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  • 11
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Plant, cell & environment 2 (1979), S. 0 
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract. The absorption of Cd by potato tissue was studied. No enhancement of the absorption capacity for Cd was observed by storage of the sliced potato tissue in aerated doubly distilled water for a period of 48 h. Cd absorption as a function of the external Cd concentration followed a typical hyperbolic isotherm. A two-phase uptake process for the absorption of Cd was found: a rapid initial phase terminating after 30 min, was followed by a slower phase with a constant rate. Efflux, studied by means of compartmental analysis, of Cd showed three phases. The two first were shown to be extracellular in origin. The third phase, involving Cd remaining in the discs after efflux, probably involved Cd in different forms. Metabolic processes, however, did not seem to contribute to this phase.
    Type of Medium: Electronic Resource
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  • 12
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Bildung flüchtiger Arsenverbindungen bei der elektrothermischen Atomisierung in der AAS kann durch Zugabe von Ni2+unterdrückt werden. Verschiedene oxydierende Reagenzien, unter anderem Salpetersäure, bewirken eine starke Signalerhöhung für As. Die Konzentrationen von Ni2+ und HNO3für die As-Bestimmung wurden mittels der Simplex-Methode optimiert. Als optimale Werte wurden 2000 ppm Ni2+als Nitrat in 2%iger HNO3 ermittelt. Trotz der Ni-zugabe ist die direkte Analyse von As in Harn jedoch unmöglich. Reproduzierbare Resultate werden nur nach 6facher Verdünnung der Harnprobe erhalten. Die Nachweisgrenze beträgt dann 50 ppb.
    Notes: Summary The formation of volatile arsenic species during electrothermal AAS analysis of arsenic can be suppressed by the addition of Ni2+. A lot of oxidizing agents, including nitric acid, have a substantial enhancing effect on the signals of arsenic. The analytical concentrations of Ni2+ and HNO3 to be used were optimized through a Simplex technique. An optimum concentration of 2000 ppm of Ni2 + as Ni(NO3)2 in 2% HNO3 was deduced. However, the direct analysis of arsenic in urine is still impossible, even with the addition of Ni2+. Reproducible results are only obtained after a sixfold dilution of the urine sample, resulting in a mean limit of detection of about 50 ppb.
    Type of Medium: Electronic Resource
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  • 13
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 89 (1986), S. 139-152 
    ISSN: 1436-5073
    Keywords: pattern recognition ; classification ; supervised techniques ; coals
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The purpose of this study is to compare the performance of UNEQ, a supervised pattern recognition technique of the classmodelling type, with other classification techniques and to demonstrate its use for a practical application, namely the classification of coals.
    Type of Medium: Electronic Resource
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  • 14
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' journal of analytical chemistry 361 (1998), S. 2-9 
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The study shows that in the classical calibration situation inverse calibration, i.e. concentration = f(measurement) yields more reliable predictions than classical calibration, i.e. measurement = f(concentration). The theoretical proof is verified by Monte Carlo simulations and by two practical examples. The improvement due to the use of inverse calibration increases with decreasing precision of the measurements.
    Type of Medium: Electronic Resource
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  • 15
    Electronic Resource
    Electronic Resource
    Springer
    European journal of clinical pharmacology 49 (1995), S. 121-125 
    ISSN: 1432-1041
    Keywords: Propranolol ; Nicardipine ; inhibitory effect ; delivery rate ; drug interaction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Abstract The influence of a single oral dose of nicardipine 30 mg on the pharmacokinetics and pharmacodynamics of propranolol 80 mg given as a conventional release formulation and as a slow release formulation was studied in two separate groups of 12 healthy volunteers. Nicardipine doubled the area under the curve (AUC) and C max of propranolol when given as a conventional formulation, but increased it only slightly when given as a slow release formulation. This pharmacokinetic interaction did not result in clinically relevant changes in pharmacodynamic responses. These results indicate that the enhancement of the bioavailability of propranolol by coadministration of nicardipine is dependent on the delivery rate of propranolol, suggesting that the interaction is mainly due to short-term haemodynamic effects of nicardipine leading to saturation of hepatic enzymes or functional shunting.
    Type of Medium: Electronic Resource
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  • 16
    Electronic Resource
    Electronic Resource
    Springer
    Archives of toxicology 31 (1973), S. 185-191 
    ISSN: 1432-0738
    Keywords: Fluoride Selective Electrode ; Sarin ; Alkaline Hydrolysis ; Enzymatic Hydrolysis ; Fluoridselektive Elektrode ; Sarin ; Alkalische Hydrolyse ; Enzymatische Hydrolyse
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Ein manuelles und ein automatisches Verfahren zur Bestimmung von Sarin nach alkalischer Hydrolyse durch Anwendung einer fluoridselektiven Elektrode werden beschrieben. Der Vergleich mit einem klassischen colorimetrischen Verfahren zeigt hohe Übereinstimmung der Resultate beider Methoden. Die enzymatische Hydrolyse (Acetylcholinesterase) unter Anwendung einer Enzymelektrode, gibt keine Resultate: die Annahme, daß Sarin bei der Reaktion mit Cholinesterase F− verliert, ist nicht richtig.
    Notes: Abstract Manual and automatic determinations of Sarin with a fluoride selective electrode after alkaline hydrolysis are presented. Comparison with a classic colorimetric method shows excellent agreement between the two methods. Enzymatic hydrolysis (acetylcholinesterase) measured with an enzyme-electrode, yields no results: the assumption that Sarin loses F− upon reaction with cholinesterase is proved to be incorrect.
