Intramolecular Aldol Condensation ofα- Oxo Ketene Dibenzylthioacetals: A Facile Route to Substituted Thiophenes

As a kind of intermediates, a-oxo ketene dithioacetals I are important in organicsynthesis"'. In our recent studies, we found that the difference of dialkythio group canbestow various properties on these kinds of compounds"'. To exploit the reactivityadjusted by the dialkythio groups in l, a-oxo ketene dibenzylthioacetals 2 were chosenand studied. Some interesting new results were obtained in these experiments. Here wereport the new results.When studying the reaction of a-oxo ketene dibenzylt…     

OPTIMAL ERROR ESTIMATE IN L~∞(J;L~2(Ω)) NORM OF FEM FOR A MODEL FOR COMPRESSIBLE MISCIBLE DISPLACEMENT IN POROUS MEDIA

We'll study the FEM for a model for compressible miscible displacement in porous media which includes molecular diffusion and mechanical dispersion in one-dimensional space.A class of vertices-edges-elements interpolation operator ink is introduced.With the help of ink(not elliptic projection),the optimal error estimate in L∞(J;L2(Ω)) norm of FEM is proved.     

具有次亚B性质的ω_（α＋1）－紧T_1空间是ω_α－LindelOf空间

在本文中，我们证明了具有次亚Ｂ性质的ω＿（α＋１－）紧Ｔ＿１空间是ω＿α－Ｌｉｎｄｅｌｏｆ空间，此结果改进并推广了［１］中的主要结果。     

Local generalized empirical estimation of regression

Let f(x) be the density of a design variable X and m(x) = E[Y\X = x] the regression function. Then m(x) - G(x)/f(x), where G(x) = m(x)f(x). The Dirac δ-function is used to define a generalized empirical function Gn (x) for G(x) whose expectation equals G(x). This generalized empirical function exists only in the space of Schwartz distributions, so we introduce a local polynomial of order p approximation to Gn(.) which provides estimators of the function G(x) and its derivatives. The density f(x) can be estimated in a similar manner. The resulting local generalized empirical estimator (LGE) of m(x) is exactly the Nadaraya-Watson estimator at interior points when p = 1, but on the boundary the estimator automatically corrects the boundary effect. Asymptotic normality of the estimator is established. Asymptotic expressions for the mean squared errors are obtained and used in bandwidth selection. Boundary behavior of the estimators is investigated in details. We use Monte Carlo simulations to show that the     

石墨炉原子吸收光谱法测定土壤中离子交换态的镉

本文研究了石墨炉原子吸收光谱法测定土壤中离子交换态的镉的适宜条件.试样经MgCl2溶液震荡提取离心后,以10%的磷酸二氢铵做基体改进剂,方法检出限为0.03840 μg/L,相对标准偏差(n=6)为0.9231%.本方法具有准确、简便之优点,可用于土壤样品中镉的测定.     

无溶剂顶空气相色谱法测定盐酸左氧氟沙星残留溶剂

采用无溶剂-顶空-气相色谱直接测定盐酸左氧氟沙星中残留溶剂乙醇、甲苯、二甲基亚砜(DMSO)等.各残留溶剂的检出限分别在0.007-0.032 μg,6次测定的相对标准偏差RSD在1.84%-1.92%,加标回收在90.9%-110%.方法简便、快速、灵敏,可应用于其他药品中残留溶剂的分析.     

高效液相色谱法测定金菊泡腾片中绿原酸的含量

采用Nucleosil C18(250mm×4.6mm,4.5μm)色谱柱,以甲醇-磷酸水溶液(pH=3.0)为流动相,其比例为25∶75,检测波长为327 nm,流速1.0 mL/min,柱温29 ℃,建立金菊泡腾片和双黄连口服液中绿原酸含量的高效液相色谱(HPLC)测定方法.绿原酸浓度在0.02-0.1 mg/mL与峰面积积分值呈良好的线性关系,A=0.9394C 0.3674(r=0.9991).该方法灵敏、简便、重现性好、结果准确,可用于金菊泡腾片中绿原酸含量的测定和产品质量控制.     

火焰原子吸收光谱法测定中药防风中铜、锰、锌和铁的不确定度评定

采用HNO3和HClO4消解防风样品,利用火焰原子吸收光谱法测定其中铜、锰、锌和铁含量.对测量过程中不确定度的产生原因进行了分析,并对防风中4种元素含量测定结果的不确定度进行了评定.     

5,7-二羟基黄酮与牛血清白蛋白相互作用的研究

用荧光光谱(FS)和紫外光谱(UV)法研究了5,7-二羟基黄酮与牛血清白蛋白之间的相互作用.实验结果表明,5,7-二羟基黄酮与BSA形成基态复合物导致内源荧光淬灭,淬灭机理主要为静态淬灭.该反应的结合常数4.16×107 L/mol,结合位点数n=1.5;并用同步荧光技术考察了5,7-二羟基黄酮对BSA构象的影响.     

济南地区表层土壤及沉积物中饱和烃分布特征及源解析

研究了济南地区不同功能区的表层土壤及沉积物中饱和烃的组成和分布特征,在此基础上初步分析了其来源.结果表明,饱和烃主要有正构烷烃、类异戊二烯、环烷烃等组成,正构烷烃碳数分布范围为n-C10-n-C34,类异戊二烯类主要是姥姣烷、植烷及甲基C13-C17烷等,同时还检出烷基环己烷,甾烷、三萜烷及藿烷等环烷烃.饱和烃总体含量分布为北高南低,北部化工区、高速入口处等饱和烃主要来源于原油或成品油等化石燃料及其燃烧产物;南部山区、水库沉积物及农田土壤等饱和烃主要来源于化石燃料的燃烧及高等植物.