985 resultados para 346.023
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土壤对疏水性有机污染物的吸附实际上是土壤中矿物和有机质两部分共同作用的结果。土壤有机质的作用相当重要,因为与矿物相比,它通常对疏水性有机污染物具有较大的热力学亲合力。因此,土壤吸附有机污染物机理的研究主要是从土壤有机质的角度进行的。土壤有机质组成复杂,主要包括非特异性有机质和腐殖质,其中腐殖质约占有机质总量的50%-80%,包括胡敏酸、富里酸和胡敏素。早期的实验研究认为疏水性有机污染物在土壤有机质相中表现为线性分配,可以用平衡分配系数来描述。但是,随着实验研究的深入,平衡分配模型不能合理解释疏水性有机污染物的一些吸附特征,如非线性吸附、溶质竞争吸附以及解吸过程的滞后现象等。后来,Weber和Huang提出土壤吸附有机污染物的三端元模型。同时Pignatello和Xing提出双模式吸附模型。都认为土壤有机质存在明显的不均匀性,并且提出了“软碳”与“硬碳”的概念.
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大兴安岭南段二叠系大石寨组发育两套火山岩,即林西地区拉斑玄武岩系列的细碧-角斑岩类和大石寨地区钙碱性岩石系列玄武岩和玄武安山岩类。细碧岩的主元素以富铁为特征,成分类似于N-MORB,微量元素表现为岛弧拉斑玄武岩的地球化学特征。细碧岩类形成于大石寨裂陷槽强烈拉张的中心位置,是地幔源区较高程度部分熔融的产生。大石寨地区玄武岩和玄武安山岩类的化学成分表现为大陆缘弧火山岩的地球化学特点,形成于大石寨裂隙槽拉张中心以外的环境,是地幔物质较低程度部分熔融和地壳物质严重混染的产物。大石寨裂隙槽中火山岩的这种独特的成分和组合特点可能反映了裂隙槽的形成是一个快速而短暂的强烈拉张过程。
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在湖北恩施渔塘坝土壤硒分布的调查过程中,发现不同地段田地土壤中存在异常高硒样品。其硒含量变化范围是346~2018mg/kg,平均(899±548)mg/kg(n=11),相对于坝内成土基岩和耕作土硒含量0.5mg/kg与3.5mg/kg的水平而言,表明这些土壤硒受到了外来源硒的严重污染。扫描电子显微镜的观察表明,这些土壤样品中均有大量晶体状自然硒的出现,其特征类似燃煤型成因的自然硒,证实了上世纪50年代后期恩施当地居民石煤火熏土作肥的耕作方式,并直接导致了田地土壤硒的骤然增加。渔塘坝当地居民在1963年间的硒中毒爆发性流行,乃至恩施地区人畜硒中毒的普遍流行,极可能是人为因素引起.
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硒同位素作为非传统稳定同位素的重要组成部分,由于具多价态、多质量数、同位素分馏效应大的特点,已成为目前发展最迅速的同位素之一。本文在综合前人研究成果基础上,结合笔者最新的研究成果,对硒同位素的测试技术做了较全面总结,内容包括样品的化学前处理(TCF技术)、在线的氢化物发生器系统、质谱测试技术、参考物质的标定等,并就自然界中硒同位素的组成、分馏机制及应用潜力做了评述。
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金宝山镁铁一超镁铁岩体是峨眉山大火成岩省一个典型的岩浆Cu-Ni—PGE成矿岩体。在根据成岩机制概算原始岩浆微量元素含量的基础上,通过模式计算,表明原始岩浆强不相容元素相对富集型式不可能由现有原始地幔或亏损地幔模型的单一源区熔融或融体混合作用形成,原始岩浆起源于类似OIB源的地幔柱高程度熔融,熔融程度在2o%左右。
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通过野外调查在渔塘坝硒矿区首次发现了一种新的硒超富集植物-遏蓝菜(Thlaspi arvense L.)。调查结果发现,在自然生长条件下,一年生遏蓝菜叶子中富集硒可高达1427mg/kg,生物富集硒系数可高达68,地上部硒含量最低也超过了500mg/kg,生物富集硒系数最低也超过了10,表现为叶〉根〉叶柄的硒富集特征。多年生遏蓝菜叶、茎和根的硒含量分别为104~163;231~346;444~459mg/奴,生物富集硒系数为2.6~12.4,均大于1,显示出根〉茎〉叶的硒富集特征。尽管多年生遏蓝菜远没有一年生遏蓝菜的硒含量高,但远比一般植物硒含量高,达到了次生硒蓄积植物富集硒的水平,显示遏蓝菜植物可以超富集硒。渔塘坝遏蓝菜的发现将为研究硒在植物中的吸收、转化、富集机理以及提取有效抗癌有机硒化物和修复硒污染生态环境提供新的材料。
