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  • 1990-1994  (9)
  • 1930-1934  (1)
  • 1991  (9)
  • 1934  (1)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 62 (1991), S. 3004-3009 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Measurements have been carried out of the position-dependent detection efficiencies of two quadrupole-type commercial mass spectrometers with electron-impact ion sources. Contours of constant detection efficiencies for different ion source parameters were determined by scanning a collimated argon beam of 1-mm diameter across the ion source. The measured results show clearly how different ion source settings influence the detection efficiency and the size of the active volume within the ion source. Furthermore it is found that the optimal performance of the instrument in the molecular-beam mode as well as in the residual gas mode occurs at the same ion source settings. The absolute value of the detection efficiency, for this particular ion source setting, is Dmax = 0.88 × 10−5. A simple model is developed connecting the conventional sensitivity factor with the measured position-dependent detection efficiency contour plots. The agreement between the measured and calculated sensitivity factors is good.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1475-2743
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract. A 2-year field experiment assessed the effectiveness of fertilizer, surface applied and injected liquid digested sewage sludge in increasing yields from reclaimed but regressing pasture on colliery spoil. At the first harvest, surface applications of sewage sludge gave the largest yields, although only a third of total fertilizer nitrogen (N) had been applied at this stage of the experiment. The greatest yields in the first year were given by fertilizer treatments which included the highest level of applied N, and large surface applications of sludge.Surface applications of sludge on plots that were ripped gave the largest residual yields in the second year of the experiment. The percentage cover of clover was inversely related to the amount of nitrogen applied. A study of plant roots indicated that soil injection supplies sludge at too great a depth to benefit grass.Taken overall the results confirm that the regression of pastures established on reclaimed colliery spoil is primarily caused by lack of nitrogen and phosphorus. But the effect of compaction in decreasing root growth, and therefore the ability of the grass to take up nutrients, is also apparent.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Industrial and engineering chemistry 6 (1934), S. 208-208 
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Weed research 31 (1991), S. 0 
    ISSN: 1365-3180
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Experiments were conducted to examine the up take, translocation and metabolism by S. vulgaris of two distinctly different herbicides: 2,4-D, a phenoxyalkanoic acid with growth regulator activity to which this species exhibits complete tolerance, and chlorsulfuron, a sul-fonylurea to which S. vulgaris is highly sensitive. Despite their structural dissimilarities 2,4-D and chlorsulfuron was readily absorbed by S. vulgaris with 65 and 69%, respectively, of the applied dosage being absorbed within 72 hours after treatment. Approximately 35% of the 2,4-D and 10% of the chlorsulfuron label was translocated out of the treated leaf after 72 hours. Neither herbicide accumulated in the terminal bud. Seventy-two hours after treatment 63% of the recovered 14C remained as unaltered 2,4-D in S. vulgaris, while in tomato, a 2,4-D sensitive species, 65% of the recovered 14C remained as intact herbicide. In S. vulgaris approximately 86% of the radioactivity remained as intact chlorsulfuron 72 hours after treatment compared to 12% in the tolerant wheat. The tolerance of S. vulgaris to 2,4-D could not be accounted for by limited absorption, translocation nor metabolic degradation of the herbicide. The sensitivity of S. vulgaris to chlorsulfuron would appear to be related to the inability of this species to metabolize the herbicide molecule.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Cambridge : Cambridge University Press
    The @classical review 41 (1991), S. 359-361 
    ISSN: 0009-840X
    Source: Cambridge Journals Digital Archives
    Topics: Classical Studies
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Cambridge : Cambridge University Press
    The @Cambridge law journal 50 (1991), S. 411-413 
    ISSN: 0008-1973
    Source: Cambridge Journals Digital Archives
    Topics: Law
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Cambridge : Cambridge University Press
    The @Cambridge law journal 50 (1991), S. 563-564 
    ISSN: 0008-1973
    Source: Cambridge Journals Digital Archives
    Topics: Law
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 165 (1991), S. 27-36 
    ISSN: 1615-6102
    Keywords: ATPase ; Cerium ; Cytochemistry ; Fixation ; Zea mays roots ; Plasma membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The cytochemical localization of ATPase activity has been investigated in maize root cells using both lead and cerium-based capture methods. With both methods, staining at the plasma membrane was observed in all cells of the root, although the precipitate obtained with cerium was more uniform and granular than that with lead. Controls using no substrate or no magnesium, β-glycerophosphate to replace ATP, vanadate or boiled tissue generally showed little or no staining. However, biochemical studies on purified plasma membrane fractions showed that ATPase activity was markedly inhibited by fixation, particularly by glutaraldehyde, and also by lead and cerium ions. Non-enzymic hydrolysis of ATP by cerium was greater than that by lead. The value and limitations of these procedures for the localization of plasma membrane H+-ATPase activity are summarized in relation to previous criticisms of these methods.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1573-5087
    Keywords: rol genes ; hairy roots ; auxins ; plant growth regulation ; Solanum dulcamara
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The effects have been investigated of various combinations of rol genes, together with Ri plasmid TR-DNA transcripts 1 and 2, upon free IAA levels in transformed roots of Solanum dulcamara L. Differences between the IAA levels were observed, including a highly significant (p=0.01) difference between the IAA levels of rol − TR+ and rol ABC+ TR+ transformed roots. Possible mechanisms are discussed for the regulation of free IAA levels by rol gene products.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Plant growth regulation 10 (1991), S. 341-353 
    ISSN: 1573-5087
    Keywords: Root initiation ; hormone analysis ; indole-3-acetic acid (IAA) ; auxin, cell division
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract This paper describes the process of the formation of adventitious roots. There appears to be good agreement that this consists of four stages, defifferentiation coupled with the formation of a meristematic locus, cell division to form a radially symmetrical cluster of cells, further divisions coupled with organisation into a bilaterally symmetrical meristem and finally growth of cells in the basal part of the meristem which causes its protursion through the epidermis. Evidence for the involvement of auxins in these various stages is reviewed and the extent to which rooting of easy- and hard-to-root species can be accounted for in terms of auxin content discussed. Peaks of IAA occur soon after excision of cuttings in some species and there is some evidence suggesting that this is correlated with changes in peroxidase activity. The possible involvement of cytokinins with auxins is briefly considered.
    Type of Medium: Electronic Resource
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