量子能谱中的长程关联

从可积系统求迹公式出发 ,运用Einstein Brillouin Keller(EBK)量子化条件 ,导出了二维无关联振子系统周期轨道作用量量子化条件 ,由此发现了量子能级与周期轨道之间的对应关系 .这种对应关系表明 ,如果两条能级对应的周期轨道的拓扑相同 ,这两条能级对回归函数的贡献相干 .回归谱中的一个峰是量子能谱中一组与具有相同拓扑的周期轨道相对应的能级之间相干的结果 ,这一组能级间存在着长程关联 .

Alpha decay half-lives of new superheavy elements through quasimolecular shapes

The lifetimes of alpha decays of the recently produced isotopes of the elements 112, 114, 116 and the element (294)118 and of some decay products have been calculated theoretically within the Wentzel-Kramers-Brillouin approximation. The alpha decay barriers have been determined in the quasimolecular shape path within a generalized liquid drop model including the proximity effects between nuclei in a neck, the mass and charge asymmetry and the precise nuclear radius. These calculations provide reasonable estimated for the observed alpha decay lifetimes. The calculated results have been compared with the results of the density-dependent M3Y effective interaction and the experimental data. It is indicated that the theoretical foundation of the generalized liquid drop model is as good as that of the microscopic DDM3Y model, at least in the sense of predicting the T-1/2 values as long as one uses a correct alpha decay energy. The half lives of these new nuclei are well tested from the consistence of the macroscopic, the microscopic and the experimental data.

基于RS与GIS的乔木层物种多样性分布格局——以辽东山区水源涵养林为例

根据ETM+遥感影像与实地考察数据,通过建立乔木层物种多样性反演模型及模型地面验证等方法,对辽东山区水源涵养林乔木层物种多样性分布格局及其在不同海拔高度和坡向上的分布状况进行了研究。结果表明:归一化植被指数(NDVI)、湿度(TC3)和绿度(TC2)与Shannon-Wiener多样性指数相关性较高,3个植被指数与Shannon-Wiener多样性指数的回归模型可靠(R2=0.637,P<0.01)。地面验证结果表明,模型能解释乔木层物种多样性的69.38%;乔木层物种多样性指数主要集中在1.0~2.2,并符合"中间海拔高度膨胀"理论;坡向对乔木层物种多样性分布的影响体现在东北坡出现高物种多样性的可能性最大,验证了由于坡向导致的水热差异,从而影响物种多样性的结论。

森林生态系统健康评估Ⅰ.模式、计算方法和指标体系

生态系统健康评估是 2 1世纪生态系统学研究的主要内容和迫切任务之一 .简单实用的生态系统健康评估理论和方法需要可操作性的概念和一个全面、简明、易操作且规范化的指标体系 ,它们是进行生态系统健康评估的基础 .以阔叶红松林生态系统为例 ,从对森林生态系统健康的理解和评价出发 ,通过引入模式生态系统集的思想 ,提出了对森林生态系统健康理解的独创看法 ,并以此提出生态系统健康评估的新方法———健康距离 (HD)法 ,并推导出计算公式 .同时 ,针对阔叶红松林生态系统的系统特征和面临的各种具体健康问题 ,提出了基于自然 经济 社会复合生态系统属性的阔叶红松林生态系统健康评估指标体系 ,并具体到各度量指标 ,为下一步的健康评估打下基础 .

Synthesis and characterization of novel poly(ester carbonate)s based on pentaerythritol

Novel poly(ester carbonate)s were synthesized by the ring-opening polymerization Of L-lactide and functionalized carbonate monomer 9-phenyl-2,4,8,10-tetraoxaspiro[5,5]undecan-3-one derived from pentaerythritol with diethyl zinc as an initiator. H-1 NMR analysis revealed that the carbonate content in the copolymer was almost equal to that in the feed. DSC results indicated that T-g of the copolymer increased with increasing carbonate content in the copolymer. Moreover, the protecting benzylidene groups in the copolymer poly(L-lactide-co-9-phenyl-2,4,8,10-tetraoxaspiro[5,5]undecan-3-one) were removed by hydrogenation with palladium hydroxide on activated charcoal as a catalyst to give a functional copolymer, poly(L-lactide-co-2,2-dihydroxylmethyl-propylene carbonate), containing pendant primary hydroxyl groups. Complete deprotection was confirmed by H-1 NMR and FTIR spectroscopy. The in vitro degradation rate of the deprotected copolymers was faster than that of the protected copolymers in the presence of proteinase K. The cell morphology and viability on a copolymer film evaluated with ECV-304 cells showed that poly(ester carbonate)s derived from pentaerythritol are good biocompatible materials suitable for biomedical applications.

