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31.
N.S. Godwin W.D. Rae B. Cooke N.J. Eyre P.S. Fisher G. Proudfoot D. Sinclair 《Nuclear Physics A》1979,331(1):237-253
The reactions 17O(11B, 8Li)20Ne, 17O(12C, 9Be)20Ne and 17O(13C, 10B)20F have been studied using beams of 115 MeV 11B and 12C and 105 MeV 13C incident on a gas target. Shell-model calculations have been performed for 20Ne and 20F, for comparison with the experimental data. It is found that the data can be interpreted using the shell model spectroscopic factors and a semi-classical reaction theory. We justify the use of the latter by applying it to the cases of three-nucleon transfer on 16O. Spin assignments are suggested for previously unidentified states in 20F. 相似文献
32.
The first early transition metal tris(methimazolyl)borate com-plexes [M(=NR)Cl2{HB(mt)3}] (M = Nb, Ta; R = C6H3(i)Pr(2)-2,6; mt = methimazolyl) have been obtained from the reactions of [Nb(=NR)Cl3(DME)] or [Ta(=NR)Cl3(THF)2] (DME = dimethyl ether; THF = tetrahydrofuran) with Na[HB(mt)3] and structurally characterized, illustrating that the HB(mt)3 ligand can indeed be compatible with "hard" metals in high oxidation states. 相似文献
33.
Sandra Rae Etson Ronald J. Mattson J. Walter Sowell 《Journal of heterocyclic chemistry》1979,16(5):929-933
A facile route for the synthesis of substituted pyrrolo[2,3-d]pyrimidine-2,4-diones from substituted 2-amino-3-cyano-4-methylpyrroles is reported. 相似文献
34.
Rae M Perez-Balderas F Baleizão C Fedorov A Cavaleiro JA Tomé AC Berberan-Santos MN 《The journal of physical chemistry. B》2006,110(25):12809-12814
A series of brominated mono-methano[60]fullerene malonate derivatives (two diads and one triad) are investigated for intramolecular and external heavy-atom effects on their fluorescence. Significant internal and external heavy-atom effects are observed in the three cases. It is shown that the internal effect doubles when going from the diads to the triad. In bromobenzene and in iodobenzene, the external effect is predominant, and diads and triad behave identically. 相似文献
35.
Most of previous research on tolerance optimization seeks the optimal tolerance allocation with process parameters such as fixed process mean and variance. This research, however, differs from the previous studies in two ways. First, an integrated optimization scheme is proposed to determine both the optimal settings of those process parameters and the optimal tolerance simultaneously which is called a parametric tolerance optimization problem in this paper. Second, most tolerance optimization models require rigorous optimization processes using numerical methods, since closed-form solutions are rarely found. This paper shows how the Lambert W function, which is often used in physics, can be applied efficiently to this parametric tolerance optimization problem. By using the Lambert W function, one can express the optimal solutions to the parametric tolerance optimization problem in a closed-form without resorting to numerical methods. For verification purposes, numerical examples for three cases are conducted and sensitivity analyses are performed. 相似文献
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37.
We provide explicit constructions of particularly convenient dual pairs of Gabor frames. We prove that arbitrary polynomials
restricted to sufficiently large intervals will generate Gabor frames, at least for small modulation parameters. Unfortunately,
no similar function can generate a dual Gabor frame, but we prove that almost any such frame has a dual generated by a B-spline.
Finally, for frames generated by any compactly supported function φ whose integer-translates form a partition of unity, e.g., a B-spline, we construct a class of dual frame generators, formed
by linear combinations of translates of φ. This allows us to chose a dual generator with special properties, for example, the one with shortest support, or a symmetric
one in case the frame itself is generated by a symmetric function. One of these dual generators has the property of being
constant on the support of the frame generator. 相似文献
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39.
Building on prior efforts, we re-conceptualize metacognition on multiple levels, looking at the sources that trigger metacognition at the individual level, the social level, and the environmental level. This helps resolve the paradox of metacognition: metacognition is personal, but it cannot be explained exclusively by individualistic conceptions. We develop a theoretical model of metacognition in collaborative problem solving based on models and modeling perspectives. The theoretical model addresses several challenges previously found in the research of metacognition. This paper illustrates how metacognition was elicited, at the environmental level, through problems requiring different problem-solving processes (definition building and operationalizing definitions), and how metacognition operated at both the individual level and the social level during complex problem solving. The re-conceptualization of metacognition has the potential to guide the development of metacognitive activities and effective instructional methods to integrate them into existing curricula that are necessary to engage students in active, higher-order learning. 相似文献
40.