建构主义教学理论在无机及分析化学教学中的探索与实践

在无机及分析化学的教学实践中，探讨了怎样结合无机及分析化学课程的特点运用建构主义教学理论。根据课程内容采取相应的教学模式，培养学生的自主学习能力，进一步提高教学质量，并促进创新人才的培养。     

The Views and Influence of Ernst Von Glasersfeld: An Introduction

Research into learners' ideas about science suggests that students often have alternative conceptions about important science concepts. Because of this dissatisfaction, constructivism has been adopted as a theoretical framework by many teachers and researchers, and it has had a curricular influence in many countries. Constructivism is much more than an educational doctrine and we are aware that a ‘science war’ about the possibility of objectivity is in progress. ‘Constructivism’ cannot necessary be a package deal: it must be possible to accept educational suggestions deemed useful without buying all the epistemology or the metaphysical implications. The claim that cognitive agents understand the world by constructing mental representations of it can be a shared suggestion for changing science instruction. Many teachers are much more concerned in finding productive teaching methods than about philosophical questions as if knowledge must be considered an objective representation of the real world or not. We have to ponder if some ideas from the constructivist theory of instruction can help instructors to become better teachers. The pragmatic suggestions that come from the constructivist theory of instruction developed by von Glasersfeld, the leading proponent of radical constructivism, could be a good start in this␣search.     

THE STATUS OF CONSTRUCTIVISM IN CHEMICAL EDUCATION RESEARCH AND ITS RELATIONSHIP TO THE TEACHING AND LEARNING OF THE CONCEPT OF IDEALIZATION IN CHEMISTRY

A review of the chemical education research literature suggests that the term constructivism is used in two ways: experience-based constructivism and discipline-based constructivism. These two perspectives are examined as an epistemology in relation to the teaching and learning of the concept of idealization in chemistry. It is claimed that experience-based constructivism is powerless to inform the origin of such concepts in chemistry and while discipline-based constructivism can admit such theoretical concepts as idealization it does not offer any unique perspectives that cannot be obtained from other models. Chemical education researchers do not consistently appeal to constructivism as an epistemology or as a teaching/learning perspective and it is shown that, while it draws attention to worthwhile teaching/learning strategies, it cannot be considered as foundational to chemical education research and tends to be used more as an educational label than as an undergirding theory.     

Organized Skepticism, Naïve Methodism, and Other -ISMS

The Science Wars have pitted defenders of science against those accused of attacking it with the weapons of constructivism and relativism. I argue that this defensive stance is in large part a consequence of two other -isms, organized skepticism and naïve methodism, that play a significant, if mostly unconscious, role in how scientists tend to think about science, and suggest that increased awareness of these -isms may help dissipate the perceptions of hostility.     

论结构主义学习观与化学教学改革

结构主义理论越来越受到教育界的关注,这种理论带给新一轮基础教育课程改革许多值得深思的理念。本文在结构主义理论的基础上,从新知识观的视角出发,着重论述了结构主义学习观在当前基础教育课程改革中的作用以及化学教学在以结构主义学习观为理论指导下教师观念的转变。     

Constructivism’s New Clothes: The Trivial, the Contingent, and a Progressive Research Programme into the Learning of Science

Constructivism has been a key referent for research into the learning of science for several decades. There is little doubt that the research into learners’ ideas in science stimulated by the constructivist movement has been voluminous, and a great deal is now known about the way various science topics may commonly be understood by learners of various ages. Despite this significant research effort, there have been serious criticisms of this area of work: in terms of its philosophical underpinning, the validity of its most popular constructs, the limited scope of its focus, and its practical value to science teaching. This paper frames this area of work as a Lakatosian Research Programme (RP), and explores the major criticisms of constructivism from that perspective. It is argued that much of the criticism may be considered as part of the legitimate academic debate expected within any active RP, i.e. arguments about the auxiliary theory making up the ‘protective belt’ of the programme. It is suggested that a shifting focus from constructivism to ‘contingency in learning’ will allow the RP to draw upon a more diverse range of perspectives, each consistent with the existing hard core of the programme, which will provide potentially fruitful directions for future work and ensure the continuity of a progressive RP into learning science.     

