你的环境就是你的健康--环境疾病纵谈

空气、水、太阳、动物、植物、化学物质、金属……支撑着我们的生活,使我们的生活美丽而愉悦,但同时它们又给人类带来疾病。与环境密切相关的疾病林林总总,环境疾病影响人的生活质量。下面让我们一同“浏览”一下与环境相关的一些常见病。     

美国的湿地保护和立法

湿地概念与分类 早在20世纪60年代美国联邦政府和州政府就开始立法保护湿地,与此同时,有关湿地科学研究工作亦广泛开展起来.然而由于研究目的的不同,各州湿地分布与特征不同,各州及联邦政府对湿地保护所立的各项法律、法规中湿地的定义也不尽相同.     

降雨影响下基坑开挖施工对邻近基桩变形响应分析

目前关于基坑开挖对邻近基桩变形响应的简化理论解研究,还较少考虑基坑开挖中支护作用的影响,尤其是没有考虑降雨环境带来的土工影响。基于一种适用于不同降雨工况的分层假定Green-Ampt模型来模拟降雨入渗过程,采用两阶段分析方法,研究了降雨影响下基坑开挖与邻近基桩相互作用的问题。首先,考虑基坑开挖土体卸荷、围护结构及支撑结构的影响,采用Mindlin基本解,分析降雨影响下基坑开挖施工导致邻近基桩位置的土体附加应力;然后,基于Pasternak双参数地基模型,探讨基桩与土体之间的相互作用,求得降雨影响下单桩和群桩随降雨历时变化的水平变形响应。通过工程监测数据与理论计算结果进行对比,获得了较好的一致性。此外,也针对降雨敏感参数（降雨强度、饱和渗透系数、初始含水率、基质吸力）与基桩敏感参数（边界条件、支撑刚度、桩径、开挖深度、桩与基坑间距）进行了影响因素分析。分析结果表明,所提出的理论方法可较好地反映降雨影响下基坑开挖施工对邻近基桩的变形响应;降雨对邻近基桩变形影响显著,降雨参数敏感程度依次为：降雨强度>初始含水率>饱和渗透系数>基质吸力;随着降雨历时的增长,湿润层发展深度不断...     

Status and Trends in Research on Deep-Water Gravity Flow Deposits

Deep-water gravity flows are one of the most important sediment transport mechanisms on Earth. After 60 years of study,significant achievements have been made in terms of classification schemes,genetic mechanisms,and depositional models of deep-water gravity flows. The research history of deep-water gravity flows can be divided into five stages: incipience of turbidity current theory; formation of turbidity current theory; development of deep-water gravity flow theory; improvement and perfection of deep-water gravity flow theory; and comprehensive development of deep-water gravity flow theory. Currently,three primary classification schemes based on the sediment support mechanism,the rheology and transportation process,and the integration of sediment support mechanisms,rheology,sedimentary characteristics,and flow state are commonly used.Different types of deep-water gravity flow events form different types of gravity flow deposits. Sediment slump retransportation mainly forms muddy debris flows,sandy debris flows,and surge-like turbidity currents. Resuspension of deposits by storms leads to quasi-steady hyperpycnal turbidity currents(hyperpycnal flows). Sustainable sediment supplies mainly generate muddy debris flows,sandy debris flows,and hyperpycnal flows. Deep-water fans,which are commonly controlled by debris flows and hyperpycnal flows,are triggered by sustainable sediment supply; in contrast,deep-water slope sedimentary deposits consist mainly of debris flows that are triggered by the retransportation of sediment slumps and deep-water fine-grained sedimentary deposits are derived primarily from finegrained hyperpycnal flows that are triggered by the resuspension of storm deposits. Harmonization of classification schemes,transformation between different types of gravity flow deposit,and monitoring and reproduction of the sedimentary processes of deep-water gravity flows as well as a source-to-sink approach to document the evolution and deposition of deep-water gravity flows are the most important research aspects for future studies of deep-water gravity flows study in the future.     

Transition-Zone Mineral Assemblages in Peridotite Massifs, Tibet: Implications for Collision-zone Dynamics and Orogenic Peridotites

<正>Diamonds have been reported from Tibetan"ophiolites"for≥30 years,but have been widely dismissed as contaminants,because their unusual morphology and light C(δ~(13)C=-18 to–27)are unlike those of kimberlitic diamonds.However,the diamonds have now been found in situ in both the chromitites and the peridotites of     

Diamonds and Highly Reduced Minerals from Chromitite of the Ray-Iz Ophiolite of the Polar Urals: Deep Origin of Podiform Chromitites and Ophiolitic Diamonds

<正>The Uralide orogenic belt is a major early Paleozoic suture zone extending more than 3000 km in a N-S direction,and geographically divides Europe from Asia(Chemenda et al.,1997).Ophiolites,podiform chromitites and high pressure metamorphic rocks are well developed in the orogenic belt(Leech and Ernst,2000).The Ray-Iz     

Our Petroleum Prospect

As a result of the wide industrial development as well as extensive construction of the public highways and the consequent demand of motor-car gasoline,the petroleum consumption in China is becoming greater and greater every year.According to the recent report of the Customs office, the import of gasoline,kerosine, fuel oil and lubricating oil has reached in 1933 a total of about eightmillion barrels, valued at 140 million Shanghai dollors.     

千难万苦亦等闲——辽宁省灯塔市第二次土地调查侧记

近日,辽宁省第二次土地调查又传出喜讯,辽宁省第二次土地调查从"百日会战"进入决战阶段.经县级自查,市级复查,省级全面核查.取得了重要的阶段性成果.截至7月中旬,全省90个县级调查单位全部完成建库成果,经省调查办核查反馈修改通过后,全部上报国家核查.目前,国家核查后已反馈我省修改的有60个,正在组织复核修改工作,其中已有9个经修改检查后正式上报国家.     

辽宁古果——世界最早的花

“无可奈何花落去 ,似曾相识燕归来”。骚人墨客把他们的情感、追求 ,甚至对人生和世界的想往和理解都幻化在千姿百态、姹紫嫣红的花的世界里。但要追问这个世界什么时候才有花 ,那可就是科学家的责任了。世界上第一朵花开何处 ?自达尔文时代以来 ,这一问题困扰了科学家 1 0 0多年。在距今 1 4 0亿年前 ,地质史称的侏罗纪 ,地球上大量繁盛的是裸子植物和蕨类植物 ,而不见有花植物 (被子植物 ) ;到了距今 1亿年前的白垩纪 ,地球已是繁花似锦、鸟语花香的多彩世界了。对于植物从无花到有花的进化 ,达尔文这位敢于向神创论挑战的伟大学者 ,穷…     

潮汐偏角法在地震预报中的应用研究

应用潮汐偏角法对山东泰安、马陵山、烟台 3个台的石英摆倾斜仪、自记水管倾斜仪资料进行了分析处理 ,结果显示 :泰安、马陵山分点潮汐偏角在华北各次 5.0级以上地震、特别是黄海地震前 1年 7个月至 1个月时段内出现了高值或低值异常 ,表明潮汐偏角可应用于地震中短期预报