城乡建设用地增减挂钩政策分析

城乡建设用地增减挂钩是提高建设用地利用效率、解决城镇政府现实用地压力的有效手段。但该政策在执行中却产生了许多问题,如区域差距扩大、城镇用地粗放、农村传统生产生活方式难以维系、耕地质量下降、村民利益受损等。造成这种局面的原因在于增减挂钩工作中政府的完全主导和农民集体失语。应让政府保持中立,并在此基础上探索有利于"三农"发展的增减挂钩方式。     

城乡建设用地增减挂钩项目区的时空联建

合理设置项目区是城乡建设用地增减挂钩规划的核心内容。该文以北京市平谷区为例,基于供需和级差地租理论,在已有农村居民点整治潜力和挂钩分区研究的基础上,开展了城镇建新适宜度与农村拆旧适宜度评价,经建新地块的规划修正和拆旧地块的空间相对集聚、适宜度一致性修正,选择出挂钩建新区和拆旧区,然后通过挂钩联建的关系原理分析,建立了挂钩时空联系的逻辑模型,将建新区和拆旧区组合形成挂钩项目区。结果表明,该方法能够有效的筛选出建新区与拆旧区,可以实现挂钩项目区的组合联建与时空配置。研究区整体上属于"供大于求"的挂钩类型区,农村居民点拆旧潜力的供给能够满足城镇建新的需求;全区城乡建设用地增减挂钩项目区可规划为22处,时序上分为近期8处、远期14处,空间上包括乡镇内挂钩17处、乡镇间挂钩5处;经建新用途、拆旧与安置方式的合理安排与设置,实现了促集约和保发展的挂钩目标。该研究为挂钩项目区条件设定与选择、空间联动和时序安排提供参考。     

Influence of treatment temperature and duration on selected biological,mechanical, physical and optical properties of thermally modified timber

Abstract

The impact of heat-treatment temperature (180, 200, 210, 220 and 240°C) and various heat-treatment durations on selected biological, mechanical, optical and physical properties of thermally modified timber (TMT) was determined. The suitability of different measures for prediction of the treatment intensity was also investigated. Resistance to impact milling (RIM), lightness L*, equilibrium moisture content (EMC), and antiswelling efficiency (ASE) were correlated with corresponding fungal resistance achieved by heat treatments. The results show that the decrease in mass by heat treatments is a suitable measurand to describe the treatment intensity, which is a product of treatment temperature and duration, where the impact of temperature is dominant over the impact of time. The properties examined showed a strong reciprocally proportional relationship with the decrease in mass. Different correlations were found for the various treatment temperatures: the higher the temperature applied, the lower the decrease in mass required for an equivalent improvement in certain wood properties, e.g. biological durability, EMC and dimensional stability. However, mass loss by Poria placenta correlated well with RIM, lightness L*, EMC and ASE of the different heat-treated specimens, depending on the heat-treatment temperature. Consequently, a reliable estimation of improved fungal resistance of TMT, as well as quality control of TMT in general, requires certain process information.     

铝逆境下植物根系有机酸的分泌及其解铝毒机理

铝元素是限制酸性土壤中作物产量的一个重要因子,本文根据铝逆境下植物根系有机酸的分泌及其解铝毒机理研究现状,详细地论述了铝逆境下植物有机酸的分泌方式及其解铝毒机理,并对铝胁迫下植物根系分泌的有机酸种类及调控其分泌的主要因素等做了介绍,提出了铝逆境下植物有机酸解铝毒的研究方向。     

农村土地资源集约利用及空间配置模式探讨——基于城乡建设用地增减挂钩视角

以成都市新都区斑竹园镇和军屯镇为增减挂钩试验区,探讨农村土地资源集约利用及空间配置模式,并提出了增减挂钩的保障措施。结果表明,试验区农村土地通过增减挂钩空间配置,可有效增加耕地0.94 hm2,农民集中居住区集约使用9.53 hm2建设用地指标,节约建设用地指标37.03 hm2。城乡建设用地增减挂钩模式是缓解城乡建设用地矛盾、保护耕地、推进土地节约集约利用、促进城乡协调发展的重要途径之一。     

Incidence of potato virus Y and potato leaf roll virus in autumn potatoes in Israel

Summary Random sampling of autumn grown potatoes in Israel revealed potato virus Y incidences of 2.7, 2.5 and 3% during the years 1976, 1977 and 1978, respectively, figures only slightly higher than those found in spring-planted fields (2.3% in 1976), and which agree with visual estimates by the Inspection Service. Assaying random samples for potato leaf roll virus (PLRV) by aphid transmission to test plants, detected incidences as high as 38.8, 28.9, 36.7 and 33.3% during 1976, 1977, 1978 and 1979, respectively, although only minor levels were visable, indicating symptom masking in the autumn. Most of the infection was found to be secondary; ca. 25% of the local seeds for autumn planting, grown during spring, are PLRV-infected. The effect of the high incidences of PLRV on autumn yields is not known, but they are consistently lower than spring yields of the same varieties. Contribution No 315-E, 1980 Series, The Volcani Center, Bet Dagan, Israel.     

城乡建设用地增减挂钩中土地权属调整的研究

“城乡建设用地增减挂钩”是国家推出缓解城镇用地压力、促进城乡统筹发展的一项重要管理措施。目前随着各地积极开展城乡建设用地增减挂钩试点工作,随之带来的土地权属问题也日益突出。基于城乡建设用地增减挂钩项目实施中所涉及的土地权属调整内容,遵循权属调整的原则,提出在实施过程中建新地块和拆旧地块内的土地权属调整方案,并总结了权属调整的相关程序,最后列出还应特别注意的问题和建议,以期能够促进城乡建设用地增减挂钩的有序、协调、高效实施。     

露地西瓜化肥减量对其产量及品质的影响

在淮南市农业科学研究所试验基地开展露地西瓜化肥减量试验,以研究对西瓜产量及品质等的影响。试验表明在长年重茬瓜菜田土壤肥力上,增施有机肥,化肥减量是可行的,化肥减量处理区西瓜最终在单瓜重、每亩产量上,均好于常规施肥处理区及不施肥处理区,证明化肥用量可减量使用。     

一万年来导致华北、西北地区天然林不断减少诸因素分析

华北、西北地区历史上曾经分布着大面积原始森林,目前这一地区的天然林已经基本消失,森林遭受破坏的原因,有自然因素和人为因素。自然因素中主要是气候改变和自然灾害,人为因素中在古代主要是火猎、火田、战争、建筑、手工业、薪炭等;到了近代,由于各种工业、手工业和日常生活消耗,使幸存于偏远之处的原始森林也遭受了毁灭。在导致我国森林减少的人为因素当中,人口的不断增加而产生的对森林资源的持续压力是根本的原因。     

台风对江苏近海海表温度的影响分析与探讨

利用中国台风网"CMA-STI热带气旋最佳路径资料数据"和多卫星遥感观测资料,本文对2011年09号梅花台风、2011年06号马鞍台风和2012年10号达维台风在发展过程对中国江苏近海海域海温的影响进行了分析与探讨,并辅助以沿岸的海温实测资料进行对比验证,借此提高对近海海域上层海洋物理环境对台风响应的认识。分析结果表明,台风对近海SST的影响程度与台风自身强度和台风的移动路径密切相关,近海SST降低区域一般位于台风路径的右侧,最大SST降低一般滞后台风中心两天或一天。当台风在远海活动并靠近江苏近海时,江苏近海海域SST略有上升;当台风进入江苏近海时,近海海域SST大幅降低;登陆台风在登陆后近海才出现最大降温。