硼化铪粉末制备研究

硼化铪(HfB_2)具有优异的抗氧化性能,作为超高温材料在耐磨涂层、航空领域具有极高的应用价值,而纯度是影响其应用的关键因素。本文采用烧结工艺制备HfB_2粉末,利用X射线衍射仪、扫描电子显微镜、X射线能谱仪等表征了粉末的结晶性能、形貌、元素分布等。研究了硼源、混料方式对HfB_2粉末结构的影响,测定C、O等杂质含量,通过差减法计算得HfB_2纯度。结果表明,碳化硼(B4C)作为硼源、混料采用机械混合的HfB_2性能最佳,X射线衍射中仅有HfB_2结晶峰,扫描电镜中均为HfB_2紧密团聚形貌,通过化学分析测定杂质含量,差减法计算HfB_2纯度可达到98.19%。     

The roles of the human major histocompatibility complex and human papillomavirus infection in cervical intraepithelial neoplasia and cervical cancer

Germ theory and pure culture methods have provided invaluable information concerning the role of bacteria in diseases resulting from a single organism which bypasses a host's defenses. However, they do not provide sufficient information concerning the synergisms which allow the members of biofilm communities to proliferate more effectively as communities rather than as individuals. The mechanisms of these synergies are potential targets for antimicrobial agents as well as potential mechanisms of resistance to antimicrobial agents. Understanding community-level phenomena in oral biology requires the culture, identification, and classification of functional plaque communities as well as new methods of identifying and quantifying communal relationships. Cultured biofilm communities also provide ideal models of bacterial self-organization in which information related to adaptive strategies arises not only through the recombination of genes within genomes, but also through the recombination of organisms within communities.     

沃益多微生物菌肥对烤烟生长发育和抗病性的影响

为了解沃益多(HYT)微生物菌肥对烤烟生长发育、产质量和抗病性的影响,通过一系列的田间试验进行了研究。结果表明,HYT能显著改善烟株农艺性状,提高烟叶的质量和产值以及增强抗病性。烤烟施用HYT后,烟株的株高、根系鲜重分别增加7.47 cm、61.2 g/株,产量、产值分别增加222.60 kg/hm²、7937.10元/hm²,同时还降低了烟叶烟碱含量,提高了烟叶钾含量,使烤烟内在化学成分更趋协调;施用HYT后对烟草病毒病、烟草黑胫病和烟草根结线虫病的防效分别达47.13%、36.06%和65.62%。由此说明,HYT是一种较好的肥药双效产品。     

改善灰铸铁断面敏感性及提高铸件品质的研究

经过实验 ,选择不同的孕育剂加入量 ,比较其对铸件断面敏感性及机械性能的影响 ,结果表明 :孕育剂的最佳加入量可改善铸件断面敏感性。在工艺和材质两方面加以完善 ,可控制因碳当量降低所造成的铸造缺陷 ,从而全面提高铸件品质