地方高校大学英语听力现状分析与新模式构建

大学英语教学改革的一个着力点,就是加强听说,这在《教学要求》和新英语四、六级题型中可略见一斑。英语听说能力在英语学习中的地位毋庸置疑,大学英语听力教学又是目前我国地方高校英语教学的薄弱环节。本文分析了大学英语听力教学之现状并提出了相应对策。     

SPAD值与杂交狼尾草施氮水平和农艺性状的关系

采用盆栽试验探讨利用叶绿素计(Chlorophyll Meter SPAD-502)预测杂交狼尾草粗蛋白含量和牧草的施氮水平.试验设5个氮肥水平(纯氮量0,100,200,300,400k9/hm2)和3次重复,利用叶绿素计读取不同氮水平不同时期杂交狼尾草倒数第3片叶子的SPAD值,同时测定部分农艺性状和茎叶粗蛋白含量.结果表明,杂交狼尾草的SPAD值和粗蛋白含量是随着牧草的生长而逐渐降低,分蘖数、株高和生物产量随着牧草的生长而提高;杂交狼尾草的SPAD值与其施氮水平、分蘖数、株高、产量和茎叶粗蛋白含量都成正相关,与牧草的株高相关性最小且都不显著;与牧草的分蘖数和产量相关性大,接近或达显著水平:与牧草的茎叶粗蛋白含量相关性最大,均达显著或极显著水平.因此,利用SPAD值可用来预测杂交狼尾草茎叶粗蛋白含量,进而诊断杂交狼尾草的氮素营养水平,为牧草的合理施肥提供依据.     

中国水稻科技发展战略

分析了现代水稻科技与产业发展的国际趋势与特点、我国国民经济和社会发展对水稻的需求,回顾了我国水稻科技创新体系的建设历史与成效,着眼于现代水稻科技发展方向和水稻行业的需求,提出了我国水稻科技发展战略和重点课题。关键词:     

主/从机器人系统设计与双向伺服控制

建立了主／从异构式机器人力反馈遥操作控制系统。主操作系统采用2个2-DOF操作手,分别采用伺服阀控制液压马达获得2个解耦的旋转自由度。用力信息对伺服阀进行控制以驱动主操作手运动,解决主手操纵力不能直接驱动主操作手液压马达的问题。从机器人为4-DOF串联关节型四自由度机器人,采用比例方向阀控制。分别采用力反射伺服型和力对称型双向伺服控制策略,对主／从机器人系统进行遥操作力反馈双向伺服控制实验研究。验证了本设计的主操作手结构的合理性,力对称型双向伺服控制策略具有较好的控制性能。     

贵州民族自治区的区位优势·制约因素与发展战略分析

民族问题是贵州省需解决的主要问题之一。由于自然环境、地理区位、文化传统等制约因素的影响,贵州省民族自治区的区位优势一直未能充分发挥,分析了其优势所在和制约因素,提出了适合贵州省民族自治区的发展战略。     

Growth,biomass partitioning,and water-use efficiency of a leguminous shrub (<Emphasis Type="Italic">Bauhinia faberi</Emphasis> var. <Emphasis Type="Italic">microphylla</Emphasis>) in response to various water availabilities

Responses of the endemic leguminous shrub Bauhinia faberi var. microphylla, to various soil water supply regimes were studied in order to assess water stress tolerance of seedlings. Two-month-old seedlings were grown under water supply regimes of 100, 80, 60, 40, and 20% water field capacity (FC), respectively, in a temperature and light-controlled greenhouse. Plant height and leaf number were measured monthly over a 4-month period, while water use (WU), water-use efficiency (WUE), leaf relative water content (RWC), biomass production and its partitioning were recorded at the end of the experiment. Seedlings exhibited the greatest biomass production, height, basal diameter, branch number, leaf number, and leaf area when soil content was at 100% FC, and slightly declined at 80% FC. These parameters declined significantly under 60% FC water supply, and severely reduced under 40 and 20% FC. RWC, WU and WUE decreased, while the ratio of root mass to stem mass (R:S) increased in response to decreasing water supply. Water stress caused leaf shedding, but not plant death. The results demonstrated that B. faberi var. microphylla seedlings could tolerate drought by reducing branching and leaf area while maintaining a high R:S ratio. However, low dry mass and WUE at 40 and 20% FC suggested that the seedlings did not produce significant biomass under prolonged severe water deficit. Therefore, before introducing B. faberi var. microphylla in vegetation restoration efforts, water supply above 40% FC is recommended for seedlings to maintain growth.     

Population viability risk management (PVRM) for in situ management of endangered tree species—A case study on a Taxus baccata L. population

Population viability risk management (PVRM) provides a framework for explicitly including qualitative information about the possible outcomes of a management decision with regard to the viability of an endangered population in conservation management. Multi-criteria decision-making (MCDM) techniques enables managers to select the most preferred choice of action in a context where several criteria apply simultaneously. In that context a combined approach of the PVRM concept and a MCDM technique is presented for the development, evaluation and finally ranking of the in situ conservation strategies. We discuss the concept based on a case study for the maintenance of a gene conservation forest of an English yew population (Taxus baccata L.) in Styria, Austria. As part of the PVRM the analytic hierarchy process (AHP) is used to evaluate six conservation strategies with regard to the viability of the yew population. The viability of the population is evaluated based on the results of an analysis of the current environmental, social and economical state and a characterization of the ecological parameters of its population. The most significant risk factors (illegal cutting, browsing by game, tree competition, light availability and genetic sustainability) are structured and prioritised according to their impact on the viability of the yew population applying the AHP. Effects of the six conservation strategies on the viability of the yew population are determined through a qualitative assessment of the probability of a decrease of the population along with four different environmental scenarios. In this context strategy IV combining selective thinning, protection measures, game control with public relation activities seems to be the most effective alternative. The benefits of the combined approach of the PVRM concept with the AHP for the rational analysis of conservation strategies for this endangered tree species are discussed.     

基于虚拟经营的木材企业运作策略初探

随着信息技术及物流技术的发展,虚拟经营模式已经成功地应用于很多企业,但是却没有在国内木材行业成功应用的先例。本文以广东鱼珠国际木材市场为例,采用定性的分析方法,结合虚拟经营运作理论,提出基于虚拟经营的木材企业运作策略,并对广东鱼珠国际木材市场虚拟经营的具体实施过程进行初步探讨。     

旅游地生命周期理论指导下的乡村旅游开发策略

通过对旅游地生命周期演化阶段模型、阶段特点进行分析,总结归纳对旅游地生命周期造成影响的相关因素,根据这些理论对乡村旅游的开发建设进行指导,提出三种乡村旅游的开发方式。     

对现行森林采伐管理制度改革的思考

森林资源采伐制度对于促进森林可持续经营、保障经营者利益,以及有效保护森林资源具有重要作用。中国以森林限额采伐管理为核心的木材采伐许可证制度,尽管对于有效保护森林资源曾经起到重要作用,但是,在新的历史条件下,森林采伐管理在目标、手段不一致,采伐管理政策单一等一系列问题,已经成为影响与制约中国林业发展的重要政策因素。为此,以森林分类经营、分类管理为基础,提出对于公益林和商品林、人工林和天然林、国有林和私有林等,必须实施森林分类采伐管理政策。