略论生物教学口语

联系中学课堂教学的实践,初步探讨了生物教学口语运用的原则和技巧.     

略论生物教学口语

联系中学课堂教学的实践,初步探讨了生物教学口语运用的原则和技巧.     

口语对话系统中的一种稳健语言理解算法

为提高口语对话系统中语言理解的稳健性,提出了一种基于最大后验统计框架的两级搜索的理解算法.第一级用概念捆绑达到提取句中关键成分并剔除某些干扰成分的目的; 第二级采用改进的基于树扩展的稳健句法分析搜索最佳理解结果,同时引入用户意图推断和句子特征短语两方面的信息对搜索空间进行约束,进一步提高了理解的稳健性和实时率.实验表明,该算法应用于火车信息查询领域,在0.22倍实时下,能得到13.6%的句意理解错误率和25.4%的概念理解错误率,相对基线系统分别为降低了23.2%和9.3%.     

Neural mechanisms of perceptual learning

The traditional view of cortical visual processing is that primary visual cortex (V1) analyzes simple visual attributes, and that object recognition involves a progressive “complexification” of receptive field (RF) properties along the visual pathway extending into the temporal lobe. Based on our studies with a combination of electrophysiological, imaging, psychophysical and computational approaches, we find to the contrary that V1 is capable of encoding much more complex stimulus features than originally believed, and that it can integrate information over large parts of the visual field. Moreover, V1 is continually involved in encoding information about learned stimulus configurations under top-down influences specific to the trained perceptual task.     

Neural mechanisms of perceptual learning

The traditional view of cortical visual processing is that primary visual cortex (V1) analyzes simple visual attributes, and that object recognition involves a progressive “complexification” of receptive field (RF) properties along the visual pathway extending into the temporal lobe. Based on our studies with a combination of electrophysiological, imaging, psychophysical and computational approaches, we find to the contrary that V1 is capable of encoding much more complex stimulus features than originally believed, and that it can integrate information over large parts of the visual field. Moreover, V1 is continually involved in encoding information about learned stimulus configurations under top-down influences specific to the trained perceptual task.     

Neural networks and perceptual learning

Sensory perception is a learned trait. The brain strategies we use to perceive the world are constantly modified by experience. With practice, we subconsciously become better at identifying familiar objects or distinguishing fine details in our environment. Current theoretical models simulate some properties of perceptual learning, but neglect the underlying cortical circuits. Future neural network models must incorporate the top-down alteration of cortical function by expectation or perceptual tasks. These newly found dynamic processes are challenging earlier views of static and feedforward processing of sensory information.     

浅谈大学英语口语的教与学

随着外语教学改革的深入，努力提高英语口头表达和交流能力是当代师生积极探讨的话题。可从培养学生说英语的动机、营造良好的氛围、听说结合、采用互动式教学方式、运用现代化信息手段、引导学生课外多练等方面进行尝试。     

口语对话系统中的词类概率模型和知识表示

语言分析和知识库管理是口语理解与对话系统的两个重要组成部分 ,作者在这两方面提出了一些新的方法。一是提出并实现了词类概率模型 ,它具有较高的性能和较低的时间复杂度 ,是基于句法规则的语义分析和语言理解的基础。此外还提出了与数据无关的多叉树层次结构模型的知识表示方法 ,它具有很强的表达能力并易于扩展。在此基础上 ,实现了一个用以提供清华大学地理、办公、商业及其它一些相关信息检索、基于文本的口语对话系统 Easy Nav。实验表明 ,上述模型和方法具有很好的性能     

Local sleep and learning

Human sleep is a global state whose functions remain unclear. During much of sleep, cortical neurons undergo slow oscillations in membrane potential, which appear in electroencephalograms as slow wave activity (SWA) of <4 Hz. The amount of SWA is homeostatically regulated, increasing after wakefulness and returning to baseline during sleep. It has been suggested that SWA homeostasis may reflect synaptic changes underlying a cellular need for sleep. If this were so, inducing local synaptic changes should induce local SWA changes, and these should benefit neural function. Here we show that sleep homeostasis indeed has a local component, which can be triggered by a learning task involving specific brain regions. Furthermore, we show that the local increase in SWA after learning correlates with improved performance of the task after sleep. Thus, sleep homeostasis can be induced on a local level and can benefit performance.     

