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  • 1
    Electronic Resource
    Electronic Resource
    Determination of bond distances and bond angles by solid-state nuclear magnetic resonance. Carbon-13 and nitrogen-14 NMR study of glycine (1981)
    s.l. : American Chemical Society
    Journal of the American Chemical Society 103 (1981), S. 2534-2539 
    Details
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ja00400a008
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  • 2
    Electronic Resource
    Electronic Resource
    Sensitivity analysis and optimization for a head movement model (1981)
    Springer
    Biological cybernetics 41 (1981), S. 33-45 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract A sixth order nonlinear model for horizontal head rotations in humans is analyzed using an extended parameter sensitivity analysis and a global optimization algorithm. The sensitivity analysis is used in both the direct sense, as a model fitting tool, and in the indirect sense, as a guide to experimental design. Resolution is defined in terms of the sensitivity table, and is used to interpret the sensitivity results. Using sensitivity analyses, the head and eye movement systems are compared and contrasted. Controller signal parameters are the most influential. Their variations and effects on head movement trajectories and accelerations are investigated, and the conclusions are compared with clinical neurological findings. The global optimization algorithm, in addition to automating the fitting of various types of data, is combined with time optimality theory to give theoretical time-optimal inputs to the model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01836125
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  • 3
    Electronic Resource
    Electronic Resource
    Simulation of head movement trajectories: model and fit to main sequence (1981)
    Springer
    Biological cybernetics 41 (1981), S. 19-32 
    Details
    ISSN: 1432-0770
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Computer Science , Physics
    Notes: Abstract A sixth order nonlinear model for horizontal head rotations in humans is presented and investigated using experimental results on head movement trajectories and neck muscle EMG. The controller signals, structured in accordance with time optimal control theory, are parameterized, and controller signal parameter variations show a dominating influence on different aspects of the head movement trajectory. The model fits the common head acceleration types over a wide range of amplitudes, and also less common (dynamic overshoot) trajectories.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01836124
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  • 4
    Electronic Resource
    Electronic Resource
    DETERMINISTIC MODELS FOR PREDICTING RESIDENTIAL WATER CONSUMPTION (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 17 (1981), S. 0 
    Details
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : Forecasts of future urban water demand traditionally have been made by the projection of historic trends in per capita consumption and population. This paper outlines the use of two deterministic models to forecast the residential component of urban water demand. The models incorporate specific representation of the activities which result in water consumption at each residence. Predictions of water use can then be made by modeling the changes expected in the number of these activities and the consumption for each such activity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1752-1688.1981.tb01940.x
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  • 5
    Electronic Resource
    Electronic Resource
    ACTIVE HEAD ROTATIONS AND EYE-HEAD COORDINATION (1981)
    Oxford, UK : Blackwell Publishing Ltd
    Annals of the New York Academy of Sciences 374 (1981), S. 0 
    Details
    ISSN: 1749-6632
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Natural Sciences in General
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-6632.1981.tb30899.x
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  • 6
    Electronic Resource
    Electronic Resource
    Two-lifetime model calculations of the quantum interference dominated transverse magnetoresistance of magnesium (1981)
    Springer
    Journal of low temperature physics 45 (1981), S. 531-574 
    Details
    ISSN: 1573-7357
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The magnetoresistance of extremely pure, strain-free magnesium is dominated by the transport properties of a narrow slab of coupled orbits in the geometry in whichJ ∥ [11 $$\bar 2$$ 0] andH lies in the (11 $$\bar 2$$ 0) plane. In samples whose quantum state lifetimeτ s exceeds 10−10 sec the conductivity of the coupled orbit system is controlled byτ s as well as the large-angle scattering lifetimeτ 1. The magnetoresistance then exhibits complicated behavior, oscillating with |H| and varying rapidly with field orientation. The behavior withH aligned to within about 0.001° of [10 $$\bar 1$$ 0] is due to manifold multiply connected open orbits, whereas forH tilted away from [10 $$\bar 1$$ 0] by more than this the behavior is due to extended, multiply connected closed orbits. Detailed models for both these regimes are developed, taking into account the interference effects resulting from the feedback paths. Within these models the transport properties are calculated exactly, taking into account to all orders the amplitude propagation of wave packets within the network. Results are compared to experimental data and previous calculations, and the limitations of the model are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00654499
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  • 7
    Electronic Resource
    Electronic Resource
    Cyclic deformation and fatigue behaviour of α-iron mono-and polycrystals (1981)
    Springer
    International journal of fracture 17 (1981), S. 193-220 
    Details
