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651.
后疫情时代,文化冲突可能会是中国入境旅游需求复苏的突出制约因子。基于2002—2018年联合国世界旅游组织关于66个客源地对中国的入境旅游人次数据和面板数据估计策略,探究了文化冲突对中国入境旅游需求的影响及其机制。结果表明:① 文化冲突显著负向影响中国入境旅游需求;② 文化冲突对中国入境旅游需求影响在不同性别、区域、年龄、目的群组中具有异质性;③ 文化认同是文化冲突影响中国入境旅游需求过程中的机制变量。研究结果能推进入境旅游需求影响因素理论研究,为实现中国入境旅游需求复苏提供新的理论依据和政策参考。 相似文献
652.
正Fluid inclusions in halite can directly record the major composition of seawater,however Ordovician halite is very rare.Ordovician is a key time during the evolution history.However there are no Ordovician seawater data reported except from the data from the halite from the 相似文献
653.
Jie Li Xiao‐Ying Jiang Ji‐Feng Xu Li‐Feng Zhong Xuan‐Ce Wang Gui‐Qin Wang Pei‐Pei Zhao 《Geostandards and Geoanalytical Research》2014,38(1):37-50
We report an improved procedure for the determination of the platinum‐group elements (PGE) and Re, and Os isotopes from a single sample aliquot by isotope dilution (ID) using inductively coupled plasma‐mass spectrometry (ICP‐MS) and negative thermal ionisation mass spectrometry (N‐TIMS), respectively. A two‐stage column method was used to purify PGE‐Re from their sample matrix and interfering elements (e.g., Mo, Zr and Hf) after Os had been separated by CCl4 solvent extraction. The first column separation step used cation exchange resin (AG50W‐X8) to concentrate PGE‐Re and some potential interfering elements (e.g., Mo, Zr and Hf). In the second step, N‐benzoyl‐N‐phenylhydroxylamine (BPHA) extraction resin was used to separate PGE‐Re from the remaining interfering elements, which all remained strongly absorbed to the resin. The method was used to determine the PGE and rhenium, and Os isotope ratios in a range of geochemical reference materials (TDB‐1, WGB‐1, BHVO‐2 and UB‐N). The obtained results agree well with those previously published. This new method enables PGE‐Re abundances and Os isotopic ratios to be determined on the same sample digestion, and circumvents the problems created by sample heterogeneity when comparing PGE and Re‐Os isotope data. 相似文献
654.
Wu Liu Xianzhu Wu Shuwen Pei Xiujie Wu Christopher J. Norton 《Quaternary International》2010,211(1-2):29-41
This contribution discusses recent paleoanthropological findings from Huanglong Cave, a Late Pleistocene human fossil site from Yunxi County, Hubei Province, China. Three excavations in the Huanglong Cave from 2004 to 2006 yielded seven human teeth, some stone and bone tools, possible burnt sediment and other evidence possibly related to hominin activities. Based on the presence of extinct faunas (20% of total taxa identified), the deposits dated to the Late Pleistocene. Electron spin resonance (ESR) and uranium-series (U-series) dating analyses on associated teeth and speleothems have resulted in divergent chronometric ages (ESR: 44–34 ka; U-series: 103–79 ka). Analysis indicates: (1) most of the morphological and metric features of the human teeth from Huanglong Cave fall within the range of variation of modern Chinese, but a few characters may still link them to more archaic hominins; (2) some activity-induced abrasion and other tooth use-marks were identified, including pronounced tooth chipping and interproximal grooves on the anterior teeth; (3) the sample of blackened deposit has a high carbon content (over 70%), experienced high temperatures, and likely was of cultural origin and not natural; (4) the mammal fossils represent the “Ailuropoda-Stegodon” faunal unit which lived in southern China throughout the Pleistocene. Synthesizing all of these findings, especially the human teeth that display modern human characteristics, Huanglong Cave will offer some new insights into various issues currently being debated in Late Pleistocene human evolutionary research. 相似文献
655.
