High-resolution stratigraphy with strontium isotopes

The isotopic ratio of strontium-87 to strontium-86 shows no detectable variation in present-day ocean water but changes slowly over millions of years. The strontium contained in carbonate shells of marine organisms records the ratio of strontium-87 to strontium-86 of the oceans at the time that the shells form. Sedimentary rocks composed of accumulated fossil carbonate shells can be dated and correlated with the use of high precision measurements of the ratio of strontium-87 to strontium-86 with a resolution that is similar to that of other techniques used in age correlation. This method may prove valuable for many geological, paleontological, paleooceanographic, and geochemical problems.     

关于灾害力学的思考

力学的发展与人类的生活、生产紧密相联。通过对人类抗灾防灾过程的回顾,提出了“软灾害”和“硬灾害”的概念。并通过对硬灾害致害机理的分析,介绍了灾害力学产生的背景、主要研究内容和研究方法,提出了灾害力学的控制方程。     

关于灾害力学的思考

力学的发展与人类的生活、生产紧密相联。通过对人类抗灾防灾过程的回顾,提出了"软灾害"和"硬灾害"的概念。并通过对硬灾害致害机理的分析,介绍了灾害力学产生的背景、主要研究内容和研究方法,提出了灾害力学的控制方程。     

农机具中的力学

通过对扁担、拖拉机中的转向轴和离合器轴等农机具结构的分析,得出其中所蕴含的力学原理,并对其受力情况进一步分析,证明农机具结构的合理性,同时说明材料力学为农机具设计提供了理论基础和计算方法。     

Magnetospheric wind

An experiment designed to detect the bulk flow of cool plasma within the magnetosphere has been flown on the ATS-1 (Applications Technology Satellite) synchronous satellite. This experiment has yielded evidence for gusts of streaming positive ions in the magnetospheric equatorial plane. This directed ion flow is interpreted as the result of large-scale electric fields of the order of several millivolts per meter.     

ЧemaeB型非完整力学的基本结构

用现代微分向何方法研究非线性非完整约束力学系统的ЧｅｍａｅＢ模型的基本结构，将ЧｅｍａｅＢ型非完整力学归结为３个基本要素：（１）丛按约束的直和分解；（２）Ｄ‘Ａｌｅｍｂｅｒｔ原理；（３）原理的约束条件，结果表明ЧｅｍａｅＢ型非完整力学实为理想型非完整力学。     

木材断裂力学的研究

该文介绍了木材断裂力学的概念、研究方法以及国内外对木材断裂力学的研究现状及发展前景     

Devon island ice cap: core stratigraphy and paleoclimate

Valuable paleoclimatic information can be gained by studying the distribution of melt layers in deep ice cores. A profile representing the percentage of ice in melt layers in a core drilled from the Devon Island ice cap plotted against both time and depth shows that the ice cap has experienced a period of very warm summers since 1925, following a period of colder summers between about 1600 and 1925. The earlier period was coldest between 1680 and 1730. There is a high correlation between the melt-layer ice percentage and the mass balance of the ice cap. The relation between them suggests that the ice cap mass balance was zero (accumulation equaled ablation) during the colder period but is negative in the present warmer one. There is no firm evidence of a present cooling trend in the summer conditions on the ice cap. A comparison with the melt-layer ice percentage in cores from the other major Canadian Arctic ice caps shows that the variation of summer conditions found for the Devon Island ice cap is representative for all the large ice caps for about 90 percent of the time. There is also a good correlation between melt-layer percentage and summer sea-ice conditions in the archipelago. This suggests that the search for the northwest passage was influenced by changing climate, with the 19th-century peak of the often tragic exploration coinciding with a period of very cold summers.     

农业机械学课程改革与初探

根据《农业机械学》人才需要的培养目标的要求,介绍了安徽农业大学工学院对《农业机械学》课程教学的一系列改革方案,主要包括教学理念、教学内容、教学方法以及实践教学改革。     

二次密封装置密封机理分析

对比了外浮顶油罐一次密封与加一次密封的密封效果，分别介绍了一次密封、二次密封结构及密封机理，着重从对储液表面温度及变化的控制以及降低风荷载引起的油气损耗等方面分析了二次密封装置的机理。     

Max Born's Statistical Interpretation of Quantum Mechanics

In the summer of 1926, a statistical element was introduced for the first time in the fundamental laws of physics in two papers by Born. After a brief account of Born's earlier involvements with quantum physics, including his bringing the new mechanics to the United States, the motivation for and contents of Born's two papers are discussed. The reaction of his colleagues is described.     

理论力学教学改革的思考

理论力学是农业类工科院系普遍开设的一门重要的专业基础课,对其开展教学实践改革具有重要意义.本文对理论力学在教学内容、教学方法和教学手段方面进行了一系列改革与实践,其中包括对理论力学与普通物理学力学的衔接与矛盾进行分析,对理论力学的教学改革有助于提高学生在教学时间内的学习效率,同时强化多媒体网络化的教学建设,优化课程教学方法,获得良好的教学效果.     

《土力学》课程教学改革探讨

本文对目前土力学课程教学中存在的主要问题,提出以下四点建议,即:激发学生兴趣,突出授课重点;充分利用多媒体教学,并与传统教学方法相结合;实验教学严格要求,开放实验室激发学生积极性;加强试题库的建设,实行考教分离等.     

管道工程环境与力学行为

长输管道所处的环境比较复杂，主要包括所输送介质的环境，运行操作环境、管道周边环境、沿线自然环境与灾害环境以及管道的施工制造环境。在这些环境的作用下，管道将产生相应的力学行为，主要有承载行为，变形行为，断裂行为，疲劳行为和腐蚀行为，为保证管道工程的经济合理性，使管道长期平稳运行，就要在设计阶段将管道所处环境与相应产生的力学行为有机地结合起来，从这一角度出发，提出合理选择线路，正确选用选材，腐蚀控制、管道保护、施工控制和管理维护等6项措施。