Bibliothek

X
Suchhistorie löschen
feed icon rss

Ihre E-Mail wurde erfolgreich gesendet. Bitte prüfen Sie Ihren Maileingang.

Leider ist ein Fehler beim E-Mail-Versand aufgetreten. Bitte versuchen Sie es erneut.

Vorgang fortführen?

Exportieren
  • 1
    Digitale Medien
    Digitale Medien
    Hc enhancement of Co-adsorbed γ-Fe2O3 particles via surface treatment with sodium polyphosphate : 38th Annual Conference on Magnetism and Magnetic Materials (1994)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 75 (1994), S. 5562-5564 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: The coercive force HC of partially reduced, acicular γ-Fe2O3 particles having an adsorbed Co layer (4 wt % Co; Fe+2/Fe+3≈0.09; 2000 A(ring)×240 A(ring) particle dimensions; 36 m2/g specific surface area) increases substantially following surface treatment with (NaPO3)n≈14⋅Na2O. The maximum observed effect occurs at a polyphosphate-to-iron oxide weight ratio P/Fe near 0.5, denoted (P/Fe)max, where HC of the Co-adsorbed oxide increases from 687 to 1096 Oe immediately following treatment. The latter value increased to 1215 Oe after a four month storage in an argon environment containing less than 1 ppm H2O and O2, suggesting that the polyphosphate-oxide interaction is sensitive to moisture or oxygen. Co-adsorbed particles containing no Fe+2 in the oxide core also exhibit HC enhancement following surface treatment, but the change in HC is substantially less than that of particles containing Fe+2. The general behavior of polyphosphate-treated Co-adsorbed particles is observed to be similar to that of treated berthollide particles having no adsorbed Co layer: (i) the magnitude and sign of change in HC varies with P/Fe, reaching a peak value at (P/Fe)max, (ii) the magnitude of increase in HC at (P/Fe)max depends on the Fe+2 content of the particle core, (iii) saturation magnetization of the particles treated at (P/Fe)max is essentially unchanged from that of the untreated precursor, (iv) HC of specimens treated at (P/Fe)max returns to the value of the untreated precursor when the polyphosphate coating is removed via washing with water, and (v) particle dissolution occurs when P/Fe(very-much-greater-than)(P/Fe)max. Studies of anisotropy field distributions show that there is no obvious bimodal character to the very broad distribution of anisotropy fields found in randomly oriented specimens of surface-treated particles.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.355689
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 2
    Digitale Medien
    Digitale Medien
    Spin-glass behavior of spinel iron oxide particles on iron metal particle recording media (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 77 (1995), S. 5853-5864 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Small (30 A(ring) diameter) spinel iron oxide particles which form the protective layer on acicular iron metal particle recording media are found to exhibit no observable magnetization. The typical experimental decrease in sample magnetization for several media specimens is about 3% from 5 to 300 K. This change is the same as the thermal decrease in metal core magnetization, determined by Mössbauer spectroscopy. The predicted decrease in sample magnetization assuming normal spinel oxide behavior is typically about 20%. Two intraparticle models for reduced magnetization in oxide nanoparticles are found to be incompatible with the magnetization data. An interparticle "super-spin-glass'' model is compatible with the magnetization data. The alignment between adjacent oxide nanoparticle moments is hypothesized to depend on the particular sublattices in contact, since the sublattice exchange interactions are all antiferromagnetic. An inverse particle size dependence is thus expected, in agreement with spinel oxide magnetization reduction and other phenomena seen in a wide range of studies on larger oxide particles and films. © 1995 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.359166
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 3
    Digitale Medien
    Digitale Medien
    Modulation speed of an efficient porous silicon light emitting device (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 86 (1999), S. 2764-2773 
    Details
    ISSN: 1089-7550
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Trends in the efficiency and small signal modulation behavior of porous silicon light emitting diodes (LEDs) are reported for devices formed by the anodization of bulk silicon p–n junctions. As the average size of the silicon skeleton is decreased, the external electroluminescence (EL) efficiency increases from 0.001% to 0.18% and there is a corresponding blue shift in the EL peak from 776 to 633 nm. An associated tenfold increase is observed in the photoluminescence efficiency while the diode resistance, at 2 V, increases from 3×103 to 1×106 Ω. Under small signal pulsed operation, the voltage dependence of the rising edge of the EL is well described by a carrier mobility of 3×10−4 cm2 s−1 V−1 which is independent of the average size of the luminescent regions of the silicon nanostructure. The falling edge of the EL transient is dominated by radiative recombination of quantum confined excitons. The modulation speed is found to be limited by a combination of carrier mobility in the silicon wires and radiative recombination processes. Evidence of charge trapping and discharge is found in an EL overshoot phenomenon. The major application of this type of porous silicon LED, with modulation speeds below 1 MHz, appears to be for displays integrated with circuitry rather than for optical interconnection.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.371123
