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331.
332.
以海区30'网格方区多年月平均统计的声速剖面作为原始数据集,提取声速剖面的表层、主跃层和深海等温层分层结构特征,把我国近海及其邻近海域预分为Ⅰ,Ⅱ和Ⅲ类区。对Ⅱ,Ⅲ类区声速剖面,应用有序样本聚类算法分别进行表层分离。根据各类区的表层声速剖面数据,通过归一化处理和Akima差值采样得到梯度剖面,建立起按月归一化后的声速剖面分层梯度样本集,并应用系统聚类法和SOFM神经网络方法分别进行聚类分析,再根据分类结果并结合各类型海区的声学特点,得到各类型海区声速剖面的典型类型。通过对大量历史数据的分析结果表明,该方法为自动分类海洋声速剖面提供了一条有效路径,弥补了长期以来海洋声速剖面主要依靠人工分类的不足。 相似文献
333.
334.
兰州城区稳定能量及其与空气污染的关系 总被引:11,自引:16,他引:11
从能量学的观点出发,提出了描述地面至特定高度大气层结构稳定度的参数-稳定能量,并给出了具体计算方法。根据1988-1992年兰州气象站逐日08:00(北京时,下同)的探空资料,计算了300-1000m每隔50m共15层的稳定能量。利用同期兰州市环境监测站自动监测系统监测的兰州城区3种主要空气污染物二氧化硫、一氧化碳和氮氧化物(SO2、CO、NOX)的日平均浓度资料,计算了地面气象要素、低空气象参数、低空风和稳定能量等气象因子与SO2、CO、NOX之间的相关。结果表明:(1)用稳定能量来描述低层大气的稳定性更为合理一些;(2)在诸多气象因子中,稳定能量与SO2、CO、NOX浓度之间的相关性最显著;(3)稳定能量的年变化规律与空气污染浓度的年变化规律基本一致;(4)逐月看,各层稳定能量与SO2浓度之间均为正相关,除7月份以外,大多数层次均通过了α=0.01显著性水平的相关性检验。 相似文献
335.
Anorthoclase megacrysts commonly occur with low pressure cumulate nodules (olivine + clinopyroxene + kaersutite ± oligoclase) in alkali basalts and their differentiates. The absence of anorthoclase from the cumulate nodules indicates that anorthoclase remained suspended in the magma while the other minerals sank, forming the cumulates, assuming a congeneric origin for megacrysts and nodules. On this basis, density calculations indicate that anorthoclase crystallised from a magma of approximately trachyandesitic composition, while the anorthoclase megacrysts usually occur in magmas more basic than trachybasalt. Thus, the anorthoclase megacrysts and the associated cumulate nodules did not crystallise from the host magma, but were picked up from a high-level partly crystallised magma pool containing a more evolved alkali basaltic differentiate by a later surge of more basic liquid which then carried both anorthoclase megacrysts and fragmented cumulates to the surface. 相似文献
336.
Chemical Separation and Isotopic Variations of Cu and Zn From Five Geological Reference Materials 总被引:6,自引:0,他引:6
John B. Chapman Thomas F.D. Mason Dominik J. Weiss Barry J. Coles Jamie J. Wilkinson 《Geostandards and Geoanalytical Research》2006,30(1):5-16
This paper presents an adapted anion exchange column chemistry protocol which allowed separation of high-purity fractions of Cu and Zn from geological materials. Isobaric and non-spectral interferences were virtually eliminated for consequent multiple-collector ICP-MS analysis of the isotopic composition of these metals. The procedure achieved ∼ 100% recoveries, thus ensuring the absence of column-induced isotopic fractionation. By employing these techniques, we report isotopic analyses for Cu and Zn from five geological reference materials: BCR-027 blende ore (BCR), δ65 Cu = 0.52 ± 0.15‰ (n = 10) and δ66 Zn = 0.33 ± 0.07‰ (n = 8); BCR-030 calcined calamine ore (BCR), δ66 Zn = -0.06 ± 0.09‰ (n = 8); BCR-1 basalt (USGS), δ66 Zn = 0.29 ± 0.12‰ (n = 8); NOD-P-1 manganese nodule (USGS), δ65 Cu = 0.46 ± 0.08‰ (n = 10) and δ66 Zn = 0.78 ± 0.09‰ (n = 9); SU-1 Cu-Co ore (CCRMP), δ65 Cu = -0.018 ± 0.08‰ (n = 10) and δ66 Zn = 0.13 ± 0.17‰ (n = 6). All uncertainties are ± 2s; copper isotope ratios are reported relative to NIST SRM-976, and zinc isotope ratios relative to the Lyon-group Johnson Matthey metal (batch 3-0749 L) solution, JMC Zn. These values agree well with the limited data previously published, and with results reported for similar natural sample types. Samples were measured using a GVi IsoProbe MC-ICP-MS, based at the Natural History Museum, London. Long-term measurement reproducibility has been assessed by repeat analyses of both single element and complex matrix samples, and was commonly better than ± 0.07‰ for both δ66 Zn and δ65 Cu. 相似文献
337.
