Chemiluminescence flow Sensor for determination of the Ammonium ion

Anunoniaisasignificantalkalinepollutantintheatmosphere.AInInoniaeInittedintothetroposphereisreadilytraPpedbyacidicclouddropletSanditneutralizestheacidityofthedropletStoformammoniumsaltS.Therefore,thedetendnationoftheanunoniumioninwetdepositionisveryimportantinatmosphericchemistry,andthereisaneedforasimPleandrapidmethodforthedetendnationofNfu .Variousdetectionmethodsandtechniquesareusedfordetendninganunoniaorammoniumion,suchasionchromatography',ion-selectiveeIectrode',BLMselectrochendcalse…     

THE THERMAL DIFFUSIVITIES OF NANOSTRUCTURED NiAl ALLOYS MEASURED BY USING PHOTOACOUSTIC TECHNIQUE

The thermal diffusivities of nanostructured NiAl (n-NiAl) alloys wit h different relative densities and the polycrystalline NiAl alloy are measured by using photoacoustic technique in which the signal is detected at the front surface while the rear-surface is excited. It is shown that the values of thermal diffusivity of the nanostructured NiAl alloy are lower than that of the polycry stalline NiAl alloy. The thermal diffusivities of n-NiAl alloys decrease with t he decrease of their relative densities when they are over 70%. When the relativ e density of n-NiAl alloys is lower than 70%, an anomalous increase of thermal diffusivity is observed, which indicates there exists a critical excess volume ΔV_c (or critical relative density) in n-NiAl alloys near 70%. Th e results are discussed.     

光谱烧孔的偏振探测

在光子选通给体０体电子转移光谱烧孔的实验基础上，新采用了偏振方法探测烧出的孔，使孔的检测灵敏度和信噪比均得到了大幅度的提高。以此为工具，烧出了很好的多孔，并做了一系列样品烧孔性能的测试和分析。     

半无限伊辛铁磁系统表面磁性的研究

本文应用平均物重整化群方法对于具有非晶化表面的半无限伊辛铁磁系统,在有表面无规场存在的情形,其表面磁性的临界性质包括临界温度、三临界点以及重入现象的可能性作了详细的研讨。 关键词：     

Synthesis of Enantionpure tert-Butylsulfinamide from tert-Butylsulfinyloxazolidinone

As a versatile chiral ammonia equivalent, chiral tert-butylsulfinylamide (6) (TBSA) is a very useful auxiliary due to the characteristics of highly stereoselectivity in asymmetric induction and the sulfinyl group being easily removed compared with other amine auxiliaries since its introduction as a stable compound by Ellman in 1997.[1] Considering the importance of TBSA 6, search for efficient methods for the preparation of enantiopure TBSA (6) is the great interesting topic in synthetic chemistry. There were only three methods for the preparation of enantiopure TBSA (6) reported in the literature.[2] In this paper, we report an alternative three-step procedure to synthesize enantiopure TBSA (6) with a key step being the formation of tert-butylsulfinyloxazolidinone (4).     

有资助的消费和最终资产的效用最大化

本文主要讨论带有随机资助过程的消费和终端财富效用最大化问题 .当对偶域为 (L∞) 时 ,利用对偶方法 ,求得问题的最优解对().     

纳米级ASnO3(A=Ca,Sr,Ba):Eu的光谱研究

采用络合溶胶-凝胶法制备出系列纳米级发光材料ASnO3(A=Ca,Sr,Ba): 1%Eu.并采用X射线衍射(XRD)、紫外光谱(UV-Vis)、透射电镜(TEM)、荧光光谱(PL)对所制备的纳米发光粉体进行表征.结果表明:所合成的物质均为具有确定结构的单一物相,并从结构上分析了其发光性质随碱土金属离子半径变化而变化的规律.     

BEPC中的电子云不稳定性研究

多束团正电子储存环中可能发生电子云不稳定性(ECI). 自1996年起, 在北京正负电子对撞机(BEPC)上开展了与这种束流不稳定性相关的系列研究. 文章扼要介绍在BEPC上进行的电子云不稳定性研究, 包括实验观测和模拟计算, 并讨论可能的抑制措施.     

Steady convection in a porous medium based upon the Brinkman model

A theoretical study of the problem of steady convection throughporous media, based upon the Brinkman model, is presented. Avariational formulation is introduced to deal with the weaksolution. The existence of a weak solution and some uniquenessand regularity results are discussed.     

非晶态合金La72Si28晶化过程中生成的新亚稳超导相

本文报道了在非晶态合金La₇₂Si₂₈晶化过程中生成新亚稳超导相的实验结果。非晶态合金La₇₂Si₂₈是用液态急冷法制备的,该合金经250℃,30min热处理后,得到了一个新的亚稳超导相,该相具有正交结构,其晶格参数为a=9.121?,b=6.821?,c=3.833?,超导临界温度T_c为3.02K,高于目前已知的La-Si系超导相的T_c值。 关键词：