表面粗糙度变化对近地层大气的影响——(Ⅰ)—风速和剪应力变异

本文系统地分析了任意分布的表面粗糙度变化,对三维和二维大气边界层近地风速和剪应力的影响,提出了一个四层结构的线性理论.由该理论得到的解与已有的结果符合得很好.

Effect of SiO2 protective layer on the femtosecond laser-induced damage of HfO2/SiO2 multilayer high-reflective coatings

Two kinds of HfO2/SiO2 800 nm high-reflective (HR) coatings, with and without SiO2 protective layer were deposited by electron beam evaporation. Laser-induced damage thresholds (LIDT) were measured for all samples with femtosecond laser pulses. The surface morphologies and the depth information of all samples were observed by Leica optical microscopy and WYKO surface profiler, respectively. It is found that SiO2 protective layer had no positive effect on improving the LIDT of HR coating. A simple model including the conduction band electron production via multiphoton ionization and impact ionization is used to explain this phenomenon. Theoretical calculations show that the damage occurs first in the SiO2 protective layer for HfO2/SiO2 HR coating with SiO2 protective layer. The relation of LIDT for two kinds of HfO2/SiO2 HR coatings in calculation agrees with the experiment result. (c) 2006 Elsevier B.V. All rights reserved.

河鲈锚首吸虫及其宿主鳜鱼组织器官中铅含量的比较

利用原子吸收分光光度计分析了寄生鳜鱼（Sinipercachuatsi）鳃部的河鲈锚首吸虫（Ancyrocephalusmogurndae）及其宿主组织器官，包括肌肉、鳃、头肾和肝脏的铅含量.结果表明，来自三湖连江水库和牛山湖两个采样点的河鲈锚首吸虫的铅含量都显著地高于其宿主组织器官中的铅含量.在所检测的宿主组织器官中，肝脏的铅含量最高，在两个采样点分别为0.138和0.114μg/g（湿重）.河鲈锚首吸虫富集铅的机理及其较高水平铅含量的特点是否与其体外寄生的特性有关，尚有待于进一步研究.

基于网格技术的密码学计算平台的设计

结合现有的网格技术、思想和密码计算的特点,分析了利用网格技术实现密码学计算的可行性,并结合J2EE开发方式的优势实现系统支持,最后提出了一种有效的、可行的密码计算网格平台构架.

Enhanced photocatalytic activity of TiO2 nano-structured thin film with a silver hierarchical configuration

TiO2 sol-gels with various Ag/TiO2 molar ratios from 0 to 0.9% were used to fabricate silver-modified nano-structured TiO2 thin films using a layer-by-layer dip-coating (LLDC) technique. This technique allows obtaining TiO2 nano-structured thin films with a silver hierarchical configuration. The coating of pure TiO2 sol-gel and Ag-modified sol-gel was marked as T and A, respectively. According to the coating order and the nature of the TiO2 sol-gel, four types of the TiO2 thin films were constructed, and marked as AT (bottom layer was Ag modified, surface layer was pure TiO,), TA (bottom layer was pure TiO,, surface layer was Ag modified), TT (pure TiO, thin film) and AA (TiO, thin film was uniformly Ag modified). These thin films were characterized by means of linear sweep voltammetry (LSV), X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy and transient photocurrent (I-ph). LSV confirmed the existence of Ago state in the TiO, thin film. SEM and XRD experiments indicated that the sizes of the TiO,, nanoparticles of the resulting films were in the order of TT > AT > TA > AA, suggesting the gradient Ag distribution in the films. The SEM and XRD results also confirmed that Ag had an inhibition effect on the size growth of anatase nanoparticles. Photocatalytic activities of the resulting thin films were also evaluated in the photocatalytic degradation process of methyl orange. The preliminary results demonstrated the sequence of the photocatalytic activity of the resulting films was AT > TA > AA > TT. This suggested that the silver hierarchical configuration can be used to improve the photocatalytic activity of TiO2 thin film.

