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  • Springer  (46)
  • 11
    Electronic Resource
    Electronic Resource
    X-Ray double crystal rocking curves of Ga1−x Al x As/GaAs laser structures (1992)
    Springer
    Il nuovo cimento della Società Italiana di Fisica 14 (1992), S. 129-139 
    Details
    ISSN: 0392-6737
    Keywords: X-ray determination of structure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Summary The double crystal X-ray rocking curves of Ga1−x Al x As/GaAs laser structures, with both a single and double confinement, have been calculated on the basis of the Takagi-Taupin dynamica theory. It has been demonstrated that very small changes in the thickness and composition of the active and the internal confining layers give rise to dramatic modifications of the rocking curves; this offers in principle a very powerful tool for measuring very precisely thickness and composition of these layers. However, the shape of the Bragg peak of the external confining layers exhibits a nearly period behaviour as a function of the thickness of the active or the internal confining layer; a simple relation between the thickness period and the composition difference of the considered layers has been obtained for the first time. Finally, the effect of the interchange of the confining layers on the rocking curves has been discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02457348
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  • 12
    Electronic Resource
    Electronic Resource
    Leu-7-positive cells with monocyte phenotype show different ultrastructural features in comparison to Leu-7-positive cells with T-cell phenotype (1985)
    Springer
    Histochemistry and cell biology 82 (1985), S. 525-527 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural features of the Leu-7-positive — Leu-M3-positive cell subpopulation and the Leu-7-positive — Leu-4-positive cell subpopulation were characterized and compared using immunogold-immunoperoxidase double labelling with immunoelectron microscopy. The majority of Leu-7-positive cells coexpressed a monocyte phenotype and showed an ultrastructural pattern specific for functional natural killer (NK) cells, i.e. a low nuclear/cytoplasmic (N/C) ratio, an irregular outline, many cytoplasmic organelles and electron-dense granules. In contrast, only a minority of Leu-7-positive cells coexpressed a T phenotype, and these were characterized by a high N/C ratio, an even surface and the absence of electron-dense granules. Thus, Leu-7-positive — Leu-4-positive cells may by an immature form of NK cells, and Leu-7-positive—Leu-4-positive and Leu-7-positive — Leu-M3-positive cell subpopulations may represent different stages of Leu-7-positive cell differentiation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00489973
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  • 13
    Electronic Resource
    Electronic Resource
    The fine structure of HNK-1 (Leu7) positive cells (1984)
    Springer
    Histochemistry and cell biology 81 (1984), S. 153-155 
    Details
    ISSN: 1432-119X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The ultrastructural characteristics of HNK-1 (Leu7) positive cells, visualized with a peroxidase labelled anti-mouse IgM serum, were analysed. Our investigation demonstrates: 1) the majority of Leu7 positive cells has a low nuclear/cytoplasmic ratio (N/C), an irregular outline, a well developed smooth endoplasmic reticulum, parallel tubular arrays (PTA) and electron dense granules; 2) the minority of Leu7 positive cells has a high N/C, regular profiles and lacks electron dense granules. The presence of two distinct ultrastructural patterns within Leu7 positive cells may represent: 1) the expression of subsequent stages of cell differentiation; 2) two distinct Leu7 positive cell subpopulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00490109
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  • 14
    Electronic Resource
    Electronic Resource
    New FIR laser lines from CHD2OH optically pumped by a cw CO2 laser (1989)
    Springer
    Applied physics 48 (1989), S. 245-248 
    Details
    ISSN: 1432-0649
    Keywords: 42.55
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract This work reports 83 new optically pumped far infrared laser lines, using deuterated methyl alcohol, CHD2OH, as active medium. For each line we list the measured wavelength, its polarization relative to the pump line, the optimum gas pressure and the CO2 laser pump power at the maximum absorption.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00694353
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  • 15
    Electronic Resource
    Electronic Resource
    X-ray flat diffractor optics I (2000)
    Springer
    Czechoslovak journal of physics 50 (2000), S. 841-849 
    Details
    ISSN: 1572-9486
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Precise knowledge of the incident and diffracted X-ray beams related to flat crystal diffractors is important for X-ray diffraction optics and for high resolution experiments. In the paper, three-dimensional reciprocal space concept has been applied to study general case of the flat diffractor. The incident and diffracted beams have been determined for the middle of the range of total reflection for both the standard asymmetrical and the inclined asymmetrical diffractor. For an asymmetric diffractor rotating about its reciprocal lattice vector unexpectedly large out-of-plane-of-diffraction components of the beams have been obtained. The largest ones have been found not for the angle of rotation ω = 90° corresponding to a symmetrical inclined diffractor but for the angle close to the grazing incidence case.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1021478414206
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  • 16
    Electronic Resource
    Electronic Resource
    Time-domain and frequency-domain differential calorimetry (1996)
    Springer
    Journal of thermal analysis and calorimetry 47 (1996), S. 75-85 
    Details
    ISSN: 1572-8943
    Keywords: calorimetry ; enthalpy ; heat capacity ; thermal conductivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The heat capacityC p of a sample can be considered as a frequency dependent quantity; its behaviour can reflect the dynamics of enthalpy fluctuations. In order to take into account the dynamic nature of the measured quantity, calorimetry can mimic experimental methods as those of dielectrometry, performing experiments in time domain or in frequency domain. In this paper, an instrument is presented which is based on a calorimetric method meeting these requirements, and thus allowing to study sample dynamics of very viscous systems as glasses and some supercooled liquids. Moreover, experimental procedures permitting investigation of samples undergoing chemical and/or physical transformations by simultaneous measurements of enthalpy variation, heat capacity and, under certain conditions, thermal conductivity, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01982687
