城市街道灰尘重金属类环境激素镉污染及防治对策

通过对城市街道灰尘重金属镉污染状况、潜在危害和防治对策等进行分析研究,发现城市街道灰尘重金属镉污染的来源较复杂,镉通常呈现在汽油、润滑油、工业和焚烧炉的排放物里;城市街道灰尘重金属镉污染危害人类的身体健康,破坏生态系统;城市街道灰尘重金属镉污染研究为城市生态环境调控及城市的可持续发展提供基础资料和科学决策依据;提高人们加强防治镉污染,保护生态环境的意识.     

超凸度量空间中的极大极小不等式和拟变分不等式

用连续迭取方法得到了超凸距离空间上集值映射的一个不动点定理。作为应用，给出了超凸距离空间中的一个极小极大定理和广义拟变分不等式解的一个存在性定理。     

基于中期基准面旋回变化的沉积微相精细研究——以松辽盆地扶余油田泉四段为例

 从区域沉积背景出发,以岩心和测井资料分析为基础,对松辽盆地扶余油田泉四段的岩石类型、粒度分布、沉积构造、泥岩颜色及地球化学特征等各类沉积相标志进行分析,确定其为三角洲沉积,包含三角洲平原和前缘亚相。其中,平原亚相可识别出分支河道、决口扇、天然堤、废弃河道、湖泊沼泽微相;前缘亚相可细分为水下分支河道、河口坝、远沙坝、水下天然堤和支流间湾等微相。依据沉积微相与地层格架的成因关系,在中期基准面旋回的控制下应用取心关键井建立了沉积微相的定量识别图板,对非取心井进行沉积微相的定量识别与划分,并在此基础上绘制了沉积微相的平面及剖面图,总结了微相类型的平面和纵向展布规律及其与含油性的关系,指出分支河道砂体发育规模、连续性、储集性、含油性最好,其次为河口坝砂体,为研究区下一步的开发方案提供地质依据。     

Fingerprints of global warming on wild animals and plants

Over the past 100 years, the global average temperature has increased by approximately 0.6 degrees C and is projected to continue to rise at a rapid rate. Although species have responded to climatic changes throughout their evolutionary history, a primary concern for wild species and their ecosystems is this rapid rate of change. We gathered information on species and global warming from 143 studies for our meta-analyses. These analyses reveal a consistent temperature-related shift, or 'fingerprint', in species ranging from molluscs to mammals and from grasses to trees. Indeed, more than 80% of the species that show changes are shifting in the direction expected on the basis of known physiological constraints of species. Consequently, the balance of evidence from these studies strongly suggests that a significant impact of global warming is already discernible in animal and plant populations. The synergism of rapid temperature rise and other stresses, in particular habitat destruction, could easily disrupt the connectedness among species and lead to a reformulation of species communities, reflecting differential changes in species, and to numerous extirpations and possibly extinctions.     

标量FDTD法分析渐变折射率光波导模场分布

用标量时域有限差分法（Finite-differece Time-domain Method,FDTD法）分析了渐变折射率平面光波导中基模的模场分布情况，采用平面光波、球面光波、高斯光波等5种不同形态的光波激励同一波导，借助计算机进行数值求解，得到的光场分布图在光场传播达到稳定后完全相同，说明波导的模式与光波形态无关，只与波导结构和光波波长有关，结果表明该方法直观、精确、快速，并与解析法分析的结果一致。     

基于单调链的平面型腔行切加工轨迹生成算法

针对平面型腔行切加工刀具轨迹生成中如何合理而最大程度地减少在加工刀具轨迹中产生的跳刀动作的次数，提出了一种基于单调链技术的行切刀具轨迹生成算法，从而使对给定平面型腔而产生的行切刀具轨迹最大程度地减少了跳刀动作的次数，而且针对给定的复杂平面型腔，该算法可以预先分析出可能产生的最大跳刀次数，这一算法已在实际开发的CAM系统中成功实现。     

EB病毒及化学致癌物DNP对人胚鼻咽粘膜裸鼠移植的诱癌研究

用EBV,DNP及PMA分别或协同对人胚鼻咽粘膜裸鼠移植物进行诱癌研究,探讨上述因素在人实验性鼻咽癌发生中的作用。免疫荧光法检查证实,经B95-8上清液体外及体内转染的人胚鼻咽粘膜上皮表达EBNA。实验结果显示,实验各组均可见各种增生性改变,对照组仅见一般增生性病变。各诱癌组均可见癌前病变,组间无显著性差异。共出现癌8例(1)EBV组:原位癌1例。 (2)EBV+PMA组:早期浸润癌1例。(3)EBV+DNP组:原位癌及浸润癌各1例。(4)EBV+DNP+PMA组:浸润癌1例。 (5)DNP组:原位癌1例。(6)DNP+PMA组:原位癌及浸润癌各1例。结果提示EBV可能在人鼻咽上皮实验性癌变过程中起病因作用。本研究成功诱发了三例浸润癌,均系DAP与其它因素(PMA、EBV)协同作用,提示人鼻咽癌的发生可能与多种致癌因素的相互作用有关。     

管内流动换热过程的性能综合分析

基于管内流动换热方程,在最小初投资的条件下导出经济合理的管长、管径比与换热参数的关系式.同时对管内流动换热过程进行火用分析,得出火用损失率最小的最佳运行参数(Reopt),以及由换热准则关系式得出的最佳换热参数(Stopt),最后得到使管内流动换热过程的结构、流动与换热性能综合优化的管长管径比.     

Symmetrical directional cloning: An efficient method to prepare hairpin RNA interference constructs

RNA interference (RNAi) is a loss-of-function approach by which double-stranded RNA (dsRNA) initiates degradation of homologous mRNAs in a sequence specific manner. The dsRNA molecules can be produced in vitro or in vivo, and can be introduced to cells in a number of ways. Here we report a more efficient method for the cloning of inverted repeat DNA fragments into expression vectors that can be transcribed into effective dsRNA molecules in vivo or in vitro. This method, named Symmetrical Directional Cloning (SDC), takes the advantage of compatible non-palindromic restriction enezyme sites, which allow one to directionally clone a single PCR product in both the sense and antisense orientations together into a vector. SDC allows for the directional cloning of inverted repeats using a single PCR product; it requires only one cut site on each side of the loop. Hence this method is more cost effective and less time-consuming. At least 21 commercially available restriction endonucleases can be used as cloning sites for the SDC method. The efficacy of dsRNA expression vectors prepared by SDC has been demonstrated by targeting a negative regulator of the signaling pathway mediating the response of cells to phytohormone, gibberellins (GA), in the aleurone cells.