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  • 11
    Electronic Resource
    Electronic Resource
    Springer
    Bulletin of mathematical biology 28 (1966), S. 501-510 
    ISSN: 1522-9602
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Mathematics
    Notes: Abstract A set of characteristic parameters is given for electrophoresis accompanied by diffusion, followed by a method of simplification of the transport equation. The concept of electrophoretic similarity is introduced in connection with the presentation of solutions and the final section contains some dimensional considerations of the potential equation.
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 1432-0827
    Keywords: Bone mineral analysis ; Hip strength analysis ; Age ; Femoral neck stress
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Summary The greater hip fracture rate among elderly women is generally ascribed to differences in femoral neck strength between the sexes. Strength of a given bone is a function of both its material properties and the magnitudes of mechanical stresses within it. This study examined the hypothesis that these apparent strength differences between the sexes are due to dissimilarities in the restructuring of the femoral neck with age, which result in higher stresses in elderly women. Using Hip Strength Analysis, a computer program developed by the authors, femoral neck cross-sectional geometric properties for stress analyses were derived from bone mineral image data of 409 community living, white subjects ranging from 19 to 93 years of age. Though both sexes show declines in femoral neck bone mineral density (BMD) and cross-sectional area with age, only females show a decline in the cross-sectional moment of inertia (CSMI, a geometric index of bone rigidity). The lack of decline in male CSMI appears to be a result of a small but significant increase in femoral neck girth. Similar age-related changes have been observed in the femoral shaft by others. The net effect of these observed changes is that mechanical stresses in the femoral neck of females appear to increase at three times the rate per decade of those of males. These results lend support to the hypothesis that the higher fracture rate in elderly women is due, at least in part, to elevated levels of mechanical stress, resulting from a combination of greater bone loss and less compensatory geometric restructuring with age.
    Type of Medium: Electronic Resource
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  • 13
    ISSN: 1615-5947
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract CT imaging of traumatic aortic rupture has been both advocated and disparaged in the current literature as a reliable diagnostic modality. In a retrospective review of blunt chest trauma patients at our institution evaluated by both thoracic CT and arteriography, we found a 17% false negative rate and a 39% false positive rate. Although we feel CT is not sufficiently sensitive at present to evaluate traumatic rupture of the aorta directly, it is an invaluable adjunctive imaging modality for stable blunt chest trauma patients with equivocal chest radiographs or arteriograms.
    Type of Medium: Electronic Resource
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  • 14
    ISSN: 1619-1560
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 30 (1969), S. 317-334 
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Field trials carried out in 1965 and 1966 showed that 2,4-DB, alone or in combination with dalapon, reduced nodulation and tended to decrease the efficiency of nitrogen fixation in birdsfoot trefoil. Dalapon appeared to enhance the inhibitory action of 2,4-DB on nodulation. No obvious cytological differences could be detected in the nodules or in the isolated bacteroids of field-treated and untreated plants. Under growth chamber conditions, 2,4-DB drastically reduced trefoil growth and nodulation particularly in treatments where the herbicide came directly in contact with the plants. It appears that the reduction in nodulation and nitrogen fixation is a result of plant damage and abnormal root growth caused by 2,4-DB application. Autoradiographs indicated that the translocation of the herbicide was rapid, with detectable concentrations observed in young leaves, leafveins, roots, and nodules 12 hours after leaf-feeding of 2,4-DB-1-C14. The radio-activity appeared to accumulate with time (up to 5 days) in the growing root tips and nodules. Fractionation of excised nodules from trefoil plants demonstrated the presence of radioactivity in the cell debris, bacteroids, 29,000g pellet, plant ribosomes, and the soluble portion. The greatest accumulation of radioactivity occurred in the soluble fraction. The degradation of 2,4-DB and 2,4-D in trefoil was demonstrated by the evolution of C14O2 from non-nodulated and aseptically growing plants leaf-fed with 2,4-DB-1-C14 or 2,4-D-1-C14.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 30 (1969), S. 360-372 
    ISSN: 1573-5036
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Summary Growth of Lotus nodule bacteria (Strain LC 296) was temporarily suppressed in a yeast-extract mineral-salts medium containing 2,4-DB at 50 and 100 µg/ml. However, the 2,4-DB concentration needed to completely suppress the growth of the bacteria appeared to be above 500 µg/ml. When added during the logarithmic phase of growth 2,4-DB at 50 and 100 µg/ml did not inhibit the growth of the cells, so that the growth-inhibiting effect of the herbicide apparently was directed primarily against lag phase cells. Pre-incubation of rhizobia in a medium containing 2,4-DB at concentrations up to 10 µg/ml did not affect the capacity of the bacteria to effectively nodulate their host plant. Attempts to induce the rhizobia to utilize 2,4-DB as a sole carbon source failed. Nevertheless, when theLotus nodule bacteria (LC 296) were grown in a medium containing 2,4-DB-1-C14, C14O2 was released. Similar results were obtained with other strains of the Lotus rhizobia and other species of Rhizobium. C14O2 evolution was also demonstrated when radioactive 2,4-DB was added to both intact (excised) and crushed trefoil nodules. The results indicate that the nodule bacteria are capable of degrading 2,4-DB; although the mechanism is still obscure it does not appear to be via cleavage of the ether link.
