贵州省退耕还林亟需解决的问题及政策建议

通过对当前贵州省退耕还林总体情况的摸底分析,提出下一步退耕还林政策建议。     

贵州省天柱县天然林资源保护工程封山育林调查分析

本文通过对天柱县1999、2000年度天保工程封山育林情况的调查分析：基于本地区丰富的水热、物种资源条件和独特的自然地理，封山育林作为保护和恢复森林资源的主要工程措施效果显著，值得推广。项目建设应选择栎类、马尾松、杂阔等先锋乔木为主要组成树种的疏林地和灌木林地作为封育对象。在天然林资源保护工程建设中，森林三大效益能否达到和谐统一，有待进一步研究。     

优化体育教学,提高学生创新能力

21世纪是知识经济的时代,需要创新型人才。学校的教学必须同社会的需求相接轨,落后的教育观念和方法妨碍学生创新能力的培养,只有创新教育才能优化实践教学环节,提高学生的创新实践机会,培养创新能力,最终达到提高学生的创新能力的目的。     

提高农村领导干部法律素质的思考

法律素质作为农村领导干部政治素质的一个重要组成部分,对农村领导干部自身整体素质的提高有着重要的影响,同时也影响着我国法治建设的进程。提高农村领导干部法律素质已成为我们面临的一项重要课题和紧迫任务。本文拟从如何提高农村领导干部自身法律素质的角度进行阐述。     

Model uncertainty in the ecosystem approach to fisheries

Fisheries scientists habitually consider uncertainty in parameter values, but often neglect uncertainty about model structure, an issue of increasing importance as ecosystem models are devised to support the move to an ecosystem approach to fisheries (EAF). This paper sets out pragmatic approaches with which to account for uncertainties in model structure and we review current ways of dealing with this issue in fisheries and other disciplines. All involve considering a set of alternative models representing different structural assumptions, but differ in how those models are used. The models can be asked to identify bounds on possible outcomes, find management actions that will perform adequately irrespective of the true model, find management actions that best achieve one or more objectives given weights assigned to each model, or formalize hypotheses for evaluation through experimentation. Data availability is likely to limit the use of approaches that involve weighting alternative models in an ecosystem setting, and the cost of experimentation is likely to limit its use. Practical implementation of an EAF should therefore be based on management approaches that acknowledge the uncertainty inherent in model predictions and are robust to it. Model results must be presented in ways that represent the risks and trade‐offs associated with alternative actions and the degree of uncertainty in predictions. This presentation should not disguise the fact that, in many cases, estimates of model uncertainty may be based on subjective criteria. The problem of model uncertainty is far from unique to fisheries, and a dialogue among fisheries modellers and modellers from other scientific communities will therefore be helpful.     

二维空间完备性基本定理的相互证明

平面上的5个定理,闭区域套定理,有限覆盖定理,聚点定理,致密性定理及Cauthy准则,刻画了R2的完备性,构成了二元函数极限理论的基础.分别以闭区域套定理,有限覆盖定理,聚点定理为基础,证明其它定理,体现了这5个定理之间的相互等价.     

高压静电场分离油菜,芝麻及湿地松种子对萌发期电导率的影响

种子在萌发期的电导率值是用来间接说明其膜系统完整程度的一项重要指标，也是衡量种子活力强度的性能指标之一，研究结果证实，采用高压静电场场效应分离芝麻、油菜及湿地松种子，落入理想分离区的种子其电导率改善值在６％～２３％，且种子的电导率值与沿电场方向的位移存在着贴切的相关规律。     

