鼓室炎症对自体骨听骨链重建术后听力的影响

目的了解鼓室炎症对自体骨塑形听骨链重建术后听力的影响。方法 45例自体骨塑形听骨链重建术的患者,根据鼓室炎症轻重程度分为炎症轻组（25例）及炎症重组（20例）。炎症轻组鼓室黏膜充血、光滑、无增厚;炎症重组鼓室黏膜肥厚、粘连、肉芽增生。比较两组术前后的平均气骨导差。结果炎症轻组术后平均气骨导差比术前减少（17.87±7.11）dB,而炎症重组减少（9.65±5.13）dB,两组手术前后平均气骨导差值的差异有统计学意义（P〈0.01）。结论鼓室炎症的轻重程度是影响术后听力的重要原因。     

城乡收入差距视角下的农村社会保障制度建设

在分析城乡居民收入差异变动的基础上,基于城乡统筹视角,研究了我国农村社会保障制度在建设与推进过程中所面临的困难,指出转移性收入的分配不均和社会保障相关制度建设中的漏洞是制约农村社会保障的重要原因,并提出了相应的对策,即加大财政支出、推进医疗保险的公平性和加强相关的法制建设。     

基于ARMA模型的云南省城乡居民收入差距分析和预测

以云南省为例,根据1978～2010年云南省城乡居民收入差距的数据,运用ARMA模型,用Eviews软件进行拟合,对云南省城乡居民收入差距情况进行分析,并给出了2011～2013年云南省城乡居民相对收入差距的预测值。结果显示,城乡居民收入差距会继续扩大。提出了缩小城乡居民收入差距的相关建议。     

西藏城乡居民收入差距特征与农牧民增收对策

本文对西藏城乡居民收入绝对差距和相对差距特征进行了分析。从产业结构层面、家庭收入层面及政策层面三方面,分析了西藏城乡居民收入差距变动形成的原因。提出了"十二.五"西藏继续缩小城乡居民收入差距实现农牧民增收的对策应从农牧民转变思想、完善家庭收入结构、建立帮扶措施和构建集中连片致富模式;政府继续调整产业结构、加大第一产业投资力度、消除城乡二元结构;保障措施配套增收奖励、带头人负责制、保险机制及完善社保制度等保障机制三个层面进行。     

Influence of Backfill Air Gap on Soil Temperature Recovery in Ground coupled Heat Pumps

Air gap may easily emerge in the progress of backfill in ground heat exchange due to field operation problems. The single U tube three dimensional numerical heat transfer model is set up and there are 3 kinds of backfill air gap assumptions for computational analysis, which are the most common situations in practical projects. Different air gap situations will have considerable effects on soil heat transfer, especially the factor of soil temperature recovery performance, which is investigated in this research, and there is practical project operating data for the comparison confirmation with the theoretical calculation results in inlet and outlet water temperatures. It can be concluded that the backfill air gap will increase the soil average excess temperature in the period of recovery inside the place where the air gap is, and degrade the heat transfer performance of the ground heat exchange.     

纳秒级气体火花开关的研制

为了研究高压脉冲电场对种子活性的影响,结合脉冲功率技术和计算机辅助设计技术,研制了满足最新高空核爆电磁脉冲模拟标准MIL-STD-461F的纳秒级气体火花开关。在分析开关放电原理的基础上,考虑火花隙电阻和开关结构电容的影响,基于Simulink建立了开关的动态放电模型,仿真分析了负载、开关电感、开关电容等因素对放电脉冲特性的影响,为开关的设计提供了参考。在此基础上,试制了纳秒级气体火花开关样品,在50Ω负载上输出脉冲峰值达到25 kV,上升时间2.5 ns,脉冲宽度18 ns,为进一步研究脉冲电场种子效应奠定了基础。     

燕山山地油松人工林林隙大小对更新的影响

林隙(gap)又称林窗,指森林群落中老龄树木死亡或偶然因素(如干旱、台风、火灾等)造成成熟阶段的优势种死亡,从而形成林冠空隙的现象(Watt,1947)。美国生态学家Runkle(1982)将林隙分为2种,一种是林冠空隙(canopy gap),指上方无树冠遮荫的部分,即太阳处于正中位置时无树冠遮荫的面积之和;另一种是扩展林隙(expanded gap),指形成该林隙周围树木基部所包围的面积(Runkle,1981)。本研究所指的林隙为应用最为广泛的扩展林隙。近年来的森林动态学研究表明:林隙在森林结构和多样性维持中起着重要的作用,已     

开林窗与封禁对华北落叶松林下植被多样性的影响

以木兰林管局典型的华北落叶松林为研究对象,对其采取开林窗、封禁等改造措施,采用样方法进行野外调查,通过丰富度、生态优势度、多样性、均匀度指数,分析不同经营措施下的生物多样性及样地的物种组成。结果表明:开林窗面积中等及较小的样地各生物多样性指数均呈上升趋势,且高于对照,而开林窗面积较大样地的Pielou均匀度指数成降低趋势;封育区的Simpson和Shannon-Wiener多样性指数与均匀度指数均大于对照区,而封育区的Margalef丰富度指数虽然呈上升趋势,但仍小于对照区;该实验区林下植被的优势物种为乌苏里苔草。     

Exploring the silvicultural and economic viability of gap cutting in Mediterranean softwood plantations

Gap cutting consists of the removal of all trees growing on a small surface,varying in size from 200 to 600 m 2.In Italy,gap cutting has been successfully tested for introducing the natural regeneration of native species into softwood plantations,thus accelerating the transition towards climax hardwood stands.Depending on plantation types and conditions,gap cutting should be started at an age between 70 and 80 years and the system should include at least 12 to 15 gaps,in order to produce enough wood to cover costs.Generally,natural regeneration is firmly established within 5-7 years from treatment.Gap cutting also offers superior results to selection thinning,the latter producing about 35% less value and incurring 25% to 30% more costs.As for all regeneration cuts,the success of gap cutting depends on wildlife control in order to prevent extensive damage to the regeneration.