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61.
有效地排除钻渣是钻井液的主要功能之一。本文结合实验及相关工程情况,从力学角度对水平孔中钻渣的运移机理及相关影响因素进行分析,采用牛顿力学定律对钻渣在钻井液中的运移速度进行了解析建模。 相似文献
62.
有研究表明从中国北部经黄海、朝鲜半岛、日本海至日本本州岛存在一个大型断裂带,被称为“北纬40°断裂带”.为了验证该断裂带的存在性,本文通过GRACE和CHAMP卫星的位场数据中的大尺度区域重力和磁力异常来研究该区的大型构造特征.区域性研究范围为24°N~56°N,90°E~150°E,详细研究范围为32°N~42°N,122°E~132°E.2008年Taylor等利用CHAMP卫星2005年6月至12月收集的轨道数据,从测量数据中消除地核和外部产生磁场效应,经化磁极之后得到磁异常图,从中来追踪构造特征,并根据地质和地球物理资料建立了数学模型来进行解释.本文在此基础上,增加了GRACE卫星2003年10月份测量的重力异常场数据.实测差分位场数据利用高斯-勒让德求积法转换为垂向重力异常值,通过减去最新地球重力场模型（EGM96）的场值来去除波长超过1100 km的长波长异常,所得的重力异常数据和磁场数据进行比较.为了能从中得到研究区的共同构造特征,建立一个球面棱柱模型进行正演模拟、并进行重、磁异常场的波数相关性分析.研究发现在重、磁异常中均发现一个呈负相关的纬向构造特征,东亚地区“北纬40°断裂带”横穿了整个朝鲜半岛. 相似文献
63.
The karst mountain areas of Southwest China contain barren farmland soils and suffer from nutritional and water deficiencies that affect crop productivity. Hence,it is imperative to apply suitable fertilizers to restore soil fertility and maintain crop yield. The aim of this study is to investigate the effects of mineral-organic fertilizer(MOF)made of potassic rock and organic waste on the growth of crops. For this purpose, green Chinese cabbage grown using three different fertilization methods including MOF,inorganic fertilizer(IF), and a control was evaluated. We determined soil water content, agronomic characteristics,and biomass of green Chinese cabbage in different treatments. Furthermore, surface runoff from the pot experiments and soil leachate from pot experiments were collected to determine water temperature, pH, and cation and anion concentrations. The results demonstrate thatMOF can improve the soil water-holding capacity of soil,and the basic agronomic characteristics of the cabbage treated with MOF were superior to those with IF. Using MOF can promote the increase in cabbage biomass.Additionally, the concentration of inorganic carbon(largely in the form of HCO_3^-) in surface runoff water treated by MOF was higher than the other treatments, establishing carbon sequestration potential. This work provides a novel and environmentally friendly fertilization pattern in karst areas, which will improve crop yield and also increase the carbon sequestration potential of crops. 相似文献
64.
α-1,4-葡聚糖裂解酶的动力学性质研究 总被引：1，自引：0，他引：1
Sun Xue 《中国海洋大学学报(自然科学版)》2000,30(Z1):230-236
红藻中的α-1,4-葡聚糖裂解酶是红藻淀粉的降解酶,除了 红藻淀粉外,它还可以作用于多种底物。文中分别以PNPG和可溶性淀粉作底物,以龙须菜的 几个品系作为材料,研究了该酶促反应的动力学方面的性质。以 PNPG作为底物,该酶在60m in内酶促反应速度与保温时间成线性关系;在野生型龙须菜品系中该酶的最适反应温度是50 ℃,在两种突变型品系中是40℃;最适pH范围在4.4～5.5;底物浓度是4mmol/L时达到最大反 应速度;葡萄糖对该酶促反应有明显的抑制作用。以可溶性淀粉作为底物,在反应60 min内 酶反应速度与保温时间成线性关系;最适反应温度为50℃;最适pH范围在5.0～5.8;底物浓 度是8mg/mL时达到最大反应速度;葡萄糖对可溶性淀粉的抑制作用比对PNPG的弱。 相似文献
65.
