活性氧自由基与嘧啶碱基及其核苷反应的ESP研究

本文以MNP（2-methyl-2-nitrosopropane）为捕捉剂，利用自旋捕捉技术和ESR方法，室温条件下，研究了活性氧自由基与嘧啶碱基及其核苷在水溶液中的反应。确定了所产生的自由基类别，讨论了自由基的形成机制。在本工作中，我们在下列三种体系中，研究了活性氧自由基与嘧啶碱基及其核苷的反应。1.核黄素（B_2）水溶液中，O_2~-与嘧啶碱基及其核苷的反应。2.H_2O_2水溶液中，OH与嘧啶碱基及其核苷的反应。3.γ射线辐照水溶液过程中，OH与嘧啶碱基及其核苷的反应。在核黄素（B_2）水溶液中，通过U.V.光辐照，我们得到了活性氧自由基与尿嘧啶、胞嘧啶、胞苷、脱氧胞苷、胸腺嘧啶、胸腺核苷反应所产生的自由基，及由这些自由基与MNP自旋加合物的ESR谱。确认了自由基Ⅰ，Ⅱ，Ⅲ，Ⅳ，Ⅴ，Ⅵ的存在。为了判别与嘧啶碱基或嘧啶核苷反应的活性氧自由基的种类，我们在下列三种条件下进行了测试：（1）加入适量DETAPAC（2）通N_2或Ar除O_2；（3）加入H_2O_2酶，均未得到ESR信号。据此，我们排除了O_2~-与嘧啶碱基或嘧啶核革直接反应的可能性。确认与嘧啶碱基或嘧啶核苷发生直接反应的是OH，其形成是Fenton反应的结果。 Fe~(2+) ＋ O_2~- → H_2O_2 ＋ Fe~(3+) （a） Fe~(2+) ＋ H_2O_2 → ·OH ＋ OH~- ＋ Fe~(3+) （b）Fe~(3+) ＋ O_2~- → Fe~(2+)＋O_2 （c）通过Fenton反应，O_2~-转化成·OH，间接与嘧啶或核苷发生了反应。U.V.光照含有MNP和1％H_2O_2的样品水溶液，我们确定了·OH与嘧啶碱基及其核苷反应所产生的自由基Ⅰ，Ⅱ，Ⅲ，Ⅳ，Ⅴ，Ⅵ，Ⅶ，Ⅷ，Ⅸ，Ⅹ。发现，·OH与尿嘧啶及其核苷，胞嘧啶及其核苷的反应，主要有二种形式：其一，·OH加合到嘧啶环的C_5－C_6双键上，形成C_5位或C_6位自由基；其二，·OH夺取C_5位上的H，开成C_5'位自由基。·OH不与胸腺核苷的糖单元发生反应，仅与其嘧啶环反应，形成Nu位和C_5位自基。γ射线辐照过程中，·OH与嘧啶碱基及其核苷的反应与H_2O_2体系中的情况类似。辐照剂量则对反应的影响较大，低于1.0 * 10~4 rad，不发生反应；1.0 * 10~6 rad，则发生交联反应，只有1.0 * 10~5 rad的辐照剂量比较适宜。

碱性矿化水灌溉对土壤溶质运移的影响

经过连续几年的灌溉试验可知,应用2.5 g稬-1以下的低矿化水灌溉是安全的,超过此值土壤积盐和碱化明显。灌溉后,土壤中溶质运移受多因素影响。在阳离子分布中,水平方向Na+随灌溉水矿化度增大而增多,Ca2+、Mg2+变化不大;土壤剖面上,从表层至60 cm土层,先以Ca2+、Mg2+为主,过渡到Na+、Ca2+、Mg2+共同占优,再发展为以Na+占优。阴离子的分布中,水平方向,随灌溉水矿化度增大HCO3-增多;土壤剖面上,从表向里,先以Cl-或SO42-为主,过渡到C1-、SO42-、HCO3-均分局面,再发展以HCO3-占优。灌溉后土壤pH值在0~20 cm变化不明显,大于20 cm土层有一定增加。土壤中的SAR和ESP均以大于1.5 g稬-1的碱性低矿化水灌溉后增加明显,碱化层由下向上抬升,小麦田碱化速度快于玉米田。

Nontoxic electrodes of solid amalgams

This is a review of electrodes based on nontoxic solid amalgams (MeSAE) (prepared by amalgamation of soft metal powders) in connection with some other kinds of voltammetric electrodes is given. Information is summarized on various types of MeSAEs (esp. AgSAE, CuSAE, AuSAE), pretreatment of their surfaces, their hydrogen overvoltage in aqueous solutions, conditions for their testing, electroanalytical parameters and use, in compared with the hanging mercury drop electrode (HMDE). Although the solid amalgam electrodes do not reach the quality of the HMDE, in many cases they represent its possible alternative. The broad range of voltammetric applications of the MeSAEs, especially of the AgSAEs, their good mechanical stability, simple handling, and new aspects of their use in electrochemical techniques are documented by numerous examples.

