声纳图象的特性探讨及相关处理

分析比较了几种经典数字图象处理方法处理声纳图象的效果及其原因，对声纳图象的特性及相应处理作出几点总结。     

当今分子筛发展纵横谈

本文拟从分子筛定义的更新、合成化学、催化进展和在功能材料方面的应用着手,介绍沸石分子筛进展的主要趋势,并提出了对这个学科发展动态的一些认识和设想。     

一类Caputo分数阶微分方程边值问题多解的存在性

研究一类Caputo分数阶微分方程边值问题:{D_0~α+u(t)+f(t,u(t))=0,t∈(0,1),u′(0)=u(1)=0,多解的存在性,其中1α≤2,f:[0,+∞)×R→[0,+∞)是连续的,D_(0+)~α是标准的Caputo微分.先将微分方程边值问题转化为积分方程,再转化为积分算子不动点问题,最后利用Leggett-Williams不动点定理得出Caputo分数阶微分方程边值问题至少有3个正解存在,其中格林函数的性质和非线性项的条件至关重要.     

一类具有非线性密度制约的捕食系统极限环的Hopf分支

本文用定性分析的方法讨论了一类具有非线性密度制约的HollingⅡ型功能反应的食饵-捕食者模型,分析了模型的正平衡点性态,得出了模型的极限环不存在与存在的充分条件,以及在给定参数满足一定条件下,利用Hopf分支理论,得到至少出现两个或三个极限环的充分条件.     

重叠材料的高能X射线双能成像识别技术

在高能(1～10 MeV) X射线双能成像物质识别技术中,为了改善对重叠的被检查物品的识别效果,提出了一种重叠材料选择剥离算法.基于双能X射线物质识别的α曲线模型,比较了材料重叠前后的α曲线从而提出了重新构造遮挡后的α曲线的方法,利用遮挡之后的α曲线对重叠物品进行识别.在9 MeV/6 MeV双能X射线成像样机上对此方法进行了实验验证,将重新构造的遮挡后的α曲线与实验结果进行了对比,对重叠物品进行了识别并统计了识别的正确率.结果表明: 该方法能够有效解决部分重叠物品的识别问题.     

历史城区居民出行活动模式选择影响因素分析

探讨了历史城区内居民出行活动模式选择的影响因素,依据扬州市历史城区居民调查数据,将居民出行活动划分为家-工作/学习(内)-家、家-工作/学习(内)-其他-家、家-工作/学习(外)-家、家-工作/学习(外)-其他-家和家-其他-家5种典型模式.采用多项Logit模型分析了5种活动模式的选择与居民个体及家庭属性之间的关系,并探索了不同活动模式下的出行方式选择情况.结果表明,个体出行者的性别、年龄、职业、有无小汽车和家庭电动自行车数量显著影响着出行活动模式的选择,而家庭人口数、有无学龄前儿童、家庭自行车数、有无摩托车及家庭收入对于历史城区居民出行活动模式选择的影响并不显著.     

Recent progress in thermoelectric materials

Direct conversion of heat into electricity through advanced thermoelectric(TE)materials has been one of the most attractive solutions to the severe environmental and energy issues facing humanity.In recent years,great progress has been made in improving their dimensionless figure of merit(ZT),which determines the conversion efficiency of TE devices.ZT is related to three‘‘interlocked’’factors—the Seebeck coefficient,electrical conductivity,and thermal conductivity.These three factors are interdependent in bulk TE materials,and altering one changes the other two.The difficulty in simultaneously optimizing them caused TE research to stagnate,until great reductions in thermal conductivity were both theoretically and experimentally proven in nanomaterials in 1993.In this review,we first introduce some TE fundamentals and then review the most recently improvements in ZT in different kinds of inorganic and organic TE materials,which is followed by an investigation of the outlook for new directions in TE technology.     

Kinetic study of the DNA annealing properties of RECQ5β helicase

RecQ family helicases are critical for maintaining genomic integrity. Many RecQ family helicases not only unwind duplex, and other more complicated DNA structures, but also possess, interestingly, DNA annealing (strand pairing) activity. Here, we systematically investigated the DNA annealing properties of RECQ5β by measuring DNA annealing kinetics, equilibrium DNA binding, and kinetics of dissociation from ssDNA. RECQ5β catalyzed DNA annealing most efficiently when the enzyme molecules covered approximately 40%-50% of the DNA strand, in the absence or presence of different nucleotide cofactors (AMPPNP, ATPγS, or ADP) under our buffer conditions. A comparative study with RECQ5β1-662 confirmed that the C-terminal region of RECQ5β was essential for its high DNA annealing activity. These results contribute to our understanding of the mechanism of DNA annealing catalyzed by RecQ family helicases.     

京西名刹摩诃庵(Ⅰ)

对京西古刹摩诃庵创建人赵政的生平、寺院建筑布局及特色,以及寺院中珍藏的<集篆三十二体金刚经>刻石,进行了简要地介绍.