西北地区沙尘暴的危害及对策

该文以大量的例证,详实的数据介绍了西北地区沙尘暴的危害,并综合分析了沙尘暴产生形成原因、危害方式,为保护生态环境提出了治沙防沙的基本对策。     

热激处理对桃,李离体花枝2n花粉产生的影响

对桃和李通过休眠的花枝在２０℃条件下进行水培,减数分裂前期Ⅰ进行３２℃、１２ｈ热激处理,小孢子母细胞减数分裂四分体时期二分体发生频率为５．８２％～１６．０６％,２ｎ花粉比例为１３．３３％～２０．３７％,处理后花粉离体萌发率较低;３０℃恒温培养导致花蕾败育。二分体频率重复间、花朵间和品种间差异显著。     

茄子创新资源的耐热及抗青枯病评价研究

优良的种质资源是品种选育的重要基础。本研究的目的是明确茄子创新资源的抗性水平,培育适应华南地区高温和青枯病易发特点的新品种。本研究利用茄子苗期耐热快速鉴定和浸根接种青枯菌鉴定方法,对12份茄子创新自交系开展耐热性和抗青枯病鉴定。获得处理4天的细胞膜相对电导率和热害指数。发现8份紫红长茄中有3份为耐热(13009-4-4-3、3309-5-4-1-2和5-1-1-2-1)和2份中等耐热(3-1-2和10009-3-2-1);3份白茄中有1份耐热(10009-5-3-1-1)和1份中等耐热(10015-5-3-4-1);苗期接种6周鉴定筛选获得1份高抗(3309-5-4-1-2)、2份抗病(10009-3-2-1和3410-14-1-4-2)和1份中抗(3-1-2)青枯病材料。根据耐热和抗病鉴定结果共获得1份(3309-5-4-1-2)耐热高抗青枯病自交系,1份(10009-3-2-1)中等耐热抗青枯病,1份(3-1-2)耐热和抗青枯病均表现为中等水平。     

Spatial and temporal variability of air temperature across urban neighborhoods with varying amounts of tree canopy

Recent studies have emphasized the presence of microclimates in urban settings, but most do not have the high resolution observations necessary to understand the interactions taking place at a neighborhood scale. This study used a network of 10 identical weather stations and high resolution land cover data in Knoxville, Tennessee, to analyze the microclimates of a medium-sized city with a temperate climate. Two stations were installed in each of four urban neighborhoods in locations with varying localized tree cover, and two additional stations were installed in the center of downtown and in a nearby urban nature center. The intra-neighborhood results suggested that there is significant temperature variability within a single neighborhood based on the tree canopy density immediately surrounding a given weather station. However, the inter-neighborhood variability (differences between neighborhoods) was similar in magnitude, which suggests that the overall differences in neighborhood characteristics also have an effect on climate. Land cover at the neighborhood scale (in particular tree canopy percentages at the 500-m radii) had the highest correlation with the minimum daily temperature (Tmin) during the summer season. Maximum daily temperature (Tmax) relied most on the distance of each station from Downtown and the amount of impervious area in the 50 m surrounding each station. Tmax was also most influenced by surrounding land cover during dry conditions (a Dry Moderate air mass). Overall, highly localized impervious land cover percentages and larger-scale forested canopy were important in explaining temperature fluctuation, pointing to the importance of scale in microclimate assessments. Dry air masses enhanced the relationship between land cover and temperature during the day, while moist air masses did the same overnight. These data can be used to better inform planning strategies to build resiliency to extreme heat into urban environments by considering the influence of tree canopy.     

