邻苯二甲酸二丁酯影响阿尔茨海默病大鼠学习记忆能力的分子机制研究

为探究邻苯二甲酸二丁酯(DBP)影响阿尔茨海默病(AD)大鼠学习记忆能力的分子机制,将56只SPF级5～6周龄雌性Wistar大鼠随机平均分为7组:阴性对照组、0.25 mg·kg-1·d-1 DBP 组、2.5 mg·kg-1·d-1 DBP 组、25 mg·kg-1·d-1 DBP 组、250 mg·kg-1·d-...     

中国污染密集型产业地理分布研究

随着资源环境约束加强,调整产业结构、优化产业空间布局已成为我国经济发展的战略选择。产业空间格局重置过程中,污染密集型产业的转移成为一个迫切需要研究的问题。论文利用2003-2008 年工业企业普查数据,采用Tobit 模型和Heckman 两阶段模型,探讨污染密集型产业地理分布的特征。论文发现,我国污染密集型产业正在进行空间结构调整,长江三角洲、珠江三角洲、京津冀地区污染密集产业不断转出,山东及中部地区开始成为污染密集型产业新的集聚地;造纸等较为轻型产业主要向中部内陆等地区转移,而化学原料及化学制品业等技术密集型产业则更主要在沿海地带重新分布。另外,要素禀赋、环境规制以及全球化对污染密集型产业分布影响显著。其中,技术以及劳动力成本是污染企业区位选择的重要影响因素;受全球化的影响,国际市场潜力对污染企业区位影响更为重要;环境规制与污染企业的成立具有倒U型关系;最后,企业的异质性对于污染企业地理分布也具有显著的影响。文章启示,在产业转移过程中,需要适当的政策引导以最小化对生态环境的破坏。     

Maternal serum inhibin levels in second-trimester down's syndrome pregnancies

Maternal serum inhibin levels were measured in 19 second-trimester pregnancies affected by fetal Down's syndrome and 95 unaffected control pregnancies matched for gestational age. A statistically significant elevation was found in the affected pregnancies compared with the controls (Wilcoxon rank sum test: one-tail P=0·02). The median level in the cases was 1·3 times that in the controls, with 95 per cent confidence limits of 0·9–1·9. Although the inhibin levels were unrelated to those of alpha-fetoprotein and unconjugated oestriol in the same samples, there was a statistically significant correlation with human chorionic gonadotropin. This together with the relatively small elevation in cases suggests that inhibin would be of limited value in maternal serum screening for Down's syndrome.     

广东沿岸海域生物可利用性重金属的地理分布

利用牡蛎做监测生物，研究了广东沿岸海域生物可利用性重金属Ｃｄ，Ｃｕ和Ｚｎ的地理分布。牡蛎体的Ｃｄ，Ｃｕ和Ｚｎ含量存在着显著的地域差异，反映了广东沿岸海域生物可利用性的Ｃｄ，Ｃｕ和Ｚｎ在地域上存在很大的梯度。由牡蛎显示出的广东沿岸海域生物可利用性重金属的地理分布与广东沿岸海域受人为来源的重金属输入状况相一致，如实地反映了广东沿岸海域重金属污染的基本特征。     

西部某气田井场分离器液相管线法兰腐蚀原因分析

目的 解决西部某气田井场分离器液相出口管线法兰严重腐蚀问题。方法 通过宏观形貌观察、无损检测、化学成分分析、金相组织分析、力学性能测试、腐蚀区域微观形貌观察、腐蚀产物物相分析以及腐蚀电化学实验的方法,分析该法兰发生腐蚀的原因。结果 A105制法兰与316L制密封圈存在较强的电偶腐蚀倾向。结论 电偶腐蚀是导致法兰面严重腐蚀的主要原因,另外,液相管线停用前放空不彻底,法兰底部存在积液,导致气液界面位置叠加发生水线腐蚀。根据法兰腐蚀原因提出了针对性的防腐建议。     

The recycling cycle of materials as a design project tool

Currently, a large number of companies consider recycling of materials as an opportunity to maximize profits and to reduce the environmental impact generated by these materials after they are disposed. However, there is also a strong constraint on the use of recycled materials mainly due to the lack of technical/scientific information, which would relate their physical properties to their recycling cycle. This information should be used in the initial phase of the product design to serve as reference for the simulation of a project to point out the physical properties obtained from recycling the Projected material (Pm). Thus, it would be possible to foresee some recycling strategy to keep the good characteristics of recycled materials by encouraging their use, regardless of the product to be designed.Therefore, the Recycling Cycle of Materials (RCM) is a tool that provides scientific/technical support in the selection of materials. It uses the information related to the physical properties of the Pm as a parameter for product design after five recycling cycles. For the case study, this tool has been applied to obtain the basic material of ABS/PC blend. Subsequently, this blend was evaluated using DSC, FTIR, traction and impact methods to obtain delimiting data for the definition of the mechanical properties resulting from the application of RCM.