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371.
通过采取"治、退、拆、清、修、整、建、营、养、植"等生态修复综合措施、建立古黄河生态保护圈,加强古黄河泗阳段周边环境的生态保护,进一步净化水体环境,同时增加古黄河泗阳段蓄水量,提高水质的稳定性,使得社会效益、环境效益和经济效益达到最佳统一,实现水资源的持续利用.同时改善古黄河地区的空气环境,给古黄河地区的人民一个蓝天,实现古黄河泗阳地区的蓝天碧水.  相似文献   
372.
关于灾害管理学的几点想法   总被引:1,自引:0,他引:1  
随着社会经济的发展,我国各种自然灾害的发生有规模大、损失严重的趋势,加强灾害管理对于建立和谐社会意义重大.本文在总结前人工作的基础上,阐述了灾害管理的含义、灾害管理系统的自组织性和协同性,概括了灾害管理的一般方法,指出灾害管理是发展管理.  相似文献   
373.
Knowledge about carbon and nitrogen in plants and soils and response to fence and graze in alpine ecosystems is still rudimentary because of extremely geographic situation. The purpose of this study was to compare the difference among carbon, nitrogen concentration, and content of unit area and dynamics of above- and below-ground biomass, soil organic carbon and total nitrogen between fencing and grazing alpine meadow. The results showed that total carbon and C: N radio in the aboveground tissue were significantly higher in fenced and ungrazing grassland (FU) than those in free grazing grassland (FG). In addition, the order of total carbon and nitrogen concentration of aboveground tissue of different function groups were not identical between them; The total carbon storage (TCS) per unit of aboveground tissue, roots and 0–30 cm soil layer increased after being fenced for 5 years from free grazing grassland (9255.17 g/m2) to fenced and ungrazing grassland (12637.10 g/m2) by 26.79%. The corresponding total nitrogen storage (TNS) increased by 751.42 g/m2. Furthermore over 95% TCS (TNS) come from 0–30 cm soil layer. However there were no significant differences between fenced and ungrazing grasslands of 10 years and 5 years. Therefore fenced to exclude grazing by Tibetan sheep and yaks was an alternative approach to sequester C to the soil in alpine meadow systems.  相似文献   
374.
Climate change has become widely accepted as a challenge that humans will face in the not-too-distant future.Mountain ecosystems and their inhabitants are among the most vulnerable to climate change.This paper seeks to explain migration drivers in specific mountain regions in the context of climate change based on Foresight’s conceptual framework.A climate change sensitive field named Shangnan County in southern Shaanxi Province is chosen as the case study area to investigate local migration drivers.A series of qualitative research methods is employed in the case study including participant observation,semi-structured interviews,and focus group discussions.The evidence of survey suggests that migration decisions are not only shaped by macro factors in aspects of environmental,economics,demographic,social,politics and psychological,but also influenced by placed-related barriers and facilitating mechanisms and personal characteristics.  相似文献   
375.
Knowledge of forest fuels and their potential fire behavior across a landscape is essential in fire management. Four customized fire behavior fuel models that differed significantly in fuels characteristics and environmental conditions were identified using hierarchical cluster analysis based on fuels data collected across a boreal forest landscape in northeastern China. Fuel model I represented the dense and heavily branched Pinus pumila shrubland which has significant fine live woody fuels. These forests occur mainly at higher mountain elevations. Fuel model II is applicable to forests dominated by Betula platyphylla and Populus davidiana occurring in native forests on hill slopes or at low mountain elevations. This fuel model was differentiated from other fuel models by higher herbaceous cover and lower fine live woody loading. The primary coniferous forests dominated by Larix gmelini and Pinus sylvestris L. var. mongolica were classified as fuel model III and fuel model IV. Those fuel models differed from one another in average cover and height of understory shrub and herbaceous layers as well as in aspect. The potential fire behavior for each fuel model was simulated with the BehavePlus5.0 fire behavior prediction system. The simulation results indicated that the Pinus pumila shrubland fuels had the most severe fire behavior for the 97th percentile weather condition, and had the least severe fire behavior under 90th percentile weather condition. Fuel model II presented the least severe fire potential across weather conditions. Fuel model IV resulted in greater fire severity than Fuel model III across the two weather scenarios that were examined.  相似文献   
376.
