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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 72 (2001), S. 2219-2220 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: In this Note the vortex sensor signal is modeled as a narrow band process, and the frequency of the vortex sensor signal is measured by the means of adaptive notch filtering. A real time processing system based on a digital signal processor is developed. The testing results show that the adaptive notch filtering method and the processing system are effective for vortex flowmeters. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Geometriae dedicata 81 (2000), S. 141-166 
    ISSN: 1572-9168
    Keywords: Monge–Ampère PDE ; affine Gauss–Kronecker curvature
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract We extend a procedure for solving particular fourth order PDEs by splitting them into two linked second order Monge–Ampère equations. We use this for the global study of Blaschke hypersurfaces with prescribed Gauss–Kronecker curvature.
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archiv der Mathematik 64 (1995), S. 534-551 
    ISSN: 1420-8938
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Communications in mathematical physics 213 (2000), S. 685-696 
    ISSN: 1432-0916
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract: Interpreting the number of ramified covering of a Riemann surface by Riemann surfaces as the relative Gromov–Witten invariants and applying a gluing formula, we derive a recursive formula for the number of ramified covering of a Riemann surface by Riemann surface with elementary branch points and prescribed ramification type over a special point.
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 23 (1997), S. 1979-1995 
    ISSN: 1573-1561
    Keywords: Phytotoxicity ; vulpia ; silvergrass ; toxicity ; weed control ; allelochemical ; residue
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Phytotoxic properties of vulpia (V. myuros) residue extracts on wheat (Triticum aestivum L. cv. Vulcan) were examined in the laboratory. Vulpia residues contained water-soluble materials that were toxic to germination and to coleoptile and root growth of wheat. There were strong correlations between extract concentration and toxicity, between extraction times and toxicity, and between extract pH and phytotoxicity. The phytotoxicity was residue rate dependent. There was no significant correlation between the phytotoxicity of residue extracts and the electrical conductivity of aqueous extracts. Milled residues were more toxic than chopped residues. The toxicity of vulpia residues increased as their decomposition proceeded, reaching a peak phytotoxicity after decomposition for 40 days and remaining potent for up to 60 days, gradually declining thereafter. Radicle elongation of wheat was the most sensitive indicator, germination was the least sensitive, and coleoptile growth was intermediate. The phytoxic effects of residue extracts on seed germination had two aspects: germination delay and inhibition. The relative magnitude of each aspect depended upon the potency of the extracts. With a strong phytotoxic potential, inhibition of germination was dominant over seed germination, whereas with a weak toxic level, delay was dominant over seed germination.
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 26 (2000), S. 1465-1476 
    ISSN: 1573-1561
    Keywords: Phytotoxicity ; allelopathy ; allelochemical ; Vulpia ; silylation ; phenolics ; phenolic compounds
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Phytotoxicity-based extraction and fractionation were employed to separate and purify the allelochemicals from an aqueous extract of vulpia (Vulpia myuros) residues. Further analyses, identification, and quantitation of these allelochemicals were conducted by gas chromatography–mass spectrometry on the most toxic fraction. Twenty-one compounds were identified in the ether fraction from the vulpia residue aqueous extract. They were catechol, hydroquinone, 3,4-dimethoxyphenol, pyrogallol, coniferyl alcohol, and benzoic, succinic, hydrocinnamic, salicylic, protocatechuic, vanillic, gentisic, syringic, p-hydroxybenzoic, α-hydroxybenzenepropanoic, p-hydroxyphenylacetic, p-hydroxybenzenepropanoic, hydroferulic, p-coumaric, hydrocaffeic, and ferulic acids. A chromatographic internal standard method with multiple-point calibration graphs was used to quantify the identified compounds. Quantities in the vulpia residues ranged from 1.36 to 81.0 μg/g dry residue, in total accounting for 0.05% of the dry weight residue. The combined syringic and hydroferulic acids were present in the largest amount, 140.11 μg/g residue. Vanillic, succinic, p-hydroxybenzenepropanoic, and salicylic acids were next in amount, ranging from 37.24 to 81.24 μg/g residue. Catechol, hydrocinnamic acid, and hydroquinone were present in the smallest quantities, ranging from 1.36 to 1.82 μg/g residue. The remainder of the compounds were intermediate in amount, ranging from 2.33 to 18.1 μg/g residue.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of chemical ecology 26 (2000), S. 2141-2154 
