实二次域Q(P(1/2))(p≡3(mod 4))类数的上界

设p是适合p≡3（Pod4）的奇素数,h,ε分别是实二次域Q的类数和基本单位．本文运用初等方法证明了：εh＜（p a 2)a 2/4(a 2)!,其中     

同步辐射X射线光刻技术

同步辐射X射线光刻（SRXL）是本世纪超大规模集成电路（VLSI）发展中最有希望的深亚微米图形加工技术,本文综述了SRXL技术研究的现状及存在的问题,并对其今后的发展进行展望。     

Eu3+掺杂2ZnO·2.2B2O3·3H2O红色荧光粉的发光性能

采用水热法合成2ZnO.2.2B2O3·3H2O:Eu3+红色荧光粉.其形貌、结构和光学性能分别用扫描电镜、X射线衍射和荧光光谱进行表征.扫描电镜图片显示样品的尺寸分布在0.1～1 μm范围内.随着Eu3+掺杂浓度的升高,样品向无定形的玻璃态转变.当激发波长为253 nm(属于Eu3+ -O2 -电荷迁移带吸收)时,样...     

电感耦合等离子体发射光谱法测定水中的总磷

建立了ICP-OES测定水中总磷的方法,并对最佳测试条件的选择进行了探讨.在优化条件下,总磷的校准曲线在0.1010mg/L范围内有良好的线性关系.在低、中、高3个添加水平,总磷的回收率为97.5％-101％,相对标准偏差为1.18％-2.13.本方法检出限为0.012mg/L.     

双硫腙修饰固体银汞合金电极吸附伏安法测定痕量铅

制作了银汞合金电极,在其表面用双硫腙进行修饰,溶液中铅离子与电极表面的双硫腙发生螯合作用被富集。当电极电位在-0.20~-0.70V间进行阴极化扫描时,配合物中铅离子在电极表面被还原,于-0.40V左右形成灵敏的还原峰。选择了反应介质并优化了pH值、双硫腙用量、富集时间等实验参数。利用该修饰电极测定铅的线性范围为0.02~1.2mg/L,检出限为10μg/L。对0.6mg/L Pb2 溶液进行11次平行测定,相对标准偏差为4.1%。该法用于实际水样铅的测定,回收率为94.8%。     

TATP-铜(Ⅱ)-氨基酸配合物的合成及其SOD活性

超氧化物歧化酶(SOD)是清除生物体内O2-的重要防卫,它能有效地催化O2-歧化成O2和H2O2,从而消除O2-对生物体的危害[1-4]。由于天然SOD在稳定性、膜穿透性、生物利用度和免疫原性等方面尚存在着一些限制应用的因素[5],因此模拟SOD活性部位结构且具有清除超氧阴离子自由基功能的小     

Theoretical Studies on Stabilities of C26BN Isomers

The possible stable stractures of substituted fullerene C26BN formed on the initial C28 cage with Td symmetry have been systematically studied on UHF/3-21g level with constrained syrnmetry(Cs or C1, the charge and multiplicity of all the isomers are zero and five, respectively.The geometry optimization and the vibrational frequencies analysis were performed on the same level with constrained symmetry(Cs or C1. The results show that the most stable isomer of C26BN is formed by boron and nitrogen atoms doping at 5,2-sites.     

On piecewise-uniform meshes for upwind- and central-difference operators for solving singularly perturbed problems

Numerical methods composed of upwind-difference operators onuniform meshes are shown analytically to be defective for solvingsingularly perturbed differential equations, in the sense that,as the mesh is refined, the error in the numerical approximationincreases until the mesh parameter has decreased to the sameorder of magnitude as the singular perturbation parameter. Itis also shown that the same is true for upwind-difference operatorson piecewise uniform meshes having a transition point that isdependent solely on the singular perturbation parameter. Itis then shown, with specific analytic examples, that both upwind-and central-difference operators on specially designed piecewise-uniformmeshes give numerical methods which do not suffer from thisdefect. Conditions are also given on the structure of a piecewiseuniform mesh that are necessary if the numerical method, composedof this mesh and an upwind-difference operator, is to be convergentuniformly with respect to the singular perturbation parameter.     

Photo-CIDNP evidence for charge-transfer interaction between synthetic water-soluble porphyrins and guanine

Abstract Photoreactions of aqueous solutions of synthetic water-soluble porphyrins were studied by the ¹H and ¹³C CIDNP technique. Strong polarizations, which were very sensitive to the presence of added acid, were observed on the cationic porphyrins (TMePyPH₂-TAPPH₂) when irradiated through continuous UV-visible light. They resulted from the reverse electron transfer between the semi-oxidized and the semi-reduced species of the derivative. When the experiments were carried out in the presence of nucleobases, guanine (and its derivatives) was the only residue that was polarized. This is thoroughly interpreted in terms of a reversible electron transfer reaction leading to guanine photooxidation by the porphyrin excited triplet state. It was shown to be drastically pH-dependent and was correlated to the redox potential of the porphyrin. It was not affected by the incident wavelength. The reaction proceeded through the intermediate formation of the correlated radical-ion pair: porphyrin radical anion-guanine radical cation. This study suggested that a Type I (free radical) reaction could be one of the primary processes in DNA photosensitization by porphyrins.