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  • 1985-1989  (4)
  • 1920-1924  (1)
  • 1910-1914  (1)
  • 1
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 104 (1920), S. 532-532 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] A FEW years ago, with a view to the observation of close objects out of doors, I procured some glass adapter lenses for use on the object glass of the half of a prism binocular (× 12) which I carried about with me. Finding, however, that this method involved the use of several glass adapters, ...
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 84 (1910), S. 363-363 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] AN article in NATURE for August 18 deals aptly with the question of testing for colour-vision. It is to be hoped that the committee at present inquiring into the matter will advocate that testing should be carried out in future in conditions resembling as nearly as possible those on which ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Plant molecular biology 9 (1987), S. 469-478 
    ISSN: 1573-5028
    Keywords: in vitro translation ; leghemoglobin ; nodulin gene expression ; Northern analysis ; Rhizobium-alfalfa symbiosis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Expression of plant genes involved in the symbiosis between alfalfa (Medicago sativa) and Rhizobium meliloti has been studied by comparing root and root nodule mRNA populations. Two-dimensional gel electrophoretic separation of the in vitro translation products of polyA+ RNA isolated from either roots or effective root nodules has allowed us to identify thirteen nodule-specific translation products, including those corresponding to the leghemoglobins (Lb). These translation products, representing putative nodulin mRNAs, are first detected between 9 and 12 days after inoculation, a result which has been confirmed for Lb mRNA by Northern blotting and hybridization with a Lb cDNA probe. Analysis of three different types of ineffective root nodules arrested in different stages of development has led to the following conclusions. (i) The transcription of eleven nodule-specific genes, including the Lb genes, is independent of nitrogen-fixing activity. (ii) Differentiation of the primary nodule structure does not require the transcription of any of these genes but can be correlated with a dramatic reduction in the level of at least five transcripts present in the root. (iii) There is enhanced expression of certain plant genes in the case of nodules elicited by an Agrobacterium strain carrying the symbiotic plasmid of R. meliloti.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 25 (1985), S. 344-353 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The mixed-mode, elastodynamic state of stress in the neighborhood of a constant-velocity crack tip is used to generate numerically unsymmetric isochromatics. Unsymmetry associated with the third-order terms of a mixed-mode stress field, with and without the Mode II singular stress term, is also investigated. In extractingK I from an unsymmetric isochromatic pattern, errors in the Mode I fracture parameters due to the assumed presence ofK II in aK I stress field were found to be significant when data are taken more than 4 mm from the crack tip.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 25 (1985), S. 399-407 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A general algorithm is presented that computes the stress-field parameters for opening-mode crack problems in a least-squares sense from full-field moiré or speckle-displacement fringe patterns. The algorithm can be used in the presence of rigid-body rotation and does not require absolute fringe numbering. Extensive numerical experiments were conducted with the algorithm to determine the sensitivity of the method to experimental errors. Small random position errors in locating the fringe maxima were found to have a negligible influence on the stress-intensity-factor calculation when the number of data points was about ten times greater than the number of unknown stress-field parameters. It was also found that systematic position errors due to an incorrectly specified crack-tip location could be minimized by assuming various crack-tip locations in the vicinity of the actual crack tip and selecting the best fit results. Bothu andv fields were found to be equally suitable for determination of the stress-intensity factor.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 28 (1988), S. 298-303 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract An experimental method is described for measuring the dynamic initiation toughness of a sharp stationary crack. A plane specimen is utilized which consists of a central region 50-mm wide and 200-mm long with integral dog-bone ends. The loading is accomplished by the detonation of four small explosive charges which produce two tensile stress waves upon reflection from the dog-bone ends. The stress waves meet at the midpoint of the specimen and reinforce to produce a relatively large, uniformly stressed region with a very high loading rate. The crack is positioned at the midpoint of the specimen at the location where the reinforcing tensile stress waves meet. A series of photoelastic experiments were conducted using Homalite 100 as the model material to observe, in a full-field view, the arrival of the dilatational waves, the subsequent development of the stress field at the tip of the stationary crack and the initiation of the crack. The isochromatic fringe pattern was also used to determine the instantaneous value of the stress-intensity factorK(t) after the characteristic fringe loops developed in the region near the crack tip. Finally,K(t) was measured using a single strain gage positioned and oriented so that its signal output was proportional toK(t) and independent of the next two higher order terms in the series representation of the strain field. A method was developed to determine the instant of initiation from the strain-time trace. Results obtained from the photoelastic and strain measurements of the dynamic-initiation toughnessK ID were consistently higher than the static value ofK IC .
    Type of Medium: Electronic Resource
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