The semantics of chemical education: constructivism, externalism and the language of chemistry

In this paper we present a semantic analysis of the application of didactic constructivism to chemical education. We show that the psychological basis of constructivism yield, when applied to chemistry, an internalist semantics for the chemical names. Since these names have been presented as typical examples of an externalism for kind terms, a fundamental incompatibility ensues. We study this situation, to conclude that it affects chemical education at every level. Finally, we present a preliminary analysis of this problem from the point of view of physics.     

Manganese in bottom water and in bottom sediments of Mozhajskoye reservoir: I. Season variations in water

Paper analyses the data on seasonal variations of Mn form content in bottom water (in 6 layers from the bottom) of drinkable reservoir. There is the information about oxidation-reduction conditions layer by layer of bottom water. The connections between Mn and N, P, Fe in the different layers of the bottom water are discussed.     

New mechanisms of 5-nitrofuran toxicity

Phenotypic screens and the target identification that follows can lead to surprising new connections between small molecules and targets. In this issue of Chemistry & Biology, Zhou and colleagues seek to understand the pigmentation of fish skin and end up uncovering an interesting clinical hypothesis about the trypanocidal compound nifurtimox.     

建构-探究式化学教学初探

本文论述了在化学教学过程中以建构主义教学思想为指导、突出探究性学习的理论构想和实施策略,并就相应的教学试验中存在的问题进行讨论。     

Universal properties of mechanisms from two-state trajectories

Finding the underlying mechanism from the statistical properties of an experimental two-state trajectory generated from dynamics in a complex on-off multisubstate kinetic scheme (KS) is the aim of many experiments. Since the data explicitly shows only transitions between substates of different states, information about the KS is lost, resulting in equivalence of KSs, i.e., the occurrence of different KSs that lead to the same data, in a statistical sense. In order to deal with this phenomenon, a canonical (unique) form of reduced dimensions (RD) is built from the data. RD forms are on-off networks with connections only between substates of different states, where the connections usually have nonexponential waiting time probability density functions. In this paper, we give a list of (about 50) relationships between properties of the data, the topology of reduced dimension forms, and features of KSs. Many of these relationships involve symmetries in RD forms, KSs, and the data and irreversible transitions in KSs. These relationships are useful both in theoretical analysis of on-off KSs and in the analysis of the data.     

环境污染是化学惹的祸吗

人们总是将环境污染与化学连在一起,并认为化学是环境污染的根源。本文在分析环境污染的产生、化学在环境保护方面的作为的基础上认为,产生环境问题的根源主要是人类对自然无节制的索取和向环境超量排放废弃物以及没有充分利用化学科学的力量根治源头。     

试论化学教学中的"自我对话"教育

“自我对话”教育强调学习者的主体作用和能动作用,它符合新课程理念和建构主义学习理论。实施“自我对话”教育必须注意激发学生的“自我对话”意识,并通过学前“知我性对话”、学中“生成性对话”和学后“反思性对话”等形式加以落实。     

Some reflections on characterizing potential surfaces for gas-phase ionic reactions

Gas phase ionic chemistry has become an essential element in our general understanding of chemical reactivity. Obtaining experimental data and then extracting information about the potential surfaces for ionic reactions in the gas phase has been critical in making the connections between gas phase and solution ionic chemistry. In this paper we discuss insights that have been important in developing some of the methodologies that are currently used in analyzing gas phase data.     

Intercellular Connections Related to Cell–Cell Crosstalk Specifically Recognized by an Aptamer

Intercellular connections are an important pathway for cell–cell crosstalk. However, their formation mechanism and functions are far from being understood. The lack of molecular probes hampers the research in this area. Herein, we report a kind of intercellular connection that is specifically recognized by aptamer M17A2 generated by cell‐SELEX against MCF‐7R cells. These connections have different morphologies, but have the same skeleton composed of F‐actin. The long filamentous connections were identified to be tunneling nanotubes (TNTs), a recently discovered cell–cell communication route. These connections could be built not only between MCF‐7R cells, but also from MCF‐7R to other cells after co‐culture. Proteins could be transported between cells through these connections, suggesting their cell communication function. Aptamer M17A2 shows the potential to act as a new probe for investigating this kind of intercellular connection, as well as for studying cell–cell communication.     

Relationship Between Morse and Murrell-Mottram Potentials at Long Range

This paper develops a relationship between the Morse potential and the Murrell-Mottram's 2-body potential. By expressing both potentials in terms of a repulsive term and an attractive term, and approximating Maclaurin's expansion, comparison of coefficients and indices of the repulsive and attractive terms leads to parametric connections between these two potential functions. Non-dimensional curves of these potentials at long range show good agreement as compared to those obtained previously. A set of parametric relationships obtained recently, together with the presently proposed connections, are useful in paving a way for the development of a potential function converter.     

