XML技术与数据库之间的转换方法

作为一种与平台无关的描述性语言，XML以其高度的可扩展性而被广泛应用。XML的数据特性使其与数据库的关系日益密切。在关系数据库与XML之间存在着一种映射规则。     

三清山土壤及其利用

通过多年的野外实地考察，对三清山地区土壤类型、剖面形态特征及垂直带谱作了较为细致的研究，为了解三清山土壤资源及其分布，进行教学实习基地建设提供了详实资料。     

一类高阶迭代边值问题的正解

基于Krasnosel'skii不动点定理考虑了一类四阶迭代边值问题u'(t)=f(t,u(t),u(αu(t))),0≤t≤1,u(0)=u'(0)=u'(1)=u'(1)=0正解的存在性.通过估计解的界,获得了上述边值问题分别存在和不存在正解的几组充分条件.最后给出例子说明了主要结果的可行性.     

Numeration and type synthesis of 3-DOF orthogonal translational parallel manipulators

Low-degree-of-freedom （Low-DOF） parallel manipulators （PMs） have drawn extensive interests, particularly in type synthesis in which two main formal approaches were established by using the reciprocal screw system theory and Lie group theory. This paper aims at numeration and type synthesis of orthogonal translational parallel manipulators （OTPMs） by resorting to an integration of the group- based method and graphical representation of the topology. For this purpose, the concept of Cartesian DOF-characteristic matrix, orig- inated from displacement subgroup and displacement submanifold, is proposed. A new approach based on the combination of the atlas of Cartesian DOF-characteristic matrix and the displacement group-theoretic method is addressed for both exhaustive classification and type synthesis of OTPMs. The proposed approach is prone to construct an orthogonal structure and is easy to realize the complete classification and exhaustive enumeration of this class of low-DOF PMs.     

Dark current mechanism of unpassivated mid wavelength type II InAs/GaSb superlattice infrared photodetector

We investigate the dark current mechanism for an unpassivated mid wavelength(MW) type II InAs/GaSb superlattice infrared photodetector by doing the variablearea diode tests. The bulk resistance-area product and the resistivity due to the surface current are determined to be17.72 X cm2 and 704.23 X cm at 77 K, respectively. It is found that for all the mesa sizes used, the dark current is dominated or predominated by the surface component, and with scaling back the mesa size, the surface current increases while the bulk component decreases. The activation energy is determined to be 145 meV for the temperature range around 140–280 K, while it is 6 meV when temperature is below 100 K. It is also found that the dark current is dominated by the generation-recombination current for the MW device when temperature is between140 and 280 K.     

Investigation and identification of breath acetone as a potential biomarker for type 2 diabetes diagnosis

Acetone is regarded as a promising biomarker for the noninvasive diagnosis and monitoring of diabetes.We collected breath acetone from 25 type 2 diabetics(T2D)and 44 healthy subjects using aluminum foil bags(3 L),and the samples were analyzed by gas chromatography–mass spectrometry.T2D patients had significantly higher acetone levels(mean=2.167 ppmv(1 ppmv=1 lL/L),standard error(SE)=0.231)than healthy volunteers(mean=0.488 ppmv,SE=0.025;P\0.0001).The receiver operating characteristics curve showed that the optimum diagnostic cutoff value for exhaled acetone was 0.891 ppmv(area under the curve 0.999,sensitivity 100%,and specificity 97.7%)in T2D patients relative to healthy subjects.Thus,breath acetone could be a useful marker for the high accuracy diagnosis and monitoring of diabetes.In addition,the ratios of the mean acetone concentration in ambient air relative to that in the total exhaled air and in the net exhaled air were 1:18 and 1:17,respectively.The post-breakfast acetone concentrations(mean=0.437 ppmv,SE=0.035)were slightly lower than the pre-breakfast levels(mean=0.553 ppmv,SE=0.047;P[0.05).Thus,the increased acetone concentrations in T2D patients are affected strongly by physiological factors related to the disease,rather than the ambient air and diet.     

科技论文标题的英译

本文论述了科技论文标题几种常见的类型,如词组型标题、动宾型标题、动宾偏正结构标题、陈述句标题等及它们的译法,并指出了需加注意的要点.     

定时截尾样本数据有缺失情形下单参数对数正态分布的参数估计

主要讨论了在定时截尾样本数据有缺失情形下单参数对数正态分布的参数估计问题,并用极大似然估计的方法对其参数σ进行了估计,最后得出了σ的估计值σ．     

外国留学生动宾式离合词的两类偏误分析

外国留学生在动宾式离合词习得的偏误中,A类偏误跟B类偏误有显著性差别。中介语和实验都表明,总偏误率随着学习阶段的上升而降低,且各阶段偏误率差异显著,但A类偏误率没有随着总偏误率降低而降低;A类偏误率显著高于B类偏误率。AB两类偏误率的这种对比关系跟学习阶段、母语背景均不相关,尽管总偏误率各阶段差异显著。因此,在习得难度上,无论对哪个阶段哪种母语背景的留学生来说,A类扩展成分的习得要难于B类扩展成分的习得,教学的重点也就应该放在A类扩展成分的使用上。     

小型猪2 型糖尿病模型研究进展

摘要: 小型猪在生理学、解剖组织学、饮食结构和营养代谢等方面与人高度相似,已成为人类疾病模型研究的关注热点。本文在简要介绍2 型糖尿病发生机制和啮齿类动物模型的局限后,重点阐述了高脂高能量饮食和药物诱导小型猪2 型糖尿病模型的特点,及基因工程小型猪模型的研究进展和存在不足,并对小型猪2 型糖尿病模型的发展进行了展望。