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依据新获得的同位素年代学资料和构造岩石地层单元,重新认识了云南哀牢山造山带形成与演化历史。认为:在哀牢山地区元古界深变质岩系属基底的造层;前造山期岩石组合及构造演化为扬子地块西缘被动大陆边缘志留纪深水相碎屑岩→陆缘泥盆纪被动裂谷盆地中火山-沉积岩→石炭纪哀牢山有限洋盆及蛇绿岩石组合→晚二叠世-早三叠世哀牢山洋-陆碰撞成陆及弧火山岩-陆相碎屑岩组合。燕山期主造山期及岩石级合为晚三叠世-侏罗纪前陆盆地磨拉石建造-同造山期中酸性侵入岩-燕山期脆性剪切带及构造岩,喜马拉雅山期陆内造山成原的岩石组合为第三-第四纪陆内山间盆地中磨拉石建造-红河韧性剪切带及构造岩-富碱侵入岩和煌斑岩。
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简述游离烃技术的方法及其特点,并介绍其在沙漠覆盖区构造含油气性评价中的应用实例。
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本论文的主要研究内容有以下三个方面:(1)蒸馏一乙基化GC-CVAFS法测定天然水体中甲基汞方法的建立及应用;(2)乌江表层河水不同形态汞分布特征的研究;(3)以乌江中上游干流不同年龄水库(乌江渡水库和东风水库)为例,探讨水库对乌江河流汞输送的影响及水库内汞的迁移转化。通过本论文的研究,取得以下成果:1.建立了一种基于蒸馏一乙基化结合气相色谱(GC)一冷原子荧光(CVAFS)测定天然水体中甲基汞的分析方法。水样中甲基汞经蒸馏后与四乙基硼化钠反应生成挥发性的甲基乙基汞,由氮气吹扫捕集于Tenax管,然后由GC-CVAFS测定。该方法的回收率为88.2%-108.4%,平均相对标准偏差为5.4%。取45mL水样测定,方法的最低检出限为0.009ng/L。该方法能准确测定天然水体中甲基汞的含量,步骤简洁、快速,明显优于国内目前使用的其余测定水体甲基汞的方法。2.乌江表层河水总汞的浓度分别为:丰水期659ng/L,枯水期16.9ng/L,明显高于北美和欧洲一些没受污染的河流,表明乌江流域已存在一定程度的污染。乌江河水汞的主要形态为颗粒态汞,其占总汞的比例为丰水期84%,枯水期占52%,乌江河流汞的分布、迁移行为主要受颗粒态物质控制。3.根据输入一输出通量模型,估算出东风水库总汞净通量为-57785.1g/yr,占总汞输入量的40.2%;乌江渡水库总汞净通量为-23273.7g/yr,占总汞输入量的14.0%,两个水库都表现为总汞的“汇”。与总汞相反,两个水库都表现为甲基汞的“源”,东风水库甲基汞净通量为+284.7g/yr,占甲基汞总输入量的4.4%;乌江渡水库甲基汞的净通量为+6622.0g/yr,占甲基汞总输入量的80.1%。乌江渡水库甲基汞的“源”作用显著大于东风水库。4.乌江渡水库和东风水库水体总汞和甲基汞都呈现明显的季节变化,表现为春季>冬季、夏季。乌江渡水库水体总汞平均为冬季9.0ng/L、春季16.0ng/L、夏季7.9ng/L;东风水库水体总汞平均为冬季8.2ng/L、春季12.5ng/L、夏季9.4ng/L。水体甲基汞的平均值分别为:乌江渡水库冬季0.74ng/L、春季0.97ng/L夏季0.89ng/L;东风水库冬季0.74ng/L、春季1.12ng/L、夏季0.38ng/L。水库水体甲基汞与总汞之间有相关关系,但未达极显著水平(乌江渡水库,r=0.451*,n=24;东风水库,r=0.471*,n=27)。水库内汞和甲基汞的形态、含量以及分布受外源性输入、降水稀释、水库初级生产力水平以及水库运行方式等因素控制。5.乌江渡水库和东风水库沉积物总汞明显高于其它未受污染地区水库沉积物总汞。乌江渡水库沉积物总汞含量为254.7±44.3ng/g,东风水库沉积物总汞为171.0±23.0ng/g。两个水库沉积物总汞没有季节变化,且在沉积物垂直剖面上也没有明显的浓度梯度变化。与总汞相反,两个水库沉积物甲基汞在垂直剖面上有明显的梯度变化和季节变化。无机汞的甲基化作用主要发生在沉积物表层5cm以内。沉积物中甲基汞含量受微生物活性影响显著,通常在水库生物生产量和营养物输入量较大时甲基汞浓度也较高。沉积物甲基汞含量在两个水库都表现为冬季<春季<夏季,甲基汞含量以及甲基汞占总汞的比例为东风水库<乌江渡水库。6.沉积物间隙水中无机汞的含量没有显著的季节变化;与此相反,沉积物间隙水中甲基汞浓度表现出明显的季节变化。沉积物间隙水中甲基汞在垂直剖面上的分布趋势与沉积物中甲基汞的分布趋势相一致,沉积物间隙水中甲基汞含量与沉积物中甲基汞含量呈显著性相关(乌江渡水库,r=0.770**,n=75;东风水库,r=0.675**,n=75)。7.