黄海绿潮（浒苔）暴发区温盐、溶解氧和营养盐的分布特征及其与绿潮发生的关系

根据2008年7月9～14日对黄海绿潮暴发区生态环境要素的调查数据,重点研究了调查海域温盐、溶解氧和营养盐的分布特征及其与绿潮发生的关系。结果表明,溶解氧的平均值为9.22mg/L,整体处于过饱和状态,呈北高南低,西高东低的分布趋势。溶解无机氮的平均值为9.07μmol/L,呈现出南高北低,苏北沿岸向离岸方向逐渐降低的趋势;活性磷酸盐的平均值为0.19μmol/L,呈现出东高西低,自外海向海洲湾方向递减的趋势。在调查海域的东部出现营养盐高值区。通过分析温度、盐度、溶解氧、营养盐与绿潮发生的关系发现,温度、盐度和溶解氧均处于浒苔藻体生长和孢子释放的适应范围内。大面积浒苔聚集区的表层海水DIN和PO34--P的平均含量分别为14.89和0.27μmol/L,营养盐含量要明显高于调查海域其他海区营养盐的含量,表明充足的营养盐是绿潮发生的物质基础。同时调查海区表层、10m层和底层N/P（摩尔比）比值的平均值分别为702、194和411,均远大于Redfield值,由此可见,该调查水域主要受到磷的潜在限制。     

Effects of all‐male,mixed‐sex and all‐female freshwater prawn in polyculture with major carps and molas in the fallow rice fields

This study was conducted to evaluate the effects of all‐male, mixed‐sex and all‐female freshwater prawn (Macrobrachium rosenbergii) in a polyculture with major carps (Catla catla and Labeo rohita) and self‐recruiting small fish molas (Amblypharyngodon mola) in the fallow rice fields of Bangladesh. There were three treatments with three replicates. All ponds were stocked with carps and molas plus either all‐male prawns (treatment MP), mixed‐sex prawns (MFP) or all‐female prawns (FP). Prawn, mola, catla and rohu were stocked 20 000, 20 000, 1750 and 750 ha^?1, respectively, in all treatments. The prawns were fed twice daily, starting at 8% body weight and gradually reduced to 3% body weight. The fish were fed in the morning with mustard oil cake and rice bran (1:2 ratios) at 3% body weight. Significantly higher production of prawns (697 kg ha^?1) was obtained in treatment MP, which yielded 34.7% and 56.2% more production than MFP and FP respectively. Significantly higher total production of 1620 kg ha^?1 and a higher benefit–cost ratio of 2.10:1 were also obtained in treatment MP. It can be concluded that an all‐male prawn culture is economically more viable than all‐female and mixed‐sex prawn cultures, along with other fish like major carps and the nutrient‐dense molas in the polyculture.     

稻鱼生态兼作轮作优质高产技术及其效益评价

Based on the Rice Fish Concurrent living theory and pond aquaculture high yield technology, combining Rice Fish Concurrent Farming technique in the model of pit pond aquaculture and the Rice Fish in turn Farming technique in the model of field pond aquaculture, the high quality and yield ecological technique model of early rice fish concurrent farming and late complete aquaculture in paddy field was established, which contain one submodel of fingerlings farming to juvenile and another submodel of juvenile fish farming to adult fish. The model demonstration base covering 20 hm2 paddy field was established in Songyang village, Gechuan town, Liancheng county of Fujian province. Production results showed： Early rice harvest average yield increased 22% very significantly （P 〈 0. 01 ） in both submodels, and 453 kg juvenile fish was produced per 667 m2 paddy field implementing the submodel of fingerlings farming to juvenile fish, whose production value and profit were 5 182￥ and 1 662 ￥ RMB, respectively, and were very significantly increased 2.5 times and 3.7 times （P 〈 0.01 ） respectively than planting only two harvests paddy without aquacuhure; 710 kg adult fish was produced per 667 m2 paddy field implementing the suhmodel of juvenile fish farming to adult fish, whose production value and profit were 6 428￥ and 2 005 ￥ RMB, respectively, and were very significantly increased 3.2 times and 4.7 times （P 〈 0. 01 ） respectively than planting only two harvests paddy without aquaculture; There were good economic, social and ecological benefit.