ge, Sn): Preparation, Characterization, and Thermolysis1)Partially substituted tetrazenes (Me3E)nN4H4 - n (E = Si, Ge, Sn) can be prepared by protolysis of higher substituted tetrazenes (Me3E)oN4H4 - o (O 〉 n) or by silylation, germylation, or stannylation of lower substituted tetrazenes (Me3E)mN4H4 - m (m 〈 n). The obtained tetrazenes (Tab. 1) are colorless compounds; they have 2-tetrazene constitution, and trans-tetrazene configuration. The tetrazene (Me3Si)2N  -  N = N  -  NHX (X = H or GeMe3) isomerize by heating in dilute solution into (Me3Si)XN  -  N = N  -  NH(SiMe3). The thermolysis of (Me3Si)2N  -  N = N  -  NH(SiMe3) leads mainly to Me3SiN3 and (Me3Si)2NH (t140°C1/2140°C = 3/4 h), of (Me3Si)2N  -  N = NH2 to Me3SiN3 and Me3SiNH2 (concentrated solution; t140°C1/240°C ca. 1/4 h), and of (Me3Si)HN  -  N = N  -  NH(SiMe3) to N2 and (Me3Si)2N  -  NH2 (dilute solution; t140°C1/2140°C 〉 1 h) or to NH3 and (Me3Si)2NH (concentrated solution; t140°C1/2 〈 1 h).
    Notes: Teilsubstituierte Tetrazene (Me3E)nN4H4 - n (E = Si, Ge, Sn) können durch Protolyse höher substituierter Tetrazene (Me3E)oN4H4 - o (O 〉 n) oder durch Silylierung, Germylierung bzw. Stannylierung niedriger substituierter Tetrazene (Me3E)mN4H4 - m (m 〈 n) dargestellt werden. Die gewonnenen Tetrazene (Tab 1) sind farblose Verbindungen: sie haben 2-Tetrazen-Konstitution und trans-Tetrazen-Konfiguration. Die Tetrazene (Me3Si)2N  -  N = N  -  NHX (X = H oder GeMe3) isomerisieren sich in verdünnter Lösung beim Erhitzen in (Me3Si)XN  -  N = N  -  NH(SiMe3). Die Haupttermolyse von (Me3Si)2N  -  N = N  -  NH(SiMe3) führt zu Me3SiN3 und (Me3Si)2NH (t140°C1/2140°C = 3/4 h), von (Me3Si)2 (Me3Si)2N  -  N = NH2 zu Me3SiN3 und Me3SiNH2 (konzentrierte Lösung; t140°C1/240°C ca. 1/4 h) und von (Me3Si)HN  -  N = N  -  NH(SiMe3) zu N2 und (Me3Si)2N  -  NH2 (verdünnte Lösung; t140°C1/2140°C 〉 1 h) oder zu NH3t140°C und (Me3Si)2NH (Konzentrierte Lösung; t140°C1/2140°C 〈 1 h).
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 104 (1971), S. 3176-3190 
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On Derivatives of Hydrazine, 2 Preparation and some Properties of Tetrasubstituted Hydrazines (Me3E)2N - N(EMe3)2 (E = C, Si, Ge, Sn)Reaction of hydrazine, N2H4, with chlorides Me3ECl (E = C, Si, Ge, Sn) or amines Me3SiNMe2 and reaction of hydrazides (Me3E)mN2HnLip (m+n+p = 4) with Me3ECl yield easily sublimable, high melting and melting and thermally stable hydrazines (Me3E′)(Me3E″)N - N(E‴Me3)-(E‴′Me3) with similar (E = E′ = E″ = E‴ = E‴′) and different ligands Me3E (for example: E′ = C, E″ = Si, E‴ = Ge, E‴′ = Sn). Only hydrazines with trimethylstannyl groups are easily solvolized and oxidized.
    Notes: Durch Reaktion von Hydrazin, N2H4, mit Chloriden Me3ECl (E = C, Si, Ge, Sn) sowie Aminen Me3SiNMe2 bzw. durch Reaktion von Hydraziden (Me3E)mN2HnLip (m+n+p = 4) mit Me3ECl konnten gleichartig substituierte (E = E′ = E″ = E‴ = E‴′) sowie gemischt substituierte Hydrazine (Me3E′)(Me3E″)N - N(E‴Me3) (E‴′Me3) (z. B. E′ = C, E″ = Si, E‴ = Ge, E‴′ = Sn) als leicht sublimierbare, hochschmelzende und thermisch sehr stabile Verbindungen gewonnen werden. Nur die trimethylstannylgruppen-haltigen Hydrazine solvolysieren leicht und werden von Oxydationsmitteln rasch angegriffen.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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