沉积物间隙水中无机汞和甲基汞是水体中无机汞和甲基汞的“源,,i但对乌江渡水库和东风水库而言,由于水体深度较大,水力停留时间较短,间隙水中扩散出来的甲基汞和无机汞对水库内水体中相应形态汞含量的影响程度有限。但这种影响作用为甲基汞>无机汞,乌江渡水库>东风水库。8.因采集的鱼多为人工饲养鱼(生长速度快、食物链短),两个水库鱼体总汞和甲基汞含量均低于国家食用标准。但乌江渡水库鱼体甲基汞含量以及甲基汞占总汞的比例均高于东风水库。可见,乌江流域水库鱼体甲基汞含量不取决于水库年龄,而受水库内水生食物链底端食物中甲基汞的含量控制。9.通过本论文的研究,得出由于被淹没土壤有机质含量较低,乌江流域水库无机汞甲基化的驱动力为水库内源性输入有机质。在一定的时间范围内,随着水库的发育,水库初级生产力水平的提高,内源性有机质输入量增加,会显著促进沉积物中无机汞的甲基化进程。
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The applicability of capillary electrophoresis/frontal analysis (CE/FA) for determining the binding constants of the drugs propranolol (PRO) and verapamil (VER) to human serum albumin (HSA) was investigated. After direct hydrodynamic injection of a drug-HAS mixture solution into a coated capillary (32 cm x 50 mu m i.d.), the basic drug was eluted as a zonal peak with a plateau region under condition of phosphate buffer (pH 7.4; ionic strength 0.17) at 12 kV positive running voltage. The unbound drug concentrations measured from the plateau peak heights had good correlation coefficients, r > 0.999. Employing the Scatchard plot, the Klotz plot and nonlinear regression, the drug protein binding parameters, the binding constant and the number of binding sites on one protein molecule, were obtained. The binding constant obtained was compared to a reported equilibrium dialysis result and they are basically in good agreement.
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The heat capacities of crystalline and liquid n-hexatriacontane were measured with an automatic adiabatic calorimeter over the temperature range of 80-370 K. Two solid-to-solid phase transitions at the temperatures of 345.397 and 346.836 K, and a fusion at the temperature of 348.959 K have been observed. The enthalpies and entropies of these phase transitions as well as the chemical purity of the substance were determined on the basis of the heat capacity measurements. Thermal decomposition temperatures of the compound were measured by thermogravimetric analysis. (C) 1999 Elsevier Science B.V. All rights reserved.