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  • 17
    Electronic Resource
    Electronic Resource
    A heuristic approach to automatic grasp planning for a 3-fingered hand (1995)
    Springer
    Journal of intelligent and robotic systems 13 (1995), S. 45-74 
    Details
    ISSN: 1573-0409
    Keywords: Grasp modelling ; grasp planning ; functional reasoning ; heuristic reasoning ; articulated hand ; implicit programming ; task planning
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract This paper presents the core of a software system able to determine a good grasp configuration on 3D objects for a three-fingered hand. The grasp planning problem has been studied considering both the constraints due to the stability and accessibility conditions, and the ones related to functionality. Physical, geometrical, spatial and task-related knowledge for solving the grasp planning problem have been properly modelled to support a heuristic-based reasoning process. A series of heuristic rules and geometric tests are used to scan the solution space, searching for a ‘good’ grasp. In fact, when considering the three-dimensional case, a purely analytical and exhaustive approach appears too complex because of the dimension of the search space. This approach results in an incremental and modular model of grasp reasoning, that has been implemented using the Flex expert system shell. This work has been developed and demonstrated within the Esprit 2 project CIM-PLATO No. 2202.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01664755
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  • 18
    Electronic Resource
    Electronic Resource
    Über die photometrische Mikrobestimmung der Kieselsäure (1951)
    Springer
    Microchimica acta 36-37 (1951), S. 585-593 
    Details
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary A new procedure for the determination of silica with the aid of the molybdenum blue reaction is described on the basis of a study of the various kinds of molybdenum blue and the determination of its range of existence. This method is similarly suited for the determination of the soluble as well as the total silica content. It completely avoids the appearance of blue colorations in the blanks, and therefore permits the making of absolute determinations. It is no longer necessary to prepare comparison solutions at the same time. The great stability of the colorations, which are obtained with an appropriate excess of the reducing agent, makes it appear that this prodecure will be especially suited for series analyses.
    Abstract: Résumé On décrit un nouveau dosage de la silice au moyen de la réaction au bleu de molybdène, sur la base d'une investigation des différentes sortes de bleu de molybdène et de la détermination de leur domaine d'existence. Ce procédé convient aussi bien pour le dosage de la silice libre ou globale. Il évite complètement l'introduction de colorations bleues dans les essais témoins et permet par conséquent d'aborder des mesures absolues. L'emploi simultané de solutions étalons n'est plus nécessaire. La grande stabilité des teintes qui sont obtenues par un excès convenable d'agent réducteur, rend ce procédé convenable pour la mise en oeuvre des analyses en série.
    Notes: Zusammenfassung Auf Grund einer Untersuchung der verschiedenen Arten von Molybdänblau und der Bestimmung ihrer Existenzbereiche wird ein neues Verfahren zur Bestimmung der Kieselsäure mit Hilfe der Molybdänblaureaktion beschrieben. Dieses Verfahren ist gleicherweise zur Bestimmung der löslichen wie der Gesamtkieselsäure geeignet. Es vermeidet vollständig das Auftreten von Blaufärbungen in den Blindproben und gestattet daher die Ausführung von Absolutmessungen. Die gleichzeitige Herstellung von Vergleichslösungen ist nicht mehr nötig. Die große Stabilität der Färbungen, die mit einem geeigneten Überschuß des Reduktionsmittels erhalten werden, läßt dieses Verfahren besonders zur Ausführung von Reihenanalysen geeignet erscheinen.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01460857
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  • 19
    Electronic Resource
    Electronic Resource
    New optically pumped FIR laser lines in CD3OH (1986)
    Springer
    International journal of infrared and millimeter waves 7 (1986), S. 1241-1250 
    Details
    ISSN: 1572-9559
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this work we report laser action in 69 new FIR laser lines in CD3OH optically pumped by a regular cw CO2 laser. We have performed measurements of laser wavelength, optimum pressure of the gas, relative polarization and intensity on all lines, including some previously known.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01011102
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  • 20
    Electronic Resource
    Electronic Resource
    Changing Concentrations of Cu, Zn, Cd and Pb in a High Altitude Peat Bog from Bolivia during the Past Three Centuries (1997)
    Springer
    Water, air & soil pollution 100 (1997), S. 289-296 
    Details
    ISSN: 1573-2932
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract A core consisting of minerogenic peat and organic-rich mineral sediments was collected at an altitude of 4275 m in the Ovejuyo valley, 100 km NE of La Paz in Bolivia. Age dating with 210Pb showed that the core represents approximately three centuries of sediment accumulation. None of the peats are ombrotrophic. Despite this, the Cd/Al, Cu/Al, Zn/Al, and Pb/Al ratios are all significantly higher in the surface layers, particularly in the top 6 cm: natural, abiological geochemical processes, therefore, cannot account for these elevated heavy metal/Al ratios. There are two possible explanations for the metal enrichments, relative to Al, in the surface layers: bioaccumulation by living plants, and anthropogenic atmospheric metal deposition. While the living plant layer may be responsible for the Cd, Cu, and Zn enrichments, this is an unlikely explanation for the Pb profile. In contrast to the other metals, the concentration of Pb in the first sample (dating from 1985-1994) is less than that of the second sample (dating from 1970-1985). The Pb/Al profile is consistent with the well documented, rapid increase in atmospheric Pb emissions during the present century (which accelerated following the introduction of leaded gasoline), and the decline in Pb pollution during the past 20 years (as a result of the introduction of unleaded gasoline). Thus, the Ovejuyo Valley mire has provided one of the first records of atmospheric Pb pollution in South America.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1018364208168
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