Process and mechanism of mountain-root removal of the Dabie Orogen—Constraints from geochronology and geochemistry of post-collisional igneous rocks

Systematical studies of post-collisional igneous rocks in the Dabie orogen suggest that the thickened mafic lower crust of the oro- gen was partially melted to form low-Mg# adakitic rocks at 143-131 Ma. Delamination and foundering of the thickened mafic lower crust occurred at 130 Ma, which caused the mantle upwelling and following mafic and granitic magmatic intrusions. Mig- matite in the North Dabie zone, coeval with the formation of low-Mg# adakitic intrusions in the Dabie orogen, was formed by partial melting of exhumed ultrahigh-pressure metamorphic rocks at middle crustal level. This paper argues that the partial melting of thickened lower and middle crust before mountain-root collapse needs lithospheric thinning. Based on the geothermal gradient of 6.6~C/km for lithospheric mantle and initial partial melting temperature of ~1000~C for the lower mafic crust, it can be estimated that the thickness of lithospheric mantle beneath thickened lower crust has been thinned to 〈45 km when the thickened lower crust was melting. Thus, a two-stage model for mountain-root removal is proposed. First, the lithospheric mantle keel was partially removal by mantle convection at 145 Ma. Loss of the lower lithosphere would increase heat flow into the base of the crust and would cause middle-lower crustal melting. Second, partial melting of the thickened lower crust has weakened the lower crust and increased its gravity instability, thus triggering delamination and foundering of the thickened mafic lower crust or mountain-root collapse. Therefore, convective removal and delamination of the thickened lower crust as two mechanisms of lithospheric thin- ning are related to causality.     

玉米幼苗对NaCl胁迫的生理响应和耐受阈值分析

以水培华农5号玉米（Zea mays L.var Huanong 5）幼苗为材料,综合分析了NaCl胁迫条件下幼苗的生理反应变化及其不同组织和生理过程的胁迫耐受阈值.结果表明：玉米叶片对NaCl胁迫最为敏感,耐受阈值约为150 mmol/L,且主要影响因素是气孔限制,非气孔限制因素对NaCl耐受性较强.PSⅡ的耐盐阈值在200～300 mmol/L之间.     

Disaggregation methods to expedite product line forecasting

This paper addresses the issue of forecasting individual items within a product line; where each line includes several independent but closely related products. The purpose of the research was to reduce the overall forecasting burden by developing and assessing schemes of disaggregating forecasts of a total product line to the related individual items. Measures were developed to determine appropriate disaggregated methodologies and to compare the forecast accuracy of individual product forecasts versus disaggregated totals. Several of the procedures used were based upon extensions of the combination of forecast research and applied to disaggregations of total forecasts of product lines. The objective was to identify situations when it was advantageous to produce disaggregated forecasts, and if advantageous, which method of disaggregation to utilize. This involved identification of the general conceptual characteristics within a set of product line data that might cause a disaggregation method to produce relatively accurate forecasts. These conceptual characteristics provided guidelines for forecasters on how to select a disaggregation method and under what conditions a particular method is applicable.     

一类二阶线性泛函微分方程的振动性

本文讨论了二阶线性常系数泛函微分方程的振动性,得到几个简便的判别准则.     

关于不定方程a~x b~y=c~z

设a,b,c都是大于1的正整数,而且(a,b)=(b,c)=(c,a)=1。考虑不定方程 a~x b~y=c~z,x≥0,y≥0,z≥0的整数解。本文给出了方程当max(a,b,c)=15时的全部解,从而得到了当max(a,b,c)≤16时的全部解。     

一道竞赛题的建模方法初探

按照"最优解"、"多种解法"的思路对2000年全国大学生数学建模竞赛B题的建模方法进行探讨,建立了5种模型,并对各种模型进行比较分析,找出了一种较好的模型,并归纳出一般建模方法的要点。重点放在模型建立的过程,至于模型的求解只给出结果。     

曲面上一点的主方向与二次曲线的主方向的关系

为了应用微分几何中关于"曲面上一点的主方向"这部分内容的观点和思想,来改进和完善解析几何中关于"二次曲线的主方向"这部分内容的教学,本文对"二次曲线的主方向"给出了与文献[1]不同的体系,并应用该体系得出了曲面上一点的主方向与二次曲线的主方向的联系曲面上一点的主方向与主曲率也可定义为曲面在该点的杜邦指标线(二次曲线)的主方向和特征根.     

根轨迹的解析研究及几何作图法

利用根轨迹本身的属性将系统的零点极分布情况简化归类,使之适用于解析研究,并对二阶系统及其他一些低阶系统的根轨迹形状,给出了几何作图方法。     

关于 F-正则 Γ-环的特征和结构

对 F-正则Г-环的性质作了初步探讨,并证明了任-Г-环恒同构于诸亚直不可约的Г-环的一个亚直和,这个结果是经典环论中著名的 Birkhoff 定理在Г-环中的推广.从而得到了 F-正则Г-环新的特征、刻画和较精细的结构定理.     

缓冲液浓度及洗涤时间对玉米根细胞质膜氧化还原活性的影响

本文阐述了玉米(Zea mays L.掖单2号)离体根氧化还原活性与缓冲液浓度及洗涤时间之间的相互关系,并测定了呼吸速率和ATP含量的变化。