Differences between males and females in the morphology of the fifth legs were found in stage IV copepodites of Boeckella hamata and in stage V cope‐podites of B. hamata, B. propinqua, B. dilatata, B. triarticulata, and Calamoecia lucasi. There were also sexual differences in overall body size. In B. hamata, B. triarticulata, and B. dilatata, the differences were sufficiently obvious for stage V copepodites to be sexed at low magnifications. The diagnostic features of all stages are described. 相似文献
338.
Jurassic Black Shales Facies from Qiangtang Basin (Northern Tibet):Rare Earth and Trace Elements for Paleoceanographic Implications 总被引:1,自引:0,他引:1
CHEN Lan YI Haisheng TSAI Louis Loung-Yie XU Guiwen DA Xuejuan LIN Andrew Tien-Shun 《《地质学报》英文版》2013,87(2):540-554
The Biluo Co and Amdo 114 station, northern Tibet, cropping out the Early Toarcian and Middle-Late Tithonian (Jurassic) organic-rich black shales, have been a focus to petroleum geologists in discussing their oil-producing potential. This paper first reports the trace elements and rare earth elements to discuss the paleoenvironments, redox conditions and sedimentary mechanisms of those black shales. Both sections exhibit variation in trace element abundances with concentrations <0.1 ppm to 760 ppm, mostly enriched in V, Cr, Ni, Cu, Zn, Mo, Ba and U. Element ratios of Ni/Co, V/Cr, U/Th and V/(V+Ni) plus U were used to identify redox conditions. The shale-normalized rare earth element (REE) patterns are characterized by the flat-shale type with instable Ce anomalies and very weekly positive Eu anomalies. Positive Ceanom values are significant with values varying between –0.064 and 0.029 in Biluo Co, which may be interpreted as release of REE and input of riverine terrestrial matter with rich Ce (resulting in pH change) during the anoxic conditions. In the middle parts of Amdo 114 station, distinct negative Ceanom values are observed (?0.238 to ?0.111) and associated surface water warming were interpreted as being related to a major sea level rise. In contrast, the formation of the black shales in the lower and upper part of the studied succession took place during a cooler (Ceanom values >–0.10), lower surface water productivity, and lower sea-level stage. Thus, we emphasize the role of different factors that control the formation of local and regional black shales. The most important factors are sea-level fluctuations and increasing productivity. 相似文献
339.
340.
A. D. Mackey A. M. N. Ferguson M. J. Irwin N. F. Martin A. P. Huxor N. R. Tanvir S. C. Chapman R. A. Ibata G. F. Lewis A. W. McConnachie 《Monthly notices of the Royal Astronomical Society》2010,401(1):533-546
We report on deep imaging of a remote M31 globular cluster, MGC1, obtained with Gemini/GMOS. Our colour–magnitude diagram for this object extends ∼5 mag below the tip of the red-giant branch and exhibits features consistent with an ancient metal-poor stellar population, including a long, well-populated horizontal branch. The red-giant branch locus suggests MGC1 has a metal abundance [M/H]≈−2.3 . We measure the distance to MGC1 and find that it lies ∼160 kpc in front of M31 with a distance modulus μ= 23.95 ± 0.06 . Combined with its large projected separation of R p = 117 kpc from M31, this implies a deprojected radius of R gc = 200 ± 20 kpc , rendering it the most isolated known globular cluster in the Local Group by some considerable margin. We construct a radial brightness profile for MGC1 and show that it is both centrally compact and rather luminous, with MV =−9.2 . Remarkably, the cluster profile shows no evidence for a tidal limit and we are able to trace it to a radius of at least 450 pc, and possibly as far as ∼900 pc. The profile exhibits a power-law fall-off with exponent γ=−2.5 , breaking to γ=−3.5 in its outermost parts. This core-halo structure is broadly consistent with expectations derived from numerical models, and suggests that MGC1 has spent many gigayears in isolation. 相似文献