Primary and secondary crystallization kinetic analysis of nylon 1212

The isothermal and non-isothermal melt-crystallization kinetics of nylon 1212 were investigated by differential scanning calorimetry. Primary and secondary crystallization behaviors were analysed based on different approaches. The results obtained suggested that primary crystallization under isothermal conditions involves three-dimensional spherulite growth initiated by athermal nucleation, while under non-isothermal conditions, the mechanism of primary crystallization is more complex. Secondary crystallization displays a lower-dimensional crystal growth, both in the isothermal and non-isothermal processes. The crystallite morphology of nylon 1212, isothermally crystallized at various temperatures, was observed by polarized optical microscopy. The activation energies of crystallization under isothermal and non-isothermal conditions were also calculated based on different approaches.

Structure, electric and magnetic properties of new compounds CdYMWO7 (M = Cr and Mn)

Two new compounds with the formula of CdYMWO7 (M = Cr, Mn) were prepared by solid state reaction. They crystallized with orthorhombic structure with the cell parameters of a = 11.7200 Angstrom, b = 7.1779 Angstrom, c = 6.9805 Angstrom (CdYCrWO7), and a = 11.7960 Angstrom, b = 6.1737 Angstrom, c = 7.6530 Angstrom (CdYMnWO7). These compounds are insulators with high resistivities at room temperature. The temperature dependence of the magnetic susceptibility of CdYMWO7 (M = Cr and Mn) show Curie-Weiss Law's behaviors from 80 to 300 K. The magnetic moments at room temperature fit very well with those corresponding to Cr3+ and Mn3+ ions. This suggests that both Cr and Mn ions exist in + 3 oxidation state in CdYMWO7 compounds. (C) 1998 Elsevier Science Ltd. All rights reserved.

步行机器人足端反力的求解

本文综述了目前国内外求解多足步行机器人足端反力的一些主要方法及求解结果,讨论了它们的特点、存在问题和今后的研究方向.

A Scheduling Algorithm for Flexible Manufacturing Cell

In this paper, a new scheduling algorithm for the flexible manufacturing cell is presented, which is a discrete time control method with fixed length control period combining with event interruption. At the flow control level we determine simultaneously the production mix and the proportion of parts to be processed through each route. The simulation results for a hypothetical manufacturing cell are presented.

贵州岩溶地区岩性与土地石漠化的相关分析

在构筑1：50万贵州岩溶地区岩石组合类型分布图的基础上，以GIS为分析手段，对贵州省石漠化分布图和地层岩性图进行了空间分析，探讨了各类岩性与不同级别石漠化之间的相关关系。石漠化与岩性具有明显的相关性，强度石漠化主要分布在纯质碳酸盐岩地区，尤其是纯质灰岩地区；中度石漠化在白云岩组合中的比例较灰岩组合中高；轻度石漠化在碳酸盐岩与碎屑岩夹层和互层中分布较广；石漠化与纯碳酸盐岩相关关系最明显.

西南岩溶山区生态危机与反贫困的可持续发展文化反思

西南岩溶山区生态环境退化严重、贫困人口集中。文章探讨民族传统文化观念在岩溶山区经济活动中的作用,力图寻找岩溶山区生态恶化和贫困的深层次原因,指出岩溶山区存在的山地文化封闭性和典型的贫困文化特性及不合理的现代性转换导致区域生态恶化和可持续发展的滞后。岩溶山区应通过生态恢复模式示范建设、开展参与式社区资源管理、改善居民聚居点环境来实现文化创新和文化整合,实现传统性与现代性的深层次互动与接纳,拓宽现代性生长的内在精神空间,变外源性的“输血”机制为内源性的“造血”机制,从而使岩溶山区实现可持续发展。