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121.
Piper L. Wall DVM PhD † Akella Chendrasekhar MD †Gregory A. Timberlake MD † 《Journal of Veterinary Emergency and Critical Care》1998,8(2):109-115
The accuracy and precision of an end-tidal infrared CO2 monitor and customized capnography tubing system designed to measure gastrointestinal intraluminal CO2 partial pressure (Pi CO2 ) were tested in vitro. Samples were taken from the customized capnography tubing placed in either 5% or 10% CO2 gas at discrete intervals ranging from one minute to twelve minutes. For a given time interval, the tubing PCO2 measurement was a constant fraction of the actual PCO2 (all standard errors < 0.02). For increasing time intervals, the ratio of the tubing PCO2 to actual PCO2 increased logarithmically. In the 5% and 10% CO2 , the regression coefficients were 0.89 and 0.85 for 8 French tubing and 0.99 and 0.91 for 6 French tubing. Beacuase of its accuracy and precision, this system may provide automated gastrointestinal CO2 partial pressure monitoring at short intervals (e.g. 5 minutes), facilitating testing of the role of gastrointestinal Pi CO2 information in treatment algorithms. (Vet Emerg & Crit Care, 1998; 8: 109–116) 相似文献
122.
Landscape patterns of nitrogen mineralization and nitrification in southern Ohio hardwood forests 总被引:10,自引:0,他引:10
This study quantified nitrogen mineralization and nitrification potentials in soils of hardwood forests of southern Ohio at three spatial scales: (1) the regional scale, represented by four study areas of 90–120 ha separated by 3–65 km, (2) the local scale, represented by three contiguous watersheds within each study area, and (3) the topographic scale, represented by xeric, intermediate, and mesic sites within each watershed, as defined by a GIS-generated Integrated Moisture Index (IMI). Organic C, NO3 pool size, net N mineralization, proportional nitrification, and net nitrification potentials all varied among study sites (i.e. at the regional scale). Using path analysis, we were able to construct scale-independent causal models explaining 30–35% of the variance in organic C and potential net N mineralization and 70% of the variance in potential net NO3 production. Site- and scale-specific differences in geology and/or land use history among study sites were likely responsible for the variation not explained by the path analysis. At the local scale, there were significant variations in organic C and inorganic N pool sizes among watersheds within a study site in two of the four study sites. In addition, most parameters we measured varied significantly along the topographic gradient (i.e. with long-term soil moisture availability/IMI). Based on our results, scaling up models of nitrification from plot scale to the regional scale should be straightforward, whereas scaling up organic C storage and N mineralization will require incorporation of independent scaling paradigms at three (or more) spatial scales. 相似文献
123.
田海芹 《内蒙古林业调查设计》2013,36(2):126-128
近年来,由于温室气体CO2在大气中含量的急剧增加,导致全球变暖日趋严重。针对这一现状,我国积极倡导发展碳汇林业。文章阐述了碳汇林业的概念、碳汇林业的项目案例以及我国发展碳汇林业的重大意义,并对发展碳汇林业过程中存在的问题提出了可行性建议。 相似文献
124.
125.
本文结合吉林省实际,重点阐述了碳汇林业发展的必要性和重要性,指出了科技、人才对碳汇林业发展的支撑作用,强调了科技研发环节前移和发挥学术组织作用的战略选择。 相似文献
126.
融雪期是北方地区可溶性有机碳(DOC)通过融雪径流从陆地生态系统向河流输出的关键时期,因此观测融雪径流DOC动态对分析流域碳流失至关重要。在帽儿山生态站选取东北东部典型天然次生林建立25 m×25 m的水量平衡场,测定分析2014年融雪期不同土层(5、35、65和95 cm)融雪径流DOC含量和通量的时间动态和垂直分布规律。结果表明: 1) 该融雪期土壤水量输入和输出分别为74.2和15.6 mm,径流率高达21%;融雪期DOC输出量与冬季大气输入量基本持平,分别为0.25和0.22 g/m2。2)高峰期DOC含量与其瞬时流量的相关性随土层而变。5和35 cm土层DOC含量与瞬时流量之间均无显著关系(P0.05);65 cm土层则表现出弱负对数关系(R2=0.29,P0.05),而95 cm土层呈现显著线性正相关(R2=0.43,P0.05)。不同土层DOC瞬时通量与瞬时流量之间均极显著正相关(R20.9,P0.001),且产流量越大的土层,其正相关回归方程的斜率也越大,表明水文驱动土壤DOC流失。3)融雪径流产流量和输出DOC通量大小均表现出35 cm5 cm95 cm65 cm土层趋势,其中5和35 cm土层是DOC的主要输出层,占总输出量的70%,而在融雪高峰期可高达90%。由于土壤的滞留作用,DOC含量波动范围随土层加深而向低浓度收敛。 相似文献
127.
128.
《Land Degradation \u0026amp; Development》2017,28(3):1122-1133
Reforestation of agricultural lands is an important means of restoring land and sequestering carbon (C). At large scales, the labour and costs of direct measurement of ecosystem responses can be prohibitive, making the development of models valuable. Here, we develop a new sampling scenario‐based modelling approach coupled with Bayesian model averaging to build predictive models for absolute values in mixed‐species woody plantings and differences from their adjacent pasture, for litter stocks, soil C stocks and soil C:N ratios. Modelling scenarios of increasing data availability and effort were tested. These included variables that could be derived without a site visit (e.g. location, climate and management) that were sampled in the adjacent pasture (e.g. soil C and nutrients) or were sampled in the environmental planting (e.g. vegetation, litter properties, soil C and nutrients). The predictive power of models varied considerably among C variables (litter stocks, soil C stocks and soil C:N ratios in tree plantings and their differences to their adjacent pastures) and the model scenarios used. The use of a sampling scenario‐based approach to building predictive models shows promise for monitoring changes in tree plantings, following reforestation. The approach could also be readily adapted to other contexts where sampling effort for predictor variables in models is a major potential limitation to model utilization. This study demonstrates the benefit of exploring scenarios of data availability during modelling and will be especially valuable where the sampling effort differs greatly among variables. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
129.
利用固体废弃物生产商品砂浆 总被引:1,自引:0,他引:1
砂浆是一类重要的建筑材料,砂浆的商品化是建筑业实施节能减排的重要方面。发展商品砂浆可以实现节约资源、减少污染。 相似文献
130.
研究了德国黄牛和比利时蓝牛的杂种后代德本F1、蓝本F1牛在甘肃省陇东地区肉牛带的适应性能,主要包括生长发育、增重、抗病性和繁殖性能等因素。结果表明德本F1、蓝本F1牛在试验期内(0~12月龄)的各项指标均优于本地牛,对当地饲养条件和环境条件表现出了良好的适应能力,可以在当地推广应用。 相似文献