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To study the relationship between mental-physical health and coping behavior,job stress and job motivation in medical laboratory scientists and technicians. A cross-section survey was conducted,using the anxiety rating scale(SAS), depression rating scale(SDS), coping behavior rating scale,self-rating subhealth scale,self-rating stress scale,and self-rating job motivation scale among 289 medical laboratory scientists and technicians with analysis of ANOVA and Regression. The study was carried out in three steps:step1 is to analyze the general situation of the mental-physical health.Step 2 is to analyze the features of the main influencial facotors.Step 3 is to study the influence of the relative factors on mental-physical health.The following are the results: 1.The anxiety and depression scores of the medical researchers and technicians were 30±6 and 37±8 respectively,both significantly lower than those of the national norm(34±6 and 42±11 respectively,both P<0.01),which are of significant difference. The depression score of the associate chief technician was 42±7, significantly higher than those of the medical researchers and technicians with any other professional titles (all P<0.05), and the anxiety score of the associate chief technicians was 32±7, significantly higher than that of the research fellows(28±4, P<0.05),with no significant difference to the score of the medical researchers and technicians with other professional titles. The depression score,anxiety score and the subhealth score of the age group of 36~49 were 39±9,31±7 and 32±9 respectively, both higher than that of the age group of 20~35 (36±8,29±6 and 29±7 respectively,both P<0.05),while there is much diference among other age groups. And the subhealth status has nothing to do with marital status,education background and professional titles. 2.The coping behaviors,job stress and motivation of the military medical laboratory scientists and technicians. 1)Coping behaviors:The seeking help score of the associate chief technicians was 2.8±0.5,not significantly different from that of the associate research fellows(2.8±0.5),but significantly lower than those of the medical researchers and technicians with other professional titles(all P<0.01),and whose self-blame score was higher than that of the research fellows,which is of significant difference.The self-blame score and the imagination score of the associate research fellows were 2.0±0.5 and 2.4±0.5 respectively, significantly higher than that of the research fellows(1.6±0.4, 2.1±0.4,both P<0.01). The seeking help score of the females was 3.1±0.5, significantly higher than that of the males(2.9±0.5, both P<0.01),and the solving problem score was 3.4±0.6,significantly lower than the male(3.6±0.7, both P<0.01).There is no any significant difference in coping behaviors among researchers and technicians of different marital status,education background and age groups. 2)Job stress: The score of job stress of the age group of 35~49 and 50~60 were 23±8 and 25±6 respectively,significantly higher than that of the 20~35(21±7,both P<0.05). There is no any significant difference in job stress among researchers and technicians of different marital status,gender,professional titles and education background. 3)The score of meeting personal desire for reputation and interests of the males was 19.6±5.4,significantly higher than that of the females(18.4±5.0, both P<0.05), while there is no significant difference in job motivation among researchers and technicians of different titles,education,age and marital status. 3.The relationship of the mental-physical health of the military medical laboratory scientists and technicians with their coping behaviors,job stress and motivations 1) Coping behaviors:Regression analysis showed that, the best predictors of subhealth were anxiety,depression and escaping (β=-0.40,β=0.23, β=0.14, both P<0.01).the best predictors of anxiety and depression were active coping behaviors and negative coping behaviors (β=-0.40,β=0.40, both P<0.01).The moderate(rational) coping behaviors is the best predictor only of anxiety and of significant difference. 2)job stress : Regression analysis demonstrated that anxiety,depression,job stress 2 and job stress 4 are the best predictor for subhealth;job stress 12 is the best retro-predictor for depression; job stress 3 and 8 are the best predictor for depression;and job stress 2 and 9 are the best predictor for anxiety ,which are of significant difference. 3)Motivation:Regression analysis demonstrated that depression is the best predictor for subhealth while motivation itself doesn't predict subhealth;with respect to the specific contents of motivation,"probing unknown rules and making contributions to the human society "is the best retro-predictor for depression and has nothing to do with anxiety prediction. 4) The combined influences of coping behaviors,job stress and motivations: Regression analysis showed that, the best predictors for subhealth were anxiety,depression and job stress(β=0.41,β=0.24, β=0.19, both P<0.01).the best predictors for anxiety and depression were active coping behaviors and negative coping behaviors (β=-0.40,β=0.40, both P<0.01).The moderate(rational) coping behaviors is the best predictor only for anxiety and of significant difference. CONCLUSIONS: Regression analysis showed that the best predictors for anxiety and depression were active coping behaviors and negative coping behaviors, the best predictors for subhealth were anxiety,depression and job stress.Coping behaviors, job stress and motivations have significant influences on the mental-physical health of the military medical researchers and and technicians. Among them,coping behavior is the most important factor while job stress and motivation follow. Seeking help more often,less self-blame ,imagination and job stress could help release the anxiety, depression and improve the subhealth of the medical researchers and technicians. The findings of this study indicate we should address the physical and mental health of the military laboratory researchers and technicians.