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 4
    Digitale Medien
    Digitale Medien
    Relationship between storage media and blue photoluminescence for oxidized porous silicon (1997)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 71 (1997), S. 107-109 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Blue photoluminescence is observed, with nanosecond decay time, from rapid thermally oxidized porous silicon as a result of accelerated aging in plastic containers. Photoluminescence measurements, combined with chemical analyses of the "aged" porous silicon, indicate that the emission is a consequence of the incorporation of trace organic (hydrocarbon) contamination from the plastic containers as they outgas at a mildly elevated temperature (80 °C) and, albeit at a reduced rate, at room temperature. Such carbonaceous contaminants can subsequently be removed by high-temperature annealing, a process which also quenches the blue photoluminescence. Consequently, it is important to take into consideration the storage medium used when making comparative luminescent and compositional studies of porous silicon and, perhaps, porous materials in general. © 1997 American Institute of Physics.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.119442
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 5
    Digitale Medien
    Digitale Medien
    Efficient visible electroluminescence from highly porous silicon under cathodic bias (1992)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 61 (1992), S. 2563-2565 
    Details
    ISSN: 1077-3118
    Quelle: AIP Digital Archive
    Thema: Physik
    Notizen: Visible electroluminescence (EL) has been obtained from porous silicon cathodically biased in an aqueous electrolyte containing either the persulphate or the peroxide ion. EL efficiencies of up to 0.1% have been obtained from porous silicon formed on both n-type and p-type substrates for the application of only a few volts bias. In subdued lighting, the EL is easily visible to the naked eye at excitation densities of 0.1 W cm−2. EL is obtained only from porous silicon capable of giving photoluminescence (PL); the EL and PL spectra are broadly similar in width and peak wavelength. The EL spectra are reversibly shifted to shorter wavelengths as the magnitude of the bias is increased. In contrast with the previously reported EL under anodic conditions, this cathodic EL process does not irreversibly oxidize the porous silicon skeleton.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1063/1.108127
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 6
    Digitale Medien
    Digitale Medien
    THE INFLUENCE OF SCHOOLING AND SEX ON TEST AND GENERAL ANXIETY AS MEASURED BY SARASON'S SCALES (1963)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of child psychology and psychiatry 4 (1963), S. 0 
    Details
    ISSN: 1469-7610
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin , Psychologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1469-7610.1963.tb02118.x
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 7
    Digitale Medien
    Digitale Medien
    CHILDREN'S ADJUSTMENT TO SCHOOL OVER SIX YEARS (1978)
    Oxford, UK : Blackwell Publishing Ltd
    The @journal of child psychology and psychiatry 19 (1978), S. 0 
    Details
    ISSN: 1469-7610
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Medizin , Psychologie
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1469-7610.1978.tb00482.x
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 8
    Digitale Medien
    Digitale Medien
    Reproductive Behavior of Hexaploid/Diploid Wheat Hybrids (1991)
    Oxford, UK : Blackwell Publishing Ltd
    Plant breeding 107 (1991), S. 0 
    Details
    ISSN: 1439-0523
