排序方式: 共有44条查询结果,搜索用时 15 毫秒
1.
2.
3.
We obtain an existence theorem for monotone positive solutions of nonlinear second-order nonlinear differential equations via principal and nonprincipal solutions of the corresponding homogeneous equation. 相似文献
4.
5.
6.
The development of a scheme to treat two-dimensional electromagneticscattering by electrically large, perfectly conducting bodiesis described. It incorporates the effects of surface curvatureand non-local phenomena and has the potential to provide thebasis for a general technique yielding more accurate predictionsthan the widely used physical optics method. 相似文献
7.
8.
The biosynthetic origin of the C(3) unit, C-6,5,5', of pyridoxamine was investigated in two yeasts, Candida utilis ATCC 9256 and Saccharomyces cerevisiae ATCC 7752. The incorporation patterns within pyridoxamine bishydrochloride derived from variously multiply (13)C- and (2)H-labeled samples of glycerol and glyceraldehyde, established by NMR spectroscopy, indicate that the three-carbon unit C-6,5,5' of pyridoxamine is derived intact from a triose. 相似文献
9.
Zoran Samard?ijaRID=""ID="" To whom correspondence should be addressed Darko Makovec Miran ?eh 《Mikrochimica acta》2000,132(2-4):383-386
Yttrium-doped BaTiO3 ceramics have been studied as a potential material for positive temperature coefficient resistors (PTCR). The mechanism of
Y incorporation into BaTiO3 plays an important role for displaying good electrical properties. Determination of the amount of yttrium in the BaTiO3 as well as microstructure characterization of the samples were performed using SEM, EDS and WDS analysis. An optimized trace
element WDS quantitative analysis was applied to determine elemental concentrations for Ba, Ti and Y in the samples as accurately
as possible. BaTiO3 and Y2O3 were used as standards. Analysis was undertaken using a JEOL JXA 840A electron probe microanalyzer. WDS X-ray intensity measurements
were performed under 20 kV, 50 nA beam current and 0.2% preset standard counting deviation (σc) using a PET crystal. Measured k-ratios were quantified by ZAF matrix correction. Average results of WDS quantitative analysis showed 20.17 ± 0.08 at % Ti,
19.95 ± 0.09 at % Ba, 0.22 ± 0.03 at % Y, and 59.66 at % O. The results suggest incorporation of yttrium in the BaTiO3 preferentially at the Ba-sites, however partial incorporation of Y at Ti-sites could not be excluded. 相似文献
10.