Jiabing Wu Dexin Guan Shijie Han Tingting Shi Changjie Jin Tiefan Pei Guirui Yu 《水文研究》2007,21(18):2425-2434
Components of the energy budget were measured continuously above a 300‐year‐old temperate mixed forest at the Changbaishan site, northeastern China, from 1 January to 31 December 2003, as a part of the ChinaFlux programme. The albedo values above the canopy were lower than most temperate forests, and the values for snow‐covered canopy were over 50% higher than for the snow‐free canopy. In winter, net radiation Rn was generally less than 5% of the summer value due to high albedo and low incoming solar radiation. The annual mean latent heat LE was 37·5 W m?2, accounting for 52% of Rn. The maximum daily evaporation was about 4·6 mm day?1 in summer. Over the year, the accumulated precipitation was 578 mm; this compares with 493 mm of evapotranspiration, which shows that more than 85% of water was returned to the atmosphere through evapotranspiration. The LE was strongly affected by the transpiration activity and increased quickly as the broadleaved trees began to foliate. The sensible heat H dropped at that time, although Rn increased. Consequently, the seasonal variation in the Bowen ratio β was clearly U‐shaped, and the minimum value (0·1) occurred on a sunny day just after rain, when most of the available energy was used for evapotranspiration. Negative β values occurred occasionally in the non‐growing season as a result of intensive radiative cooling and the presence of water on the surface. The β was very high (up to 13·0) in snow‐covered winter, when evapotranspiration was small due to low surface temperature and available soil water. Vegetation phenology and soil moisture were the key variables controlling the available energy partitioning between H and LE. Energy budget closure averaged better than 86% on a half‐hourly basis, with slightly greater closure on a daily basis. The degree of closure showed a dependence on friction velocity u*. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
656.
渤海湾西海岸带地区的路堤多为填方型式,且以滨海盐渍土为主要填料.以滨海盐渍土填筑路堤,须解决土的盐胀、溶陷和吸湿软化带来的强度下降和稳定性降低问题,以进行土的改性或固化处理.为降低工程费用,固化材料应以常规的无机材料为主,辅助少量的高分子材料.为研究滨海盐渍土填筑路堤的力学性能,完成了石灰固化土和石灰+SH固土剂固化土... 相似文献
657.
658.
赣东北地区是我国重要的铜铅锌金银多金属矿集区,银山铅锌(银)铜(金)多金属矿床是赣东北地区一个重要的大型次火山热液型多金属矿床。银山铅锌矿发育有闪锌矿-方铅矿-石英脉,前人研究认为金属矿物与脉石矿物为伴生关系,但是没有强调它们的成因上的联系。本次研究开展了矿石矿物中闪锌矿和伴生脉石矿物中石英的流体包裹体对比研究。通过详细的岩相学观察、显微测温、显微激光拉曼探针工作,对伴生石英脉和闪锌矿内原生包裹体,伴生石英脉中的晚期微细石英脉和闪锌矿内部次生包裹体进行流体特征的对比研究。研究结果显示,伴生石英脉原生流体包裹体比闪锌矿的原生包裹体的平均均一温度高约30℃,明显富集CH4、N2、CH4、CO2等挥发份,伴生石英脉中的晚期微细石英脉流体包裹体比闪锌矿次生包裹体的平均均一温度高23℃。闪锌矿原生包裹体与想伴生的早期石英脉在平均均一温度有所差别,气相成分差异明显,均表明矿石矿物与伴生脉石矿物可能形成于不同的地质环境,具有不同的温度和流体成分。 相似文献
659.
660.
We used the 13.7 m millimeter-wave telescope of the Qinghai Station of Purple Mountain Observatory at Delingha to carry out simultaneous mapping observations in the 12CO(J = 1 − 0), 13CO(J = 1 − 0) and CO18 (J = 1 − 0) lines towards 11 isolated star-forming molecular cores selected from the sample of Spitzer's c2d program. For all three lines, these sources were all observed to the positions of half the peak intensity of the 13CO(J = 1 − 0) line. The volume density, local thermodynamic equilibrium mass MLTE and virial mass MVIR were derived for each of the molecular cores. The obtained ratio of MVIR to MLTE is 0.85 ± 0.40 for the 13CO(J = 1 − 0) cores and 0.77 ± 0.35 for the CO18 (J = 1 − 0) cores. The density profiles of the cloud cores were also calculated. 相似文献