全球变暖对青藏高原腹地草地资源的影响

全球变化导致青藏高原腹地气候的暖干化趋势,也引起该区高寒草甸植被向高寒草原植被的退化。研究区内为高寒草甸一高寒草原过渡区,高寒草甸植被的退化速率为14.2km/10a,而相应地在退化区内生物总量亦呈下降趋势。气候暖干化是引起高原腹地植被退化的原因。而植被退化与区域生物总量的下降将成为影响该区环境自调能力和牧业经济发展的消极因素。     

全社会资金波动的安全预警模型及实证分析

利用聚类分析、时差相关分析、K -L信息量等方法 ,以国内生产总值发展速度的波动曲线为基准循环曲线 ,对各种经济指标进行分类和筛选 ,从而选定先行、一致、滞后三类指标组 ,运用主成分分析方法编制景气指数 ,以对社会资金的运动安全预警。在此基础上 ,笔者结合我国改革开放以来经济周期波动的实际情况 ,利用所编制的景气指数进行实证仿真分析 ,得到令人满意的结果     

依靠科技进步,坚持可持续发展,为保护我们共同生存的环境而努力

通过对大庆石油管理局2000年度在水环境、大气环境、固体废物排放等方面的现状分析,总结了大庆石油管理局2000年环境保护工作,并针对石油化工废水处理、脱硫、废钻井液处理、垃圾处理和资源化等技术提出重点注意的问题。最后介绍了管理局“十五”期间环境保护技术发展的总体思路和环保科技主攻方向。     

MODELING TRANSIENT pH DEPRESSIONS IN COASTAL STREAMS OF BRITISH COLUMBIA USING NEURAL NETWORKS1

ABSTRACT: Transient events in water chemistry in small coastal watersheds, particularly pH depressions, are largely driven by inputs of precipitation. While the response of each watershed depends upon both the nature of the precipitation event and the season of the year, how the response changes over time can provide insight into landscape changes. Neural network models for an urban watershed and a rural‐suburban watershed were developed in an attempt to detect changes in system response resulting from changes in the landscape. Separate models for describing pH depressions for wet season and dry season conditions were developed for a seven year period at each watershed. The neural network models allowed separation of the effects of precipitation variations and changes in watershed response. The ability to detect trends in pH depression magnitudes was improved by analyzing neural network residuals rather than the raw data. Examination of sensitivity plots of the models indicated how the neural networks were affected by different inputs. There were large differences in effects between seasons in the rural‐suburban watershed whereas effects in the urban watershed were consistent between seasons. During the study period, the urban watershed showed no change in pH depression response, while the rural‐suburban watershed showed a significant increase in the magnitude of pH depressions, likely the result of increased urbanization.     

档案工作要坚持三个面向

本文从分析档案工作的重要性入手,提出了搞好档案工作要坚持面向社会、面向科技、面向未来的工作思路,以此推动档案事业的健康发展,充分发挥其在国民经济和人民生活中应有的效益。     

Agricultural Biotechnology and the Future Benefits Argument

In the face of criticisms about the current generationof agricultural biotechnology products, some proponents ofagricultural biotechnology offer a ``future benefitsargument'(FBA), which is a utilitarian ethical argument thatattempts to justify continued R&D. This paper analyzes severallogical implications of the FBA. Among these are that acceptanceof the FBA implies (1) acceptance of a precautionary approach torisk, (2) the need for a more proportional and equitabledistribution of the benefits of agricultural biotechnology, andmost important, (3) the need to reorient and restructurebiotechnology R&D institutions (and the agriculturalbiotechnology community's values and attitudes) so that futurebenefits are indeed achieved through agricultural biotechnology.     

东北地区近50年来霾天气气候特征

利用东北地区194个地面气象观测站的1961~2013年观测资料,对东北地区霾日及不同等级霾日的空间分布特征和时间演变规律进行分析.结果表明:东北地区霾日空间分布差异显著,辽宁中部和黑龙江中北部霾日相对较多,年平均霾日超过50d,吉林西部地区霾日最少,年平均霾日不超过2d,不同等级的霾日日数空间分布与总霾日日数基本一致;东北地区霾日主要集中在冬季,占全年霾日57.9%,秋季次之,春季最少;1961~2103年东北地区平均霾日呈显著增加趋势(2.9d/10a),其中1981~2000年时段增加最为显著,轻微霾日、轻度霾日、中度霾日和重度霾日均呈增加趋势,但轻度霾日、中度霾日和重度霾日21世纪以来较80年代略有减少.     

Orbal氧化沟的应用及发展趋势

Orbal氧化沟自1970年开发至今已有广泛应用,在实际工程应用中取得了很好的处理效果,但也存在着同时硝化反硝化不够稳定、脱氮除磷困难、运行能耗偏高等问题。通过采用增加内回流、推流与曝气转碟相结合和微孔曝气与推流相结合的运行方式使这些问题得到了解决,同时Orbal氧化沟工艺也朝着高效低耗的方向发展。     

长距离人工输水渠道水质时空演变规律研究——以南水北调中线总干渠为例

以南水北调中线工程通水6年来沿线30个常规水质监测断面逐月的水质监测数据为基础,基于斯皮尔曼秩次相关检验,系统分析总干渠水质时空变化趋势.结果表明,总干渠水质总体良好,主要指标能够达到Ⅱ类及以上水平.空间尺度上,总干渠水温(r=-0.897,p＜0.01)、总磷(r=-0.820,p＜0.01)、生化需氧量(r=-0....     

焊接面罩的发展历程

焊接面罩是一种焊工防护装备,也是重要焊接辅助工具。本文主要介绍自焊接面罩出现100多年以来,经历了众多的改进,从手持式焊接面罩到头戴式焊接面罩、从黑玻璃焊接面罩到自动变光焊接面罩、从单一功能焊接面罩到多种功能集结的焊接面罩。同时指出,基于材料和技术的进步,焊接面罩不会停止创新的步伐,焊接面罩将在保护焊工、提高焊接质量和效率方面扮演重要角色。