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  • Wiley  (14)
  • Springer  (11)
  • Elsevier  (8)
  • American Economic Association  (1)
  • American Economic Association (AEA)  (1)
  • American Meteorological Society (AMS)
  • 2010-2014  (32)
  • 1955-1959  (3)
  • 1950-1954
  • 1935-1939
  • 2011  (32)
  • 1956  (3)
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  • 2010-2014  (32)
  • 1955-1959  (3)
  • 1950-1954
  • 1935-1939
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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Microchimica acta 44 (1956), S. 760-769 
    ISSN: 1436-5073
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Die Verfasser haben eine semimikro- und eine mikrogravimetrische Methode und ein spektrophotometrisches Verfahren zur Bestimmung von Calcium mit Loretin (7-Jod-8-hydroxychinolin-5-sulfonsäure) ausgearbeitet. Nach Festlegung des Umrechnungsfaktors des Calciumloretinats auf gravimetrischem und thermogravimetrischem Wege wurde gezeigt, daß durch Semimikrogravimetrie Calciummengen von 5 bis 50 mg mit einem mittleren Fehler von 0,35% bestimmbar sind. Die mikrogravimetrische Methode eignet sieh für 0,2 mg Calcium/ml mit einem mittleren Fehler von 0,45%. Der Einfluß einer Reihe von Fremdionen wurde untersucht. Die meisten davon stören nicht, auch wenn sie in bedeutender Menge vorhanden sind. Durch indirekte Spektrophotometrie, nämlich durch Auflösen des Calciumloretinats in überschüssiger Eisen(III)lösung gelang es, Calciummengen in der Größenordnung von 20μg mit einem mittleren Fehler von 0,35% zu bestimmen.
    Abstract: Summary The authors have elaborated a method (semi-micro and micro-gravimetric) and also a spectrophotometric method for determining calcium by means of loretin. After establishing the analytical factor for calcium loretinate by the gravimetric and the thermogravimetric methods, they showed the possibility of determining calcium on the semimicro gravimetric scale for quantities ranging from 5 mg to 50 mg, the mean error being 0.35%. The microgravimetric method allows the minimum quantity to be determined to be reduced to 0.2 mg calcium per ml, the mean error being 0.45%. A study was made of the influence of a number of foreign ions. Most of them do not harm the determination, even though they are present in considerable amounts. By indirect spectrophotometry, notably by dissolving the calcium loretinate in an excess of ferric solution, the writers have succeeded in determining amounts of calcium of the order of 20μg with a mean error of 0.35%.
    Notes: Résumé Les auteurs ont élaboré une méthode semi-micro et micro-gravimétrique et une méthode spectrophotométrique pour le dosage du calcium par la lorétine. Après avoir établi le facteur analytique du lorétinate de calcium par voie gravimétrique et thermogravimétrique, ils ont démontré la possibilité de doser le calcium à l'échelle semi-micro gravimétrique pour des quantités allant de 5 mg à 50 mg, l'erreur moyenne étant de 0,35%. La méthode microgravimétrique permet de ramener la quantité minima à doser à 0,2 mg de calcium par ml, l'erreur moyenne étant de 0,45%. L'influence d'une série d'ions étrangers fut étudiée. La plupart ne gênent pas le dosage, même s'ils sont présents en quantités importantes. Par spectrophotométrie indirecte, notamment en redissolvant le lorétinate de calcium dans un excès d'une solution ferrique, les auteurs ont réussi à doser des quantités de calcium de l'ordre de 20μg avec une erreur moyenne de 0,35%.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0878