Signal but not noise changes with perceptual learning

Perceptual discrimination improves with practice. This 'perceptual learning' is often specific to the stimuli presented during training, indicating that practice may alter the response characteristics of cortical sensory neurons. Although much is known about how learning modifies cortical circuits, it remains unclear how these changes relate to behaviour. Different theories assume that practice improves discrimination by enhancing the signal, diminishing internal noise or both. Here, to distinguish among these alternatives, we fashioned sets of faces and textures whose signal strength could be varied, and we trained observers to identify these patterns embedded in noise. Performance increased by up to 400% across several sessions over several days. Comparisons of human performance to that of an ideal discriminator showed that learning increased the efficiency with which observers encoded task-relevant information. Observer response consistency, measured by a double-pass technique in which identical stimuli are shown twice in each experimental session, did not change during training, showing that learning had no effect on internal noise. These results indicate that perceptual learning may enhance signal strength, and provide important constraints for theories of learning.     

网络自主学习环境下大学生英语口语学习策略探索

通过调查分析,可知非英语专业学生在使用英语口语学习策略上有诸多不足.而通过对学生元认知策略、交际策略、情感策略等学习策略的培养,能够帮助学生有效地学习英语口语.     

我国扩张性货币政策实施的原因及效果分析

近年来我国政府推行了扩张性的货币政策 ,它的实施一方面是为了扩大投资需求 ,保证经济增长速度的持续和稳定 ,另一方面为了刺激消费需求的增长实现社会主义的生产目的。但目前我国的经济环境限制了货币政策作用的充分发挥 ,因此为配合货币政策的实施 ,今后必须进一步深化经济体制改革     

浅析二外学习中的母语语法迁移

探讨了母语语法在目的语学习中的迁移,着重分析了母语迁移在语法上的主要表现,指出了由于各种语言的语法体系的不同,因而在动词形式、词序、并列句、复合句等方面的形式也不相同.学习者应在学习中注意两种语言的异同,及时输入新的信息,避免语言语法学习中的石化现象,尽快地排除母语所造成的负迁移.     

教师对语言学习的促进作用

讨论了教师对于语言学习的促进作用,即教师的中介作用.对教师中介作用的基本概念和各种理论,以及如何应用相关理论于课堂教学进行了探讨.通过对教师对语言学习促进作用的研究,使教育者能够意识到中介作用的重要性,进而在教学过程中最大程度上帮助学习者,达到事半功倍的效果.     

教师对语言学习的促进作用

讨论了教师对于语言学习的促进作用,即教师的中介作用。对教师中介作用的基本概念和各种理论,以及如何应用相关理论于课堂教学进行了探讨。通过对教师对语言学习促进作用的研究,使教育者能够意识到中介作用的重要性,进而在教学过程中最大程度上帮助学习者,达到事半功倍的效果。     

视知觉学习的自组织机制研究

在Hebb学习法和侧向相互作用的基础上,建立了具有知觉学习功能的神经网络模型,以汉字学习过程为例,模拟了视知觉模式从整体知觉到局部知觉的转变.知觉模式的转变源于网络权重的结构性变化,即由初始的随机分布变为块状分布,而局部的侧向相互作用是导致宏观有序结构产生的核心机制.     

深度学习的睡眠脑电特征波检测

回顾了深度学习（deep learning,DL）技术在睡眠脑电检测上的应用．以睡眠脑电过程中的纺锤波检测问题为例,探讨了睡眠脑电检测的各类方法,以及相较于传统信号处理算法,DL算法在睡眠脑电纺锤波检测问题上具有精度较高、对数据适应性更强的特点．针对进一步提高网络检测性能与硬件适用性需求,提出特征融合与脉冲神经2种改进型网络,并获得较高的检测性能,进一步阐释了DL技术在睡眠脑电特征波检测方面的应用潜力．      

感知学习风格及对大学英语分级教学的启示

通过对113名非英语专业学生的调查表明，大学英语分级教学后同一层次的学生，因性别、专业不同仍然存在感知学习风格的差异，而学习者的感知学习风格在一定程度上影响着学习效果。结合分级教学的理论原则，就如何把感知学习风格和提高分级教学效果结合起来提出了建议和设想。     

外语学习中学习策略与交际策略的对比分析

介绍了外语学习中对学习策略和交际策略的不同看法,对比分析了这两种策略的内在联系和区别,说明此分析对外语学习和教学方法的研究有重要意义。     

大学英语计算机辅助教学研究

时代发展对外语的新要求及高校连续扩招 ,给外语教学带来巨大的压力 ,而现代教育技术的迅猛发展又给外语教学带来很好的机遇。本文通过分析多媒体网络技术的特点 ,探讨了在英语教学中使用多媒体网络技术 ,把计算机和英语在教学中结合起来的问题 ,同时也讨论了教师在多媒体教学环境中的作用以及作为一个现代外语教师应具备的基本素质