阿富汗公路路堑高陡边坡爆破开挖技术

本文论述了高陡路堑爆破开挖中减振技术,通过采用预裂深孔松动控制爆破技术、同段位高段别微差起爆技术,实现了降低爆破震动、控制高程振动放大效应、减轻累积爆破损伤作用,减轻了爆破震动带来的边坡破坏扰动作用,保证了高陡边坡的长期稳定。     

谈数列极限证明中的“放大法”

介绍了既可以简化证明过程、又便于学生接受的一种证明方法--"放大法".通过"放大法"在几个典型例子中的应用,使学生掌握和理解"放大法"在解题中的本质和目的,给极限的证明带来方便.     

科技期刊充实和稳定作者队伍的措施

论述科技期刊充实和稳定作者队伍的措施.科技期刊只有准确定位,特色鲜明,所刊登的论文内容新、水平高,编校质量好,编辑对工作高度负责,对作者亲切、热情,期刊才能赢得作者的首肯,期刊的作者队伍才能稳定并不断充实.     

课堂教学涨落点的创设与效果评价

课堂教学过程本质上是非线性的,具有涨落放大效应。在课堂教学的各个环节创设能促进学生发展的涨落点,并通过建立涨落的相关概念,进一步构建以涨落概念为核心的课堂教学评价体系,可以使课堂教学非线性机制研究从理论形态走向实践应用。     

课堂教学涨落点的创设与效果评价

课堂教学过程本质上是非线性的,具有涨落放大效应。在课堂教学的各个环节创设能促进学生发展的涨落点,并通过建立涨落的相关概念,进一步构建以涨落概念为核心的课堂教学评价体系,可以使课堂教学非线性机制研究从理论形态走向实践应用。     

Characterizing and estimating rice brown spot disease severity using stepwise regression,principal component regression and partial least-square regression

Detecting plant health conditions plays a key role in farm pest management and crop protection. In this study, measurement of hyperspectral leaf reflectance in rice crop (Oryzasativa L.) was conducted on groups of healthy and infected leaves by the fungus Bipolaris oryzae (Helminthosporium oryzae Breda. de Hann) through the wavelength range from 350 to 2 500 nm. The percentage of leaf surface lesions was estimated and defined as the disease severity. Statistical methods like multiple stepwise regression, principal component analysis and partial least-square regression were utilized to calculate and estimate the disease severity of rice brown spot at the leaf level. Our results revealed that multiple stepwise linear regressions could efficiently estimate disease severity with three wavebands in seven steps. The root mean square errors (RMSEs) for training (n=210) and testing (n=53) dataset were 6.5% and 5.8%, respectively. Principal component analysis showed that the first principal component could explain approximately 80% of the variance of the original hyperspectral reflectance. The regression model with the first two principal components predicted a disease severity with RMSEs of 16.3% and 13.9% for the training and testing dataset, respec-tively. Partial least-square regression with seven extracted factors could most effectively predict disease severity compared with other statistical methods with RMSEs of 4.1% and 2.0% for the training and testing dataset, respectively. Our research demon-strates that it is feasible to estimate the disease severity of rice brown spot using hyperspectral reflectance data at the leaf level.     

都支杜鹃ISSR扩增条件的优化

对珍稀濒危物种都支杜鹃的ISSR扩增体系中的Mg2+浓度、dNTP浓度、Taq酶含量和底物含量进行优化,并在优化后的基础上筛选出8条效果较好的引物,在梯度PCR仪中设置温度梯度,找到这些引物的最佳退火温度。优化结果表明,至少在一定的范围内底物浓度和Taq酶含量对PCR反应结果影响不大,相对而言,dNTP浓度和Mg2+浓度对反应结果的影响更加显著。优化后的15 ul PCR反应体系中包括20 ng模板DNA、0.3μM引物、1.5 ul Buffer(Mg2+free),0.5 U Taq酶、1.5 mM MgCl2和0.1 mM dNTP。     

双引物PCR检测抗草甘膦豆粕饲料中的转基因成分

在一个PCR反应体系内,同步扩增大豆内参照基因lec和抗草甘膦大豆外源基因盒中的CaMV35s启动子、nos终止子或cp4 epsps基因,建立转基因大豆双引物PCR检测方法.PCR产物用限制性内切酶酶切进一步鉴定.结果表明,用双引物PCR扩增出标准转基因大豆阳性对照、阿根廷大豆、美国RR大豆及豆粕中的lec基因和相应的特异性外源基因;酶切反应确证PCR产物为特定片段大小的目的序列.建立的双引物PCR法适用于抗草甘膦大豆原料和豆粕饲料中转基因成分的简单化、高精度和高灵敏检测.     

嗜酸乳杆菌培养条件的优化及菌株鉴定

从肠道分离嗜酸乳杆菌,以MRS培养基作为基础培养基,对不同浓度的增殖因子进行筛选,得到了最优的培养基：基础培养基＋5％番茄汁＋0．3％肝浸汁（pH=6．4）。合成嗜酸乳杆菌16S rRNA的特异性引物,并建立了PCR方法从分子水平对其进行鉴定,为嗜酸乳杆菌的深入研究奠定基础。