    Type of Medium: Electronic Resource
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  • 17
    ISSN: 1573-1561
    Keywords: Plant defense ; air pollution ; acidic deposition ; biological indicators ; plant polyphenols ; total phenolics ; proanthocyanidins ; condensed tannins ; secondary metabolites ; Pinus taeda
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Tannin and total phenolic levels in the foliage of loblolly pine (Pinus taeda L.) were examined in order to evaluate the effect of atmospheric pollution on secondary plant metabolism. The trees were exposed to four ozone concentrations and three levels of simulated acid rain. Tannin concentration (quantity per gram) and content (quantity per fascicle) were increased in foliage exposed to high concentrations of ozone in both ozone-sensitive and ozone-tolerant families. No effect of acid rain on tannins was observed. Neither total phenolic concentration nor content was significantly affected by any treatment, indicating that the ozone-related increase in foliar tannins was due to changes in allocation within the phenolic group rather than to increases in total phenolics. The change in allocation of resources in the production of secondary metabolites may have implications in herbivore defense, as well as for the overall energy balance of the plant.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neural transmission 89 (1992), S. 103-110 
    ISSN: 1435-1463
    Keywords: TRH ; hypothalamus ; asymmetry ; suicide patients
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The aim of the present study was to investigate the functional and/ or pathological significance of the hemispherical lateralization of TRH using radioimmunoassay to determine the TRH concentration of nuclei and areas within the hypothalamus of suicide patients, with matching measurement being carried out on control subjects. In suicide patients, we found no significant difference in TRH concentration between the left and right intrahypothalamic structures, while the group used as control subjects (see Borson-Chazot, 1986) showed a significant left side predominance in the ventromedial nucleus, paraventricular nucleus and area dorsalis. As regards the TRH concentration in the right intrahypothalamic structures, no significant difference was found between the suicide patients and the control subjects. The absence of the left TRH predominance for the three intra-hypothalamic structures in question may be of pathological significance.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Human evolution 9 (1994), S. 331-342 
    ISSN: 1824-310X
    Keywords: birth ; bone density ; Neanderthal ; obstetrics ; robusticity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Neanderthal pelvic morphology is not well understood, despite the recent find and analysis of the Kebara 2 pelvis. Many of the proposed hypotheses focus on the possible need for a larger birth canal. A previously unexplored aspect involves possible direct obstetric implications of bone robusticity and density. These characteristics ocan affect obstetrics in modern humans, especially the molding of the neonate's head during parturition: engineering studies have shown that denser neonate cranial bones undergo less deformation, and thicker (more robust) cranial bones would also be expected to deform less during the birth process. These bone characteristics may also result in a less flexible birth canal. Thus, more robust or denser bones could result in the need for a larger birth canal or a smaller neonate head, due to decreased flexibility. Examples from modern populations are discussed and the conclusions applied to Neanderthals, who are known to have had high bone robusticity and may have had high bone density, given their heavy musculature. (A positive association between muscle mass and bone density has been observed repeatedly in modern humans.) We conclude that bone robusticity and density may have obstetrical implications for Neanderthals, with particular importance for neonate head molding during birth.
    Type of Medium: Electronic Resource
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  • 20
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A: General Papers 3 (1965), S. 1941-1948 
    ISSN: 0449-2951
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The concentration dependence of the reduced viscosity has been studied for several polyelectrolytes in conductivity water. It is shown that the viscosity maximum previously reported for polyelectrolyte solutions without added electrolyte can be explained either by the presence of ionic impurities in the solvent or by the contamination of the solutions. It is concluded that the folding chain theory of polyelectrolyte solutions requires amendment to account for the experimental results on counterion association. A suggested amendment to the theory implies that the application of the Huggins equation to the concentration dependence of polyelectrolyte solutions in the presence of added electrolyte may not lead to information concerning the interactions between the polyions in solution.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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