稠油热采井数值试井新方法

稠油热采使得地层中的温度发生变化，从而导致地层中流体性质参数在地层中存在一定分布，其中对于无限大稠油藏和圆形稠油油藏中的两区同心圆分布和三区同心圆分布已经研究的比较成熟。但是对于任意形状稠油区域中的径向分布目前研究还较少，而且用一般解析或半解析方法都较难获得理论解。同时随着稠油热采的深入进行，地层温度大多不再是按径向分布的，而且存在部分高温条带。这时用目前所建立的热采试井模型进行解释会产生较大误差，因此建立了热采井数值试井的新方法。主要解决了以下两方面的问题：(1)复杂外边界条件下流体参数呈多区径向分布时的热采井试井资料解释方法问题；(2)复杂边界条件下流体参数呈条带分布时的热采井试井分析方法。所建立的模型已通过其简化形式与解析解进行对比并获得一致性结果。文中给出了现场实际解释的例证。\newline 建立了复杂边界条件下热采井的数值试井模型，并利用非结构化网格生成技术对求解区域进行划分，通过有限元方法计算出了流体参数径向分布和条带分布条件下的试井理论曲线，分析了理论曲线在不同外边界及不同流体参数分布下的特征，以及非牛顿流幂律指数、流度比、热采前缘位置等因素的影响。通过模型简化形式的计算结果与解析解的对比说明了数值计算的正确性，并给出了现场实例分析。分析得到了地层压力、渗透率、热采前缘位置、不同区域的稠油流体参数分布、井筒存储以及表皮效应等参数。\newline 从地下流体渗流场的热－流耦合理论出发，所建立和求解的新的不定常流动模型，解决了稠油油田热采开发过程中，通过油气井单点测试进行地层评价的技术难题，为稠油油田热采开发方案的调整提供了有力的技术保障。

新兴电子商务中的安全问题

全球经济发展已逐渐步入信息经济时代,电子商务已迅速发展成为推动社会经济发展的重要力量。我国电子商务的发展已初具规模,并呈现大规模、跨行业、跨组织的发展趋势。但其发展也正面

Altitudinal differences in the leaf fitness of juvenile and mature alpine spruce trees (Picea crassifolia)

In many plant species, leaf morphology varies with altitude, an effect that has been attributed to temperature. It remains uncertain whether such a trend applies equally to juvenile and mature trees across altitudinal gradients in semi-arid mountain regions. We examined altitude-related differences in a variety of needle characteristics of juvenile (2-m tall) and mature (5-m tall) alpine spruce (Picea crassifolia Kom.) trees growing at altitudes between 2501 and 3450 m in the Qilian Mountains of northwest China. We found that stable carbon isotope composition (delta C-13), area- and mass-based leaf nitrogen concentration (N-a, N-m), number of stomata per gram of nitrogen (St/N), number of stomata per unit leaf mass (St/LM), projected leaf area per 100 needles (LA) and leaf mass per unit area (LMA) varied nonlinearly with altitude for both juvenile and mature trees, with a relationship reversal point at about 3 100 m. Stomatal density (SD) of juvenile trees remained unchanged with altitude, whereas SD and stomatal number per unit length (SNL) of mature spruce initially increased with altitude, but subsequently decreased. Although several measured indices were generally found to be higher in mature trees than in juvenile trees, N-m, leaf carbon concentration (C.), leaf water concentration. (LWC), St/N, LA and St/LM showed inconsistent differences between trees of different ages along the altitudinal gradient. In both juvenile and mature trees, VC correlated significantly with LMA, N-m, N-a, SNL, St/LM and St/N. Stomatal density, LWC and LA were only significantly correlated with delta C-13 in mature trees. These findings suggest that there are distinct ecophysiological differences between the needles of juvenile and mature trees that determine their response to changes in altitude in semi-arid mountainous regions. Variations in the fitness of forests of different ages may have important implications for modeling forest responses to changes in environmental conditions, such as predicted future temperature increases in high attitude areas associated with climate change.

