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排序方式: 共有736条查询结果,搜索用时 0 毫秒
731.
M. Büscher R. Eßer A. Franzen L. v. Horn D. Kopyto H. Ohm H. Seyfarth K. Sistemich H. Müller B. Prietzschk B. Rimarzig C. Schneider C. Schneidereit A. Akindinov M. Chumakov V. Demechin V. Ergakov A. Gerasimov V. Goryachev Y. Kiselev V. Kostromin A. A. Sibirtsev V. Sopov V. Tchernyshev V. Kruglov A. Petrus V. Koptev S. Mikirtychyants 《Zeitschrift für Physik A Hadrons and Nuclei》1996,355(1):93-100
The production ofK + andπ + mesons and protons inpBe collisions atT p=2.9 GeV has been studied at the ITEP proton synchrotron. Ejectiles with a momentum ofp=545 MeV/c were observed under an emission angle ?=17°. The detectors which have been developed for the identification of kaons out of a six orders of magnitude more intense background of pions and protons are described. A cross-section ratio d2σ K +/dΩdp: d2 σ p /dΩdp: d2σ p /dΩdp of (1±0.34):(85±1):(31±1) has been measured. Normalization with existing pion data yields an invariant differential cross sectionE·d3σ K +/d3 p=(3.1±1.2) mbGeV?2c3sr?1 and a total cross section of σtot(pBe)=(3.7±1.5) mb. These cross sections are compared with existing data and theoretical predictions. TheA dependence ofK + production in the few-GeV range is analyzed. 相似文献
732.
Boris Bornemann Manja Foth Judith Horn Jan Ries Elke Warmuth Isabell Wartenburger Elke van der Meer 《ZDM》2010,42(6):555-567
Individuals scoring higher in tests of general cognitive abilities tend to perform better on novel and familiar mathematical tasks. It has been scarcely investigated how this superior mathematical performance relates to the amount of cognitive resources that is invested to solve a given task. In this study we propose that, on novel tasks, individuals with high cognitive abilities outperform less able individuals, because they allocate a higher amount of resources. On familiar tasks, however, individuals with higher abilities profit from more efficient processes compared to individuals of lower cognitive abilities. We tested this hypothesis by administering to 11th graders a geometric analogy task not practiced at school and an algebraic transformation task comprising operations that are routinely required during mathematical courses. General cognitive abilities were measured with Ravens Advanced Progressive matrices (fluid intelligence), the d2 (focused attention) and KAI-N (working memory capacity). Resource allocation was measured by assessing pupil diameter during the problem-solving process. Performance on both the analogy and the algebra task was correlated with general cognitive abilities, especially fluid intelligence. In line with our assumptions, a positive correlation between fluid intelligence and resource allocation was observed in the novel geometric analogy task, whereas the correlation was not significant in the more familiar algebra task. 相似文献
733.
734.
Siegfried Dbritz Herwig R. Horn Karlheinz Kleinstück Hanns Waltinger Volker Hoffmann 《Crystal Research and Technology》1986,21(12):1531-1539
A supplementary device to a scanning electron microscope allows the simultaneous taking of wide-angle interferences in the directions of transmission and back reflection of identical specimen areas. A developed computer program simulates the complete reflex system so that the identity with the pattern is obtained. This results, on the one hand, in qualitative and quantitative statements concerning the real structure of the specimen and, on the other hand, shadings of reflexes caused by the target holder tube can be distinguished from interruptions of reflexes caused by the grain size effects. The efficiency of the supplementary device for the characterizing of mono- and polycrystalline specimens is demonstrated by several examples. 相似文献
735.
736.
Solid solutions of UxTh1−xSe for x = 1.00 ÷ 0.80 and the solid solutions of UxY1−xSe for x = 1.00 ÷ 0.60 were studied by the X-ray diffraction over the temperature range 100 ÷ 200 K. In both systems rhombohedral distortions of the cubic rock-salt crystal structure was observed below the Curie temperatures. The temperature and composition dependences of the rhombohedral angle ω of the rhomboedral cell and the \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{c' - a'}}{{a'}} $\end{document} ratio were determined. 相似文献