天然水中NO2-和NO3-的毛细管电泳分离测定

在ｐＨ８．２硼酸缓冲液中,用高效毛细管电泳分离硝酸根,硝酸根,并用内标地直接检测了矿泉水,井水中的ＮＯ＾－２,ＮＯ＾－３,以ＣＴＡＢ为电渗流改性剂,离子迁移时间相对标准偏差小于１．５％;二甲亚砜夜为内标,样品对内标的峰高比重现性较好。     

煤中镍的研究进展

镍是煤中毒害性元素之一,燃煤过程中镍对大气、水、土壤、生物的危害性是不可低估的。本文综述了镍的地球化学特征,以及煤中镍的分布、赋存状态与迁移规律。     

陕西省城市雷电灾害分析

通过对2000-2007年的雷电灾害资料进行分析,给出我省雷电灾害的时空分布特征;分析了城市雷电灾害的成因;对典型城市雷灾个例进行了研究,提出一些防雷减灾措施.     

Impact of alkyl methacrylate–maleic anhydride–alkyl methacrylate terpolymers as cold flow improver on crystallization behavior of diesel fuel

Alkyl methacrylate–maleic anhydride–alkyl methacrylate terpolymers (MR₁–MA–MR₂) is one of the widely used cold flow improver. In order to develop more efficient MR₁–MA–MR₂, it is necessary to study the crystallization behavior of n-alkanes when adding MR₁–MA–MR₂ into diesel fuel. In this paper, MR₁–MA–MR₂ is prepared by the reaction of long-chain alkyl methacrylate (MR₁), maleic anhydride (MA), and short alkyl methacrylate (MR₂). The diesel fuel before and after adding MR₁–MA–MR₂ is in situ filtrated at its cold filter plugging point (CFPP) in a manual CFPP apparatus. Extensive measurements of composition variation of n-alkanes are done by gas chromatograph and the results are compared. The experimental results show that after adding MR₁–MA–MR₂, the concentration distribution of n-alkanes in the filtrate is wide and arranges from 8 to 26, and mainly centralizes from 10 to 19. For the precipitate, the concentration distribution of n-alkanes gets richer in the lighter n-alkanes and poorer in the heavier n-alkanes. The concentration distribution of n-alkanes in the crystal solid shows a decreasing trend, especially with high carbon number n-alkanes (heavier than C₂₀). About 60–70% of the residual crystal solid is composed of non-paraffins such as isoparaffin, naphthene and other components. Crystallinities of n-alkanes show a slow decrease trend from C₈ to C₂₀. When the carbon number n-alkanes are heavier than C₂₀, the crystallinities of n-alkanes begin to sharply reduce with an increase of carbon number. The largest decline of crystallinity is C₂₆ n-alkane from 38.39% to 7.90%.     

微生物沥浸法去除底泥中的重金属

以硫酸亚铁盐为底物,培养以氧化亚铁硫杆菌为主要菌种的土著沥滤微生物,采用批式方法对湘江长沙段底泥进行微生物沥浸实验。实验结果表明,底物投加量与底泥固体浓度比(Sd/Sc)为1.5时已能满足底泥的微生物沥浸要求,进一步研究发现底泥固体浓度为13%、底物投加量为19.5 g/L、沥浸时间为6 d时,底泥中超标重金属Cd、Zn和Cu的去除率可分别达到83.1%、75.3%和61.2%;沥浸后底泥中大部分重金属以残渣态存在,且含量低于农用污泥中污染物控制标准,其中硫化物有机结合态Cu浸出较Zn、Cd需更低的pH,且Cu以间接机理浸出为主;以Fe2+为底物的沥浸体系中,黄铁矾的重吸附或共沉淀是沥浸实验后期重金属浸出率下降的原因之一。     

痕量壬基酚及相关化合物的样品预处理和测定

对近年来环境样品中痕量内分泌干扰物壬基酚及相关化合物的分离富集方法和测定技术的研究进展进行了综合评述。重点讨论了索氏提取、液液萃取、液膜分离、回流萃取、固相萃取、固相微萃取、超临界流体萃取、超声提取八种样品预处理方法和气相色谱质谱联用、高效液相色谱两种测定方法,而且针对以上方面提出了尚需进一步研究的问题。     

城市生活垃圾堆肥过程控制技术的现状和发展

介绍了堆肥处理过程的特点 ,叙述了国内外城市生活垃圾过程控制技术的发展现状 ,指出了该技术今后的主要发展方向及发展趋势 ,并讨论了垃圾堆肥过程控制面临的理论与实际问题。     

知识经济条件下传统资源学面临的选择

传统的资源学目前正面临着知识经济的挑战。为适应知识经济的要求,传统的资源学应在研究内容、研究方法及学科观念上进行创新     

世界农业思潮与中国农业的现代化和自然化选择

关于世界农业发展方向与道路的理论问题,目前学术界存在着三种思潮,现代化与自然化问题是这些思潮争论的重要焦点之一。从中国国情看,农业现代化是努力方向,集约持续农业是主要发展道路,自然农业从总体上难于推行,但其保护资源环境的思路与作法在局部上是可取的。     

Study on Dynamic Mechanism of Urban Expansion： A Case Study of Shandong Province

This paper aims at studying the dynamic mechanism of urban expansion and its role. Based on the economic model of urban spatial structure and applying panel data in Shandong Province, the paper concludes. Economic growth and transition of economic structure have played the most powerful role in urban expansion. An increase in population helps the core to extend. Increasing agricultural productivity can provide a countervailing force. An increase in transportation costs will limit urban expansion. An increase in the marginal productivity of land in housing production will increase urban expansion. Fiscal and taxation policies also have encouraged the extensive shift of cultivated land into build-up area. This paper also suggests that if high rate increasing GDP is needed, the urban core will continue to expand. The government should take measures to improve the rapid growth of the city.