郑州市城市边缘区土地利用及影响因素分析

城市边缘区是城市向乡村的过渡地带,是城市化最直接、最敏感的地区,也是目前全球范围内土地利用问题最多、矛盾最尖锐的地区,在土地利用上具有其特殊性.因此,选择以城市边缘区土地利用为研究对象,试图通过理论研究与郑州市实证研究相结合来分析城市边缘区土地利用的总体结构和地域结构特征,揭示影响城市边缘区土地利用格局的主要因素,以期为政府和学术界提供政策建议和理论参考.     

基于膨胀土蠕变试验的粘弹性模型对比研究

对广西南宁膨胀土进行了一系列室内压缩蠕变试验,得出了相应的蠕变曲线.运用K-H体模型和Bu体模型进行对比研究,确定了正常应力条件下非饱和南宁膨胀土的粘弹性模型和各流变常数,提出了正常应力条件下南宁膨胀土的本构方程及蠕变方程.为膨胀土工程设计和分析提供可靠的理论依据.     

秋季平补

中医曰“四季五补“,即春季“升补”,夏季“清补“,秋季“平补”,冬季”滋补”,四季宜“通补”。     

Effects of cadmium on forearm bone density after reduction of exposure for 10 years in a Chinese population

The main focus of this study was to evaluate long term effects of cadmium on forearm bone mineral density after stopping ingestion of cadmium-polluted rice for 10 years in a Chinese population. A total of 532 persons (338 women and 194 men), living in control, moderately and heavily polluted areas, were included in this study. The residents living in the polluted area ceased ingesting cadmium-polluted rice in 1996. All participants were require to answer a questionnaire and the bone mineral density (BMD) was measured by dual energy X-ray absorptiometry (DXA) at the proximal radius and ulna. Samples of urine and blood were collected for determination of cadmium in urine (UCd) and blood (BCd).The BMD of subjects living in the heavily polluted area was significantly lower than that of those living in control area in both men and women (p < 0.01). For the people living in the moderately polluted area, only the women's BMD was greatly lower compared to that in the control area (p < 0.05). The BMD declined with the increasing BCd and UCd in both sexes, especially in the highest level (BCd > 5 µg/L, UCd > 10 µg/g crea) groups (p < 0.01). It was found that there were significant differences in the prevalence of osteoporosis among the different areas (χ² = 13.046, p = 0.0003) and different UCd groups (χ² = 4.511, p = 0.0337) in women, but not in men (χ² = 0.962, p = 0.3268; χ² = 1.906, p = 0.1675). But a significant difference exists in the prevalence of osteoporosis among different BCd groups in both genders (χ² = 9.304, p = 0.00229, in women; χ² = 4603, p = 0.0319, in men). This study suggested that cadmium could play a long-term role on bone and more attention should be paid to cadmium effects on bone metabolism after reduction of exposure.     

废聚碳酸酯水解法制双酚A

以1,4-二氧六环为溶剂、NaOH为催化剂,采用废聚碳酸酯(PC)常压水解法制双酚A(BPA).对反应影响因素进行了研究.实验结果表明,在反应温度为100℃、反应时间为8h、m(NaOH):m(水+溶剂)=1:33、m(溶剂):m(PC)=4:1、m(水):m(PC)=1:1的最佳反应条件下,PC水解率大于98%,BPA收率大于95%.     

Methanolysis and Hydrolysis of Polycarbonate Under Moderate Conditions

Alkali-catalyzed methanolysis and hydrolysis of polycarbonate (PC) in a solvent in which PC can substantially dissolve such as N-methyl-2-pyrrolidone, 1,4-dioxane, tetrahydrofuran and so on were studied. Reaction conditions were optimized for the purpose of recycling PC in the form of bisphenol A and carbon carbonate. The results showed that both the methanolysis and hydrolysis of PC could take place under moderate conditions. Under the conditions of reaction temperature 40 °C, m(PC):m(MeOH) = 1:1, m(PC):m(NaOH) = 50:1, reaction time 35 min and using tetrahydrofuran as solvent, the methanolysis conversion of PC was almost 100% and the yield of bisphenol A was over 95%. Moreover, under the conditions of reaction temperature 100 °C, m(PC):m(H₂O) = 1:0.7, m(PC):m(NaOH) = 10:1, reaction time 8 h and using 1,4-dioxane as solvent, the hydrolysis conversion of PC was almost 100% and the yield of bisphenol A was over 94%.     

垃圾处理产业化的内涵

垃圾处理产业化是造就一种特定模式,聚合已进入垃圾处理行业的事业体并培育核心事业体的一种过程,一般包括导入、扩散、发展和聚变等4个子过程.产业化应将垃圾处理由公有公益性服务事业转化成服务产业,并最终转化成物质生产的基础产业,涉及到社会再生产的4个环节.宏观来看,涉及到经济、文化和政治等层面.     

产品废弃物管理是企业的基本职能

企业是产品废弃物的源头,产品废弃物管理理应成为企业的基本职能.项目环评、区域规划和战略环评是强制和引导企业做好废弃物管理的有效手段.     

铁路运输含硫原油过程中H_2S挥发规律模拟试验研究

以塔河12区含硫原油为研究对象,通过模拟铁路运输原油工况,研究罐内原油中H_2S挥发规律.结果表明,铁路运输过程中原油里H_2S析出浓度与时间的关系近似为6次多项式,并建证了H_2S浓度随时间变化的曲线方程;对影响罐内原油中H_2S挥发的2个主要因素罐内原油温度和罐车振动强度进行了分析.结果表明,罐内原油温度是原油中H_2S挥发的主要影响因素,升高罐内原油温度可以明显增加H_2S的挥发浓度.加大罐车振动强度对原油中H_2S挥发有促进作用,但不明显.     

基于状态监测的井喷风险动态安全评价

井喷是钻井作业引发的最严重事故之一.通过分析钻井作业过程各个环节,确定钻井过程的风险因素和指标因素,实时监测钻井作业各参数变化,利用模糊综合层次评价法计算出钻井过程井喷风险概率,实现井喷事故动态风险评价.给出了模糊综合评价法的具体步骤,基于该方法还开发了井喷动态安全评价软件,为钻井过程中钻井液参数和钻井工程参数的优选、调整提供理论依据,同时也为钻井过程的安全生产和管理提供了参考依据.