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Zusammenfassung Umladebereich und mittlerer isoelektrischer Punkt (IEPM) verschiedener menschlicher Gewebe wurden mit Hilfe von gestuften Reihen gepufferter Lösungen vom Fluorochrom Acridinorange auf fluoreszenzmikroskopischem Wege bestimmt. Zum Vergleich wurde an Schnittpräparaten der gleichen Gewebe die Bestimmung von Umladebereich und IEPM mit den Diachromen Methylenblau und Rubin S durchgeführt. Es zeigte sich, daß das Fluorochrom Acridinorange in der Bestimmung des Umladebereiches und IEPM den Diachromen überlegen ist. Infolge der höheren Nachweisempfindlichkeit von Acridinorange und seiner Fluoreszenzmetachromasie läßt sich der Umladebereich viel leichter als bei den Hellfeldfarbstoffen einengen und somit genauer bestimmen. Während man bei Verwendung von Diachromen zur exakten Bestimmung des IEPM zwei Farbstoffe benötigt, genügt bei der Acridinorange Methode ein Farbstoff. Die mit Acridinorange bestimmten Werte vom Umladebereich und IEPM der einzelnen Gewebselemente liegen meist weiter im sauren Bereich als bei Bestimmung mit Diachromen. Bei dem Vergleich unfixierter, in Alkohol oder Formalin gehärteter Gewebe ergab sich, daß nach Fixierung die untere Grenze vom Umladebereich gegenüber der an unfixiertem Gewebe bestimmten weiter in den sauren Bereich verschoben ist.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2011-06-16
    Description: A new copper(II) phosphonatobenzenesulfonate incorporating 4,4′-bipyridine (4,4′- bipy ) as auxiliary ligand has been discovered through systematic high-throughput (HT) screening of the system Cu(NO 3 ) 2 ·3H 2 O/H 2 O 3 PC 6 H 4 SO 3 H/4,4′- bipy using different solvents. The hydrothermal synthesis of [Cu(HO 3 PC 6 H 4 SO 3 )(C 10 H 8 N 2 )]·H 2 O ( 1 ) was further optimized by screening various copper(II) salts. The crystal structure of 1 was determined by single-crystal X-ray diffraction and unveiled the presence of isolated sixfold coordinated Jahn–Teller-distorted Cu 2+ ions. The isolated CuN 2 O 4 octahedra are interconnected by phosphonate and sulfonate groups to form chains along the c- axis. The organic groups, namely phenyl rings and 4,4′- bipy molecules cross-link the chains into a three-dimensional framework. Water molecules are found in the narrow voids in the structure which are held by weak hydrogen bonds. Upon dehydration, the structure of 1 undergoes a phase transition, which was confirmed by TG measurements and temperature dependent X-ray powder diffraction. The new structure of 1-h was refined with Rietveld methods. Detailed inspection of the structure revealed the directional switching of the Jahn–Teller distortion upon de/rehydration. Weak ferro-/ferrimagnetic interactions were observed by magnetic investigations of 1 , which switch to antiferromagnetic below 3.5 K. Compounds 1 and 1-h are further characterized by thermogravimetric and elemental analysis as well as IR spectroscopy.
    Print ISSN: 0044-2313
    Electronic ISSN: 1521-3749
    Topics: Chemistry and Pharmacology
    Published by Wiley
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  • 4
    Publication Date: 2011-02-22
    Description: The bifunctional metalloligand bis(carboxyethylgermanium)sesquioxide, (HOOCCH 2 CH 2 Ge) 2 O 3 , was employed in the systematic high-throughput (HT) investigation of the system Zn 2+ /(HOOCCH 2 CH 2 Ge) 2 O 3 /H 2 O/C 4 H 9 OH. Two new metal-organogermanates Zn[(OOCCH 2 CH 2 Ge) 2 O 3 ] ( 1 ) and Zn 2 (O 3 GeCH 2 CH 2 COO) ( 2 ) were discovered that show two new structural motifs for this class of compounds. Whereas in compound 1 a formal intercalation in the structure of (HOOCCH 2 CH 2 Ge) 2 O 3 is observed, 2 exhibits a new layered structure composed of CGeO 3 and ZnO 4 unit linked by μ 3 -oxygen atoms. Both connectivity modes lead to dense three-dimensional framework structures.
    Print ISSN: 0044-2313
    Electronic ISSN: 1521-3749
    Topics: Chemistry and Pharmacology
    Published by Wiley
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  • 5
  • 6
    Publication Date: 2011-06-02
    Description: American Economic Review 101 (3): 176-187 Abstract This paper describes the progress, eight years after matriculating, of 586 individuals who entered one of 27 economics Ph.D. programs in fall 2002. By October 2010, 59 percent of the fall 2002 entering cohort had earned a Ph.D. in economics at the university where they initially matriculated, 37 percent had dropped out, and 4 percent were still writing their dissertations.We examine student outcomes by Ph.D. program tier and investigate factors associated with completion and time to degree. We document and describe the rise in median time to degree from 5.0 to 5.6 years during the period 1996–2010.