    Type of Medium: Electronic Resource
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  • 17
    ISSN: 1432-1459
    Keywords: Calcification of choroid plexus ; Low temperature ashing ; Scanning electron microscopy ; Trace elements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Plexus chorioidei menschlicher Gehirne wurden bei niedriger Temperatur verascht, um die Verkalkungen zu isolieren. Der Aschenrückstand wurde dann morphologisch, chemisch sowie in bezug auf seine Struktur mit Hilfe von Scanning-Elektronenmikroskopie, Atomabsorptionsspektrometrie mit und ohne Flamme sowie infraroter Spektrometrie und Röntgendiffraktionsmethode untersucht. Morphologisch bestanden die Verkalkungen aus aufgewickelten Fasern, die Granula mit einem Durchmesser zwischen 0,05 und 0,15 mm bildeten. Diese bestanden aud kristallinem Ca3(PO4)2 und Hydroxylapatit. Der Gehalt an Spurenelementen ist hoch, jedoch innerhalb der bei anderen biologischen Apatiten üblichen Grenzen. In einzelnen Fällen allerdings überschreitet der Eisengehalt diese Grenzwerte.
    Notes: Summary Human choroid plexus was submitted to low temperature ashing (LTA) in order to isolate the calcification. The ashing residue was then subjected to morphological, chemical and structural studies using technics such as scanning electron microscopy, flame and flameless atomic absorption spectrometry, infrared spectrometry and X-ray diffraction. Morphologically, the calcification consisted of wound-up fibers forming granules with a diameter of 0.05 to 0.15 mm. The concretions were identified as cristalline Ca3(PO4)2 and hydroxylapatite. The content of trace elements was high, but within the limits found in other biological apatites. In some cases, however, the Fe content exceeded these limit values.
    Type of Medium: Electronic Resource
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  • 18
    Electronic Resource
    Electronic Resource
    Springer
    Journal of neurology 215 (1977), S. 209-219 
    ISSN: 1432-1459
    Keywords: Pineal gland calcification ; Low temperature ashing ; Trace elements ; Scanning electron microscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Es wird ein allgemeines Schema für die Analyse kleiner Verkalkungen vorgelegt. Nach Veraschung bei niedriger Temperatur werden die Proben chemisch, in ihrer Struktur und morphologisch untersucht unter Verwendung von atomarer Absorptionsspektrometrie, Infrarotspektrometrie, Röntgendifraktion und Scanning Elektronenmikroskop. Es werden detailliert die Ergebnisse beim Studium von Verkalkungen der menschlichen Epiphyse dargelegt. Der Gehalt an Spurenelementen ist sehr hoch, jedoch innerhalb der Normgrenzen bei anderen biologischen Apatiten. Es wird gefolgert, daß die Verkalkungen der Epiphyse häufiger sind, als bisher angenommen wurde.
    Notes: Summary A general scheme of analysis for the investigation of minute calcification is presented. After low temperature ashing, the samples are subjected to chemical, structural and morphological study, using atomic absorption spectrometry, infrared spectrometry, X-ray diffraction and scanning electron microscopy. Details about the calcification of the human pineal gland are given. The content of trace elements is very high, but within the limits found in other biological apatites. It is concluded that calcification of the pineal is a more general occurrence than has been realized.
    Type of Medium: Electronic Resource
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  • 19
    Electronic Resource
    Electronic Resource
    Springer
    Fresenius' Zeitschrift für analytische Chemie 294 (1979), S. 140-144 
    ISSN: 1618-2650
    Keywords: Best. von Tanninen in Tee ; Potentiometrie/Spektralphotometrie, Atomabsorption ; Cu-Fällung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Summary Different alternatives for the determination of tannins in tea with Cu ionspecific electrodes and atomic absorption spectrometry are discussed. The methods are based on the precipitation of tannins with copper acetate. A screening of methods is carried out in three successive steps: determination of (1) Cu in a simple aqueous solution, (2) tannic acid in aqueous solution and (3) tannins in tea. Two procedures are proposed as suitable tools for tannin determination in tea, i.e. direct potentiometry of excess Cu2+ and AAS, the first being the easiest and most rapid.
    Notes: Zusammenfassung Verschiedene Möglichkeiten zur Bestimmung von Tanninen in Tee mit Hilfe einer kupferionenselektiven Elektrode sowie der AAS werden diskutiert. Die Methoden beruhen auf der Tanninfällung mit Kupferacetat. Im einzelnen wurden folgende Stufen untersucht: Kupferbestimmung in wäßriger Lösung, Gerbsäurebestimmung in wäßriger Lösung, Tanninbestimmung in Tee. Sowohl die potentiometrische Bestimmung des Kupferüberschusses bei der Fällung als auch die AAS-Bestimmung haben sich als geeignet erwiesen, wobei erstere als das einfachste und schnellste Verfahren empfohlen wird.
    Type of Medium: Electronic Resource
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  • 20
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; α1 glycoprotein ; Enantioseparation ; β-blocking agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary The enantioselectivity of the α1 glycoprotein chiral stationary phase, Chiral AGP® has been evaluated for a number of β-blocking agents. A correlation has been found between the retention behaviour on this stationary phase and the hydrophobicity of the compounds. The separation factor α is higher for compounds that are well retained. Retention, and thus α, are also controlled by pH and the percentage of organic modifier in the mobile phase.
    Type of Medium: Electronic Resource
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