对流扩散方程的三阶迎风格式的数值摄动高精度重构

利用高智提出的数值摄动算法,把求解对流扩散方程常用三阶迎风格式(3-UDS)(粘性项和对流项分别用二阶中心格式和3-UDS离散)进行了高精度重构,包括使用离散单元内所有节点的全域重构和分别使用上下游节点的上下游重构,得到两类新的更高阶精度迎风差分格式,称为高的迎风差分格式(记作GUDS)。讨论了GUDS的数学性质,GUDS比原来的3-UDS精度显著提高;全域重构的GUDS和3-UDS均为条件稳定,一些上下游重构GUDS为绝对稳定。本文通过稳定性分析和四个算例(一维常系数、变系数、非线性及二维变系数对流扩散方程)的计算证实了GUDS的优良性质。上下游重构GUDS为避免在3-UDS中使用人工粘性提供了一条有效途径,适合于求解高Reynolds数线性和非线性问题。

Probing into the catalytic nature of Co/sulfated zirconia for selective reduction of NO with methane

In this work, the structural and surface properties of Co-loaded sulfated zirconia (SZ) catalysts were studied by X-ray diffraction (XRD), N-2 adsorption, NH3-TPD, FT-IR spectroscopy, H-2-TPR, UV-vis diffuse reflectance spectroscopy (DRS), X-ray photoelectron spectroscopy (XPS), and NO-TPD. NH3-TPD and FT-IR spectra results of the catalysts showed that the sulfation process of the support resulted in the generation of strong Bronsted and Lewis acid sites, which is essential for the SCR of NO with methane. On the other hand, the N-2 adsorption, H-2-TPR, UV/vis DRS, and XPS of the catalysts demonstrated that the presence of the SO42- species promoted the dispersion of the Co species and prevented the formation Of Co3O4. Such an increased dispersion of Co species suppressed the combustion reaction of CH4 by O-2 and increased the selectivity toward NO reduction. The NO-TPD proved that the loading of Co increased the adsorption of NO over SZ catalysts, which is another reason for the promoting effect of Co. (C) 2004 Elsevier Inc. All rights reserved.

Study on conical columns for semi-preparative liquid chromatography

The dynamic flow profiles and column efficiencies in conically shaped semi-preparative liquid chromatographic columns (inlet ID larger than outlet ID) with two different conical angles (7degrees and 15degrees) were studied. The dynamic flow profiles were studied by an on-column visualization method. Conical columns were compared with cylindrical column of the same length and internal volume. The results showed that the flow profile of a sample band in the conical column of 7degrees (50 mm x 17 mm --> 11 mm ID) was parabolic in shape. The sample band migrated slower in the wall region than in the central region, as in the cylindrical column (50 mm x 14 mm ID). However, the sample band in the conical column of 15degrees (50 mm x 20 mm --> 7 mm ID) migrated slower in the central region than in the wall region, resulting in a reverse parabolic flow profile, in contrast to that in cylindrical column. This indicated that a flat flow profile might be realized in a conical column with a conical angle between 7degrees and 15degrees. The conical column of 15degrees had the highest column efficiency among the three columns under the same conditions. Compared with the cylindrical column packed with identical packing material, the conical column of 15degrees had 22%-45% higher column efficiency and 11%-27% higher peak height.

东北地区生态环境中的Se及其生态效应

对东北地区不同环境要素（基岩、土壤、植物、动物和人体）Ｓｅ的分布与转化规律的研究表明，基岩、土壤、粮食和动物毛Ｓｅ含量分别为０．１２、０．１５０－０．５４０、０．００９６－０．０７６５和０．０４０５－０．１４１４μｇ·ｇ（－１）；城市和农村儿童发Ｓｅ含量为０．４６０和０．１８２μｇ·ｇ（－１）．根据不同要素Ｓｅ含量和生态效应，可将该区分为Ｓｅ适宜区、缺乏区和过渡区３个１级区．每个１级区又分为高Ｓｅ源区和低Ｓｅ源区．

Evaluation of the interaction between netropsin and double stranded DNA by capillary zone electrophoresis

Capillary zone electrophoresis (CZE) was applied to study the interaction between netropsin and a 14mer double stranded DNA (dsDNA). The binding constant of this interaction calculated from Scatchard plot was (1.07+/-0.10) X 10(5) (mol/L)(-1). The binding stoichiometry was 1:1. The use of polyacrylamide coated capillary showed better effect in the analysis of DNA than noncoated capillary.

