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51.
52.
杞麓湖主要污染物的动态变化特征研究 总被引:1,自引:0,他引:1
以1997年杞麓湖水质监测结果为基础,运用相关分析,双因子方差分析等方法,对杞麓湖主要污染物动态变化特征的研究结果表明,杞麓湖主要污染物的空间分布较为均匀;BOD5和TN都有较为明显的季节变化。 相似文献
53.
In this paper, impacts of climate change on wheat development rate and production in the northern China are discussed. The results show that the temperature is a controlling factor of development rate but the precipitation is not. The higher the temperature is. the faster the development and the shorter development period will be. Without consideration to varieties and cropping system, meteorological yield of winter wheat would decrease 170.40, 134.25, 98.70 and 97.20 kg/hm2 in the north China and 13.97, 7.95, 39.60 and 19.80 kg/hm2 in the northwest China compared with that in 1950s, 1960s, 1970s and 1980s, respectively, when the CO2 concentration in the atmosphere is doubled. In drought and semi-drought regions, the spring wheat yield would drop with the temperature rise in and raise with the precipitation increase. The influence of temperature on weight of leaf and stalk is also remarkable. 相似文献
54.
本文叙述了锰砂表面改性(以下简称旧锰砂)处理含酚饮用水的实验研究,陈酚率可达99%。本实验对除酚因素(温度、pH值、流速和接触时间等)进行了实验研究。当进水酚浓度≤2.0mg/l时,经旧锰砂的吸附,可使酚浓度≤0.002mg/l。 相似文献
55.
黑龙江省森林资源动态变化与发展趋势预测 总被引:6,自引:0,他引:6
以黑龙江省2004年统计年鉴的统计数据为依据,分析了全省森林资源现状的特点,并以近50多年来森林资源清查数据为基础,对森林资源主要项目的动态变化进行了客观的分析,力求寻找变化的原因.通过建立灰色预测GM(1.1)模型,预测未来时期森林资源发展趋势,提出了相应对策,以期实现科学经营森林以及森林资源的可持续发展. 相似文献
56.
Xi Haiyan Cai Qiang He Miao Shi Hanchang 《Frontiers of Environmental Science & Engineering in China》2007,1(3):381-384
This research describes a fast detection method on the basis of enzyme-linked immunosorbent assay (ELISA) for Escherichia coli in drainage of wastewater treatment plants. Optimized conditions such as the reaction format (sandwich or direct), the concentrations
of diluted horseradish peroxidase (HRP)-E. coli conjugate, and anti-HPR antibody and pretreatment of E. coli were studied. Those results showed that the linear range of detection for E. coli was 10 cfu/mL-6 × 104 cfu/mL. Compared with conventional methods, it is a convenient and sensitive detection method with low cost.
Translated from Environmental Science, 2005, 26(5): 128–131 [译自: 环境科学] 相似文献
57.
CLIMATE CHANGE AND NATURAL HAZARDS IN NORTHERN CANADA: INTEGRATING INDIGENOUS PERSPECTIVES WITH GOVERNMENT POLICY 总被引:1,自引:0,他引:1
John?NewtonEmail author C.?D.?James?Paci Aynslie?Ogden 《Mitigation and Adaptation Strategies for Global Change》2005,10(3):541-571
A study of the relationship between natural hazards and climate change in the international context provides the background
for a discussion of the expected changes. In the context of this global discussion, this paper reviews the current perspectives
of those natural hazards that are likely to be influenced by climate change, using northern Canada as a regional case study.
The northern implications of the United Nations Framework Convention on Climate Change are examined, including the status
of climate change action by the northern territorial governments, the evolving role of indigenous people, and the responsibility
for climate change impacts. The difficulties surrounding natural hazards research in remote locations, and the approaches
of indigenous people to natural hazards are then presented. The paper concludes with a suggested policy approach for climate
change and natural hazards in northern Canada, underscoring the need for more comprehensive adaptive strategies to complement
the current tendency to focus on the mitigation of greenhouse gases produced in this region. 相似文献
58.
Keith E. Schilling Robert D. Libra 《Journal of the American Water Resources Association》2003,39(4):851-860
ABSTRACT: Historical trends in annual discharge characteristics were evaluated for 11 gauging stations located throughout Iowa. Discharge records from nine eight‐digit hydrologic unit code (HUC‐8) watersheds were examined for the period 1940 to 2000, whereas data for two larger river systems (Cedar and Des Moines Rivers) were examined for a longer period of record (1903 to 2000). In nearly all watersheds evaluated, annual base flow, annual minimum flow, and the annual base flow percentage significantly increased over time. Some rivers also exhibited increasing trends in total annual discharge, whereas only the Maquoketa River had significantly decreased annual maximum flows. Regression of stream discharge versus precipitation indicated that more precipitation is being routed into streams as base flow than as storm flow in the second half of the 20th Century. Reasons for the observed stream flow trends are hypothesized to include improved conservation practices, greater artificial drainage, increasing row crop production, and channel incision. Each of these reasons is consistent with the observed trends, and all are likely responsible to some degree in most watersheds. 相似文献
59.
入侵检测的1类支持向量机模型 总被引:2,自引:3,他引:2
计算机网络尤其是互联网的迅速发展与普及 ,使得信息安全已经成为一个全球瞩目的重要研究课题。随着攻击技术的不断进步与更新 ,迫切需要一种有效的入侵检测技术来保护信息系统的安全。由于几乎所有的攻击与滥用都被记录在系统的网络数据中 ,因而可以基于计算机系统的网络数据构造入侵检测系统。在对网络数据进行深刻的分析和研究的基础上 ,提出了入侵检测的 1类支持向量机模型。第一 ,构造适于异常点检测的1类支持向量机模型 ;第二利用抽象化的网络数据对该模型进行训练以确定其中各个参数的值。实验表明 ,该方法是行之有效的 相似文献
60.
Foreword Inglobalview ,droughtdisasterisregardedasthemostserioustypeofnaturaldisasterintheworld ,whichhascausedthewidestrangeofeffectsandthebiggesteconomiclosses .Se veredroughtsmainlyoccurinAfrica ,India ,China ,formerSovietUnion ,NorthAmerica ,andAustralia,accountingforalmosthalfofcountriesintheworld .Droughtdisasteroccursfre quentlyinChina ,withwiderangeofinfluence ,whichisthemostseriousmeteorologicaldisas ter ,causingeconomiclossesinagriculture .Fromthe 50’stothe 80’sinthe 2 0thcent… 相似文献