土壤改良剂MDM对草甸碱土和水稻生长的影响

研究了盆栽条件下,改良剂MDM对松嫩平原草甸碱土和水稻生长的影响。结果表明,施用MDM可显著改善草甸碱土的交换能力和降低土壤溶液的含盐量,与对照相比,经0.90L/m2MDM处理后的草甸碱土碱化度(ESP)降低了64.47%,水溶性盐中CO32-含量降低了72.80%,Na++K+/Ca2++Mg2+降低了87.20%,土壤的电导率下降了27.18%,此外土壤的pH下降了0.5;改良剂的施用促进了水稻的生长发育,最终提高其产量,与对照相比,经0.90L/m2MDM处理后的水稻出苗率提高了14.29%,株高增加了36.19%,水稻的单株产量增加了117.43%。

土壤改良剂MDM对松嫩平原草甸碱土的改良效果

通过盆栽及田间小区试验,研究了改良剂MDM对松嫩平原草甸碱土的改良效果。结果表明,MDM可显著改善草甸碱土的理化性质。与对照相比,经MDM处理后的碱土钠碱化度(ESP)降低了46.2%,水溶性盐中CO32-含量降低了84.1%,Na++K+/Ca2++Mg2+降低了60%。此外玉米出苗率提高了12%,株高增加了14.4%,作物的干重和鲜重分别增加了52.69%和53.47%。

M-HMS的合成、表征及在苯酚羟化反应中的催化性能

以同晶取代方法合成了 M-HMS(M=Fe、Cu、Co、V,HMS:Hexagonal Mesoporous Silicates)中孔分子筛 .经 XRD、IR、ESP表征 ,证明过渡金属离子已进入 HMS骨架中 .在苯酚羟化反应中考察了 M-HMS的催化性能 .结果表明 ,M-HMS的催化性能明显高于相对应的 M/Si O2 负载型催化剂 .依据引入 HMS骨架的过渡金属离子是苯酚羟化反应的活性中心 ,以及 H+ 和 OH- 可能参与反应的结果提出了可能的反应机理

松嫩平原西部景观地球化学特征及其演化

盐渍化的发生是一个盐分动态过程，利用植物生长条件下盐分迁移模型对这个过程进行了定量模拟和预测研究，根据松嫩平原西部水、土环境特征，计算过程中综合考虑了土壤中多组分迁移及主要离子的化学作用。松嫩平原西部景观地球化学环境的演化受多种物质体系、能量体系、结构体系和功能体系的共同作用与控制。地带性气候是景观地球化学环境演化的基础动力条件；地质环境为表生地球化学元素提供了物源；地形地貌控制着表生地球化学元素的迁移方向；水文地质条件促进景观地球化学环境的演化；同时人为因素是松嫩平原西部景观地球化学环境演化的重要驱动因子。松嫩平原西部景观地球化学环境在长期的历史演化过程中，存在地质时期、土壤时期、生态时期、技术时期等演化时间尺度，并且这些尺度具有密切的相互联系。松嫩平原西部不同群落生态系统的平衡与土壤中景观地球化学元素之间具有耦合关系。景观地球化学元素的迁移和积累受地表水和潜水系统的双重影响。人类生存行为影响景观地球化学环境的演变及景观地球化学流在不同方向上强度的改变，使得景观内原始积累状况发生改变，造成不同景观带中元素迁移积累，形成不同的景观群落。植物群落与一定的景观地球化学条件相互适应，当景观中土壤及水环境条件变化时，引起群落在不同方向上的演替；反之，植物生态系统的演替过程也会影响到土壤地球化学条件的改变，二者之间存在着密切的耦合关系。松嫩平原西部干旱-半干旱的气候条件与地貌、及生态地质条件相互叠加，构成本区特殊的景观结构。在不同的景观地球化学梯度影响下，植物的生长发育状况不同，大多数植物沿景观地球化学梯度，生长状况表现为钟形曲线，这是地球化学梯度和植被生态梯度的耦合效应。生态脆弱带景观地球化学障的形成是景观地球化学分异的根本原因，由于分异造成不同的景观地球化学条件，从而引起生态梯度变化。松嫩平原西部土壤及潜水中盐分离子特别是Na+、HCO3-、Cl-离子含量高，其对植物的生长产生重要的影响。一方面，环境中过高的盐分浓度影响植物对营养物质的有序吸收，并产生毒害作用，表现在：(1)延缓土壤中营养元素的迁移和固定，(2)干扰根系对营养物质的吸收，(3)干扰植物体内营养物质的新陈代谢，减少营养物质利用的有效性。通过对盐渍化环境和非盐渍化环境下植物生长实验分析，土壤中盐分引起土壤溶液渗透势、土壤水势、植物水势及冠层水势降低，从而引起植物蒸腾作用减弱，植物的生长受到抑制，生物量明显降低。另一方面，西部土壤中高含量的代换性Na+(ESP)，是抑制植物生长的又一重大因素，其主要是影响土壤物理性状，使土壤的通透性变差，土壤持水力和水渗透率明显降低，影响根系发育和植物对土壤水分的吸收，从而间接影响植物群落的分布及演化，土壤盐渍化对松嫩平原西部景观地球化学特征起着决定性作用。松嫩平原西部景观地球化学恢复的关键是在研究区域地区地球化学障的基础上，调整破坏的地球化学流，采用生物、物理及化学措施综合进行治理，使生态系统回到平衡发育的状态。在此过程中必须坚持生产功能与保护功能相结合，人与生物控制共生的原则。根据潜水与植物生长关系模型分析，通过淋洗，可使土壤中“盐峰”接近潜水面。但在干旱-半干旱条件下，降雨很难满足淋洗的需求。为此，灌溉淋洗和洪水“淡化”成为人类和自然两种有效的调节。水利工程在调控江河湖泊自然水量及蓄洪的同时，也从根本上改变了江河、湖泊一体的环境结构，从而影响到水域景观中的景观地球化学流，使景观内水文地球化学环境发生改变。在利用水资源进行农业生产时，应进行科学合理规划和建立科学的灌溉用水管理制度，以确保西部景观地球化学环境的平衡发育及恢复。

