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101.
102.
The 2D Rancieite type manganic acid was prepared by reduction of KMnO4 in acidic medium. Its ion exchange behavior allows to prepare alkali derivatives. All compounds were characterized with use of a combination of X-ray diffraction, chemical analyses, TGA, magnetic measurements and spectroscopic techniques. The evolution of their chemical composition versus temperature was studied between 180 and 400 °C. It shows that the dehydration process is partly reversible in these compounds whereas the weak reduction is irreversible. The 2D Rancieite-type manganic acid is readily different from a Birnessite-type phyllomanganate, as shown by several features: the interlayer distance, the ion exchange capacity, the thermal behavior, the interlayer cation content, the manganese average oxidation state, the magnetic behavior and the IR spectrum. 相似文献
103.
Jati K. Sengupta 《The Journal of the Operational Research Society》1996,47(11):1387-1397
A method is developed here for characterizing the empirical distribution of the efficient units in data envelopment analysis. Two empirical applications illustrate the various uses of the distribution approach. One involves the cost frontier which exhibits increasing returns to scale and the other involves a dynamic production frontier, where technological change causes a shift of the production frontier over time. 相似文献
104.
A radioactive tracer technique is described for the quantitative measurement of the sputtering yield of a target material electroplated on a copper substrate. Sputtering yields of chromium by argon and xenon ions with energies from 50 to 500 eV are reported. The ion beams, having a current density ranging from 0.01 to 0.1 mA/cm2 at an operating pressure of 2×10–5 Torr, were produced by a low-energy ion gun. The sputtered atoms were collected on an aluminum foil surrounding the target. 51Cr was used as the tracer isotope. The results indicate that the radioactive tracer technique is sensitive enough in measuring the extremely small amount of sputtered material at low ion currents and low ion energies. 相似文献
105.
Semi-empirical molecular orbital calculations were carried out for the compounds (C2H5)3As, (C2H5)3Ga and RAsH2 (R = C2H5, i-C3H7, i-C4H9, and t-C4H9) by using the CNDO/2-U program, and their capability of β-elimination reaction is compared on the basis of the torsion energy to the transition state, electrostatic interactions and orbital overlapping between the central atom and the β-hydrogen, and bond order of the metal-carbon, and carbon-hydrogen bond. In the comparison of (C2H5)3As with (C2H5)3Ga, we found that the β-elimination of (C2H5)3As could hardly be expected to take place in the thermal decomposition. The capability of β-elimination would be smaller in C2H5AsH2 than that in (C2H5)3As. Moreover when the ethyl group is replaced by a t-butyl group in RAsH2, the β-elimination reaction appears to become more difficult and a large possibility for a radical process is suggested. 相似文献
106.
A. R. Kuznetsov S. G. Lunter S. I. Nikitina A. G. Plyukhin Yu. K. Fedorov 《Journal of Applied Spectroscopy》1992,56(1):68-72
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 56, No. 1, pp. 90–95, January, 1992. 相似文献
107.
108.
Intense multi- and single-line laser operation is reported from semiconductively preionised atomic fluorine lasers employing an optimised capacitor transfer excitation circuitry. The performance and spectral characteristics of these lasers are discussed and compared to the characteristics of previously described atomic fluorine lasers. The efficiency of one of these lasers described, at optimum conditions, is reaching a value as high as 0.14%. To the best of our knowledge, this is the highest efficiency reported up date, for an atomic fluorine laser. 相似文献
109.
110.
This paper discusses a number of issues relating to the analysis of uncertain systems or data in the context of (low-frequency) structural dynamics. In order to illustrate potential problems in applying ‘classical’ uncertainty analysis methods to nonlinear systems, a simple nonlinear system is simulated and the breakdown of two standard approaches is demonstrated on data from the system. By relaxing the requirements of the analysis, it is shown that an alternative uncertainty theory gives useful qualitative information about the system. This motivates a discussion of how uncertainty frameworks should be chosen to suit the problem in hand and leads to a clustering of uncertainty problems in structural dynamics into three types: quantification, fusion and propagation. 相似文献