The power dissipation index (PDI), which is defined as the sum of the cube of tropical cyclone (TC) maximum wind speed during TC lifetime, is widely used to estimate the TC destructive potential. However, due to the lack of high-resolution observations, little attention has been paid to the contribution of TC size change to TC destructive potential in response to ocean warming. In this study, sensitivity experiments are performed by using the high-resolution Weather Research and Forecasting (WRF) model to investigate the responses of TC size and TC destructive potential to prescribed sea surface temperature (SST) increase under the present climate condition. The results show that TC size increases with the ocean warming. Possible reasons for TC size change are investigated with a focus on the outer air-sea moisture difference (ASMD). As SST increases, ASMD in the outer zone of the TC is larger than that in the inner zone, which increases the surface entropy flux (SEF) of the outer zone. This change in the radial distribution of SEF causes the increase of tangential wind in the outer zone, which further increases SEF, resulting in a positive feedback between outer-zone SEF and outer-zone tangential wind. This feedback leads to the increase of the radius of gale-force wind, leading to the expansion of TC size. Moreover, to estimate the contribution of TC size change to TC destructiveness, we calculate TC size-dependent destructive potential (PDS) as the storm size information is available in the model outputs, as well as PDI that does not consider the effect of TC size change. We find that PDS increases exponentially as SST increases from 1 to 4°C, while PDI increases linearly; hence the former is soon much greater than the latter. This suggests that the growth effect of TC size cannot be ignored in estimating destructiveness under ocean warming. 相似文献
66.
本文中作者以祁连山中段为研究区域提出了评估中长期预报区内烈度的方法。本方法的特点是对相对稳定的发震地段在某预报期内进行烈度概率分析。文申指出了本方法与确定性方法以及地震危险性分析方法的不同之处。计算表明,对本区,烈度提高一度,遭受该烈度袭击的概率即减少20％左右。根据计算结果,将研究区域划分为若干小区,给出了每小区Ⅵ——Ⅷ度发生的概率,并以此作为估算预报期内损失期望值的依据。 相似文献
67.
长坑金银矿赋矿硅质岩的硅氧同位素地球化学特征及其成因意义孙晓明孙凯陈敬德陈炳辉（中山大学地球科学系,广州５１０２７５）关键词硅质岩δ３０Ｓｉδ１８Ｏ组成热水沉积长坑金银矿长坑大型金银矿是一种新型的浅成低温热液贵金属矿床,国内外尚未见类似者［１～２... 相似文献
69.
Submarine landslide is a widespread marine geohazard and an important part of the global ‘source to sink’ system. In this article, multi-channel seismic and topographic data are utilized to investigate the distribution, calculate the geomorphologic parameters, and discuss the genesis of the submarine landslides in the northeastern South China Sea. In the study area, which can be divided into two tectonic provinces: passive continental margin province and accretionary wedge province, 101 landslides are identified, with a total size of 2,358.22 km2. Statistics show that most landslides are of small sizes (<15 km2) and developed along small slope gradient regions. There is a high correlation between the slope gradient and the ratio of headscarp height to runout distance. The size and runout distance of landslide also correlate well. However, there is a low correlation coefficient including slope gradient versus runout distance and slope gradient versus size. The distribution of submarine landslides is consistent with that of bottom simulating reflections (BSRs) and seabed activities, which may imply a possible inner correlation among them. The calculated base of gas hydrate stability zone (BGHSZ) pinches out the seafloor at about 555–556 m below the sea level, where most of the landslide headscarps are located. And the BGHSZ depths are often shallower than the BSRs bottom depths in the upper slope area. Combined with previous studies, we consider that the influence factors of submarine landslides in the study area are earthquakes, canyons, seabed fluid activities, and gas hydrate dissociation. Gas hydrate dissociation is a global influence factor in the study area. In the passive continental margin province, the submarine landslides are mainly canyon-associated landslides. While in the accretionary wedge province, they are mainly controlled by seabed fluid activities and earthquakes. 相似文献
70.
Scott J Goetz Alessandro Baccini Nadine T Laporte Tracy Johns Wayne Walker Josef Kellndorfer Richard A Houghton Mindy Sun 《Carbon balance and management》2009,4(1):2-7
Mapping and monitoring carbon stocks in forested regions of the world, particularly the tropics, has attracted a great deal of attention in recent years as deforestation and forest degradation account for up to 30% of anthropogenic carbon emissions, and are now included in climate change negotiations. We review the potential for satellites to measure carbon stocks, specifically aboveground biomass (AGB), and provide an overview of a range of approaches that have been developed and used to map AGB across a diverse set of conditions and geographic areas. We provide a summary of types of remote sensing measurements relevant to mapping AGB, and assess the relative merits and limitations of each. We then provide an overview of traditional techniques of mapping AGB based on ascribing field measurements to vegetation or land cover type classes, and describe the merits and limitations of those relative to recent data mining algorithms used in the context of an approach based on direct utilization of remote sensing measurements, whether optical or lidar reflectance, or radar backscatter. We conclude that while satellite remote sensing has often been discounted as inadequate for the task, attempts to map AGB without satellite imagery are insufficient. Moreover, the direct remote sensing approach provided more coherent maps of AGB relative to traditional approaches. We demonstrate this with a case study focused on continental Africa and discuss the work in the context of reducing uncertainty for carbon monitoring and markets. 相似文献