国有企业管理者裁员决策特征及其对留岗者心理影响的研究

In China, orgnizational change and downsizing are the primary topics studied in I/O psychology and Human Resource Management. Due to the great need in reality, both theorists and practitioners raised the same questions: Does downsizing increase the organizational performance? What is the relationship between organizational downsizing strategies and survivors' psychological reations? Which factors influence managers' downsizing decision-making most? How can managers manage the process successfully? The purpose of this study is trying to answer these questions, and then to establish the downsizing decision-making model of China's SOE (State owned enterprise) managers. The hypothetical model of SOE managers' downsizing decision-making was put forward, based on a tremendous amount of literature on downsizing decision-making, especially on the downsizing decision-making model built by B. Shaw, and also based on the results of the interviews conducted to the SOE managers who have the downsizing decision-making experiences. In order to test and verify the model, 322 SOE managers were investigated by a questionnaire study. And the statistic results supported the hypothetical downsizing decision-making model. Further, 259 survivors (those who are still working in the SOEs) from 7 downsized SOEs and 1 non-downsizing SOE, were also investigated by a questionnaire study. The statistic results also supported the hypothetical downsizing decision-making model. A subsequent case study was performed upon one downsized SOE; and a deliberate focus group interview study within 6 SOE mangers from another downsized SOE was also conducted. Both fundings from the two studies surported the hypothetical model again. Thus, China's SOE managers' downsizing decision-making model was established. This China's SOE managers' downsizing decision-making model suggests the following: Firstly, the characteristics of managers'downsizing decision-making were the center of the model. Those characteristics displayed during the process of the downsizing decision planning, the participation of downsizing decision-making and the communication concerning downsizing events, were influenced by managers' sense of crisis, controlling factors out of the organization and the managing experience within it. Especially, the latter two factors were more important. Secondly, in downsizing decision-making problems, the perceived crisis of China's SOE managers was mainly influenced by the outer factors, esp. the controlling factors from the government or the high authorities, but not by the inner factors including manufacturing management, HRM skills and organizational competition strategies. Thirdly, survivors'psychological reactions (including job satisfaction, job motivation, team working cooperation, etc) were mainly influenced by the characteristics of the managers' downsizing decision-making, at the same time, also by the outer factors (including controlling and social security factors) and the inner factors (including competition strategy and HRM skills). Finally, according to the model and the results from this study, the conclusions were reached in the followings: The stronger the controlling effort upon the SOE managers, the worse the effect displayed during the downsizing process. And in order to improve the effect and quality of downsizing decision-making, SOE managers need a lot of training to ameliorate their competencies such as competition strategies and HRM skills.