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32.
The oxidation of perfluoroquinoline with nitric acid (98%) yields perfluoropyridine-2.3-dicarboxylic acid (V) besides 2.3.4.6.7-pentafluoro-5.8-dioxo-5.8-dihydro-quinoline (IV) and 3.4.5.6.7.8-Hexafluoro-2-oxo-1.2-dihydro-quinoline (VIa). 相似文献
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Single crystals of anhydrous thallium acetylenedicarboxylate (Tl2(C4O4), 1) and thallium acetylenedicarboxylate oxalate (Tl4(C4O4)(C2O4), 2) precipitated from aqueous solutions containing thallium(I)-acetate and the respective organic acids. Both compounds crystallize in non-centrosymmetric space groups (1: P212121; 2: C2) and contain stereochemically active lone pairs at Tl(I). The crystal structures of 1 and 2 show some similarities. Tl atoms are organized in corrugated layers, which are connected by the respective carboxylate anions. Upon heating 1 decomposes at 195 °C to form elemental pyrophorous thallium powder. 2 starts decomposing at approx. 150 °C forming elemental thallium next to another compound, which could not be identified up to now. TlHADC was also synthesized, but its crystal structure could not be solved either from powder or single crystal diffraction data. Upon heating it decomposes to form 1. 相似文献
37.
Modelling of self-aligned total internal reflection waveguide mirrors: an interlaboratory comparison
J. Čtyroký H. Hoekstra G. J. M. Krijnen P. V. Lambeck L. Joannes D. Decoster A. P. Leite R. Pregla E. Ahlers J. -F. Vinchant M. Adelaide Andrade 《Optical and Quantum Electronics》1995,27(10):935-942
Results of modelling of light propagation in 45° self-aligned total internal reflection rib waveguide mirrors on InP substrate are compared. Six laboratories participated in the comparison with the following six modelling methods: the standard fast-Fouriertransform beam propagation method (BPM), the standard finite-difference (FD) BPM using the Crank-Nicholson scheme (two laboratories), the FD-BPM with the correction for the slowly varying envelope approximation, the method of lines, the eigenmode expansion and propagation method, and a simple method based on the field overlap. All the laboratories used the effective-index method to reduce the three-dimensional problem to two dimensions. The differences among the results obtained by different methods are briefly discussed and qualitatively compared to measured values. 相似文献
38.
A photometric method for the determination of silicon based on the yellow color of α-silicomolybdic acid is described. The pH must be kept within the range 3.0–3.7, and the equilibrium state is established by beating the solution. Since the color of this modification is remarkably stable and reproducible, a high degree of precision can be attained. 相似文献
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We present measurements of the thermal resistivity rho(t,P,L) near the superfluid transition of 4He at saturated vapor pressure and confined in cylindrical geometries with radii L=0.5 and 1.0 microm [t identical with T/T(lambda)(P)-1]. For L=1.0 microm measurements at six pressures P are presented. At and above T(lambda) the data are consistent with a universal scaling function F(X)=(L/xi(0))(x/nu)(rho/rho(0)), X=(L/xi(0))(1/nu)t valid for all P (rho(0) and x are the pressure-dependent amplitude and effective exponent of the bulk resistivity rho, and xi=xi(0)t(-nu) is the correlation length). Indications of breakdown of scaling and universality are observed below T(lambda). 相似文献
40.
We present measurements of the Nusselt number N as a function of the Rayleigh number R in cylindrical cells with aspect ratios 0. 5=gamma identical withD/d=12.8 ( D is the diameter and d is the height). We used acetone with a Prandtl number sigma = 4.0 for 10(5) less, similarR less, similar4x10(10). A fit of a power law N = N(0)R(gamma(eff)) over limited ranges of R yielded values of gamma(eff) from 0.275 near R = 10(7) to 0.300 near R = 10(10). The data are inconsistent with a single power law for N(R). For R>10(7) they are consistent with N = asigma-1/12R1/4+bsigma-1/7R3/7 as proposed by Grossmann and Lohse for sigma greater, similar2. 相似文献