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  • 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.
51

The diffusion of carbon into tungsten

Withop, Arthur, 1940- January 1966 (has links)
No description available.
52

The removal of copper from tungsten ores

Perez, Gines, 1908- January 1933 (has links)
No description available.
53

Transformations of cyclic olefins mediated by tungsten and molybdenum nitrosyl complexes

Buschhaus, Miriam Sarah Anne 11 1900 (has links)
Thermolysis of Cp*W(NO)(CH ₂CMe₃) ₂,CpW(NO)(CH ₂CMe₃)₂, Cp*W(NO)(CH₂SiMe₃)(η²-CPhCH₂), or Cp*W(NO)[CH(Ph)CH₂CH(nPr)CH₂]in cyclic olefins results in the formation of ring-retaining oligomers having lengths up to dodecamers. The main cyclohexene dimer is 3-cyclohexylcyclohexene. A small percentage of oligomers contain neopentyl or CH=CHPh end groups. Turnover frequencies for the Cp*-tungsten precatalysts range from 5.5 to 6.5 mol/h at 100 °C. In room temperature solutions, Cp*Mo(NO)(CH₂CMe₃)₂ generates the alkylidene intermediate [Cp*Mo(NO)(=CHCMe₃)], which couples with cyclic olefins to form cismetallacycles. The isolable cyclopentene-derived cis-metallacycle, Cp*Mo(NO)[cis-η² CH(CH₂)₃CHCHCMe₃], converts in the solid state to the allyl-hydride complex Cp*Mo(NO)(H)(η³-CH(CH₂)3CCHCMe₃). With larger cyclic olefins (cyclohexene through cyclooctene) the initial cis-metallacycles isomerize to trans-metallacycles of the form Cp*Mo(NO)[trans-η²-CH(CH₂)nCHCHCMe₃] (n = 4, 5, 6), and these subsequently convert with loss of dihydrogen to η⁴-diene complexes, Cp*Mo(NO)[η⁴-CHCH(CH₂)n-₁CCHCMe₃]. Thermolysis of the η⁴-diene complexes in cyclohexene results in decomposition of the organometallic complex with small amounts of oligomer formation. Thermolysis of Cp*W(NO)CH₂CMe₃)₂ in cyclic-olefm substrates generates the alkylidene intermediate [Cp*W(N0)(=CHCMe₃)], which couples with cyclic olefins in a manner analogous to the Cp*Mo-system. Tungsten trans-metallacycles are observed by ¹H NMR spectroscopy, but the organometallic subsequently reacts further with loss of the coupled neopentyl-cyclic olefin and coordination of two substrate molecules to form the putative Cp*W(NO)(cyclic olefm)₂ complex. Two additional cyclooctene products are isolated, the 1,4- diene Cp*W(N0)[η⁴-CHCH(CH₂)₅CHCCH(CH₂)₆] and the allyl hydride Cp*W(NO)(H)[η³- CH(CH₂)₆CCCHCH(CH₂)₅], both containing two coupled cyclooctene molecules. A tungsten cis-metallacycle forms with 2,5-dihydrofiiran, but a ring-opened alkoxy-allyl complex forms with 3,4-dihydro-2H-pyran, and 1,2,3,6-tetrahydro-pyridine undergoes N -H bond activation to afford an amido product. CpW(NO)(CH₂CMe₃)₂ produces some oligomers of cyclohexene, but in all other reactions bimetallic decomposition pathways predominate.
54

Mechanical properties of zirconia-tungsten composites

Gates, Antonio Alfonso 08 1900 (has links)
No description available.
55

Factors determining the unidirectional solidification behavior of the system UO[subscript 2]-W

Grynkewich, Nicholas Elias 12 1900 (has links)
No description available.
56

The equilibrium composition of tungsten burning in air

Scheuerman, Curtis Howard 12 1900 (has links)
No description available.
57

The effect of very high hydrostatic pressure on the mechanical properties of Tungsten Carbide

Brew, P. A. January 1979 (has links)
No description available.
58

The preparation, characterisation and catalytic activity of tungsten bronzes

Stevenson, Sheena January 1987 (has links)
The structure and catalytic aspects of tungsten bronzes have been considered. A series of potassium tungsten bronzes, KxW03, 0.05 =< x =< 0.8, and the corresponding series of sodium tungsten bronzes, NaxW03, 0.05 =< x =< 0.8 were prepared by a thermal method. The thermal stability of the prepared samples was studied in the presence of both an oxidising and a reducing gas. The number and strength of acid sites present on the bronzes was studied by temperature-programmed desorption of ammonia. Xps, xrd and electrical resistivity measurements gave information about the bulk and surface properties of the bronzes. The activity of the tungsten bronzes for isopropanol decomposition and propene metathesis was investigated. In addition, a silica-supported tungsten bronze and a copper-potassium tungsten bronze, CUyKxW03, were prepared. Their structures and catalytic values were considered.
59

An experimental study of transition metal halides, directed towards the text of a stereochemical theory / by Graham Bruce Allison.

Allison, G. B. (Graham Bruce) January 1968 (has links)
Includes bibliography. / 157 leaves : ill. ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Physical and Inorganic Chemistry, 1968
60

Effects of impurities on deuterium retention in single crystal tungsten.

Quastel, Aaron D. January 2005 (has links)
Thesis (M.A. Sc.)--University of Toronto, 2005.

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