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  • 1
    ISSN: 1572-901X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary By inhibiting the copper(II) assisted TPT (TPT = 2,4,6-tris(2-pyridyl)-1,3,5-triazine) hydrolysis, monomeric and dimeric copper(II) complexes having as general formulae Cu(TPT)X, · nH2O (X = Cl, Br, NCS, NCO or N3) and [Cu(TPT)X]2(PF6)2 · nH2O (X = Cl, Br, NCS or N3) have been synthesized and characterized by i.r., electronic and e.p.r. spectra, x-ray powder diffraction and analytical data. Spectroscopic results indicate five-coordinate geometry around the copper(II) ion, intermediate between trigonal-bipyramid and square-pyramid structures. The half-field absorption in the ΔMS = 2 region of powdered X-band e.p.r. spectra has been observed for the dimeric species.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Machine learning 1 (1986), S. 249-285 
    ISSN: 0885-6125
    Keywords: goal regression ; problem solving heuristics ; example generation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This research examines the process of learning problem solving with minimal requirements for a priori knowledge and teacher involvement. Experience indicates that knowledge about the problem solving task can be used to improve problem solving performance. This research addresses the issues of what knowledge is useful, how it is applied during problem solving, and how it can be acquired. For each operator used in the problem solving domain, knowledge is incrementally learned concerning why it is useful, when it is applicable, and what transformation it performs. The method of experimental goal regression is introduced for improving the learning rate by approximating the results of analytic learning. The ideas are formalized in an algorithm for learning and problem solving and demonstrated with examples from the domains of simultaneous linear equations and symbolic integration.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Machine learning 1 (1986), S. 249-285 
    ISSN: 0885-6125
    Keywords: goal regression ; problem solving heuristics ; example generation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract This research examines the process of learning problem solving with minimal requirements for a priori knowledge and teacher involvement. Experience indicates that knowledge about the problem solving task can be used to improve problem solving performance. This research addresses the issues of what knowledge is useful, how it is applied during problem solving, and how it can be acquired. For each operator used in the problem solving domain, knowledge is incrementally learned concerning why it is useful, when it is applicable, and what transformation it performs. The method of experimental goal regression is introduced for improving the learning rate by approximating the results of analytic learning. The ideas are formalized in an algorithm for learning and problem solving and demonstrated with examples from the domains of simultaneous linear equations and symbolic integration.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract Human complement component C4 is coded by two genes situated between HLA-D and HLA-B. Both genes are highly polymorphic; C4-A gene products normally carry the blood group antigen Rodgers and C4-B proteins usually carry the Chido antigen. Using a monoclonal antibody which binds Rodgers-positive and Chido-positive proteins with different affinities, we have purified a number of less common C4 allotypes and compared their properties. All C4-B allotypes tested have similar specific hemolytic activities and binding efficiencies to small molecules. All C4-A proteins tested had similar binding to small molecules and hemolytic activities except for the C4-A6 proteins from two individuals with different extended haplotypes, both of which had identical hemolytic activities and much lower ones than other C4-A allotypes. Two allotypes, C4 Al, Rodgers-negative but Chido-positive, and C4-B5, Chido-negative but probably Rodgers-positive, were found to behave as typical C4A and C4-B proteins, respectively, apart from the switch in their antigenic properties.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 21 (1986), S. 803-809 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The development of uniaxial orientation by solid-state extrusion at 60 to 90° C has been evaluated for both the amorphous and crystalline components of a polyethylene terephthalate). Analyses involved X-ray diffraction, birefringence and visable dichroism. The dichroism was evalulated from a host dye molecule. The initial PET film for draw was amorphous and isotropic. Orientation functions for the amorphous and the developed crystalline phases are reported at a series of draw ratios up to 4.4.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 21 (1986), S. 705-710 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The creep properties of a commercial, single phase aIurnina have been determined in the temperature range of 1623 to 1723 K. The stress exponent,n, in the relationship ɛ ∝ σ n was determined to be 1.9 and the true activation energy was found to be 635 kJ mol−1. Normal primary stage creep transients were observed up to strains of 1%. At low stresses, steady-state conditions were not obtained due to the occurrence of concurrent grain growth. It is shown that the steady state creep results are consistent with the occurrence of an interface controlled diffusionaI creep mechanism.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 159 (1986), S. 667-674 
    ISSN: 1432-1351
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Adaptation to light and darkness involves major transformations of the smooth endoplasmic reticulum (SER) in the retinula cells of the crayfish and other invertebrates, the mechanisms of which are unknown. This paper presents measurements of SER stereological parameters at three levels along the main axis of light-adapted and dark-adapted retinula cells of the crayfish. Both the volume density and the surface density of SER in the perinuclear region of dark-adapted cells are more than double the values found in light-adapted cells. This relationship is inverted in the axoplasm above and below the basement membrane, where SER volume and surface in dark-adapted cells are approximately half of the quantities measured in light-adapted cells. Although this proportional correspondence between changes in separate regions of the cells might suggest merely an intracellular shifting of SER membrane, calculation of the approximate absolute amounts of membrane involved makes this possibility very unlikely. It is concluded that the vast increase of SER in the perinuclear region of dark-adapted cells implies a large input of membrane, which is subsequently removed during light-adaptation.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1573-0646
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract We have observed three forms of skin toxicity induced by the new antifol trimetrexate in a Phase I trial. They are: radiation recall, cellulitis at the infusion site, and generalized skin eruptions with erythroderma. A total of 25 episodes of some form of skin reaction occurred in 31 patients. The generalized eruption began about four days after drug administration and cleared within a week. The mechanism of skin toxicity of trimetrexate and other antifols is unknown.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-5036
    Keywords: Development ; Model ; Root ; Shoot ; Thermal time ; Wheat
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary A model has been developed of root growth in winter wheat based on cumulative thermal time with description of the extension and branching of individual age classes of seminal and crown root axes. The model requires, as input, the sowing date and average monthly mean air temperatures and gives, as output, the maximum depth of penetration of each age class of root and the root length density or root weight in any 10 cm layer of soil contributed by main axes, first-order and second-order laterals on any calendar date. The impact of soil temperature on root length density distributions with time was assessed by comparing a warm site (Perth, Australia) with a cool site (Rothamsted Experimental Station, England). Simulated values of root length density for plants with six leaves were consistently high when soil temperature was held constant at 10°C, but variable soil temperatures at each site resulted in rooting profiles characteristic for the two sites, although root length densities were larger than commonly observed at either location. The model simulates well described sequences of root production and permits calculation of maximal root development rates for unstressed plants growing in moist soil with no mechanical impedance to growth. It allows the co-development of root and shoot to be modelled and since it uses only about 5 K bytes of computer memory could be easily used for the assessment of management practices in the field.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Rheologica acta 25 (1986), S. 69-71 
    ISSN: 1435-1528
    Keywords: Perfluoropolyether ; shear dependence ; viscosity ; Couette high-shear viscometer
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Abstract The shear dependence of the bulk viscosities of two structurally different types of perfluoropolyether fluids was determined by two different techniques. The first involved direct measurement in a high shear Couette viscometer, the second utilized the time-temperature superposition principle to establish master curves from viscosity determinations at low shear rates and temperature; the results are comparable. Both fluids begin to show non-Newtonian behavior at shear rates above 10,000 s−1.
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