Cluster-cluster aggregation controlled by the number of intercluster connections: kinetics of aggregation and cluster mass frequency

The aggregation of colloids in the presence of hydrodynamic forces was investigated, employing a numerical model that took into account the masses of the individual clusters and the number of intercluster connections established when two clusters stuck together. The number of possible connections was determined by analyzing all the possible nonoverlapping configurations of stuck clusters. This operation was done for a couple of clusters of various masses, taking into account the assembly of clusters of even and uneven masses. The formulation of the constraints established a certain hierarchy in the sticking on a basis compatible with the irregular fracture model of Horwatt and co-workers. As a result, the permanent sticking of large clusters required the formation of a large number of connections, whereas that of small clusters might be realized even with a small number of connections. Thus, the aggregation started with the features of the standard reaction-limited process and this cluster growth became progressively inhibited as a result of the prevailing effects of the connection constraints. The cluster-mass frequency showed the emergence at least of a second population whose bell-shaped mass distribution was superimposed on the monotonically decreasing distribution resulting from the reaction-limited aggregation process. The results of the numerical study were confronted with those previously obtained in the aggregation of hydrated polystyrene latex particles dispersed in 1 M sodium chloride solution. The two striking features--the aggregate growth kinetics and the mass distribution function--were common to the computer-generated clusters and the latex aggregates.     

The Foundations of Radical Constructivism: An Interview with Ernst von Glasersfeld

Constructivism rejects the metaphysical position that “truth”, and thus knowledge in science, can represent an “objective” reality, independent of the knower. It modifies the role of knowledge from “true” representation to functional viability. In this interview, Ernst von Glasersfeld, the leading proponent of Radical Constructivism underlines the inaccessibility of reality, and proposes his view that the function of cognition is adaptive, in the biological sense: the adaptation is the result of the elimination of all that is not adapted. There is no rational way of knowing anything outside the domain of our experience and we construct our world of experiences. In addition to these philosophical claims, the interviewee provides some personal insights; he also gives some suggestions about better teaching and problem solving. These are the aspects of constructivism that have had a major impact on instruction and have modified the manner many of us teach. The process of teaching as linguistic communication, he says, needs to change in a way to involve actively the students in the construction of their knowledge. Because knowledge is not a transferable commodity, learning is mainly identified with the activity of the construction of personal meaning. This interview also provides glimpses on von Glasersfeld’s life.     

Mass spectrometry differentiation of isomeric alkyl porphyrins. Fragmentation analysis of meso-tetraoxoporphyrinogens

The mass spectra of lead dioxide oxidation products of three etiotype porphyrins and one meso-substituted etiotype porphyrin have been analyzed. The meso-tetraoxo products formed, fragment upon electron-impact to give mono-, di-, and tri-pyrrole fragments with the pyrrole substituents still intact. From this fragment information it is possible to differentiate many isomeric alkyl porphyrins. Due to the inability to assign exact positions to the substituents on each pyrrole unit, however, definite isomeric identification is impossible without further information. High resolution gas chromatography retension data of volatile (trimethylsiloxy) Si^IV derivatives may eventually provide the necessary additional information to make absolute structural assignment possible. The described method has been designed to prove detailed structural information about geoporphyrin materials. Geochemical conclusions from such data should help provide information about the origin of organic materials and thus help establish possible connections with early life processes.     

Thixotropic organogels based on a simple N-hydroxyalkyl amide: rheological and aging properties

The thixotropic properties ofthermoreversible organogels composed ofN-3-hydroxypropyl dodecanamide and various apolar fluids have been investigated by X-ray scattering, light microscopy, and rheo-optics experiments. This revealed that gel formation occurs via a precipitation process. Depending upon the cooling rate, large interconnected aggregates are formed and induce an elastic behavior. When submitted to a shear flow, these aggregates disentangled and became aligned in the direction of the velocity. Nevertheless, shear does not alter the structure of the individual aggregate and connections between the aggregates are quickly rebuilt due to gravity and thermal fluctuations when the applied flow is stopped. The alignment under flow and the reformation of the connections after the cessation of the shear induces the thixotropic behavior.