133 resultados para 393
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With Mass Analyzed Ion Kinetic Energy Spectrometry (MIKES), Collisional Induced Dissociation(CID), and Electron Capture Induced Decomposition(ECID) technigues, the doubly charged ions and singly charged ions from o(-), m(-), and p(-) diol benzene in the EI source have been studied. In terms of the values of the kinetic energy releases(T) of the charge separation reactions of the doubly charged ions and the estimated intercharge distances(R) of the exploding doubly charged ions the transition structures were proposed. Some structural information about the transition states was also obtained. It is of interest that the MIKES/CID spectra of singly charged ions [C6H6O2](+) from the three isomers are of significant differences.
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本文利用质量分析离子动能谱(MIKES)、碰撞诱导解离(CID)技术和电子捕获诱导解离(ECID)技术,研究了邻、间、对苯二酚分子在电子轰击质谱(EIMS)中产生的双电荷离子[C_6H_6O_2]~(2+),[C_6H_4O]~(2+)和单电荷离子[C_6H_6O_2]~+.根据测定的电荷分离反应动能释放值T和由此计算出的两电荷间距R,推测出过渡态的结构.有趣的是,可利用单电荷离子[C_6H_6O_2]~(+)的MIKES/CID谱区分苯二酚异构体.
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Melt mixing of nylon 8 with neodymium oxide particles was carried out with a single-screw extruder. The crystal behaviors of plain nylon 6 and the neodymium oxide filled nylon 6 mixture were studied by means of isothermal crystallization kinetic analysis. Isothermal crystallization thermograms obtained by differential scanning calorimetry (DSC) were analyzed based on the Avrami equation. The neodymium oxide particles acted as a nucleating agent in the mixture. The overall rate of di-isothermal crystallization of the neodymium oxide filled nylon 6 mixture is higher than that of plain nylon 6. The mechanism and modes of plain nylon 6 were the same as those of neodymium oxide filled PA6 mixture.
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研究了金鸡纳碱与丙烯酰胺的自由基共聚反应。发现在氯仿/乙醇混合溶剂中采用硫酸奎宁作为金鸡纳碱共聚单体可以合成收率和金鸡纳碱含量均较高的新型水溶性共聚物。对共聚物用元素分析、核磁共振、粘度和旋光度测定等方法进行表征,发现在假定丙烯酰胺链节为非光活性的条件下共聚物中金鸡纳碱链节的比旋光度随聚合配方中金鸡纳碱含量的增加而增加。
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利用荧光偏振,自旋标标顺磁共振波谱和激光拉曼技术研究了钆和镱对人红细胞膜结构和功能的影响。结果表明,低浓度的Gd3+(0.5μmol/L)对(Na++K+)-ATP酶和Mg2+-ATP酶有轻微的激活作用,而随着其浓度的增大,则明显抑制酶的活性,Gd3+与Yb3+和人红细胞膜作用后,降低膜脂流动性,并使膜蛋白酰胺I'-α螺旋振动强度减弱.
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激光光热位移光谱法是一项高灵敏度高分辨率和无损伤无接触的新型激光光谱探测方法,已成功地应用于表层、亚表层和薄膜的光热特性研究。它的研究对象主要是固体样品。本工作把光热位移光谱法扩展到液体样品,采用测量光束偏转的方法研究了重油类的表面光
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本文研究了新型分离富集剂的各种制备条件。实验表明用这种方法合成的富集剂是一种非常好的固体吸附剂,能吸附各种重金属离子,其饱和吸附量是巯基棉的3~20倍。
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The adsorption of cationic surfactant cetylpyridinium bromide (CPB) on a glassy carbon (GC) electrode surface has been studied by spectroelectrochemistry with a long optical path length thin-layer cell (LOPTLC) for the first time. A fine adsorption isotherm of CPB molecules from an aqueous solution containing 0.10 M KBr has been obtained over the range of (1.00-8.00) x 10(-5) M. From theoretical calculation and experimental data, adsorption of CPB on the GC electrode surface shows four distinct orientations and three large orientation transitions. Compared with the ordinary isotherm, the differential isotherm is more characteristic and would be suitable for the study of orientation transitions of organic compounds. With a theoretical treatment of the adsorption isotherm, four orientations of adsorbed CPB on a GC electrode surface coincide with the Frumkin-Langmuir type. From adsorption parameters the Frumkin-Langmuir equations, the adsorption free energy and, therefore, the equilibrium constants of orientation transitions of the CPB molecule can be obtained.
