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  • Electronic Resource  (10)
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  • Electronic Resource  (10)
  • 1
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 83 (1961), S. 2608-2610 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 36 (2000), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : Field experiments were conducted from 1992 to 1995 to estimate ground water recharge rates at two sites located within a 2.7-hectare agricultural field. The field lies in a sand plain setting in central Minnesota and is cropped continuously in field corn. The sites are located at a topographically high (upland) site and a topographically low (lowland) site in an effort to quantify the effects of depression focusing of recharge. Three site-specific methods were used to estimate recharge rates: well hydrograph analysis, chlorofluorocarbon age dating, and an unsaturated zone water balance. All three recharge methods indicated that recharge rates at the lowland site (annual average of all methods of 29 cm) exceeded those at the upland site (annual average of 18 cm). On an annual basis, estimates by the individual methods ranged from 12 to 44 percent of precipitation at the upland site and from 21 to 83 percent at the lowland site. The difference in recharge rates between the sites is primarily attributed to depression focusing of surface water runon at the lowland site. However, two other factors were also important: the presence of thin lamellae at the upland site, and coarser textured soils below a depth of 1.5 m at the lowland site.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 42 (2004), S. 0 
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: To complement a large-scale geophysical investigation of occurrence and discharge of fresh water beneath Delaware, Maryland, and Virginia (Delmarva) coastal bays, we measured (1) salinity and nutrient concentrations in ground water samples from several offshore coring sites and (2) a suite of chemical and isotopic parameters, including age tracers, in ground water samples from a Delaware site. Samples were collected in a variety of Holocene and Plio-Pleistocene sediments in nearshore and offshore areas of the bays. Ground waters that were significantly fresher than overlying waters were found in plumes up to at least 15 m thick extending to more than 500 m offshore in some areas. Steep salinity and nutrient gradients occur within a few meters of the sediment surface in most locations studied. The zone of transition from deeper fresher waters to shallower brackish waters is generally thin near shore, but thickens and becomes more gradual offshore. Ground water ages at the Delaware site were mostly 〈 50 yr in both fresh waters and brackish waters up to 22 m below the bay bottom. Water chemistry and age data indicate that fresh water plumes beneath the estuary are active extensions of the surficial aquifer carrying nitrate from recharge areas on land, whereas brackish ground water surrounding the fresh water plumes is recharged beneath the estuary and contains ammonium and phosphate released by diagenesis of shallow estuarine sediments. Denitrification affects some of the fresh water nitrate before it mixes with brackish ground water or discharges to surface water.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 82 (1960), S. 5616-5618 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    s.l. : American Chemical Society
    Journal of the American Chemical Society 82 (1960), S. 2647-2648 
    ISSN: 1520-5126
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Veterinary radiology & ultrasound 36 (1995), S. 0 
    ISSN: 1740-8261
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Contrast echocardiography has traditionally been used in conjunction with conventional echocardiography to document right-to-left intracardiac shunting congenital anomalies. This technique does not clearly demonstrate shunting of blood in patients with right-to-left patent ductus arteriosus, as the shunt is extracardiac. We used a variation of contrast echocardiography, contrast echoaortography, to confirm the presence of a right-to-left shunting patent ductus arteriosus in two dogs.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Journal of molecular medicine 3 (1924), S. 2395-2397 
    ISSN: 1432-1440
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    International journal of legal medicine 9 (1927), S. 603-617 
    ISSN: 1437-1596
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Law
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 302 (1959), S. 103-120 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: The effect of nucleophilic reagents on the quasi-aromatic system of trimeric phosphonitrilic chloride and the mechanism of the substitution reactions are investigated. 2, 3, 4 or 6 Cl-atoms of (PNCL2)3 are easily substituted by nucleophilic ligands. Strongly nucleophilic reagents attack in 1- or 3-position. Further substitution follows in 5-position of the sixmembered ring system. With weak electron donators as reagents substitution takes place in another sequence. The substitution rules are checked by the synthesis of isomers. The nuclear magnetic resonance spectra which we owe to J. R. VAN WAZER are in agree with the chemical reasoning.
    Notes: Der Mechanismus der Substitutionsreaktionen bei der Einwirkung nucleophiler Reagentien auf das quasi-aromatische System des trimeren Phosphornitrilchlorids wird untersucht. 2, 3, 4 oder 6 Cl-Atome von (NPCL2)3 werden von nucleophilen Liganden leicht ersetzt. Stark nucleophile Reagentien greifen zunächst in 1- und in 3-Stellung an. Weitere Substitution erfolgt dann an der 5-Stellung des sechsgliedrigen Ringsystems. Bei schwachen Elektronendonatoren als Reagens findet Substitution in anderer Reihenfolge statt. Die Substitutionsregeln werden durch die Synthese von Isomeren gesichert. Mit dieser chemischen Beweisführung stehen die kernmagnetischen Resonanzspektren im Einklang, deren Aufnahme wir JOHN R. VAN WAZER verdanken.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 304 (1960), S. 126-136 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: By interaction between (PNCl2)3, AlCl3, and C6H6, a diphenyl compound is formed having both phenyl groups at the same P-atom. Reaction of this product with NH3 yields a diamine and tetramine derivative; the latter one exists in two forms.The reaction mechanisms and thermal decomposition reactions of the amine compounds as well as the results of nuclear magnetic resonance measurements are discussed.
    Notes: Bei der Umsetzung von trimerem Phosphornitrilchlorid mit Aluminiumchlorid und Benzol entsteht leicht ein Diphenylderivat, in dem beide Phenylgruppen an das gleiche P-Atom gebunden sind. Durch Reaktion dieses Stoffes mit NH3 kann man ein Di-oder ein Tetramin erhalten; letzteres kommt in zwei Formen vor. Der Angriff des NH3 erfolgt zunächst in 3- und 5-Stellung; d. h. die beiden NH3-Gruppen des Diamins sitzen nicht am gleichen P-Atom. Weiterer Angriff starker Basen auf das Diamin führt zu einem Tetra-substitutionsprodukt des Diphenylphosphornitriles. Die Aminoverbindungen lassen sich durch Abspaltung von NH3 zu polymeren Produkten kondensieren. Die kernmagnetischen Resonanzspektren stehen im Einklang mit den Strukturvorschlägen.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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