• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 269
  • 202
  • 138
  • 108
  • 54
  • 23
  • 19
  • 18
  • 16
  • 14
  • 9
  • 8
  • 8
  • 8
  • 7
  • Tagged with
  • 1002
  • 92
  • 90
  • 66
  • 65
  • 65
  • 64
  • 62
  • 62
  • 62
  • 62
  • 61
  • 59
  • 58
  • 57
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
301

Schiff's bases as solvent extraction reagents

Richardson, Ralph Alan January 1972 (has links)
The solvent extraction of metal chelates has been used for a long time for separation and determination of metal ions. The first quantitative description of the extraction process was, however, not made until 1941 when Kolthoff and Sandell compared experimental data with theoretical predictions for the extraction of metal dithizonates. They found that the theory they proposed was valid under wide experimental conditions. However, the systems used by Kolthoff and Sandell were simple ones and hence relatively simple theory was used to successfully explain their behaviour. In practice solvent extraction systems are complicated by other factors, e.g. hydrolysis, polymerisation and complex formation in the aqueous phase. It has subsequently become apparent that such factors have an important influence on the solvent extraction of chelates. Several authors have published reports since 1941 on the theory of solvent extraction of metal chelates which take these factors into account. In particular two publications by Irving, Rossotti and Williams and Stary (chapter 3) should be noted for their comprehensive treatment of the subject. The influence of these factors will be discussed in the following sections.
302

Aspects of the chemistry of titanium dioxide in fused salt solvents

Udy, David John January 1973 (has links)
An investigation into the chemistry of solutions of titanium dioxide in fused alkali metal borates has been made, with the emphasis on the ability of the alkali borate melts to dissolve TiO2 and subsequently crystallize TiO2 and/or complex alkali metal titanates. The preparation and properties of potassium titanates with K2O/TiO2 mol ratio ≤1 has been studied. In addition the thermal decomposition of potassium hexafluorotitanate monohydrate (reported to yield potassium tetratitanate) has been investigated. The decomposition product has been identified as an oxyfluorotitanate. The compounds crystallized on slow cooling of alkali borate + TiO2 melts have been identified. The titanium containing product(s) have been correlated with the concentration of borate groups containing non-bridging oxygens, which depends on the alkali metal cation. Phase diagrams for the M2O.B2O3 + TiO2 (M = Na, K) systems have been obtained. Mass transport in M2O.2B2O3 + TiO2 (M = Li, Na, K) systems has been studied, via measurements of electrical conductivity, as a function of temperature and TiO2 concentration. Additional information on the alkali borate melts has been obtained from measurements of the optical basicity of M2O + B2O3 (M = Li, Na, K, Rb, Cs) glasses, using Pb(II) as probe ion. The results of these measurements have confirmed that the nature of the alkali metal cation significantly affects the basicity of fused alkali borate solvents. Extraction of TiO2 from ilmenite and titaniferous slag, using selected low-basicity alkali borate solvents has been attempted. The results indicate that TiO2 may be separated from ilmenite in essentially a one-step process.
303

Schiff's bases as solvent extraction reagents

Richardson, Ralph Alan January 1972 (has links)
The solvent extraction of metal chelates has been used for a long time for separation and determination of metal ions. The first quantitative description of the extraction process was, however, not made until 1941 when Kolthoff and Sandell compared experimental data with theoretical predictions for the extraction of metal dithizonates. They found that the theory they proposed was valid under wide experimental conditions. However, the systems used by Kolthoff and Sandell were simple ones and hence relatively simple theory was used to successfully explain their behaviour. In practice solvent extraction systems are complicated by other factors, e.g. hydrolysis, polymerisation and complex formation in the aqueous phase. It has subsequently become apparent that such factors have an important influence on the solvent extraction of chelates. Several authors have published reports since 1941 on the theory of solvent extraction of metal chelates which take these factors into account. In particular two publications by Irving, Rossotti and Williams and Stary (chapter 3) should be noted for their comprehensive treatment of the subject. The influence of these factors will be discussed in the following sections.
304

Aspects of the chemistry of titanium dioxide in fused salt solvents

Udy, David John January 1973 (has links)
An investigation into the chemistry of solutions of titanium dioxide in fused alkali metal borates has been made, with the emphasis on the ability of the alkali borate melts to dissolve TiO2 and subsequently crystallize TiO2 and/or complex alkali metal titanates. The preparation and properties of potassium titanates with K2O/TiO2 mol ratio ≤1 has been studied. In addition the thermal decomposition of potassium hexafluorotitanate monohydrate (reported to yield potassium tetratitanate) has been investigated. The decomposition product has been identified as an oxyfluorotitanate. The compounds crystallized on slow cooling of alkali borate + TiO2 melts have been identified. The titanium containing product(s) have been correlated with the concentration of borate groups containing non-bridging oxygens, which depends on the alkali metal cation. Phase diagrams for the M2O.B2O3 + TiO2 (M = Na, K) systems have been obtained. Mass transport in M2O.2B2O3 + TiO2 (M = Li, Na, K) systems has been studied, via measurements of electrical conductivity, as a function of temperature and TiO2 concentration. Additional information on the alkali borate melts has been obtained from measurements of the optical basicity of M2O + B2O3 (M = Li, Na, K, Rb, Cs) glasses, using Pb(II) as probe ion. The results of these measurements have confirmed that the nature of the alkali metal cation significantly affects the basicity of fused alkali borate solvents. Extraction of TiO2 from ilmenite and titaniferous slag, using selected low-basicity alkali borate solvents has been attempted. The results indicate that TiO2 may be separated from ilmenite in essentially a one-step process.
305

Frederic Leightons Ausbildung unter Edward Jakob von Steinle an der Städelschule zu Frankfurt am Main

Wippermann, Katharina. Unknown Date (has links)
Universiẗat, Diss., 2005--Marburg.
306

Perspektiven der Orientierung ein Integrationskurs aus der Sicht seiner Teilnehmenden

Fuchs, Mathias Unknown Date (has links)
Univ., Magisterarbeit, 2007--Frankfurt (Main)
307

Regionsmarketing und die Bedeutung regionsbezogener Identität der Übergangsbereich der Verdichtungsräume Rhein-Main und Rhein-Neckar als Beispiel /

Lindstaedt, Tamara. Unknown Date (has links)
Techn. Universiẗat, Diss., 2006--Darmstadt.
308

Die Beurteilung der Börsenreife im Rahmen von Privatisierungen : dargestellt am Beispiel eines Eisenbahnunternehmens /

Kim, Mi-Sonn. January 2006 (has links) (PDF)
Univ., Wirtschafts- und Sozialwiss. Fak., Diss.--Rostock, 2006.
309

Liberalismus und Nation : die Deutsche Zeitung ; 1847 - 1850 /

Hirschhausen, Ulrike von. January 1998 (has links) (PDF)
Univ., Diss./97--Tübingen, 1996. / Literaturverz. S. [331] - 341 und Index.
310

Die Rechtsstellung der theologischen Fakultäten Trier, Paderborn, Frankfurt St. Georgen und Fulda /

Himmelsbach, Rainer. January 1997 (has links) (PDF)
Univ., Diss.--Freiburg (Breisgau), 1996.

Page generated in 0.0492 seconds