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本文评述了环境无机分析化学现状并展望了它的发展前景。
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Well-dated, high-resolution records of planktonic foraminifera and oxygen isotopes from two sediment cores, A7 and E017, in the middle Okinawa Trough reveal strong and rapid millennial-scale climate changes since similar to 18 to 17 thousand years before present (kyr B.P.). Sedimentation rate shows a sudden drop at similar to 11.2 cal. kyr B.P. due to a rapid rise of sea level after the Younger Dryas (YD) and consequently submergence of the large continental shelf on the East China Sea (ECS) and the retreat of the estuary providing sediment to the basin. During the last deglaciation, the relative abundance of warm and cold species of planktonic foraminifera fluctuates strongly, consistent with the timing of sea surface temperature (SST) variations determined from Mg/Ca measurements of planktonic foraminifera from one of the two cores. These fluctuations are coeval with climate variation recorded in the Greenland ice cores and North Atlantic sediments, namely Heinrich event 1 (H1), Bolling-Allerod (B/A) and YD events. At about 9.4 kyr B.P., a sudden change in the relative abundance of shallow to deep planktonic species probably indicates a sudden strengthening of the Kuroshio Current in the Okinawa Trough, which was synchronous with a rapid sea-level rise at 9.5-9.2 kyr B.P. in the ECS, Yellow Sea (YS) and South China Sea (SCS). The abundance of planktonic foraminiferal species, together with Mg/Ca based SST, exhibits millennial-scale oscillations during the Holocene, with 7 cold events (at about 1.7, 2.3-4.6, 6.2, 7.3, 8.2, 9.6, 10.6 cal. kyr BP) superimposed on a Holocene warming trend. This Holocene trend, together with centennial-scale SST variations superimposed on the last deglacial trend, suggests that both high and low latitude influences affected the climatology of the Okinawa Trough. (c) 2006 Elsevier B.V. All rights reserved.
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海洋沉积环境中多氯联苯(PCBs)和多环芳烃(PAHs)的研究对于揭示其污染历史、来源途径、迁移转化以及评价其对环境的潜在生态风险都有重要的科学意义和应用价值,本研究选择我国典型近海中比较开阔的南黄海和受人为影响严重的渤海湾沉积物中的PAHs和PCBs作为主要研究对象,结合对生态环境对应关系的剖析,系统研究了沉积物中PAHs和PCBs的地球化学分布特征、影响控制因素、演变趋势、潜在生态风险等,获得了以下系统的认识: 1.南黄海表层沉积物中多环芳烃和多氯联苯的分布与沉积类型及模式相一致,受控于“沉积类型-动力过程-来源途径”。PCBs含量(范围:518~5848 pg/g,平均值:1715 pg/g)低于受人为影响严重的长江口、珠江口和渤海,分布具有中部海区>东部海区>西部海区的特征;PCBs随着沉积物粒径的减小和粘土含量的增加而增加,且与总有机碳(r=0.61,p<0.01)含量呈显著线性正相关,表明PCBs在沉积物中的分布受控于被水动力过程原动力控制的沉积类型与沉积模式。 2. 1914~2004年间,南黄海沉积物中PAHs和PCBs的变化比较显著,在时间序列上经历了三个明显的不同阶段。近90年来,PAHs和PCBs在柱状样中垂直分布随深度的增加而降低,即近年南黄海沉积物中PAHs和PCBs的残留水平比上世纪初明显增加。其中1914~1932年间,PAHs和PCBs保持在较低的水平;1932~1962年间,PAHs和PCBs的含量发生急剧的变化,在1932~1944和1956~1962年两个时间段,PAHs和PCBs的含量达到峰值;自1962年至今,PAHs和PCBs呈稍有增加趋势。PAHs的组成和特征组分比值分析显示,1920~1944年间PAHs主要来自石油产品泄漏,1944~1980年间,主要来自草/木材/煤燃烧,1980年至2004年则显示出石油和燃烧产物混合来源的特征。 3.渤海湾沉积物中的PAHs、PCBs、DDTs和HCHs的分布模式不同,反映了这四种污染物的地球化学行为存在着明显的差异性。PAHs、PCBs、DDTs和HCHs的含量范围为149.0~393.4 ng/g,360.8~1728.3 pg/g,462.2~2007.3 pg/g和4.31~33.8 ng/g。马颊河口、海河口和黄河口附近的海区的沉积物中PAHs和PCBs的含量显著高于渤海湾内其它站位,DDTs在湾外沉积物中的含量大于湾内,在海河口附近站位测得HCHs含量的最高值,在其它站位其浓度变化不大。PAHs特征成分的比值显示渤海湾沉积物中PAHs主要来源于草/木材/煤燃烧的产物经过大气的输运过程进入水体;DDTs和HCHs的组成显示,在DDTs和HCHs被禁用后仍有新的输入源。 4.南黄海沉积物POPs总体水平不高,其环境污染危害和潜在生态风险不大,从沉积物POPs的角度来说南黄海的环境质量较好。潜在生态危害指数评价表明,渤海湾沉积物中芴可能会产生潜在的生态风险,DDTs和HCHs的含量低于一类沉积物质量标准值,总体而言,其沉积物质量良好,潜在生态风险较低。 论文的创新性点在于:1)首次研究了近百年南黄海沉积物中多环芳烃和多氯联苯的演变趋势,判断了其来源并对近百年二者的潜在生态风险进行评价。2)系统剖析了南黄海及渤海湾的生态环境与PAHs和PCBs的耦合关系,对阐明POPs的毒理效应有重要的科学意义。3)系统解析了渤海湾沉积物中PAHs,DDTs和HCHs的污染现状,来源和迁移途径,可为科学开发和利用渤海海域提供重要的理论依据。
