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1.
In this paper, we shall prove that the Marcinkiewicz integral operator #n, when its kernel Ω satisfies the L^1-Dini condition, is bounded on the Triehel-Lizorkin spaces. It is well known that the Triehel-Lizorkin spaces are generalizations of many familiar spaces such as the Lehesgue spaces and the Soholev spaces. Therefore, our result extends many known theorems on the Marcinkiewicz integral operator. Our method is to regard the Marcinkiewicz integral operator as a vector valued singular integral. We also use another characterization of the Triehel-Lizorkin space which makes our approach more clear.  相似文献   

2.
Ml0.7Mm0.3Ni3.7Co0.7Mn0.4Al0.2 nanocrystalline hydrogen storage materials are prepared by melt-spinning(MS).X-ray diffraction is used for the measurement of the nanocrystalline size.Compared to the electrode of polycrystalline alloys,the property of activation MH9metal hydride)electrode of the alloys with nanometer scale became worse and the inital discharge capacity decreased.It may be ascribed to the decrease of the total amount of rare earth metals and the increase of oxygen on the surface from the analysis of components of the alloys.After heat-treatment,the electrochemical performance of MH electrode of as-spun alloys could be improved,which could be attributed to the alleviation of the lattice strain.  相似文献   

3.
用概率论的思想方法,能够解决一些积分中的问题,并能体现思想方法的简捷性和独特性,本文在积分不等式的证明和积分计算中引进了概率方法,取得了较好的效果。  相似文献   

4.
Surface morphologies of Zr52.5 Al10 Ni10 Cu15 Be12.5 bulk metallic glass after being rolled at both a temperature around T9 and near （ Tx - 50） K were investigated with a scanning electron microscopy. Macroscopic and microscopic observation results show that squamae, cracks, steps and wedges exist on the surface when the samples were rolled at temperatures around Ty. However, a smooth and fiat surface appears when the samples were rolled at temperatures near （ Tx - 50） K. These results indicate that the mode of deformation in the supercooled liquid region is a partially homogeneous flow at a temperature around T9, and a fully homogeneous one at temperatures near （ Tx - 50） K. According to the results, it is more feasible to roll the amorphous alloys at temperatures near （ Tx - 50） K to obtain parts with smooth and fiat surface.  相似文献   

5.
Supersaturated solid solutions Fe1-xCx （0≤x≤0.9 ） of wide composition range have been prepared by mechanical alloying process. Nanocrystalline phase was formed for 0 ≤ x ≤ 0.67 and a large grain phase for 0.75 ≤ x ≤ 0.9. The large fraction of graphite volume puts off formation of nanocrystalline phase for high carbon content. In the large grain phase, magnetization follows simple magnetic dilution, and eoereivity He is mainly due to dissolution of carbon at grain boundaries. In the nanocrystalline phase the alloying effect of carbon is revealed by a distinct reduction of average magnetic moment. The increasing lattice constant with increasing carbon content is observed for x ≤ 0.5, suggesting that the high carbon concentration may enhance diffusion of carbon into the Fe lattice. It shows a discontinuity in the Hc variation with a grain size D of nanocrystalline phase. For small grain D below the critical value, Hc increases with D. For a large grain D, Hc decreases with increasing D. The solubility limit of carbon in a-Fe extended by nanocry- stalline phase formation is discussed.  相似文献   

6.
This study explores the ways in which eleven preservice elementary teachers used a web-based teacher resource to apply a mathematical definition, to correct a procedural error in arithmetic, and to make sense of a story requiring the multiplication of fractions. In our analysis we propose a framework to compare the behaviors and values expressed by our participants with the values and norms of the mathematical community. This analysis suggests that many preservice elementary teachers are profoundly mathematically unsophisticated. In other words, they displayed a set of values and avenues for doing mathematics so different from that of the mathematical community, and so impoverished, that they found it difficult to create fundamental mathematical understandings.  相似文献   

