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231.
The XPS valence bands and core levels of the alloys Pd1?xZrx (0<x<1) and Cu1?xZrx (0<x<1) have been measured. The alloys prepared by coevaporation are crystalline — but their valence band spectra are close to those of the metallic glasses of the same compositions. The large valence band and core level shifts observed for Pd can be explained by a simple theory, not necessitating the postulation of a new type of bonding in these systems. 相似文献
232.
233.
Herbert Danninger Tayfun Kara Michael Ruhnow Hans -Jürgen Ullrich 《Mikrochimica acta》1990,101(1-6):219-229
Homogenization of Mo, W and Cr in alloyed P/M carbon steels during sintering with a transient liquid phase has been investigated by microscopic and microanalytical means. The reaction was found to start with carburization of the VIa metal, continues with the formation of different carbides, and generation of a liquid phase between the carbide and -Fe. The steady state equilibrium remains stable until all VIa metal has been consumed. Microprobe analysis was found to yield optimum results if selected model samples, in which homogenization should not proceed too fast, are investigated.Dedicated to Professor Günther Tölg on the occasion of his 60th birthday 相似文献
234.
235.
236.
Steiner M. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》1994,40(3):721-731
The design of M average-energy-constrained signals in additive white Gaussian noise is addressed. The long-standing strong simplex conjecture, which postulates that the regular simplex signal set maximizes the probability of correct detection under an average-energy constraint, is disproven. A signal set is presented that performs better than the regular simplex signal set at low signal-to-noise ratios for all M⩾7. This leads to the result that, for all M⩾7, there is no signal set of M signals which is optimal at all signal-to-noise ratios. Furthermore, the optimal signal set at low signal-to-noise ratios is not an equal energy set for any M⩾7. The regular simplex is shown to be the unique signal set which maximizes the minimum distance between signals. It follows that a signal set which maximizes the minimum distance is not necessarily optimum. However, the regular simplex is shown to be globally optimum in the sense of uniquely maximizing the union bound on error probability at all signal-to-noise ratios 相似文献
237.
238.
A series of four dichromophoric rigid macrocycles 6a-6d, two with diphenyloligothiophene chromophores, the other two with more electron-rich diphenyl-EDOT or diphenyl-bis-EDOT chromophores, have been synthesized. The absorption spectrum of the diphenyl-bis-EDOT based macrocycle 6d displayed the most pronounced vibronic resolution with a well-resolved 0-0 transition, indicating a fully planarized geometry of the diphenyl-bis-EDOT chromophores. The (1)H NMR spectra of the macrocycles displayed weak to moderate chemical shifts of characteristic signals upon addition of pi-conjugated oligonitro-9-fluorenone acceptors. X-ray single-crystal analysis showed that columnar pi-stacked donor/acceptor complexes are formed with the stacks composed of alternating donor and acceptor molecules. The stoichiometry of the crystalline, dark-colored complexes was found to be 1:1 by elemental analysis and integration of the (1)H NMR peaks. The complex formation is accompanied by remarkably large Stern-Volmer constants of fluorescence quenching. 相似文献
239.
Shigeki Akiyama Horst Brunotte Attila Pethő Wolfgang Steiner 《Periodica Mathematica Hungarica》2006,52(1):1-17
Summary The periodicity of sequences of integers <InlineEquation ID=IE"3"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"4"><EquationSource
Format="TEX"><![CDATA[<InlineEquation ID=IE"5"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"6"><EquationSource
Format="TEX"><![CDATA[<InlineEquation ID=IE"7"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"8"><EquationSource
Format="TEX"><![CDATA[<InlineEquation ID=IE"9"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"10"><EquationSource
Format="TEX"><![CDATA[$]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation>(a_{n})_{n\in\mathbb
Z}$ satisfying the inequalities <InlineEquation ID=IE"1"><EquationSource Format="TEX"><![CDATA[<InlineEquation ID=IE"2"><EquationSource
Format="TEX"><![CDATA[$$]]></EquationSource></InlineEquation>]]></EquationSource></InlineEquation> 0 \le a_{n-1}+\lambda a_n
+a_{n+1} < 1 \ (n \in {\mathbb Z}) $$ is studied for real $ \lambda $ with $|\lambda|< 2$. Periodicity is proved in case $
\lambda $ is the golden ratio; for other values of $ \lambda $ statements on possible period lengths are given. Further interesting
results on the morphology of periods are illustrated. The problem is connected to the investigation of shift radix systems
and of Salem numbers. 相似文献
240.
Recent work by Pejova [Mater. Res. Bull. 43, 2887 (2008)] showed that the widely cited classical photocurrent theory of DeVore [Phys. Rev. 102, 86 (1956)] does not necessarily apply for photocurrent experiments carried out on thin-film semiconductors. In this Letter, we theoretically and experimentally justify the successful use of the photocurrent model published by Bouchenaki et al. [J. Opt. Soc. Am. B 8, 691 (1991)]. 相似文献