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551.
Whether simple syntax (in the form of simple word order) can emerge during the emergence of lexicon is studied from a simulation perspective; a multiagent computational model is adopted to trace a lexicon‐syntax coevolution through iterative communications. Several factors that may affect this self‐organizing process are discussed. An indirect meaning transference is simulated to study the effect of nonlinguistic information in listener's comprehension. Besides the theoretical and empirical argumentations, this computational model, following the Emergentism, demonstrates an adaptation of syntax from some domain‐general abilities, which provides an argumentation against the Innatism. © 2005 Wiley Periodicals, Inc. Complexity 10: 50–62, 2005 相似文献
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553.
Effect of gravity on the vibration of vertical cantilevers 总被引:1,自引:0,他引:1
The free vibration of a vertically-oriented, thin, prismatic cantilever is influenced by weight. That is, the natural frequencies (and to a lesser extent, mode shapes) are affected by the application of a linearly varying axial load. A beam with an “upward” orientation, i.e., with the free end above the clamped end, will experience a de-stiffening effect, up to the point of self-weight buckling (at zero effective stiffness). A beam in a “downward” orientation will be stiffened by the weight of the beam. This technical note describes some simple experiments on very slender strips and their (vertical) orientation and shows a close correlation with theory. 相似文献
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555.
The gauche conformation of the 1,2-difluoroethane motif is known to involve stabilising hyperconjugative interactions between donor (bonding, σC–H) and acceptor (antibonding, σ*C–F) orbitals. This model rationalises the generic conformational preference of F–Cβ–Cα–X systems (φFCCX ≈ 60°), where X is an electron deficient substituent containing a Period 2 atom. Little is known about the corresponding Period 3 systems, such as sulfur and phosphorus, where multiple oxidation states are possible. Conformational analyses of β-fluorosulfides, -sulfoxides and -sulfones are disclosed here, thus extending the scope of the fluorine gauche effect to the 3rd Period (F–C–C–S(O)n; φFCCS ≈ 60°). Synergy between experiment and computation has revealed that the gauche effect is only pronounced in structures bearing an electropositive vicinal sulfur atom (S+–O–, SO2). 相似文献
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557.
Antimony silicate glasses, of general formula xSb2O3·(1−x)SiO2 (0.1≤x≤0.78), have been prepared by melt-quenching and their structures studied using 29Si MAS NMR spectroscopy, 121Sb Mössbauer spectroscopy and Raman spectroscopy. Oxidation during melting gives rise to Sb5+ in concentrations, which increase linearly with x to give a value of ∼10% when x=0.78. 121Sb Mössbauer spectra show Mössbauer shifts and quadrupole splittings consistent with Sb3+ in a [:SbO3] trigonal pyramid, similar to that in crystalline Sb2O3. A broad band in the Raman spectrum at ∼410 cm−1 is due to the vibrations of such a unit. The dependence of the silicon Qn speciation on x can be interpreted by the formation of Sb-O-Sb links possibly to form rings of 4 [:SbO3] units such as are found in valentinite. 相似文献
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559.
Herbert L. Holland Peter R. Andreana Reza Salehzadeh-Asl Aaron van Vliet Nancy J. Ihasz Frances M. Brown 《Monatshefte für Chemie / Chemical Monthly》2000,131(6):667-672
Summary. Biotransformation of a series of racemic N-benzoyl α-amino acids by the fungus Beauveria bassiana ATCC 7159 results in isolation of the corresponding D-amino acid benzamides in high enantiomeric purity and yield.
Received December 20, 1999. Accepted January 21, 2000 相似文献
560.
This paper describes the development and preliminary analysis of a mathematical test targeted for high mathematical ability elementary school students, the Stanford Education Program for Gifted Youth (EPGY) Mathematical Aptitude Test (SEMAT). A version was administered to 248 students, 9–11 years old, in EPGY. The SEMAT was developed because no other satisfactory test was designed or normed for this population. Most standardized tests assess mathematics proficiency for the general population so that gifted students' scores cluster in the few top percentiles. The SEMAT discriminated among this extreme upper end. Item response theory determined proficiency estimates, which were then used as scores to predict various outcomes in EPGY. The SEMAT proved to be a strong predictor of acceleration in EPGY. 相似文献