Identification and occurrence of novel C36–C54 3,4-dialkylthiophenes with an unusual carbon skeleton in immature sediments

A series of novel long-chain 3,4-dialkylthiophenes (C₃₆–C₅₄) was identified in a number of sediments ranging from Pleistocene to Cretaceous. The identifications were based on mass spectral characterisation, desulphurisation and mass spectral data of synthesised model compounds. These organic sulphur compounds are probably formed by sulphur incorporation into mid-chain dimethylalkadienes with two methylenic double bonds. These putative precursor lipids are unprecedented and may be considered rather unusual. The distribution of 3,4-dialkylthiophenes in sediments varies considerably with the depositional palaeoenvironment, indicating that these compounds have a potential as molecular markers reflecting changes in palaeoenvironment.     

Development of the instantaneous unit hydrograph using stochastic differential equations

Recognizing that simple watershed conceptual models such as the Nash cascade ofn equal linear reservoirs continue to be reasonable means to approximate the Instantaneous Unit Hydrograph (IUH), it is natural to accept that random errors generated by climatological variability of data used in fitting an imprecise conceptual model will produce an IUH which is random itself. It is desirable to define the random properties of the IUH in a watershed in order to have a more realistic hydrologic application of this important function. Since in this case the IUH results from a series of differential equations where one or more of the uncertain parameters is treated in stochastic terms, then the statistical properties of the IUH are best described by the solution of the corresponding Stochastic Differential Equations (SDE's). This article attempts to present a methodology to derive the IUH in a small watershed by combining a classical conceptual model with the theory of SDE's. The procedure is illustrated with the application to the Middle Thames River, Ontario, Canada, and the model is verified by the comparison of the simulated statistical measures of the IUH with the corresponding observed ones with good agreement.     

黄原酯棉富集分离—全差示光度法测定痕量银

在5—35％HClO_4介质中,0.1g黄原酯棉可定量吸附500μg Ag,灰化解脱后Ag回收率在99％以上。Ag-金试剂-OP络合物的显色条件是:pH为4.5—6.5,最大吸收波长505nm,摩尔吸光系数1.0×10~5,络合物组成是Ag:金试剂=1:4,Ag量在0—10μg/25ml范围内符合比尔定律。采用全差示分光光度法测定地质样品中的Ag,操作简单快速、灵敏度高、选择性好、测定范围宽.     

反演地层电阻率的单调同伦法

本文从电法测井的数学模型出发,给出了一种反演地层参数的单调同伦法,把非线性方程组的求解转化成常微分方程初值问题的数值求解,从而给出一种大范围收敛的反演方法.最后的数值结果表明,本文给出的算法是十分有效的.     

RAP－10型桩基检测仪放大器频率补偿

本文叙述了ＲＡＰ－１０仪中一种新型的差动放大器。进行了理论分析、模拟计算和实验。结果表明：这种新型的差动放大电路与通用的差动放大电路相比，具有宽带频率补偿作用。是一种宽带差动放大器。关键词     

伊朗卡尔赫水电站坝址松散砾岩钻探工艺

在伊朗卡尔赫水电站坝址工程勘察中，采用金刚石双管单动钻具和ＳＭ胶冲洗液进行取样钻探，用清水钻进压水试验，由于钻探工艺合理，钻探质量均达到了设计要求。     

递归相似和线性多步法

在递归相似的基础上提出数值求解初值问题的一种新方案，与传统方法的区别，在于求解归结为演化系数的计算。这里给出常微（组）初值问题的算法；并指出新方法与传统方法的关系。