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581.
根据 1998年 5月的调查资料 ,分析并讨论了春季黄海南部海区溶解无机氮的分布特征。结果表明 :( 1)因受长江冲淡水及沿岸流的影响 ,NH+4 - N、NO-2 - N浓度的平面分布基本呈周边高、中央低 ,NO-3 - N的浓度则基本呈长江口外海域高、中北部深水区低的分布规律。 ( 2 )调查海域深水区的溶解无机氮存在明显的层化现象 ,且底层等值线上凸密集。 10 m以浅水体 ,NO-3 - N的浓度分布均匀 ,10 m以深水体 ,NO-3 - N的浓度急剧增加 ,且呈现出随深度增加而增加的趋势 ,NH+4 - N、NO-2 - N浓度的垂直分布比较均匀。 ( 3)黄海南部表层叶绿素 a的浓度呈现周边高、中央低的分布特征。 相似文献
582.
实时荧光定量PCR(qRT-PCR)是定量分析基因表达的常用方法,选择合适的内参基因对准确分析目的基因表达水平至关重要。本研究以不同铁浓度培养条件下的玛氏骨条藻为材料,定量分析Cytb、EF-1α、HPRT、UBC、GAPDH、β-actin以及β-tubulin 7个内参基因的表达情况,并利用GeNorm、NormFinder和BestKeeper软件对这些内参基因的稳定性进行综合评价。结果表明,Cytb和EF-1α的表达稳定性较好,EF-1α+Cytb组合的稳定性最佳,是玛氏骨条藻基因表达研究的理想内参基因,而其他基因的表达稳定性较差,不适合作为内参基因。本研究为玛氏骨条藻基因表达研究过程中内参基因的选择提供了方法学上的依据。 相似文献
583.
With the aim of better understanding the tight gas reservoirs in the Zizhou area of east Ordos Basin, a total of222 samples were collected from 50 wells for a series of experiments. In this study, three pore-throat combination types in sandstones were revealed and confirmed to play a controlling role in the distribution of throat size and the characteristics of gas-water relative permeability. The type-Ⅰ sandstones are dominated by intercrystalline micropores connected by cluster throats, of which the distribution curves of throat size are narrow and have a strong single peak(peak ratio 30%). The pores in the type-Ⅱ sandstones dominantly consist of secondary dissolution pores and intercrystalline micropores, and throats mainly occur as slice-shaped throats along cleavages between rigid grain margins and cluster throats in clay cement.The distribution curves of throat size for the type-Ⅱ sandstones show a bimodal distribution with a substantial low-value region between the peaks(peak ratio 15%). Primary intergranular pores and secondary intergranular pores are mainly found in type-Ⅲ samples, which are connected by various throats. The throat size distribution curves of type-Ⅲ sandstones show a nearly normal distribution with low kurtosis(peak ratio 10%), and the micro-scale throat radii(0.5 μm) constitute a large proportion. From type-Ⅰ to type-Ⅲ sandstones, the irreducible water saturation(Swo) decreased; furthermore, the slope of the curves of Krw/Krg in two-phase saturation zone decreased and the two-phase saturation zone increased,indicating that the gas relative flow ability increased. Variations of the permeability exist in sandstones with different porethroat combination types, which indicate the type-Ⅲ sandstones are better reservoirs, followed by type-Ⅱ sandstones and type-Ⅰ sandstones. As an important factor affecting the reservoir quality, the pore-throat combination type in sandstones is the cumulative expression of lithology and diagenetic modifications with strong heterogeneity. 相似文献
584.
A naturally selenium-accumulating Cardamine sp. is growing in Yutangba Selenium Mining Field, Enshi area, Hubei Province, China, where the geochemical environment is selenium-enriched and endemic selenosis ever occurred in humans. The present study investigated the characteristics of accumulation, speciation and quantity of selenium in Cardamine sp. with HPLC-ICP-MS. Results show that Cardamine sp. can accumulate Se at most 1427 mg/kg in seedling leaves. Even after the biomass incensement of growing up, the plant still could accumulate Se up to several hundred of mg/kg in concentration. Moreover, the biomass enrichment coefficient (BEC) of Se is exceedingly high, in the seedling leaves mostly, higher than 50 mg/kg; in the range of 43.7-68 mg/kg; and the lowest value is higher than 3 mg/kg in mature fronds. Se is present in the plant predominantly in form of SeCys2 with the highest concentration in seeds; up to 1081 mg/kg as Se. In contrast, SeCysz levels are low during early growth period; they are 136.1 mg/kg as Se in seedling fronds and 39.4 mg/kg as Se in mature fronds, respectively. SeMet concentration is comparatively low; 10.6 mg/kg as Se in seedling frond and 5.3 mg/kg as Se in half mature fronds, respectively. This indicates that Cardamine sp. is extremely efficient in extracting Se from soil and translocating it into its above-ground biomass. Therefore, Cardamine sp., found in Yutangba Se Mining Field may be a new Se hyperaccumulator. It is still uncertain whether the Se-accumulation or detoxification of Cardamine sp. happens through the pathway of SeCys methylated to form Se-methylselenoCys or through the formation of Se-carboxymethyl- selenohomocysteine. Indeed, further study should be carried out on the determination of more Se species to explain the high Se hyperaccumulation in Cardamine sp. 相似文献
585.
