不同林地清理方式下生物炭和氮添加对桉树红锥混交林土壤养分的影响

【目的】阐明不同林地清理方式下(火烧清理和人工清理)生物炭和氮添加对桉树红锥混交林土壤养分的影响,为人工林的经营管理提供参考。【方法】在火烧清理和人工清理林地的桉树红锥混交林中,设置生物炭和氮添加的控制实验,研究生物炭和氮添加对土壤有机碳(SOC)、全氮(TN)、全磷(TP)、全钾(TK)、有效磷(AP)和有效钾(AK)含量的影响。【结果】不同林地清理方式下,生物炭和氮添加对林地土壤养分的影响存在差异:与对照相比,人工清理林地时,添加生物炭显著增加了20～40cm土层的AP含量;氮添加极显著增加了0～10cm土层的SOC、TP、AP含量和C∶N;10～20cm土层的SOC、AK含量,20～40cm土层的AP和AK含量也显著增加;而0～10cm土层的N∶P则极显著降低。林地清理方式为火烧清理时,生物炭添加极显著增加0～10cm土层的TP含量,而0～10cm、10～20cm土层的SOC和AK含量,0～10cm土层的C∶N,10～20cm的AP∶TP、C∶P以及0～10cm、10～20cm、20～40cm土层的AK∶TK显著降低,0～10cm土层的AP含量、AP∶TP、C∶P和N∶P更是极显著降低。氮添加显著降低10～20cm土层的N∶P以及0～10cm土层的AP∶TP,0～10cm土层的AP含量以及10～20cm的TN含量下降达到极显著水平。【结论】人工清理林地条件下,实施生物炭和氮添加有利于提高桉树红锥混交林的土壤养分。     

城市二级排水回用作循环冷却水处理技术

城市二级排水回用作循环冷却水 ,重点是应去除二级排水中的COD和氨氮 ,本文介绍了相关的净化技术 ,并对其进行了评价     

海南省部分旅游区公众环境意识的调查与思考

环境保护是我国一项基本国策,关系着经济和社会发展.公众的环境意识对于环境保护工作的成效有极大影响.经调查,海南省旅游区公众环境意识与公众的文化程度、环境保护法规的宣传教育、旅游区的环境管理等有关联.     

Transferability of tag SNPs in genetic association studies in multiple populations

A general question for linkage disequilibrium-based association studies is how power to detect an association is compromised when tag SNPs are chosen from data in one population sample and then deployed in another sample. Specifically, it is important to know how well tags picked from the HapMap DNA samples capture the variation in other samples. To address this, we collected dense data uniformly across the four HapMap population samples and eleven other population samples. We picked tag SNPs using genotype data we collected in the HapMap samples and then evaluated the effective coverage of these tags in comparison to the entire set of common variants observed in the other samples. We simulated case-control association studies in the non-HapMap samples under a disease model of modest risk, and we observed little loss in power. These results demonstrate that the HapMap DNA samples can be used to select tags for genome-wide association studies in many samples around the world.     

Multiple regions within 8q24 independently affect risk for prostate cancer

After the recent discovery that common genetic variation in 8q24 influences inherited risk of prostate cancer, we genotyped 2,973 SNPs in up to 7,518 men with and without prostate cancer from five populations. We identified seven risk variants, five of them previously undescribed, spanning 430 kb and each independently predicting risk for prostate cancer (P = 7.9 x 10(-19) for the strongest association, and P < 1.5 x 10(-4) for five of the variants, after controlling for each of the others). The variants define common genotypes that span a more than fivefold range of susceptibility to cancer in some populations. None of the prostate cancer risk variants aligns to a known gene or alters the coding sequence of an encoded protein.     

高校图书馆人力资源的开发与继续教育

本文分析我国高校图书馆人力资源的现状,论述人力资源的概念和特征以及人力资源开发的含义和内容,最后提出了图书馆员继续教育的原则和途径.     

断面一体化系统在山区高速公路测量中的应用

根据道路设计信息,推导出线路坐标系下任意中桩点的坐标计算公式和横断面方位角,由计算得到的横断面方向指导野外GPS断面测量.在测量过程中引入Windows CE技术,采用嵌入式编程对GPS采集的数据实时进行处理,重点对GPS数据通讯模块、GPS数据实时显示模块、横断面碎步测量模块进行了设计和研究.解决了山区高速公路断面测量自由设站的难题,实现了断面图形实时动态显示、内外业处理一体化的功能.该系统用于沪蓉西高速路的测量,结果表明:采用RTK(real-time kinematic)技术的内外业一体化系统能够实现山区高速路外业测量和内业处理的一体化.     

A common genetic risk factor for colorectal and prostate cancer

Variants on chromosome 8q24 contribute risk for prostate cancer; here, we tested whether they also modulate risk for colorectal cancer. We studied 1,807 affected individuals and 5,511 controls and found that one variant, rs6983267, is also significantly associated with colorectal cancer (odds ratio = 1.22; P = 4.4 x 10(-6)) and that the apportionment of risk among the variants differs significantly between the two cancers. Comprehensive testing in the region uncovered variants capturing significant additional risk. Our results show that variants at 8q24 have different effects on cancer development that depend on the tissue type.