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131.
Research has shown that prediction has the potential to promote the teaching and learning of mathematics because it can be used to enhance students' thinking and reasoning at all grade levels in various topics. This article addresses the effectiveness of using prediction on students' understanding and reasoning of mathematical concepts in a middle school algebra context. In the treatment classroom, prediction questions were utilized at the launch of each algebra lesson, and in the control classroom such questions were not used. Both classrooms were taught by the same teacher and used the same curriculum. After completing each of the linear and exponential units, the two classrooms were compared in terms of their mathematical understanding and reasoning through unit assessments. Overall, the treatment classroom outperformed the control classroom on the unit assessments. This result supports that prediction is a valid construct with respect to enhanced conceptual understanding and mathematical reasoning. 相似文献
132.
Melting gels are a class of organically modified silica gels that are rigid at room temperature, flow at temperature T1 and
consolidate at temperature T2 (T2 > T1), when crosslinking is complete. The process of (a) softening, (b) becoming rigid and
(c) re-softening can be repeated many times. Mixtures of mono-substituted alkoxysilanes and di-substituted alkoxysilanes have
been studied in a systematic way to identify suitable melting gel compositions. The mixtures and the resulting melting gels
have been characterized for their softening temperatures and consolidation temperatures. With an interest in using these materials
for sealing microelectronics, their physical properties have been measured. 相似文献
133.
Thomas M. Baker Lisa A. Sloan Lokman H. Choudhury Masahito Murai David J. Procter 《Tetrahedron: Asymmetry》2010,21(9-10):1246-1261
A cascade reaction involving sequential conjugate reduction, stereoselective aldol cyclisation and chemoselective lactone reduction mediated by SmI2–H2O provides access to a cyclopentanol bearing two vicinal quaternary stereocentres with good stereocontrol. The functionalised cyclopentanol product has been converted to a key intermediate in ongoing asymmetric studies towards stolonidiol. 相似文献
134.
Cristian Bodin Fredrik Mauritzson Rob Horsefield Anna Aagaard Hongwei Guo Linda Öster Lisa Wissler Margareta Ek 《Journal of synchrotron radiation》2012,19(2):288-289
Currently there is no rack system for the long‐term storage of SPINE pucks in spite of their commercial availability and heavy usage at the ESRF. The only way to store pucks is in transport dewar canisters which presents a number of limitations and drawbacks. Here a simple affordable rack for storing SPINE pucks is described, which we believe is accessible to not only synchrotrons but also both academic and industrial research laboratories. 相似文献
135.
Andrea Desii Federica Chiellini Celia Duce Lisa Ghezzi Susanna Monti Maria R. Tiné Roberto Solaro 《Journal of polymer science. Part A, Polymer chemistry》2010,48(4):889-897
We investigated the self‐aggregation of 12 short ionic oligopeptides constituted by 4–7 amino acid residues to establish useful structure–property relationships that might be exploited in the biomedical field by using the concept of molecular Lego. We show that the critical aggregation concentration (CAC) of tetrapeptides decreases with increasing hydrophobicity of neutral residues. Additionally, the dependence of the CAC of isomeric oligopeptides on the distribution of amino acid residues confirms the high tendency to self‐organization of molecules with alternating ionic and neutral residues. Indeed, atomic force microscopy (AFM) images recorded on oligopeptide solutions above the CAC show the presence of either fibrillar or spherical aggregates depending on oligopeptide structure and concentration, steric hindrance, solution pH, and time. The potential of the investigated oligopeptides in tissue engineering applications is supported by their in vitro cytocompatibility. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 889–897, 2010 相似文献
136.
137.
Andrei Jitianu John Doyle Glenn Amatucci Lisa C. Klein 《Journal of Sol-Gel Science and Technology》2010,53(2):272-279
Hybrid melting gels were prepared by a sol–gel process, starting with a mono-substituted siloxane and a di-substituted siloxane.
Methyl-modified melting gels were prepared using (a) methyltriethoxysilane (MTES) with dimethyldiethoxysilane (DMDES) and
(b) methyltrimethoxysilane (MTMS) together with dimethyldimethoxysilane (DMDMS). The gels with MTES–DMDES were prepared with
concentrations between 50–50 and 75–25 mol%. The gels with MTMS–DMDMS were prepared with concentrations between 50–50 and
70–30 mol%. For both systems, the consolidation temperature, after which the melting gel no longer softens, increased with
an increase in the amount of the mono-substituted siloxane, increasing from 135 to 160 °C for MTES–DMDES and increasing from
145 to 170 °C for MTMS–DMDMS. Coatings formed on mica substrates were about 1 mm thick, and showed no visible cracks. The
surfaces of the coatings were profiled using micro-Raman spectroscopy, which revealed that methyl groups were concentrated
at the surfaces of the films. All contact angles measured with water were greater than 90°. 相似文献
138.
The present work is a continuation of an earlier investigation of the effect of severe thermal pretreatment on the redox
properties of platinum electrodes in aqueous media. The most interesting observation was that raising the solution temperature
to ca. 75 °C resulted in a dramatic anodic response in the positive sweep at ca. 0.25 V (RHE). Such behaviour was noted earlier
at room temperature but only when the thermally pretreated sample was further activated by cathodic polarization. This transition
at 0.25 V was partially reversed on the negative sweep, but the cathodic process involved was subject to severe inhibition.
There is independent evidence for similar behaviour for gold in aqueous acid solution. The relevance of the present results
to the operation of fuel cell anodes is outlined.
Received: 2 December 1999 / Accepted: 24 February 2000 相似文献
139.
Elin S. Karlsson Caroline H. Johnson Sunil Sarda Lisa Iddon Mazhar Iqbal Xiaoli Meng John R. Harding Andrew V. Stachulski Jeremy K. Nicholson Ian D. Wilson John C. Lindon 《Rapid communications in mass spectrometry : RCM》2010,24(20):3043-3051
The use of high‐performance liquid chromatography/mass spectrometry (HPLC/MS) and proton nuclear magnetic resonance (1H NMR) spectroscopy for the kinetic analysis of acyl glucuronide (AG) isomerisation and hydrolysis of the 1‐β‐O‐acyl glucuronides (1‐β‐O‐AG) of phenylacetic acid, (R)‐ and (S)‐α‐methylphenylacetic acid and α,α‐dimethylphenylacetic acid is described and compared. Each AG was incubated in both aqueous buffer, at pH 7.4, and control human plasma at 37°C. Aliquots of these incubations, taken throughout the reaction time‐course, were analysed by HPLC/MS and 1H NMR spectroscopy. In buffer, transacylation reactions predominated, with relatively little hydrolysis to the free aglycone observed. In human plasma incubations the calculated rates of reaction were much faster than for buffer and, in contrast to the observations in buffer, hydrolysis to the free aglycone was a significant contributor to the overall reaction. A diagnostic analytical methodology based on differential mass spectrometric fragmentation of 1‐β‐O‐AGs compared to the 2‐, 3‐ and 4‐positional isomers, which enables selective determination of the former, was confirmed and applied. These findings show that HPLC/MS offers a viable alternative to the more commonly used NMR spectroscopic approach for the determination of the transacylation and hydrolysis reactions of these AGs, with the major advantage of having the capability to do so in a complex biological matrix such as plasma. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
140.