基于热中子探测评价裂缝的示踪剂特性研究

针对裂缝热中子示踪探测方法,从中子双组扩散理论入手结合蒙特卡洛数值模拟方法,分析压裂前后地层热中子分布影响因素,并模拟不同类型示踪剂及含量的热中子裂缝响应规律,筛选最佳示踪剂并给出其在支撑剂中含量的上、下限。结果表明:压裂前后热中子计数变化量主要受裂缝宽度和标记支撑剂中示踪剂含量的影响;钆对裂缝宽度变化反应最灵敏,钆元素是作为标记支撑剂的最佳示踪元素;随支撑剂中Gd 2O 3含量的增加,热中子计数率降低,热中子计数变化量D增加;示踪剂中氧化钆的上、下限值随裂缝宽度呈指数降低,且当裂缝宽度为1.0 cm时,Gd 2O 3的质量分数上限为0.68%,下限为0.03%。     

THE INDUSTRIAL UTILIZATION OF CHEMICAL MODIFIED AGRICULTURAL RESIDUES

INTRODUCTIONToday, the world's industry is utilizing less than 10% of biomass of raw materials from plantation [1]. Agricultural residues, such as cereal straws are important and abundant renewable organic resources of energy and production of a diversity of chemicals, including ethanol production [2], activated carbon [3] and ion exchangers [4]. Many other applications for Cereal straws are in the process of being developed.In china, wheat, maize and sorghum are the three major crops, w…     

关于信息技术与教学整合的探讨

本文讨论了信息技术与教学整合的基本概念、作用和意义。并分析了影响信息技术与教学整合的主要因素．     

三峡库区移民区曲溪小流域能源利用分析

通过分析小流域的能源资源现状、不同时期能源需求变化对生态环境的影响、秸秆利用对坡耕地生产力的影响、经济发展对生物质能需求影响、节能及替代能源对生物质能需求的影响等,提出了解决能源问题,促进生态环境持续改善的对策.     

与企业全方位深度融合建设精品专业

行业发展是专业建设的前提,与企业结合是专业建设的关键,与生产结合是专业建设的核心,与就业结合是专业建设的根本。航空制造业的快速发展需要大量的数控技术专业人才。数控技术专业的发展离不开与企业的良好合作。企业为专业建设注入活力,专业建设为企业发展提供保障。     

关于蒲县水土保持工作的探索

文章阐述了蒲县通过多年水土保持工作的治理总结,探索出一些经验,这些经验在实践中产生了强大的能动作用和显著成绩,取得了明显的经济效益、社会效益和生态效益。     

Structure of astacin and implications for activation of astacins and zinc-ligation of collagenases.

Astacin, a digestive zinc-endopeptidase from the crayfish Astacus astacus L., is the prototype for the 'astacin family', which includes mammalian metallo-endopeptidases and developmentally regulated proteins of man, fruitfly, frog and sea urchin. Here we report the X-ray crystal structure of astacin, which reveals a deep active-site cleft, with the zinc at its bottom ligated by three histidines, a water molecule and a more remote tyrosine. The third histidine (His 102) forms part of a consensus sequence, shared not only by the members of the astacin family, but also by otherwise sequentially unrelated proteinases, such as vertebrate collagenases. It may therefore represent the elusive 'third' zinc ligand in these enzymes. The amino terminus of astacin is buried forming an internal salt-bridge with Glu 103, adjacent to His 102. Astacin pro-forms extended at the N terminus, as observed for some 'latent' mammalian astacin homologues, did not exhibit this 'active' conformation, indicating an activation mechanism reminiscent of trypsin-like serine proteinases.     

无私利性规范的内涵、合理性和适用范围

本文对默顿的“无私利性”规范做新的解读，力图消除翻译上和理解上的错误；归纳了批评“无私利性”规范合理性的四种类型，并针对性地提出反批评和辩护；界定了“无私利性”规范的适用范围。     

Development of Full Automatic External Welding Machine for Annular Welds of Pipeline

To meet the demands of rapid development of pipeline constructions in China, a complete set of full automatic external welding machine for annular welds of pipeline and welding procedure have been developed thereof. The system has been applied in the “West-East Pipeline Project” and its performance is proven. With this welding machine the welding parameters can be either preset before or adjusted in real time during the welding process, which avoids the blemishes of same type domestic and international products. Thus it is best propitious to in-situ construction conditions and workers‘ technical level in China. In this article the development of mechanical and control systems of this product is introduced and typical welding procedure parameters are provided.     

师范院校体育教育专业篮球普修课教学改革的思考

通过对师范院校体育教育专业篮球教学目标、教学内容、教学模式、课的结构及对学生的学业成绩评价进行分析和思考 ,提出了当今篮球教学中存在的问题及其解决方法。