基于QuickBird卫星影像的沈阳城市绿地景观格局梯度分析

基于2006年QuickBird卫星影像数据解译的沈阳城市绿地分布图,在GIS的支持下,通过幅度效应的研究,在确定出研究区的适宜幅度为5 km的基础上,应用梯度分析与景观指数相结合的方法,研究了沈阳城市绿地景观结构及其梯度上的空间特征。结果表明:类型水平上,不同的绿地类型沿景观格局梯度表现出明显的空间特征;在城市中心,公园绿地为优势类型,而在郊区,农业用地为优势类型;城市绿地整体上破碎化程度高,绿地斑块形状较为复杂;景观水平上,不同景观指数沿样带梯度表现出差异性,表明城市化导致景观的破碎化程度增大,景观异质性增高;斑块密度、景观形状指数和景观聚集度指数具有明显的梯度特征,而最大斑块指数、多样性指数则不明显;景观格局指数和梯度分析相结合是研究城市绿地空间的有力工具。

宁夏黄土区不同植物群落土地利用方式对土壤质量的影响

本文研究了宁夏南部山区典型植物群落土地不同利用方式下土壤质量的变化。结果表明:(1)典型长芒草群落土地,开垦地比封禁地土壤有机质、全氮、全磷、速效氮、速效磷、速效钾养分含量明显降低,降低幅度分别为19.5%、20.1%、17.6%1、3.0%、77.8%和47.5%。脲酶活性为开垦地>封禁地,蔗糖酶则表现为封禁地>开垦地,中性磷酸酶差异不明显。(2)铁杆蒿群落土地三种利用方式下:放牧地土壤有机质、全氮、全磷、速效钾等养分含量较封禁地与开垦地有一定幅度的增加;放牧地的土壤脲酶、蔗糖酶和中性磷酸酶活性均高于封禁和开垦的同土层土壤,封禁地的脲酶和蔗糖酶次之,开垦地的脲酶和蔗糖酶活性最小,开垦地的中性磷酸酶活性高于封禁地。脲酶活性在土层之间变化较小,最高为放牧地表层177.6 mg/(kg.h),最低为开垦地表下层114.5 mg/(kg.h),蔗糖酶活性层次之间变化明显,其中放牧地表层为表下层的3倍左右。长芒草群落土壤表层各级微团聚体表现为封禁地远大于开垦地,铁杆蒿群落土地不同利用方式下各级微团聚体表现不同,结构系数表现为表层>表下层,保持率则为表层<表下层。结构系数与保持率均表现为封禁地>放牧地>开垦地。(3)在...

硫酸盐还原菌对水解聚丙烯酰胺黏度的影响

目的:研究硫酸盐还原菌对油田驱油用水解聚丙烯酰胺体系黏度的影响。方法:以油田回注水配制不同分子量的HPAM溶液,考察硫酸盐还原菌在不同分子量聚合物中的生长繁殖情况及对HPAM溶液黏度的影响。结果:中分、高分、超高分HPAM-采出水体系初始黏度为21.7、25.4、38.9mPa·s,低于灭菌处理的23.0、27.8、45.8mPa·s。上述体系黏度在24h内明显下降。SRB的数量也由初始的3.0×103cfu/mL降低至10～102cfu/ml。结论:短期内SRB对高浓度的HPAM降解作用有限。SRB培养物中的Fe2+是造成HPAM黏度下降的主要原因。SRB对HPAM黏度的影响是间接的。

慢生大豆根瘤菌(Bradyrhizobiumjaponicum)聚羟丁酸合成酶基因(phbC)的克隆和序列测定

以苜蓿根瘤菌Rm10 2 1的 phaC基因突变体菌株Rm1114 4 (phaC ::Tn5 - 2 33)为受体菌 ,通过功能互补 ,成功地从构建的Bradyrhizobium japonicum USDA110基因文库中 ,筛查到能与Rm1114 4互补 ,使之恢复在以乙酰乙酸为唯一碳源的M9培养基 (M9-AA)平板上 5d形成明显可见菌落 ,以及在MOPS平板上形成粘液型菌落的表型的重组粘粒 pDC2 ;经证实 ,该粘粒带有 phbC基因 .完成了该基因的全序列测定并已在GenBank登记 ,登记号为AY0 775 80 .B .japonicumphbC基因由 180 3碱基对组成 ,GC含量 6 1.8% ,AT含量 38.2 % ;编码 6 0 0个氨基酸 ,Mr=6 6 .95× 10 3 .图 3表 3参 13

森林冠层上湍流尺度、耗散率和湍流结构参数

利用新型三维超声风速 温度仪 ,在中国东北长白山原始森林冠层以上观测的湍流资料 ,计算并分析了森林冠层上的湍涡特征长度尺度、湍流动量和热量耗散率、湍流动量和热量结构参数的特征。结果表明 :湍流动量湍涡特征长度尺度与稳定度参数Z L成正相关 ;湍流热量特征长度尺度与稳定度参数Z L在不稳定层结时 ,成正相关 ,在稳定层结时近似成负相关 ;在不稳定和稳定层结大气中 ,利用湍流谱方法和利用风速垂直分量方差、温度脉动方差和Richardson数计算的湍流动量、热量耗散率和湍流动量、热量结构参数有较好的一致性 ;无量纲湍流结构参数C2vz2 3 σ-2w和C2Tz2 3 σ-2T 是Richardson数的函数 ;湍流热力结构参数C2T 与感热通量w′T′具有较好的线性关系。