分析金属熔滴快速凝固过程的双倒易边界元方法

本文发展了非线性边界条件相变传热过程的轴对称双倒易边界元方法,数值模拟了金属熔滴在快速冷却条件下的快速凝固过程。分别研究了在微重力落管和落塔中及喷射成形过程中金属熔滴的快速凝固过程,得到了过冷度,再辉时间,温度变化及相变界面随时间的变化等数值结果。     

用原子荧光法研究硒酸盐的微生物转化过程

本文用氢化物发生－原子荧光法研究水体中硒酸盐的微生物转化，其中单质硒是主要产物，同时有挥发态硒生成。在反应器中测定到了亚硒酸根，认为亚硝酸根是硒酸根是微生物卖座经的中间产物。     

非等温相变问题的双倒易边界元法求解

对铅-锡合金的相变问题,本文采用含扩展项的轴对称双倒易边界元方法计算了圆柱中界面沿轴向运动的非等温相变过程。与特定条件下解析解的比较,验证了该方法的正确性,为类似的晶体生长非等温相变问题提供了一种有效的求解方法。     

Influence of substrate process tolerances on transmission characteristics of frequency-selective surface

Frequency-selective surface （FSS） is a two-dimensional periodic structure consisting of a dielectric substrate and the metal units （or apertures） arranged periodically on it. When manufacturing the substrate, its thickness and dielectric constant suffer process tolerances. This may induce the center frequency of the FSS to shift, and consequently influence its characteristics. In this paper, a bandpass FSS structure is designed. The units are the Jerusalem crosses arranged squarely. The mode-matching technique is used for simulation. The influence of the tolerances of the substrate＇s thickness and dielectric constant on the center frequency is analyzed. Results show that the tolerances of thickness and dielectric constant have different influences on the center frequency of the FSS. It is necessary to ensure the process tolerance of the dielectric constant in the design and manufacturing of the substrate in order to stabilize the center frequency.     

多相泵设计方法初探

１引言由于多相泵输送的是气液两相混合介质,而且其中气或液的含量往往高于常规泵或压缩机的工作范围,所以多相泵应兼备压缩机和泵的性能,这使多相泵的设计成为一个难点。到目前为止,国外已开发研制出的多相泵主要有容积式和叶片式［１］,业已进入现场试验和工业化应用阶段,但离形成完整的设计方法还有一定距离,国内这方面的工作则刚刚起步。所以目前对于多相泵尚没有成熟的设计方法,还不能象清水泵那样,按给定的流量、扬程、转速等参数进行可靠的设计。在多相泵的设计中,人们关心的主要问题是：泵型选择、总体设计方案的确定、效…     

原子吸收光谱法测定益寿回春口服液中砷铅镉铬汞的含量

采用原子吸收光谱法测定了益寿回春口服液中砷、铅、镉、铬和汞的含量，并参照食品中重金属的限量规定进行了比较。结果表明，益寿回春口服液中的砷、铅、镉、铬和汞均低于限量标准，为该产品的质量控制提供了依据。     

双核Cu(Ⅱ)-2，4-二羟基苯甲醛缩邻氨基苯甲酸Schiff碱配合物的合成、表征和晶体结构

The novel dinuclear copper(Ⅱ) complex with with N-(2，4-dihydroxybenzalidene)-o-aminobenzoic acid ligand， [Cu(C₁₄H₉NO₄)]₂·2H₂O， has been synthesized and characterized by elemental analysis， IR， UV-Vis and thermal analysis. Its crystal structure was determined by single crystal X-ray diffraction techniques. The crystal belongs to monoclinic with space group P2₁/c. The cell parameters are: a=0.82510(11)nm， b=0.68870(9)nm， c=2.3007(3)nm， β=100.847(2)°， V=1.2840(3)nm³， Z=2，D_c=1.742Mg·m^-3， μ(Mo Kα)=1.723mm^-1， F(000)=684. The structure was refined to final R₁=0.0267， wR₂=0.0735. The complex molecule structure has dinuclear centrosymmetric dimeric structure in which a planar Cu₂O₂ core features. The ligand N-(2，4-dihydroxybenzalidene)-o-aminobenzoic acid dianion is μ₂-tridentate， chelating one copper(Ⅱ) ion via one nitro-gen， one hydroxy oxygen atom and one carboxylate oxygen atom， and the hydroxy oxygen atom simultaneously co-ordinates to the other copper(Ⅱ) ion of the dimer. In the structure the copper(Ⅱ) ion rendered four-coordination in a distorted square-planar geometry structure. CCDC: 212695.     

红景天苷及其酯化产物的ESI MS和MS/MS裂解途径

糖苷广泛存在于自然界中,常以糖苷酯形式存在,这有效地提高了它们的酯溶性,增加它们在肠内和胞内的吸收[1-3]。红景天苷是一种具有抗疲劳、抗辐射、抗缺氧、提高记忆、延缓衰老等药理活性的天然糖苷[4-8],在此先导化合物的基础上合成了各种红景天苷酯。本文对这类红景天苷酯的E