    ISSN: 1573-1561
    Keywords: Allelopathy ; phenolic acids ; 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one ; DIMBOA ; GC-MS-MS ; wheat ; Triticum aestivum ; weed suppression ; annual ryegrass ; Lolium rigidum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Wheat allelopathy has potential for weed suppression. Allelochemicals were identified in wheat seedlings, and they were exuded from seedlings into agar growth medium. p-Hydroxybenzoic, trans-p-coumaric, cis-p-coumaric, syringic, vanillic, trans-ferulic, and cis-ferulic acids and 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one (DIMBOA) were identified in both the shoots and roots of 17-day-old wheat seedlings and their associated agar growth medium. Wheat accessions with previously identified allelopathic activity tended to contain higher levels of allelochemicals than poorly allelopathic ones. The allelopathic compounds present in the shoots generally also were identified in the roots and in the agar medium. Allelochemicals were distributed differentially in wheat, with roots normally containing higher levels of allelochemicals than the shoots. When the eight allelochemicals were grouped into benzoic acid and cinnamic acid derivatives, DIMBOA, total coumaric, and total ferulic acids, the amount of each group of allelochemicals was correlated between the roots and the shoots. Most of the allelochemicals identified in the shoots and roots could be exuded by the living roots of wheat seedling into the agar growth medium. However, the amounts of allelochemicals in the agar growth medium were not proportional to those in the roots. Results suggest that wheat plants may retain allelochemicals once synthesized. The presence of allelochemicals in the agar growth medium demonstrated that wheat seedlings were able to synthesize and to exude phytotoxic compounds through their root system that could inhibit the root growth of annual ryegrass.
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  • 8
    ISSN: 1573-1561
    Keywords: Phytotoxicity ; allelopathy ; allelochemicals ; Vulpia ; phenolic compounds ; dynamics ; plant residues
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The behavior and dynamics of 20 identified allelochemicals in Vulpia residues were collectively and individually monitored, and their kinetic phytotoxicity was assessed. The total content of the identified allelochemicals in decaying Vulpia residues increased from 0.31 mg/g to 1.24 mg/g dry residue over a 21–day decomposition period, while the total phenolic content increased from 1.86 mg/g to 2.16 mg/g dry residue. This corresponded to a phytotoxicity increase from 42% to 82% of radical inhibition. Allelochemicals changed in composition and quantity over the duration of the residue decomposition. Addition of soil to the residues reduced the total allelochemical contents extracted and altered the dynamic pattern. In the same period, the total content of allelochemicals declined from 0.061 mg/g to 0.046 mg/g residue + soil, with the total phenolics dropped from 0.20 mg/g to 0.11 mg/g residue + soil, corresponding to a radical length increase from 53% to 109% of control. Only 14 of the identified allelochemicals were detected in the mix of soil and residues, in contrast to 20 present in the residues alone. The implications of these findings are discussed.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Computational Chemistry 17 (1996), S. 1108-1111 
    ISSN: 0192-8651
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Computer Science
    Notes: In the research of electron transfer (ET) reactions, the theoretical calculation of the ET matrix element VBA is of special importance. Some examples in which the two electron-localized states have a zero overlap were found. Thus, a new procedure for VBA calculation was developed and applied to the investigation of the donor-acceptor 90° oriented ET reactions. This procedure, which is a supplement necessary to the recently developed approach suitable for a nonorthogonal case, was derived in detail. To check the rationality of the zero value of VBA in the reaction O2O-2 → O-2O2, the angle dependence of SBA and VBA between two electron-localized states was calculated. © 1996 by John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Publication Date: 1996-07-01
    Print ISSN: 1050-2947
    Electronic ISSN: 1094-1622
    Topics: Electrical Engineering, Measurement and Control Technology , Physics
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