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31.
Fourteen glass beads and one glass fragment from Khami‐period (ad 1400–1830) sites of Danamombe, Naletale, Gomoremhiko, Nharire and Zinjanja, in Zimbabwe, were analysed by pXRF and Raman spectroscopy with the intention of correlating the results with associated radiocarbon dates. The results show that Zinjanja and an earlier part of the Danamombe stratigraphic context had Khami Indo‐Pacific beads (15th–17th centuries) corresponding with Torwa occupational layers. Other European beads and one bottle fragment [high‐lime, low‐alkali (HLLA) glass] dating from the 16th to the 19th centuries were confined to the top stratigraphic layers of Danamombe and Naletale, which coincide with the later Rozvi occupational layers. Gomoremhiko had one Mapungubwe–Zimbabwe bead series (13th–15th centuries), which suggests that it was probably earlier than the other sites. All European beads are made of soda–lime plant‐ash glass with high alumina, which makes them comparable with glass produced through the Mediterranean traditions in Southern Europe.  相似文献   
32.
A new approach has been presented to characterise phase spectra for simulating realistic nonstationary characteristics in synthetic accelerograms. The phase characteristics of the recorded earthquake accelerograms have been studied for this purpose and it has been found that the phase curve/unwrapped phases exhibit a monotonic downward trend which allows the problem of phase characterisation to be cast as a constrained nonlinear programming problem. The phase spectrum is first characterised by matching mean and variance of the generated distribution of relative phases with those obtained from recorded motions. As a practical application, it is shown how phase spectra can be characterised for an ensemble of synthetic accelerograms so as to maximise the severity of sample realisations.  相似文献   
33.
This study presents a geospatial analysis of surficial hydrology and geomorphology and their relationship to potential agricultural productivity in order to better understand the economic role of water in Chaco Canyon during the Bonito Phase (ca. AD 850–1150). Defined as the Natural Agricultural Suitability Analysis, the foundation of this study is a hierarchical geospatial analysis that integrates six key natural factors: slope, soil texture, soil depth, non-catastrophic overbank flooding potential, drainage flow length, and drainage proximity and flow potential. These factors are combined through a raster weighted overlay function to generate composite suitability map that offers a testable proxy for variability in relative agricultural potential during the Bonito Phase at Chaco. The rationale for including this set of natural factors is based largely on ethnographic and modern agricultural studies, but the predictive model differs from previous studies of agricultural potential in that it is independent of the specific archaeological distribution of evidence of agriculture in the study area. The results of this analysis suggest that previous models of Chacoan agricultural productivity have underestimated local production capacity. Previous studies have focused solely on floodplain contexts, whereas this study points to a more comprehensive and geographically distributed use of the landscape.  相似文献   
34.
晋侯稣编钟铭文对研究西周历法及月相词语的含义和所指时间有着极其重要的价值。研究认为,西周金文月相词语所表示的时间是定点的,各表示太阴月中固定而又明确的一日;晋侯稣编钟铭文中的历法关系表现为月分大小,干支相连续;晋侯稣编钟属于厉王三十三年(公元前846年)器。  相似文献   
35.
赵文亮 《安徽史学》2005,(6):102-107
中国学者对第二次世界大战性质和阶段划分问题的研究历来十分重视.早在20世纪40年代就有学者对第二次世界大战的性质进行论述;50年代中后期曾进行过一次激烈的争鸣;80年代以来,关于二次大战性质问题的观点更加多样化.与此同时,学者们也对与第二次世界大战相关的阶段划分问题进行了深入的探讨,并提出了确定二次大战性质的标准和依据.  相似文献   
36.