    ISSN: 1573-2673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Résumé Les résultats rapportés dans le mémoire sont basés sur une série d'essais de déformation cyclique qui ont été conduits à température ambiante sur des échantillons de fer α décarburés à haute pureté sous une forme mono- et polycristalline. Les données expérimentales couvrent les amplitudes de déformation plastique Δε pl correspondant à 10−4 ≲ Δε pl ≲ 10−2 ainsi que des variations dans la vitesse de déformation plastique comprises entre 10-5 et 10-2 s-1. Dans le cas de cristaux simples, on a également étudié les effects du C en solution (∼30 ppm). Les données mécaniques ont été complétées par des études détaillées des arrangements des dislocations, en utilisant la microscopie électronique à transmission, ainsi que les aspects des surfaces en utilisant la microscopie optique et la microscopie électronique à balayage. On a traité dans le détail les sujets suivants: accroissement cyclique et saturation, mécanisme de dislocation, modification de forme associée à des glissements assymétriques de dislocation vis, réponse cyclique contrainte/dilatation et amorcage de la fissure de fatigue. Sous les conditions conventionnelles de haute vitesse de déformation plastique (supérieure à 10-4 s-1) le comportement en fatigue du fer α à la température ambiante rend compte de la faible mobilité des dislocations vis, ce qui est caractéristique d'un mode de déformation à basse température des métaux cubiques centrés. En conséquence, le comportement fait état de différences significatives par rapport aux métaux cubiques faces centrés soumis à fatigue tels que: une intense multiplication des dislocations en-dessous Δε pl ∼ 5 × 10−4, un glissement secondaire appréciable pour des valeurs de Δε pl supérieures qui conduit à une structure en cellules (c.à.d que des bandes de glissement persistantes ne se forment point), des modifications de forme dues à des glissements assymétriques de dislocation vis, ainsi qu'un niveau de contrainte effective relativement élevé. La réduction de la vitesse de déformation plastique et la presence d'atomes de C en solution modifient ce comportement de manière significative, et le rapprochent davantage de celui des métaux cubiques centrés. Dans tous les cas, on a prouvé que seule la composante athermique de la contrainte de saturation, à défaut de cette dernière, représente une mesure appropriée des propriétés des substructures de dislocation. Sur base du comportement à la déformation cyclique et des observations d'amorcage de fissure de fatigue trans-et intergranulaire, on a conclu que la limite de fatigue du fer α est une propriété intrinsèque d'une structure cubique centrée dont les caractéristiques toutefois, se trouvent être sensiblement affectées par la teneur en impuretés intersticielles et par la vitesse de déformation de l'essai de fatigue.
    Notes: Abstract The reported studies are based on a series of cyclic deformation tests that were conducted at room temperature on decarburized high-purity α-iron specimens in mono-and polycrystalline form. The experimental data cover plastic strain ranges Δε pl in the regime 10−4 ≲ Δε pl ≲ 10−2 and variations in cyclic plastic strain rates έ pl between ∼10-5 and ∼10−2 s−1. In the case of single crystals, the effect of solute carbon (∼30 wt. ppm) was investigated as well. The mechanical data were supplemented by detailed studies of the dislocation arrangements by transmission electron microscopy and of the surface patterns by scanning electron and optical microscopy. Detailed accounts are given of the following topics: cyclic hardening and saturation, dislocation mechanisms, shape changes due to asymmetric slip of serew dislocations, cyclic stress-strain response and fatigue crack initiation. Under conventional conditions of “high” έ pl (≲10−4 s−1) the fatigue behaviour of α-iron at room temperature reflects the low mobility of the screw dislocations which is characteristic of the lowttemperature mode of deformation of body-centred cubic (b.c.c.) metals. As a consequence the behaviour exhibits significant differences with respect to that of fatigued face-centred cubic (f.c.c.) metals such as: strongly impeded dislocation multiplication below Δε pl ∼ 5 × 10−4, appreciable secondary slip at higher Δε pl leading to a cell structure (persistent slip bands do not form), shape changes due to asymmetric slip of screw dislocations and a relatively high effective stress level. The reduction of έ pl and the presence of solute carbon atoms modify this behaviour significantly, making it more similar to that of f.c.c. metals. In all cases it was found that only the athermal component of the peak (saturation) stress but not the latter itself represents a suitable measure of the properties of the dislocation substructure. On the basis of the cyclic deformation behaviour and of observations of trans-and intergranular fatigue crack initiation it was concluded that the fatigue limit of α-iron is an intrinsic property of the b.c.c. structure whose characteristics, however, are affected sensitively by interstitial impurity content and by the strain rate of the fatigue test.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00053520
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  • 8
    Electronic Resource
    Electronic Resource
    1,2-Photoadditionen von Stilbenen und Diarylacetylenen an bicyclische 1,4-Cyclohexadiene: Propellane und 1,2-Substitutionsaddukte (1981)
    Weinheim : Wiley-Blackwell
    Berichte der deutschen chemischen Gesellschaft 114 (1981), S. 2217-2237 
    Details
    ISSN: 0009-2940
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 1,2-Photoadditions of Stilbenes and Diarylacetylenes to Bicyclic 1,4-Cyclohexadienes: Propellanes and Substitutive 1,2-AdductsThe photoreactions of stilbene, 4,4′-dichloro-, 4,4′-dicyano-, 4,4′-dimethoxystilbene, diphenylacetylene, and bis(4-cyanophenyl)acetylene with 2,3,4,7-tetrahydroindene and 1,4,5,8-tetrahydronaphthalene have been investigated. Despite severe steric hindrance and because of electrostatic support the propellanes 3, 12, 23, 26 are formed as the major [2 +2]-cycloadducts. The products of dehydrogenation 41, 44, 45 and hydrogenation 29 are obtained from them. Further major products of the photolyses are the substitutive 1,2-adducts 4, 5, 14, 15, 24, 27, whereas the ene-adducts 25, 28 occur only in trace amounts. The mechanistic grounds are discussed in terms of diradicals with consideration of exciplex emissions and with the aid of comparative reactions involving 1,4-cyclohexadiene and methyl cinnamate. The photolyses of several propellanes with varying degrees of hydrogenation are described (decomposition, dehydrocyclization, intramolecular cycloaddition, and 1,5-shift). The structures of the products have been determined spectroscopically (IR, UV, fluorescence, 1H-NMR, 13C-NMR) and in part by chemical degradation and independent synthesis.
