Periodic solutions for discrete predator–prey systems with the Beddington–DeAngelis functional response

Sufficient criteria are established for the existence of positive periodic solutions of discrete nonautonomous predator–prey systems with the Beddington–DeAngelis functional response using a continuation theorem.     

Replication of biological organizations through a supercritical fluid route

A novel and simple method to replicate biological organizations (cotton and pollen grains) with high precision was proposed, in which the precursor dissolved in supercritical CO2 reacted with the surface active groups and adsorbed surface water on biological templates, followed by in situ SCF extraction of the byproducts and unreacted precursor, resulting in inorganic replicas faithfully copying both the macro- and microstructures of the biotemplates.     

Facile synthesis of sheet-shaped Co2P grown on carbon cloth as a high-performance electrocatalyst for the hydrogen evolution reaction

Journal of Solid State Electrochemistry - Here, we demonstrate the synthesis of sheet-shaped Co2P grown on carbon cloth (sheet-shaped Co2P-CC) through a facile route. Electrochemical measurements...     

岩体分类实例分析与研究

通过岩体分类的大量实例 ,利用统计学和模型原理 ,探讨了RMR值、Q值和自稳时间各自所服从的分布规律 ,同时评价了它们与岩石类型之间和自身的相关关系 ,旨在通过实例及岩石类型的分析与研究 ,为以后工程实践及其理论研究起到一定的指导和帮助作用     

中国海洋工程地质研究

本文阐述了我国在海岸带、河口三角洲和港口建设,海洋石油开发以及技术方法等方面的海洋工程地质研究所取得的成就,理论研究、海洋沉积物微结构研究、海浪作用下的土动力特性及液化预测研究和水下软基处理等的研究现状,提出了海洋工程地质学的发展趋势、研究课题与建议。     

Synthesis and applications of novel attapulgite-supported Co(II)-imprinted polymers for selective solid-phase extraction of cobalt(II) from aqueous solutions

A simple and reliable approach using surface imprinting technique combined with chitosan incorporated sol-gel process was established to synthesise a novel Co(II)-imprinted polymer (Co-IIP) with attapulgite as the support material. Then the prepared polymer was characterised by using fourier tranmission infrared spectra (FT-IR) and scanning electron microscopy (SEM), and the imprinting mechanism of Co-IIP was proposed. Batch experiments studies were performed to evaluate the adsorption kinetics, selective recognition, adsorption isotherm, desorption and regeneration characters of Co-IIP. Results showed that Co-IIP offered fast kinetics for the adsorption and desortion Co²⁺ under the optimum conditions. The adsorption and selective recognition Co²⁺ were both followed the order Co-IIP?>?attapulgite?>?NIP. Moreover, Langmuir adsorption isotherm fitted well for the experimental equilibrium data of Co-IIP, and the maximum adsorption capacity of Co-IIP was 31.5?mg?g^?1. Furthermore, Co-IIP could be reused four times with only about 13.42?～?16.17% regeneration loss, and the enrichment factor was more than 10.0. The developed method was also successfully applied to the determination of trace Co²⁺ in river sediments with satisfactory results. The relative standard deviation of the method (RSD) and the detection limit (3σ) were 1.35% and 0.0263, respectively.     

2021-03期目录

针对毁伤试验数据少、不均匀、不连续、范围窄等带来的计算精度不高的问题。研究通过数据挖掘技术进行毁伤效应计算。利用数据库管理毁伤数据,通过数据清洗技术识别并清除数据异常点,以保证数据库中数据的质量。建立了算法评价方法以选择最优经验算法。通过特征选择对高维毁伤数据进行降维,确定毁伤效应的主要控制参数进行神经网络学习和k-近邻检索。在此基础上建立基于数据融合的“三阶段”毁伤效应计算模型,可依据试验数据、经验算法和神经网络模型进行毁伤效应计算。实际应用表明,所提出的计算方法,能够满足实际应用需求。     

原子核的振动与转动模型(Ⅱ)奇A核正常转动谱分析

应用推转玻尔-莫特逊哈密顿量,对奇A核正常转动带进行分析,对模型适用条件及其与Harris展开式的比较作了讨论.     

原子核振动与转动模型（Ⅰ）推转玻尔─莫特逊哈密顿量和偶偶核正常转动谱分析

从推转壳模型出发，导出了转动频率未量子化的集体振动－转动哈密顿量，称为推转玻尔－莫特逊哈密顿量（ＣＢＭＨ）．引入合理的集体运动位势，由ＣＢＭＨ可以得到解析形式的转动谱公式．应用这一振动－转动模型，对偶偶变形核的正常转动能谱进行了分析，取得了满意的结果．