浅谈孔隙率对沥青路面的影响

沥青混合料的孔隙率是一个重要的设计参数，其对于沥青路面的强度和使用性能有着重要的影响。在施工时，由于施工条件和设备的影响，不可能达到设计的孔隙率，于是一般要求用压实度作为施工时的一个控制指标，将沥青路面施工后的孔隙率控制在一个可接受的范围。在路面使用的初期，必然会有一段时间处于未完全压实工作状态，这种工作状态下，沥青路面能够提供的是未完全稳定的早期强度。在设计时，需要对比多个级配的混合料，确定合理的早期强度。     

沙漠地区农业种植技术初探

沙漠地区在没有造林或造林初期防护效益不显著情况下，农业种植受风沙危害比较严重，提高农业种植产量是我们面临的一道难题。本文对中国林科院沙漠林业实验中心井灌区第四实验场风沙环境和三年来的种植情况进行分析，得出农业防风害的措施有以下几个方面：农作物品种的选择；种植时间的调整；以增加起动风速为目的的各项抗风害措施的采用；以减小风沙流强度和目的的阻沙林和固沙工程的建造。这些措施能有效地减小和防止风沙灾害的发     

植物性抗生育剂防治幼林地兔害研究

在山西省吕梁山国有林管理局下李林场新造油松和侧柏混交林内,以20m×40m的面积投放一堆植物性抗生育剂和红胡萝卜混合药饵200g,对照地不放药。通过对施药前后试验地与对照地兔粪和苗木为害率调查数据进行统计分析,结果表明,与对照相比,投放植物性抗生育剂能显著减少幼林地内野兔活动频率和对苗木的为害。     

Splenectomy enhances sensitivity of islets to STZ in mice

AIM: To explore the protective role of spleen in damage of islet beta cells induced by streptozotocin (STZ).METHODS: Splenectomy in mice was performed by surgery. Sixty splenectomy mice were divided into 3 groups as the mice were intraperitoneally injected with STZ at doses of 80 mg/kg or 160 mg/kg, and saline, respectively. Sixty normal mice (without splenectomy) were also grouped and treated as above for controls. One week later, fasting blood glucose and serum insulin were monitored,and beta cell mass and the apoptosis of islet cells were analyzed by the methods of immunohistochemistry and ELISA, respectively. The content of reactive oxygen species was determined by the method of luminol-enhanced chemiluminescence.RESULTS: Compared to the normal control mice, the concentrations of fasting blood glucose significantly increased, and serum insulin reduced in splenectomy mice treated with STZ at the dose of 80 mg/kg. Moreover, beta cell mass decreased, enrichment factor of nucleosomes of islet apoptotic cells and reactive oxygen species produced in pancreas tissues significantly increased in splenectomy mice treated with STZ at the dose of 80 mg/kg.CONCLUSION: Splenectomy increases the sensitivity of islets to STZ in mice by increasing the production of reactive oxygen species in pancreas.     

不同化肥农药减施组合对水稻主要病虫害发生及产量的影响

为探索化肥农药减施融合使用技术，设计肥料和农药两因素三水平试验，研究不同化肥农药减施组合对水稻主要病虫害发生及产量的影响。结果发现：减肥有减轻病虫发生程度的趋势，减药有加重病虫发生程度的趋势；减肥可显著影响水稻纹枯病、第4代稻飞虱、稻纵卷叶螟发生程度，减药可显著影响水稻纹枯病、第3和4代稻飞虱、稻纵卷叶螟发生程度，但两者均对稻瘟病、稻曲病、二化螟发生程度无显著影响。减肥30%时实测减产10.29%，对产量影响显著；减肥低于20%时，绿色助剂替代处理和生物农药替代处理实测产量比对照处理增产0.38%和2.49%，生物农药替代和绿色助剂替代均可作为化学农药减量的技术措施。     

冷季提高猪舍环境温度方式之效益分析

寻找温度与猪的生长之间关系的有关数据,得出在临界温度下,育成猪的生长随温度变化而变化的规律;总结了我国各地现有的各种养猪舍建筑形式;分析、探索了冷季提高、维持猪舍环境温度的各种方式;通过估算其成本和它们各自能带来的经济效益经行经济性比较得出全封闭式暖床保温。