Optimal production and pricing policy for a closed loop system   总被引:1,自引:0,他引:1  
A closed loop system is investigated, in which the manufacturer has two channels to satisfy the demand: manufacturing brand-new products and remanufacturing returns into as-new products. Remanufactured products have no difference from brand-new products and can be sold in the same market at the same price. The demand is uncertain and sensitive to the selling price, while the return is also stochastic and sensitive to the acquisition price of used products. A mathematical model is developed to maximize the overall profit of the system by simultaneously determining the selling price, the production quantities for brand-new products and remanufactured products, and the acquisition price of used products. Some properties of the problem are analyzed, based on which a solution procedure is presented. Through a numerical example, the impacts of the uncertainties of both demand and return on the production plan, selling price, and the acquisition price of used products are analyzed.  相似文献   
377.
埋地管道的腐蚀是影响油气田地面工程安全运行的重要因素之一,玻璃钢管道的非金属特性根除了腐蚀环境的形成,杜绝了管道腐蚀穿孔事件的发生,降低了污染土壤等环境问题发生的机率,塔里木油田管道服役现状、史密斯公司30a的研究结果对此做了充分的诠释。英—红外输油管道和哈森-威廉姆斯公式分别从实践和理论上展示了玻璃钢管卓越的水力特性,英买力潜山玻璃钢管线具有良好的经济和社会效益。  相似文献   
378.
以正丙醇、氯气和硫脲合成了2-氨基-5-甲基噻唑,将上述产物作为碱组分,与苯甲醛和苯乙酮反应得到曼尼希碱,最后采用溴代十二烷作为季铵化试剂,制得目标产物溴代2-氨基(1,4-二苯基-3-氧代丁基)-5-甲基噻唑铵(QADT)。静态失重法表明,QADT缓蚀效果显著。当温度为50℃,QADT的用量在200 mg/L时,缓蚀率达到95%以上。  相似文献   
379.
Barium to calcium (Ba/Ca) ratio in corals has been considered as a useful geochemical proxy for upwelling, river flood and other oceanic processes. However, recent studies indicated that additional environmental or biological factors can influence the incorporation of Ba into coral skeletons. In this study, Ba/Ca ratios of two Porites corals collected from Daya Bay, northern South China Sea were analyzed. Ba/Ca signals in the two corals were ‘anomalous’ in comparison with Ba behaviors seen in other near-shore corals influenced by upwelling or riverine runoff. Our Ba/Ca profiles displayed similar and remarkable patterns characterized by low and randomly fluctuating background signals periodically interrupted by sharp and large synchronous peaks, clearly indicating an environmental forcing. Further analysis indicated that the Ba/Ca profiles were not correlated with previously claimed environmental factors such as precipitation, coastal upwelling, anthropogenic activities or phytoplankton blooms in other areas. The maxima of Ba/Ca appeared to occur in the period of Sr/Ca maxima, coinciding with the winter minimum temperatures, which suggests that the anomalous high Ba/Ca signals were related to winter-time low sea surface temperature. We speculated that the Ba/Ca peaks in corals of the Daya Bay were most likely the results of enrichment of Ba-rich particles in their skeletons when coral polyps retracted under the stresses of anomalous winter low temperatures. In this case, Ba/Ca ratio in relatively high-latitude corals can be a potential proxy for tracing the low temperature stress.  相似文献   
380.
将曼氏无针乌贼幼体置于24 h半致死剂量的亚硝态氮和氨态氮溶液中(10 mg·L-1 NaNO2和300 mg·L-1 NH4Cl),检测6、12和24 h各点及对照组曼氏无针乌贼幼体血液生化指标的变化.结果表明,随着处理时间的延长,NaNO2处理组血细胞密度(THC)(p<0.05)、甘油三酯(TG)(p<0.05)...  相似文献   
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