湖北恩施表生高硒环境中有机结合态硒的形态研究

硒是人体和动物必需的微量元素，摄入过高或过低均可导致不同的健康效应。已有的研究表明，硒的生物有效性不仅与地质环境中的总硒有关，更取决于硒的形态分布。不同形态的硒具有显著差异的地球化学特性，影响着环境中硒的迁移、循环、生物有效性和毒性。渔塘坝是中国唯一发生过人群硒中毒爆发性流行的地区，该地区风化富硒碳质岩和高硒土壤中有机结合态硒可达到总硒的60%以上，而有机结合态硒的进一步研究有助于深入了解硒的分布和生物可利用性，阐明富硒碳质岩风化及其成土过程中硒的生物地球化学次生富集过程与循环机制。本论文利用改进的7步连续化学浸提技术和优化的有机结合态硒提取方案，使用氢化物发生－原子荧光光谱法，研究了恩施表生高硒环境中有机结合态硒的形态分布，得出了以下几点结论： 1. 在硒七步连续提取方案的基础上，对影响硒提取的因素如液固比、提取剂浓度等进行了优化、并对不同结合态（相态）硒提取中的若干问题进行了讨论。研究结果表明，硒的连续化学提取过程中，液固比为20:1到50:1时能够满足不同结合态硒提取的要求；在水浴加热条件下，NaOH浓度0.1M～0.5M时能有效提取有机结合态硒；1M Na2SO3溶液是元素硒的较好提取剂；而对于硫化物/硒化物结合态硒，合适配比的NaOH＋H2O2混合液有利于H2Se的完全吸收，500～600mL/min的载气气流能保证其被CrCl2+HCl混合液还原所产生H2Se气体的完全吸收。 2. 利用优化的连续化学浸提方案提取风化富硒碳质岩石和高硒土壤样品的有机结合态硒，进而分离出富里酸硒和胡敏酸硒，并用高压密闭消化－氢化物原子荧光光谱法测定了硒的含量。该方案的回收率为84.4～104.2%，平均回收率为96.1%；有机结合态硒与胡敏酸富里酸硒加和值之间有良好的一致性，线性相关系数为0.999（n＝14），斜率为1.0026。而后使用自制的氢化物反应发生和吸收装置进一步分离了与富里酸（胡敏酸）吸附的Se(IV)和强结合的硒，其中分离富里酸硒的回收率为86.3%～107.6%，平均值为97.1%；分离胡敏酸硒的回收率为85.5%～105.9%，平均值为97.9%。表明本论文所采用的实验方案是切实可行的。 3. 风化富硒碳质岩石样品中胡敏酸硒比例较高，所占比例为36.3%～75.8%，平均值为58.1%，但胡敏酸硒并不是占有绝对的优势，且各个样品之间存在较大差异。高硒土壤样品中富里酸硒占有机结合态比例在25.4%～85.0%，除个别样品外，多数样品的富里酸硒所占比例均在70%～80%，表明富里酸硒是渔塘坝土壤有机结合态硒的一种主要存在形式，在适当的条件下（如环境的pH-Eh变化），能够被转化从而被植物吸收利用。并且这种岩石中胡敏酸硒含量高、土壤中富里酸硒含量高的分布特征指示了硒在风化过程中可能的迁移和转化规律。 4. 富里酸硒和胡敏酸硒的形态分析表明，不同岩石样品中各有机结合态硒的形态分布差异较大，分布规律不明显，这可能与岩石样品的风化程度有关；而对于土壤样品，不论是在富里酸还是胡敏酸中，吸附Se(IV)的含量都大于强结合硒，尤其是富里酸中的吸附Se(IV)，平均值为83.4%，最高达95.4%。这部分吸附的Se(IV)相对于强结合的富里酸硒更容易被释放，而这也进一步佐证了富里酸硒易于受环境变化（pH-Eh）和倍半氧化物等的影响而转变为生物可利用态硒。 5. 无论是胡敏酸强结合硒（HA-Se）还是富里酸强结合硒（FA-Se）均在有机结合态硒中以一定的比例存在，对这部分硒的研究还仅局限于定量，而其究竟是以何种形态、以何种方式与腐殖质结合尚不清楚。因此，有必要对这部分硒进行进一步研究。