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: The bottleneck restricting introgression of useful genes directly from diploid into hexaploid wheats is the low number of BC1F1 seeds obtained. In crosses between hexaploid wheat (Triticum aestivum L.; AABBDD) and Aegilops squarrosa L. (DD) or T. urartu Thum. (AA), this bottleneck may be overcome simply by pollinating a sufficient number of F1 spikes. However, hybrids between hexaploid wheat cultivars (T. aestivum) and T. monococcum L. (AA) generally are highly female-sterile, often having no pistils. One T. monococcum accession, PI 355520, when crossed with T. aestivum, produced hybrids with female fertility in the same range as that of T. aestivum/A. squarrosa or T. aestivum/T. urartu hybrids, ca. 0.5 to 1.0 backcross seed per spike. We found that female fertility was controlled by two duplicate genes in PI 355520, and that this accession can be used as a bridging parent to introgress genes from other T. monococcum accessions into hexaploid wheat. Pairing of homologous chromosomes was less frequent and weaker in such crosses than in T. aestivum/A. squarrosa crosses, but homoeologous bivalents occurred at a rate of almost 0.5 II per cell. Restitution division was detected in crosses involving all three diploid species and was confirmed cytologically in crosses with PI 355520. Chromosome numbers of BC1F1 plants ranged from 35 to 67; plants with 49 or more chromosomes occurred at frequencies of 0.09 to 0.21 among progeny of A. squarrosa and T. urartu and 0.29 in progeny of T. aestivum/T. monococcum crosses involving PI 355520. These results are consistent with those of previous studies, demonstrating the potential of direct Hexaploid/diploid crosses for rapidly introgressing useful genes into Hexaploid wheat with minimum disturbance of the background genotype.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1439-0523.1991.tb00537.x
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 9
    Digitale Medien
    Digitale Medien
    THE DEVELOPMENT OF SELECTIVE HERBICIDES FOR KALE IN THE UNITED KINGDOM (1965)
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 5 (1965), S. 0 
    Details
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Summary. The purpose of this paper is firstly to describe the background of an investigation started in 1961 to develop new herbicides for the control of weeds in agricultural kale, Brassica oleracea vars. acephala D.C. and fruticosa Metz, and secondly to present the results of four experiments concerned with the effects of weeds on the yield of kale. The results of the herbicide investigation are to be presented in subsequent papers.Kale as grown in the United Kingdom is a valuable fodder crop and relatively easy to grow, but beset by weeds against which existing mechanical and chemical methods of control have not usually been successful. The effect of weed competition on the yield of four farmers’crops was investigated in 1961 and 1962. When grown entirely free of weeds, the crops provided yields in the range of 20.9–34.5 tons of green material per acre. Where no attempt was made to control the weeds, the yields were reduced by 9.4, 14.5 and 18.9 tons/ac, respectively, in three experiments. In no case did kale, hoed only between the rows, produce as high a yield as the weed-free crop. Although variable in effect, uncontrolled weed growth early in the life of the crop always lowered the yield of kale.Le développement de l'usage des herbicides selectifs pour le chou fourrager dans le Royaume-Uni. La plante cultivée, les mauvaises herbes et le problème
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-3180.1965.tb00350.x
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
  • 10
    Digitale Medien
    Digitale Medien
    Seasonal emergence of weeds in cultivated soil in New Zealand (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 35 (1995), S. 0 
    Details
    ISSN: 1365-3180
    Quelle: Blackwell Publishing Journal Backfiles 1879-2005
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Patterns of seedling emergence of ten weed species from soil cultivated at intervals of approximately one month are described. All species examined showed clearly defined emergence patterns. Polygonum persicaria L. seedlings emerged in spring and early summer. Seedlings of Chenopodium album agg., Portulaca oleracea L. and Solanum nigrum L. emerged in late spring, summer and early autumn.Plantago major L., Rumex spp. (mostly R. obtusifolius L.) and Trifolium spp. (mostly T. repens L.) emerged mostly in spring and early summer. Coronopus didymus (L.) Sm. and Juncus bufonius L. tended to emerge in both autumn and spring.Veronica persica Poir. emerged in spring, summer and autumn. Close similarity between emergence patterns in New Zealand and northern Europe, despite differences in rainfall and temperature, suggests that annual dormancy:nondormancy cycles of seeds buried in the soil are largely responsible for seedling emergence patterns. In New Zealand, seedling emergence tended to be more spread out than in Europe, although seasonal patterns were still distinct. Further work on dormancy cycles in these species would be useful, as would a comparison of the factors inducing and breaking dormancy of comparable seed populations in northern and southern Europe and New Zealand. When seeds were left buried for several years before being encouraged to germinate, seedling emergence patterns tended to be of smaller amplitude, although the overall patterns were still very similar.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1111/j.1365-3180.1995.tb01639.x
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
    BibTip Andere fanden auch interessant ...
    Artikel (Nationallizenzen)
    Volltext
Schließen ⊗
Diese Webseite nutzt Cookies und das Analyse-Tool Matomo. Weitere Informationen finden Sie hier...