甘蓝型油菜基因组文库的构建及与硼高效基因相连锁克隆的筛选

以甘蓝型油菜宁RS-1为材料,构建了含有82944个克隆的甘蓝型油菜的BAC基因组文库.从文库中随机挑取克隆进行DNA长度检测,BAC克隆平均插入片段大小为80 kb,覆盖甘蓝型油菜基因组的5.1倍.随机挑取108克隆进行继代培养100代,分离质粒酶切检测表明不存在插入片段丢失现象,表明该文库的克隆在大肠杆菌中稳定存在;以与硼高效基因相连     

Development of interspecific somatic hybrid cell lines in cultivated jute and their early characterization using jute chloroplast RFLP marker

A strong sexual incompatibility barrier that exists between the two cultivated jute species, Corchorus capsularis and Corchorus olitorius, limits the scope for improvement through genetic introgression. Protoplast fusion was carried out to generate interspecific hybrid cell lines. Cotyledonary cell protoplasts of C. capsularis and anthocyaninpigmented hypocotyl protoplasts of C. olitorius were used in the fusion experiments, which appeared to be visually useful in the early selection of the fused products. A chloroplast DNA (cpDNA) marker was developed in jute, which showed species‐specific hybridization patterns with EcoRI‐digested total genomic DNA of C. capsularis and C. olitorius. This cpDNA marker was used in the characterization of the somatic hybrid cell lines at their early stages of growth. Evidence for the presence of both types of cpDNA in the hybrid cell lines was obtained when the total genomic DNA of 4‐ to 7‐month‐old hybrid cell lines was challenged with the chloroplast DNA marker through Southern analysis. It was shown that the early segregation of the parental chloroplasts did not occur in jute, although this is common in other plant species. The hybrid nature of the fused cell lines could also be identified through peroxidase isozyme analysis. Isozyme banding patterns were complex and varied among the hybrid cell lines.     

Causes, Processes and Consequences of Sandstorms in Northern China : A case study of sandstorms in 2000

Serious land degradation exists in the marginal areas of North China, the important ecological transition between semi-arid and sub-humid climate zones, which is a relatively narrow belt with 100-250 km in width and about 2 000 km in length. The annual rainfall varies between 300-400 mm. In the past hundred years (before 2000), most of the land in the region had been used for grazing and dryland cropping. As land-use is intensifying, particularly since 1970s and 1980s, desertification has accelerated. Our case studies in 2000 indicated that: (1) Sand-dust storms are the result of a combination of climate change, such as strong winds and dry weather, but their frequency and intensity are mainly related to precipitation variations. The El Nina/El Nino effect is strongly implicated. (2) Human economic activities result in sufficient sand-dust sources to create a hazard. Large-scale land conversion for cropping, deforestation, irrational use of water resources and over-exploitation of groundwater have all c     

黑龙江省林火规律研究Ⅰ .林火时空动态与分布

根据黑龙江省 1980～ 1999年的林火资料 ,利用地理信息系统等工具 ,对黑龙江省林火时空动态和分布规律进行了研究。结果表明 ,黑龙江省林火可分为 1980～ 1987年的多发段和 1988年以后的低发段。人为火与总林火规律相似 :次数频谱周期为 16、4 5a和 2 3a ,面积频谱周期为 6a。雷击火次数频谱周期为 9 1a和 3 0a左右 ,面积频谱周期为 9 1a。总林火次数和面积显著正相关 ,雷击火的次数与面积不相关。林火主要发生在 4月、5月。人为火面积集中在 3月、4月 ,雷击火面积集中在 5月。林火由西北向东南呈条带状分布 ,西部、西南部和东北部林火较少。有 5个林火多发区。林火面积、平均蔓延速率、持续时间呈对数正态分布 ,具有自组织特点 ,分数维分别是 0 86、1 0 5和 0 6 8。对火频谱周期、自组织性进行了讨论 ,指出自组织函数将林火的时空特性结合在一起 ,采用负幂函数描述时存在适用下限并给出计算公式。对不同区域的自组织分数维进行了比较。对人为引入火烧的适宜强度和频度进行了简单探讨     

几个杨树新品种抗旱能力与生理反应研究

利用扦插苗对 6个杨树品种进行抗旱指标与叶片水分、净光合产物、蒸腾速率等生理反应研究。确定了各品种的正常生长、抑制生长及死亡阶段的土壤含水率范围 ,对各树种抗旱性进行了定量评价。为杨树新品种推广利用提供科学依据。     

五种木质地板阻燃性能的测试方法比较

为全面评价5种木质地板的燃烧性能,采用辐射热源法及锥形量热法对其进行测试.结果表明,采用辐射热源法,5种地板均能达到难燃材料要求;采用锥形量热法,阻燃实木地板的阻燃性能良好,而2种实木复合地板均易被点燃,且具有较高的热释放速率,强化木地板及微晶石木地板表现出良好的阻燃特性,但微晶石木地板生烟量较大.     

基于“人人网”的高校共青团网络舆情引导探究

从“人人网”的发展与特点入手，介绍了校园SNS对学生的思想导向作用，从实践的角度探究了高校网上建团的思路与舆情引导的关系，提出开展网络思想政治教育的新思路。     

黄河下游河道泥沙淤积测验技术分

传统方法河道淤积测验由于作业劳动强度大，需要人员和测量设施多、测量设施维护工作量大及测验速度低而逐渐被淘汰，随着测量技术的发展，以GPS为代表的新的技术将逐渐成为测量的主要方法，它具有测量精度较高，测量数据可以自动采集，不受测量现场通视和天气条件的影响，不需断面基线标志杆等优点。特别是它的测量成果能够自动为有关数字处理软件所利用，对快速发挥测验成果的效益具有重要意义。