7.
Using SnxTi1-xO2 as carriers, CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 catalysts with different loading amounts of copper oxide (CuO) were prepared by an impregnation method. The catalytic properties of CuO/Sn0.9Ti0.1O2 and CuO/Sn0.7Ti0.3O2 were examined using a microreactor-gas chromatography (GC) NO CO reaction system and the methods of BET (Brun- auer-Emmett-Teller), TG-DTA (themogravimetric and differential thermal analysis), X-ray diffraction (XRD) and H2-temperature programmed reduction (TPR). The results showed that NO conversions of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 were 47.2% and 43.6% respectively, which increased to 95.3% and 90.9% at 6 wt% CuO loading. However, further increase in CuO loading caused a decrease in the catalytic activity. The nitrogen adsorption-desorption isotherm and pore-size distribution curve of Sn0.9Ti0.1O2 and Sn0.7Ti0.3O2 represented type IV of the BDDT (Brunauer, Deming, Deming and Teller) system and a typical mesoporous sample. There were two CuO diffraction peaks (2θ 35.5° and 38.7°), and the diffraction peak areas increased with increasing CuO loading. TPR analysis also detected three peaks (α, β and γ) from the CuO-loaded catalysts, suggesting that the α peak was the reduction of the highly dispersed copper oxide, the β peak was the reduction of the isolated copper oxide, and the γ peak was the reduction of crystal phase copper oxide. In addition, a fourth peak (δ) of the catalysts meant that the SnxTi1-xO2 mixed oxides could be reductive.  相似文献   

8.
We begin by outlining the life cycle of a tall cloud, and then briefly discuss cloud systems. We choose one aspect of this life cycle, namely, the rapid growth of water droplets in icefree clouds, to then discuss in greater detail. Taking a single vortex to be a building block of turbulence, we demonstrate one mechanism by which we believe droplets grow rapidly.  相似文献   

9.
When a crime is committed and the culprit responsible for the crime is nabbed, the job of the investigators is not over. To convince the judge, they have to prove beyond doubt that it was the accused who committed the crime. Likewise, mathematical statements require proofs for their veracity to be established. Further, to make these statements precise we need to have a set of proper definitions. It was Euclid, who more than two thousand years ago, started this tradition when he bequeathed to the world his book entitled The Elements. This tradition has continued since then. Definitions, proofs besides axioms have become an inalienable part of mathematical lore. We owe all this to Euclid, one of the greatest pioneers of rigour and reasoning. In this article we discuss the work of Euclid.  相似文献   

10.
Zusammenfassung Negativit?t und das Neue in John Deweys Theorie vom Lernen und der Demokratie — Für einen erneuten Blick auf Lernkulturen Die Rolle des Neuen in Lernprozessen bezieht sich auf die grundlegende Frage, wie Lernen überhaupt m?glich ist und wo es beginnt. In diesem Beitrag wird zun?chst John Deweys Lernkonzeption als Basis für die Analyse entwickelt. Dann wird die Beziehung zwischen Negativit?t und dem Neuen erarbeitet. Beim übergang vom Alten zum Neuen und vom Gewussten zum Ungewussten entstehen Verwirrungen und Schwierigkeiten, die in diesem Papier als Negativit?t im Lernprozess untersucht werden. Au?erdem vermittelt der Beitrag Einsichten in praktische p?dagogische Probleme, etwa bezüglich der Frage, wie Lehrer und andere Erzieher Lernprozesse f?rdern und wie Lernkulturen als besondere Lernumwelten Lehr-Lern-Prozesse unterstützen k?nnen.
Negativity and the new in John Dewey’s theory of learning and democracy Toward a renewed look at learning cultures
Summary The role of the New in learning processes relates to basic questions of how learning is possible, and where learning begins. Using John Dewey’s concept of learning as the basis for analysis, this inquiry looks into the relation between Negativity and the New and seeks to uncover the negativity in learning processes associated with the perplexities and difficulties which arise in the transitions from Old to New and Known to Unknown. Furthermore, it offers insight into practical pedagogical issues, such as how teachers and educators can support learning processes and how learning cultures, as particular environments for learning, can assist processes of teaching and learning.
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11.
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12.
Systematic studies of the transport properties of La0.67Ca0.33Mn1?xFe x O3 (x=0–0.3) systems showed that with increasing Fe-doping contentx the resistance increases and the insulator-metal transition temperature moves to lower temperature. For small doping content, the transport property satisfies metal transport behavior below the transition temperature, and above the transition temperature it satisfies the small polaron model. This behavior can be explained by Fe3+ doping, which easily forms Fe3+?O2??Mn4+ channel, suppressing the double exchange Mn3+?O2??Mn4+ channel and enhancing the spin scattering of Mn ions induced by antiferromagnetic clusters of Fe ions.  相似文献   

