广义风险过程中渐近方差的非参数估计

本文对广义风险过程中的渐近方差作了非参数估计,得出并证明了两个定理,为广义风险过程中破产概率的区间估计作了理论准备．     

3,3,6,6-四甲基-9-邻氯苯基-1,8-二氧代-3,4,5,6,7,9-六氧化氧杂蒽的合成和晶体结构

标题化合物C23H25对O3Cl是由邻氯苯甲醛与5，5-二甲基1，3-环己二酮在N，N-二甲基甲酸腹中反应而得。结构通过单晶X-射线衍射法确定，其晶体属于单科晶系，空间群=1632。晶体结构用直接法解出，使用全矩阵最小二乘法对原子参数进行修正，最后的偏离因子为R=0．054，Rw一0．063。在晶体结构中，吡喃环与苯环之间的两面角为92．43°。     

Influence of surface treatments in the initial stages of anodizing Al–Ag alloys in neutral electrolytes

Using voltage-time responses and cyclic voltammetry, the initial stages of anodizing of Al–2.1 at.% Ag and Al–4 at.% Ag alloys are shown to depend upon the heat treatment of the alloys and the pre-treatment of the alloy surfaces. Chemical polishing of solution-treated alloys leads to relatively uniform anodic oxidation on a relatively smooth alloy surface, in the absence of significant effects of coarse, silver-rich intermetallics. In contrast, losses of current to oxygen generation arise for the roughened alloy surface from mechanical polishing. With ageing, secondary reactions at the relatively silver-rich intermetallics are more prevalent, although the effects on the voltage-time response depend upon the balance between processes occurring on the matrix and intermetallic regions, including film growth, oxygen generation within the anodic film, film damage due to release of oxygen, dissolution of silver species and re-growth of damaged film.     

Total Synthesis of Several 8, 8",-Biflavones

8,8"-Biflavonoidsareantw0rtantclass0fbiflavonoids.Asasystematicresearchofthe8,8"-biflav0noids,wehavepreviouslyreportedthestudyonthereactionof2'-hydroxychaloneswithl2-H2SO4-DMSOsystem.'InthispaPer,thesynthesisof5,5",7,7',-tetTameth0xy-8,8"-biflavonela2,4,4",7,7"-tetramethoxy-8,8"-biflavone1b',4',4",,5,5,',7,7"-hexamethoxy-8,8"-biflav0ne1c4and4,4"-dibenZyl0xy-5,5",7,7"-tetramothoxy-8,8"-biflavoneldisreported.ThesyntheticmethodisshownintheSchemebelow.2-Hydroxyacet0phenonescondensedwithsubsti…     

Voltammetric studies of a psychotropic drug with nitro groups. Determination of flunitrazepam in urine using HMDE

The adsorption behaviour of flunitrazepam at the hanging mercury drop electrode was studied by staircase voltammetry and by adsorptive stripping differential pulse voltammetry. Flunitrazepam is adsorbed in the whole potential range, from the most positive values up to the reduction potential. Flunitrazepam reduction product is also adsorbed. The time dependence of the voltammetric response proves that a diffusion-controlled adsorption takes place. Flunitrazepam can be determined (down to nanomolar levels) by using adsorptive preconcentration prior to the differential pulse voltammetric scan. An application of such a method to flunitrazepam determination in human urine is described. The detection limit was 30 ng per milliliter of urine with a 20-sec accumulation time; the mean relative standard deviation was lower than 3.2% and the mean recovery 97.8%.     

高效液相色谱氮杂冠醚键合固定相的合成及性能研究

我们曾用γ－氯丙基键合硅胶（ＣＰＳ），在氢化钠（ＮａＨ）作用下合成了３－（氮杂－１８－冠－６）丙基键合固定相（ＢＣＰ）［１］．该固定相对碱基、核苷酸、硝基苯酚等有较好的分离选择性，但由于ＮａＨ对硅胶基质腐蚀作用较大，导致ＢＣＰ柱效及渗透性较低．本文采...