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The intramolecular and long-range ferromagnetic coupling between p-phenylenediamine radical cations in head-to-tail coupled oligo(1, 4-phenyleneethynylene)s and oligo(1,4-phenylenvinylene)s between neighbors and next-nearest neighbors is described. UV/vis/near-IR experiments show that the radical cations are localized in the pendant p-phenylenediamine units of the conjugated oligomers. The ESR spectra of these oligo(1,4-phenyleneethynylene) and oligo(1, 4-phenylenvinylene) di(radical cation)s are consistent with those of a triplet state. A linear behavior is observed for the doubly integrated ESR intensity of the DeltaM(s) = +/-1 and DeltaM(s) = +/-2 signals with the inverse temperature (I approximately 1/T), consistent with Curie's law. This behavior indicates a triplet ground-state diradical with a large triplet-singlet energy gap or possibly a degeneracy of singlet and triplet states. 相似文献
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C. Brunner H. Hutter K. Piplits M. Gritsch G. Pöckl M. Grasserbauer 《Analytical and bioanalytical chemistry》1998,361(6-7):667-671
Non-metallic impurities or phases are often unintentional but important constituents in steel – they primarily influence
the properties and behavior of the material by forming crystallization nuclei during the solidification process of the molten
material. The kind, formation and spatial distribution of these inclusions has been investigated in this work by 2D SIMS,
depth profiling and scanning SIMS. These non-metallic phases can be divided into oxides, nitrides, carbides, sulfides and
gas bubbles. Probably the most important phase, the oxygenic, results from reactions of the molten bath with the ambient air
and from the admixture of de-oxidation components. The investigated HSS specimen exhibits two different classes of inclusions.
The first class mainly contains sulfide precipitates and differs widely from the second. The latter exhibits a spherical structure
with the outer sphere combining the oxygenic precipitation and the core containing nitrides and sulfides. Due to the small
size of the inclusions, they have been investigated by high resolution scanning SIMS to separate the different phases.
Received: 30 July 1997 / Revised: 9 February 1998 / Accepted: 15 February 1998 相似文献
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Martinez-Diaz MV Rodriguez-Morgade MS Feiters MC van Kan PJ Nolte RJ Stoddart JF Torres T 《Organic letters》2000,2(8):1057-1060
[formula: see text] New unsymmetrically substituted DB24C8-phthalocyanines, which are able to form complexes with suitable dialkylammonium cations, have been prepared. These complexes most probably have a pseudorotaxane geometry. 相似文献
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