    Notes: Die Photoreaktionen von Stilben, 4,4′-Dichlor-, 4,4′-Dicyan-, 4,4′-Dimethoxystilben, Diphenyl-acetylen und Bis(4-cyanphenyl)acetylen mit 2,3,4,7-Tetrahydroinden und 1,4,4,8-Tetrahydronaphthalin werden untersucht. Durch [2 + 2]-Cycloaddition enstehen trotz sterischer Hinderung elektrostatisch gefördert überwiegend die Propellane 3, 12, 23, 26, aus denen Dehydrierungsprodukte (41, 44, 45) und das Hydrierungsprodukt 29 gewonnen werden. Weitere Hauptprodukte bei den Photolysen sind 1,2-Substitutionsaddukte (4, 5, 14, 15, 24, 27), während En-Addukte (25, 28) nur spurenweise auftreten. Die mechanistischen Gründe werden anhand von Exciplex-Emissionsspektren und unter Zuhilfenahme von Vergleichsreaktionen mit 1,4-Cyclohexadien sowie Zimtsäure-methylester auf der Grundlage von Diradikalen diskutiert. Die Photolysen mehrerer Propellane unterschiedlichen Hydrierungsgrads werden beschrieben (Zerfall, Dehydrocyclisierung, intramolekulare Cycloaddition und 1,5-Verschiebung). Die Konstitutionen der Produkte werden spektroskopisch (IR, UV, Fluoreszenz, 1H-NMR, 13C-NMR) und zum Teil durch chemischen Abbau und unabhängige Synthesen aufgeklärt.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cber.19811140619
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  • 9
    Electronic Resource
    Electronic Resource
    Hochselektive Totalsynthese von 19-Nor-Steroiden mit photochemischer Schlüsselreaktion: Racemische Zielverbindungen1,4) (1981)
    Weinheim : Wiley-Blackwell
    Liebigs Annalen 1981 (1981), S. 2335-2371 
    Details
    ISSN: 0170-2041
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Highly Selective Total Synthesis of 19-Nor-Steroids via a Photochemical Key Reaction: Racemic Target Compounds1,4)Ring A and ring D building blocks 17b and rac-15, easily available from m-cresyl methyl ether (19a) or (E)-1,4-dibromo-2-butene (13b) and methyl malonate (14a), respectively, react by Michael addition affording the key compound rac-9a. The latter compound by successive photoenolization, intramolecular Diels/Alder reaction, and dehydration furnishes the pretarget compounds rac-5 and rac-6. From here the 19-norsteroids rac-estrone (rac-1a), rac-19-norandrost-4-ene-3,17-dione (rac-2a), rac-estradiol-17β (rac-3a), and rac-19-nortestosterone (rac-4a) are optionally accessible (cf. schemes 1 and 2 as well as tables 3 and 4).
    Notes: Die Ring A- und Ring D-Bausteine 17b und rac-15, die bequem aus m-Kresolmethylether (19a) sowie (E)-1,4-Dibrom-2-buten (13b) und Malonsäure-dimethylester (14a) zugänglich sind, fügen sich in einer Michael-Addition zur Schlüsselverbindung rac-9a zusammen. Letztere reagiert nacheinander durch Photoenolisierung, intramolekulare Diels/Alder-Reaktion und Dehydratisierung zu den Präzielverbindungen rac-5 und rac-6. Von hier aus erhält man wahlweise die 19-Nor-Steroide rac-Östron (ra-1a), rac-19-Norandrost-4-en-3,17-dion (rac-2a), rac-Östradiol-17β (rac-3a) und rac-19-Nortestosteron (rac-4a) (s. Schemata 1 und 2 sowie Tab. 3 und 4).
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jlac.198119811220
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  • 10
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    Unknown
    Determination of bond distances and bond angles by solid-state nuclear magnetic resonance. Carbon-13 and nitrogen-14 NMR study of glycine (1981)
    American Chemical Society
    Details
    Publication Date: 1981-05-01
    Print ISSN: 0002-7863
    Electronic ISSN: 1520-5126
    Topics: Chemistry and Pharmacology
    Published by American Chemical Society
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