SPME/GC-MS鉴别地沟油新方法(Ⅲ)

该文通过气相色谱-质谱法研究调味品的化学成分,进而对地沟油进行鉴别,发现乙酸来源于醋、3-丁烯腈来源于腌菜酱汁、异硫氰酸烯丙酯来源于芥末、糠醛来源于酱油、茴香脑来源于八角茴香、姜烯来源于生姜和老姜。通过检测油脂样品中是否含有这些调味品的特征成分,即可鉴别是否餐厨废弃油。该文采用顶空固相微萃取(SPME)富集微量外源杂质成分,并研制专用的气相色谱柱,用气相色谱-质谱联用法(GC-MS)测定乙酸、3-丁烯腈、糠醛、异硫氰酸烯丙酯、茴香脑、姜烯6种成分,样品中若含有这些微量成分中的一种或多种,则判定为餐厨废弃油。     

Y2O3—Ir阴极的发射机理的研究

根据Ｙ２Ｏ３－Ｉｒ阴极研制过程中观察到的一些物理现象，结合扫描电镜对Ｙ２Ｏ３－Ｉｒ阴极表面化学成份分析的图谱，运用物理化学理论对该阴极的发射物质结合态进行研究。最后，在综合比较氧化物阴极的二种发射模型的基础上，探讨了氧化钇－铱阴极的发射机理。     

Partitions and Compositions Defined by Inequalities

We consider sequences of integers (₁,..., _k) defined by a system of linear inequalities _{i j>i}a_ijj with integer coefficients. We show that when the constraints are strong enough to guarantee that all _i are nonnegative, the generating function for the integer solutions of weight n has a finite product form , where the b_i are positive integers that can be computed from the coefficients of the inequalities. The results are proved bijectively and are used to give several examples of interesting identities for integer partitions and compositions. The method can be adapted to accommodate equalities along with inequalities and can be used to obtain multivariate forms of the generating function. We show how to extend the technique to obtain the generating function when the coefficients a_i,i+1 are allowed to be rational, generalizing the case of lecture hall partitions. Our initial results were conjectured thanks to the Omega package (G.E. Andrews, P. Paule, and A. Riese, European J. Comb. 22(7) (2001), 887–904).Research supported by NSA grants MDA 904-00-1-0059 and MDA 904-01-0-0083.     

A counterexample to the ``composition conjecture"

In this note we construct a class of counterexamples to the ``composition conjecture" concerning an infinitesimal version of the center problem for the polynomial Abel equation in the complex domain.

     

稀土氧化物在复合PSZ材料中的作用

复合稳定ＺｒＯ２在高温热处理过程中,发生立方相向四方相的相变,由于Ｙ２Ｏ３或Ｃｅ２Ｏ３和ＭｇＯ的复合稳定作用,相变过程产生大量介稳的ｔ－ＺｒＯ２析出体。可相变四方相含量随热处理时间而增加,其中外２ｍｏｌ％Ｙ２Ｏ３的（Ｙ,Ｍｇ）－ＰＳＺ／ＭｇＡｌ２Ｏ４材料处理至８００ｈ仍未降低。热处理过程中Ｙ２Ｏ３和Ｃｅ２Ｏ３始终存在于晶格中稳定ＺｒＯ２．复合稳定剂充分体现了对立方和四方相的稳定作用,多元ＰＳＺ的稳     

湿地松针叶挥发油化学成分研究

采用常压水蒸气蒸馏法提取了湿地松针叶挥发油,得油率为0．22％－0．25％,用GC,IR,NMR,GC－MS等方法对该精油进行了定性,定量分析,在分出的36个色谱峰中共鉴定出33个化合物,占该精油总量的99．79％,其中含有α－蒎烯,Δ3－蒈烯,γ－松油烯,乙酸龙脑酯,乙酸萜品酯及长叶烯等,含量最多的成分是β－蒎烯（36．536％）。     

大蒜制品的开发和应用

大蒜含有多种含硫化舍物,稀有元素以及人体所需的各种营养素,有极高的药理学价值和保健作用,大蒜制品的开发有着十分广阔的应用前景,本文详细介绍大蒜的化学成分、生物活性以及国内外大蒜制品开发和应用的现状和发展前景．     

机电专业士官岗位分析及教学体系构建

在分析新装备机电液技术构成特点的基础上,从专业技能特别是职业素质等方面探讨了对机电专业士官的岗位需求,阐明了基于岗位工作过程教学体系的构建策略,为机电专业的士官教学起到了借鉴与参考作用。     

Structural and kinetic aspects of hydrostatic pressure effect on polymer network formation

Abstract

Effect of hydrostatic pressure up to 250 MPa on structurization kinetics and morphology of network polymers based on epoxy oligomers has been studied using the methods of measurements of resistivity and optical microscopy.     

QSym over Sym has a stable basis

We prove that the subset of quasisymmetric polynomials conjectured by Bergeron and Reutenauer to be a basis for the coinvariant space of quasisymmetric polynomials is indeed a basis. This provides the first constructive proof of the Garsia-Wallach result stating that quasisymmetric polynomials form a free module over symmetric polynomials and that the dimension of this module is n!.