13.
This article draws on critical disability studies, challenging the exclusion of right‐brained thinkers from an education system designed to privilege left‐brained thinkers. It focuses on individuals who are labelled dyspraxic, providing data from qualitative interviews with adults about childhood experiences in school and the impact on their emotional well‐being and peer relationships. Utilising Ornstein's pioneering research on the bilateral specialisation of the brain and hemispheric dominance in addition to a critical disability studies theoretical framework, this article innovatively argues that the fact that education in England continues to be delivered in a logical sequential form, even 40 years after Ornstein's work, is systemic discrimination in which dyspraxic children are constructed as ‘deviant’. The article concludes by arguing that individuals with dyspraxia should be seen as having a ‘diff‐ability’ in thinking style rather than a disability and therefore recommends both change and awareness‐raising at institutional level in the education system.  相似文献   

14.
α-diketones and β-diketones react with Grignard reagents in the presence of a catalytic amount of Cp2TiCl2 to yield α-ketols and corresponding ketones respectively. Sulfoxides can be deoxygenated by Cp2TiCl2/Al system. The possible mechanisms are also discussed. Project (No. 20072033) supported by the National Natural Science Foundation of China and the Specialized Research Fund for the Doctoral Program of Higher Education Ministry, China  相似文献   

15.
CD-ROMs are becoming more widely used now and one particular genre seems to have a good deal to offer as a medium for the development of reading. These so-called ‘interactive books’ have not yet been investigated in terms of their usefulness in teaching reading and Clare Burrell and John Trushell make a useful beginning to this. They are particularly concerned with whether the eye catching graphics of these books helps or hinders children’s reading of them and their report raises many interesting issues.  相似文献   

16.
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17.
Objective: to explore a new serological method for detectingHelicobacter pylori (H. pylori) infection. Methods: Serum soluble antigen ofH. pylori was detected by using avidin-biotin ELISA technique to evaluate the status ofH. pylori infection and for comparison with rapid urease test (RUT), histologic examination and serology. Results: The sensitivity, specificity, positive predictive value and negative predictive value were 77.46%, 91.07%, 91.67% and 76.12%, respectively. The prevalence rate of serumH. pylori soluble antigen in 138 patients undergoing endoscopy was similar to the rate obtained by14C-UBT methods (P>0.05). Conclusions: The detection of serumH. pylori soluble antigen(HpSAg) could be used as a new serological method which is accurate, and convenient, not affected by the memorizing reaction of serum antibody; is more sensitive, more specific and suitable for clinical diagnosis, and evaluation of eradication and for follow-up ofH. pylori as well as for detection in children and pregnant women. Project supported by Zhejiang Provincial Health Bureau (No. 2000A118), China  相似文献   

18.
§ 27 Abs. 4 der Satzung der Universit?t X- Satzungsteil Studienrecht (Satzung) r?umt zwar das Recht ein, eine Betreuerin/einen Betreuer ihrer Dissertation auszuw?hlen; dieses Recht ist jedoch auf die Auswahl auf die "zur Verfügung stehenden" Betreuerinnen/Betreuer eingeschr?nkt und besteht auch in Ansehung dieses Personenkreises nur "nach Ma?gabe der M?glichkeiten".  相似文献   

19.
This book looks at the impact of digital technologies on the teaching and learning of mathematics. The focus is on learning at school and most of the twenty‐nine invited contributions are drawn from England and the US. Mathematics education with digital technology will be of interest to school teachers, teacher‐educators and educational technologists. If it is likely to be relevant to you, I recommend that you borrow a copy for a while. Pete Cannell  相似文献   

20.
The European Co‐operation in Science and Technology Research Network supported European research on learning to write effectively from 2008 to 2011. This book outlines the results—with eight editors presenting over ninety contributions from people in a dozen or more European countries. There are four sections: writing development; learning and teaching writing; document design; and tools for studying writing. Thus the coverage is broad, but thin. It's probably best to order this text for the library unless you are personally involved in research on writing. James Hartley  相似文献   

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