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To analyze and evaluate the status of organochlorine pollutants in the Changjiang (Yangtze River) estuary and adjacent waters, the concentrations of hexachlorocyclohexane (HCHs) and dichlorodiphenyltrichloroethane (DDTs) in shellfish collected in study area from 2006 to 2007 were determined with gas chromatography (GC). The concentration range of HCHs was (ND-12.13)x10(-3) mg/kg wet weight and averaged at 0.54x10(-3) mg/kg while the concentration of DDTs was in the range of (4.06-281.73) x10(-3) mg/kg with a mean of 57.52x10(-3) mg/kg in the survey areas. The concentrations of DDTs in the shellfish were higher than HCHs', so that DDTs could be considered as typical organochlorine pollutants in the areas. The concentrations of DDTs in the shellfish were higher than HCHs', so that DDTs could be considered as typical organochlorines pollutants. The HCHs in all the shellfish conformed to the first level of criterion (0.02 mg/kg) of the Marion Biology Quality (GB 18421-2001), and that of DDTs in most samples were beyond the first level (0.01 mg/kg) but conformed to the second level (0.10 mg/kg). On average, alpha-HCH and delta-HCH occupied the most part of HCHs, while O,P'-DDT and P,P'-DDT occupied the most part of DDTs. The concentrations of organocholorine pesticides in shellfish samples varied in site and in species. The highest level occurred at the Shengsi (SS), followed by Yangkougang (YKG), Lvsi (LS), Dongyuan (DY) and Beibayao (BBY), low concentrations were observed at Changsha (CS), Beidaodi (BDD), and Gouqi (GQ). The concentration of HCHs and DDTs in most sites decreased clearly from 2006 to 2007 except for YKG, DY, BDD, LYS, and SS. All of above results suggested that the study area was slightly affected by organochlorine pesticide, special by DDTs.
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Biosorption is an effective means of removal of heavy metals from wastewater. In this work the biosorption behavior of Cladophora fascicularis was investigated as a function of pH, amount of biosorbent, initial Cu2+ concentration, temperature, and co-existing ions. Adsorption equilibria were well described by Langmuir isotherm models. The enthalpy change for the biosorption process was found to be 6.86 kJ mol(-1) by use of the Langmuir constant b. The biosorption process was found to be rapid in the first 30 min. The presence of co-existing cations such as Na+, K+, Mg2+, and Ca2+ and anions such as chloride, nitrate, sulfate, and acetate did not significantly affect uptake of Cu2+ whereas EDTA substantially affected adsorption of the metal. When experiments were performed with different desorbents the results indicated that EDTA was an efficient desorbent for the recovery of Cu2+ from biomass. IR spectral analysis suggested amido or hydroxy, C=O, and C-O could combine strongly with Cu2+.
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调查青藏高原高寒草甸生态系统中两种主要啮齿动物及其天敌动物的种群密度,分析天敌动物对两种啮齿类的捕食方式、捕食强度,探讨啮齿类动物的捕食风险及生存对策。研究结果表明,高原鼠兔和高原鼢鼠的种群密度分别为4.97只/hm~2和10.6只/hm~2,而它们的主要天敌赤狐、艾虎和香鼬的种群密度分别为0.16只/100hm~2、0.37只/100hm~2、3只/100hm~2。艾虎和香鼬在取食过程中主要搜寻啮齿类的洞道系统,全部食物几乎都来源于洞道系统内;赤狐或取食地面活动的鼠兔,或挖掘洞口待高原鼢鼠封闭洞口时取食猎物。高原鼠兔在赤狐、艾虎和香鼬的食物中所出现的频次分别为100%、96.1%、100%,高原鼢鼠在3种天敌动物的食物中所出现的频次分别为87.5%、73.2%、0%。3种天敌动物对高原鼠兔和高原鼢鼠的捕食强度分别为0.703%和0.038%,高原鼠兔和高原鼢鼠所承受的捕食风险分别为0.780和0.393。高原鼠兔在高的捕食风险下通过行为对策和繁殖对策增加其适合度,而承受捕食风险较小的高原鼢鼠主要通过封闭的洞道系统和高的存活率增加其适合度。