    Print ISSN: 0002-8282
    Electronic ISSN: 1944-7981
    Topics: Economics
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  • 7
    Publication Date: 2011-09-30
    Description: Using the bifunctional metalloligand bis(2-carboxyethylgermanium sesquioxide), (HOOCCH 2 CH 2 Ge) 2 O 3 , a high-throughput(HT) study was performed to investigate the systemCa 2+ / (HOOCCH 2 CH 2 Ge) 2 O 3 / H 2 O / 2-propanol. The HT experiment comprised 72 individual reactions, developed to explore the influence of the molar ratio of the starting materials and the volume fraction of the solvents. With this approach one new compound Ca 2 [(OOCC 2 H 4 Ge) 2 O 3 ] 2 ·3H 2 O ( 1 ) (monoclinic, P 2 1 / c , a = 8.9562(18), b = 9.6638(19), c = 27.087(5) Å, β = 92.78(3)°, V = 2334.4(8) Å 3 , Z = 4) was obtained and characterized by single-crystal X-ray diffraction. The crystal structure consists of alternating layers of corner-sharing GeO 3 C tetrahedra and chains of edge-sharing CaO 7 polyhedra, which are connected via carboxylate groups of the bis(2-carboxyethylgermanium sesquioxide) entities. Scale-up of the synthesis procedure allowed the detailed characterization of the title compound using IR and Raman spectroscopy, TG analysis and temperature resolved XRPD measurements.
    Print ISSN: 0044-2313
    Electronic ISSN: 1521-3749
    Topics: Chemistry and Pharmacology
    Published by Wiley
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  • 8
    Publication Date: 2011-12-13
    Description: Progressive rock-fall failures in natural rock slopes are common in many environments, but often elude detailed quantitative documentation and analysis. Here we present high-resolution photography, video, and laser scanning data that document spatial and temporal patterns of a 1.2-year-long sequence of at least fourteen rock falls from the Rhombus Wall, a sheeted granitic cliff in Yosemite Valley, California. The rock-fall sequence began on 26 August 2009 with a small failure at the tip of an overhanging rock slab. Several hours later, a series of five rock falls totaling 740 m 3 progressed upward along a sheeting joint behind the overhanging slab. Over the next three weeks, audible cracking occurred on the Rhombus Wall, suggesting crack propagation, while visual monitoring revealed opening of a sheeting joint adjacent to the previous failure surface. On 14 September 2009 a 110 m 3 slab detached along this sheeting joint. Additional rock falls between 30 August and 20 November 2010, totaling 187 m 3 , radiated outward from the initial failure area along cliff (sub)parallel sheeting joints. We suggest that these progressive failures might have been related to stress redistributions driving fracture propagation along sheeting joints behind the cliff face. Mechanical analyses indicate that tensile stresses should occur perpendicular to the cliff face and open sheeting joints, and that sheeting joints should propagate parallel to a cliff face from areas of stress concentrations. The analyses also account for how a sheeting joint can propagate to lengths many times greater than its depth behind a cliff face. We posit that as a region of failure spreads across a cliff face, stress concentrations associated with previous failures will likely tend to spread with it, inciting further crack propagation and rock falls. Copyright © 2011 John Wiley & Sons, Ltd.
    Print ISSN: 0197-9337
    Electronic ISSN: 1096-9837
    Topics: Geography , Geosciences
    Published by Wiley
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  • 9
    Publication Date: 2011-12-27
    Print ISSN: 0006-8314
    Electronic ISSN: 1573-1472
    Topics: Geosciences , Physics
    Published by Springer
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  • 10
    Publication Date: 2011-11-01
    Print ISSN: 1047-8477
    Electronic ISSN: 1095-8657
    Topics: Biology
    Published by Elsevier
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