以重庆綦江、南川和涪陵地区的下志留统龙马溪组下部页岩样品为例,通过X射线衍射(XRD)、场发射扫描电镜、TOC测试、RO测试、高压压汞和低温氮吸附等手段,对研究区龙马溪组下部页岩储集层的矿物成分、有机组分、孔隙特征及成岩作用进行研究。实验结果表明,龙马溪组页岩成岩作用类型主要包括机械压实作用、化学压实作用、溶蚀作用、交代作用、破裂作用及矿物转化等,演化阶段介于晚成岩作用与极低级变质作用之间;成岩作用对页岩储集层的孔渗特征、孔隙成因类型、非均质性和形貌特征均有显著影响。对成岩作用与孔隙演化进行了匹配,认为机械/化学压实作用、溶蚀作用及过程中的有机生烃、矿物转化对孔隙发育影响最为显著,并将储集层成岩作用划分为溶蚀作用等建设性成岩作用与压实作用等破坏性成岩作用。 相似文献
586.
Geographic information has a great potential to be re-used when supported by mechanisms for its discovery. Above all, the quality of a catalogue service is the key feature supporting users in the discovery process. So far, there have been in existence various methodologies dealing with the normalized evaluation of quality with respect to catalogue services. Their biggest weakness seems to be in the depth of quality testing, i.e. some influences are beyond the scope of evaluation of these methodologies with respect to quality in catalogue services. In this study, the quality of 45 catalogue services across Europe was verified with the proposed normalized evaluation methodology originating from documents within the INfrastruture for SPatial InfoRmation in Europe (INSPIRE) framework. This paper discusses the (statistical) influence of factors that may significantly change the results of catalogue service testing. The proposals for improving the existing INSPIRE normalized evaluation procedure are applicable for any spatial data infrastructure and/or Digital Earth component using the Open Geospatial Consortium Catalogue Service for the Web as a basis. 相似文献
587.
Nak Won Heo Sang Hee Hong Gi Myung Han Sunwook Hong Jongmyoung Lee Young Kyung Song Mi Jang Won Joon Shim 《Ocean Science Journal》2013,48(2):225-233
The spatial distribution of small plastic debris on Heungnam beach in February 2011 was investigated. The abundances of small plastic debris over 2 mm in size along the high strandline and cross-sectional line of the beach were determined. The mean abundances of small plastics were 976 ± 405 particles/m2 at the high strandline in the upper tidal zone along the shoreline and 473 ± 866 particles/m2 at the cross-section perpendicular to the shoreline. Specifically, styrofoam (expanded polystyrene) spherules accounted for 90.7% of the total plastic abundance in the high strandline and 96.3% in the cross-section. The spatial distribution patterns of small plastic debris differed between the high strandline and cross-sectional line. The cross-sectional distribution of small plastic abundance differed among plastic types, indicating that representative sampling of small plastic debris on a beach is necessary. 相似文献
588.
本文探讨了盐湖副产氯化镁应用于炼钢冶金造渣的可行性。以盐湖水氯镁石和石灰为原料,通过化学合成制备了氧化镁,再将氧化镁与石灰、粘结剂混配成型制备炼钢用镁钙造渣剂,考察了粘结剂硼酸的不同用量时造渣剂形成的球团强度和抗压强度及微观结构变化;同时研究了不同煅烧温度、煅烧时间、氧化镁掺杂量的情况下,造渣剂的活性及杂质脱除率。实验结果表明,利用该方法制备的镁钙造渣剂应用于钢铁冶金造渣过程,可有效地脱除碳、磷、硫、硅等杂质成分,提高转炉冶炼的冶金效果的同时实现了盐湖资源再利用,具有较好的推广应用前景。 相似文献
589.
仅用虚拟控制点的超大区域无控制区域网平差 总被引:1,自引:1,他引:1
利用光学卫星影像进行无控制测图是摄影测量追求的目标。针对超大区域无控制测图的需求,本文提出了一种以单景影像为平差单元,基于虚拟控制点的光学卫星影像超大规模无控制区域网平差方法。该方法利用待平差影像的初始RPC模型生成虚拟控制点,并将其作为带权观测值引入平差模型中以改善平差模型的状态,克服了在无控制点条件下平差精度不稳定、误差过度累积引起的网的扭曲变形等问题。为了验证本方法的有效性和精度,利用资源三号卫星获取的覆盖全国的26 406景影像进行区域网平差试验,并利用全国范围内分布的约8000个高精度控制点对平差后自动生产的DOM和DSM产品的几何精度进行验证。试验结果表明,平面和高程中误差均达到了4m以内,同时,区域网内部相邻影像之间的几何拼接精度优于1个像素,满足无缝拼接的要求。 相似文献
590.