Br/Cl ratios of hydrothermal fluids are widely used as geochemical tracers in marine hydrothermal systems to prove fluid phase separation processes. However, previous results of the liquid–vapour fractionation of bromine are ambiguous. Here we report new experimental results of the liquid–vapour fractionation of bromine in the system H2O–NaCl–NaBr at 380–450°C and 22.9–41.7 MPa. Our data indicate that bromine is generally more enriched than chlorine in the liquid phase. Calculated exchange coefficients KD(Br‐Cl)liquid‐vapour for the reaction Brvapour + Clliquid = Brliquid + Clvapour are between 0.94 ± 0.08 and 1.66 ± 0.14 within the investigated P–T range. They correlate positively with DClliquid‐vapour and suggest increasing bromine–chlorine fractionation with increasing opening of the liquid–vapour solvus, i.e. increasing distance to the critical curve in the H2O–NaCl system. An empirical fit of the form KD(Br‐Cl)liquid‐vapour = a*ln[b*(DClliquid‐vapour?1) + e1/a] yields a = 0.349 and b = 1.697. Based on this empirical fit and the well‐constrained phase relations in the H2O–NaCl system we calculated the effect of fluid phase separation on the Br/Cl signature of a hydrothermal fluid with initial seawater composition for closed and open adiabatic ascents along the 4.5 and 4.8 J g?1 K?1 isentropes. The calculations indicate that fluid phase separation can significantly alter the Br/Cl ratio in hydrothermal fluids. The predicted Br/Cl evolutions are in accord with the Br/Cl signatures in low‐salinity vent fluids from the 9 to 10°N East Pacific Rise.  相似文献   
37.
After ca 1000 BC , coinciding with the transition to sedentism, tertiary stage treponemal disease apparently becomes osteologically pervasive in pre‐Columbian North America. However, varying interobserver treponemal disease diagnostic thresholds, sampling error and the possibly ecosensitive nature of the pre‐Columbian nonvenereal treponemal disease variants (i.e. yaws and treponarid) prevents subsistence‐settlement pattern from becoming a reliable predictor of treponemal disease prevalence. This is particularly true of later prehistory with the transition from horticulture to intensive, maize‐based agriculture. To address whether treponemal disease visibility does vary across this specific subsistence‐settlement threshold, subadults (4+ years of age) and adults from 11 late prehistoric sites (N = 997) from the same geographic area of East Tennessee were sampled for the presence of treponemal disease. Six sites (N = 279) primarily date to the Late Woodland period (AD 700–900) and culturally belong to what is referred to as the Hamilton mortuary complex. The sample is archaeologically characterised as horticulturalist with presumably a dispersed farmstead or hamlet settlement pattern. Six sites (N = 718) date to the Late Mississippian (AD 1300–1550, Dallas phase) and are maize‐intensive agriculturalists with a large, aggregate village settlement pattern. The sites were examined using three different levels of treponemal disease diagnostic confidence. Treponemal disease raw frequency does indeed differ across the levels of diagnostic confidence between the total Late Woodland horticulturalist sample (4.3–5.5%) and total Late Mississippian maize agriculturalist sample (5.4–6.5%). The meaning is complex as the Dallas phase sample may have a socially segregated elite; the mound‐interred (1.8%) relative to the village‐interred (6.1–7.4%) exhibited significantly fewer cases of treponemal disease. Tentatively, treponemal disease visibility does appear to co‐associate with sedentism and perhaps (if the mound‐interred Dallas individuals are elites) also aggregated settlement. Copyright © 2013 John Wiley & Sons, Ltd.  相似文献   
38.
近三十年来中国城市旅游发展的阶段性和变化趋势   总被引:4,自引:0,他引:4  
文章首先对城市旅游研究的相关文献进行回顾。本文提出,伴随着三大旅游市场的演化,中国城市旅游经历了从城市主要作为旅游目的地的“单一功能阶段”逐步进入城市同时作为旅游目的地、客源地和旅游流节点的“一体化阶段”。同时,本文还剖析了城市旅游的未来趋势:从城市旅游的国际比较来看,旅游者会越来越偏好良好的人居环境、城市文脉的延续、标志性的城市建筑和良好的地理位置。  相似文献   
39.
纸张是传承中华文明的重要信息载体,液相脱酸法是应对纸张酸化并延缓纸张劣化的优选手段。事实证明,制备性质优良的脱酸液以高效去酸留碱并采用适宜工艺以保持纸张平整是实现优异脱酸效果的重要前提。本文对国内外近十年内多数液相脱酸工作进行调研,在此基础上从浸润性、分散性、加固性、抗菌性及防皱工艺五方面对纸张液相脱酸效果影响因素进行梳理并总结相应对策,为后续研究工作提供一定参考。  相似文献   
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