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991.
992.
993.
Fe2O3--V2O5 catalysts doped with Cs2SO4 (molar ratio: V:Fe:Cs=1:0.74:0.06) were found to be a rather inhomogeneous mixture of various crystalline and amorphous iron
vanadate phases. After calcination in air the catalyst was divided into three different parts which were analyzed separately
revealing the formation of FeVO4 in the top and bottom fraction of the crucible and Fe2V4O13 in the middle fraction. As compared to the well crystallized FeVO4 reference sample, the quadrupole splittings of FeVO4 in the Cs-doped catalysts were larger pointing to more distorted iron sites which were assumed to be responsible for high
catalytic selectivities. In contrast, the quadrupole splittings of FeVO4 in the less selective K- and Rb-doped Fe2O3--V2O5 catalysts were smaller. Additional components in the bottom fraction were also α-Fe2O3 and Fe1-xS. As indicated by the CEMS spectra the latter is located preferentially on the surface of the catalyst particles.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
994.
995.
We prove the following. Let G be an undirected graph. Every partially specified symmetric matrix, the graph of whose specified entries is G and each of whose fully specified submatrices is completely positive (equal to BBT for some entrywise nonnegative matrix B), may be completed to a completely positive matrix if and only if G is a block-clique graph (a chordal graph in which distinct maximal cliques overlap in at most one vertex). The same result holds for matrices that are doubly nonnegative (entrywise nonnegative and positive semidefinite). 相似文献
996.
997.
We fill a gap in [4], and provide a rigorous example of a local ringR whose Jacobson radical is locally nilpotent, butM
2(R) is not strongly π-regular.
The online version of the original article can be found at
The work of the first author was partially supported by the DGICYT (Spain), through the grant PB92-0586, and by the Comissionat
per Universitats i Recerca de la Generalitat de Catalunya. 相似文献
998.
H. Yamaguchi K. Shinohara K. Sonogashira K. Yamaguchi 《Journal of polymer science. Part A, Polymer chemistry》1987,25(8):2281-2288
Ethynylated polystyrene resins were prepared as functionalized polymer supports by the iodination reaction of macroporous polystyrene resins and reacted with transition metal diethynyl complex (Mt = Ni) and metal halides (Mt = Rh, Pd, and Pt) in a basic solvent using cuprous iodide as a catalyst to obtain macroporous polystyrene resins containing organotransition metals. The distribution of the metal acetylide complexes in the modified macroporous resins was determined by an electron probe microanalyzer. A gradient in the transition metal distribution was observed in any case of the modified resins. The stability of the organotransition metal complexes in the polymer matrix could be compared with a low molecular weight analogous complex quantitatively. 相似文献
999.
We have studied isospin symmetry violation in nuclear reactions by measuring simultaneously the cross-section of the following
two reactionsp +d →3H π+ andp +d →3He π0. The experiment was perfomed at the cooler synchrotron accelerator COSY, Jülich at several beam energies close to the correspondingη production threshold. We also have ongoing programmes onη-nucleus final-state interaction studies viap+6 Li →7 Be +η reactions, high resolution search for dibaryonic resonances and lambda-proton final state interaction studies. The experimental
details and results obtained so far are presented here 相似文献
1000.