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571.
572.
王芳  周年兴  关健  彭鹏 《热带地理》2015,35(6):797-803
民歌作为中国传统民间文化的艺术代表之一,是在特定地域空间上的景观文化表达。文章根据景观基因理论从本体形态和文化环境2个维度,识别民歌文化景观的基因结构,并结合定量数据分析民歌文化景观基因的空间分布特征。结果表明:就体裁而言,号子主要分布于平原区域,山歌分布于山地,而小调则分布于东部地区长江流域;就题材而言,劳动生产类民歌分布于精耕细作的东部地区,爱情婚姻类民歌分布于远离中原文化的地区;音韵特点而言,徵调式民歌所占比重最大,羽调次之,而角调最少。少数民族的民歌主要分布于西北西南和东北等少数民族人口较多的地区。表演形式也因地域差别具有较大差异。民歌文化景观的形成是人与地理环境相互作用的结果,不同地理环境的居民形成不同的感知空间,从而创造出具有地域文化符号特征的地方民歌。  相似文献   
573.
Herbicide residues have been measured in the Great Barrier Reef lagoon at concentrations which have the potential to harm marine plant communities. Monitoring on the Great Barrier Reef lagoon following wet season discharge show that 80% of the time when herbicides are detected, more than one are present. These herbicides have been shown to act in an additive manner with regards to photosystem-II inhibition. In this study, the area of the Great Barrier Reef considered to be at risk from herbicides is compared when exposures are considered for each herbicide individually and also for herbicide mixtures. Two normalisation indices for herbicide mixtures were calculated based on current guidelines and PSII inhibition thresholds. The results show that the area of risk for most regions is greatly increased under the proposed additive PSII inhibition threshold and that the resilience of this important ecosystem could be reduced by exposure to these herbicides.  相似文献   
574.
This study quantifies benthic nutrient fluxes and sedimentation rates in the Ahe Atoll lagoon (French Polynesia), in two stations located under pearl oyster frames, and two control stations away from the pearl culture facility. Dissolved inorganic nitrogen fluxes ranged between 2 and 35μmolNm(-2)h(-1) and Soluble Reactive Phosphorus varied between -3 and 8.2μmolPm(-2)h(-1). Particulate sedimentation rates beneath the oysters were approximately five times higher than in the control zone and the percentage of small particles (?63μm) were about the twice. In contrast, sediment composition was similar under and outside the direct influence of oyster frames. In this ecosystem, where primary production is dependent on the available nitrogen, our study revealed that, while highly variable, benthic fluxes could sometimes contribute up to 28% of the nitrogen demand for primary production.  相似文献   
575.
In this paper the Marine Fish Community Index (MFCI) for the assessment of ecological status of marine environment is proposed. The MFCI was divided into 4 typologies: Rocky subtidal; shallow, intermediate and deep soft-bottoms. Based on the typical community associated to each typology and the DPSIR analysis performed, a set of metrics were selected and tested through a multiple correlation matrix (Pearson’s coefficient) and the core ones included in the index. The MFCI was applied in all typologies and the scores obtained with each metric were analyzed. In order to test the robustness of the MFCI the final ecological value of each zone was recalculated by removing successively one metric at a time. The MFCI showed a sensitive and robust response in the ecological status assessment. Since it incorporates both functional and structural community information, the MFCI can be useful in the context of the Marine Strategy Framework Directive as well as in other contexts of conservation and sustainable management of the marine environment.  相似文献   
576.
本研究利用辽宁本溪庙洞石笋MD12,通过230Th定年和高分辨率氧同位素分析,并集成庙洞另一支石笋MD11序列,重建了3.04~2.60 ka B.P.时期辽东地区夏季风(降水)变化历史。该石笋氧同位素序列记录了2.8 ka事件的详细过程,事件的核心阶段起止时间约为2.76~2.66 ka B.P.,中心点位于2.68 ka B.P.,稍微晚于西南石笋氧同位素记录(约2.71 ka B.P.),但是在事件的开始时间上,庙洞石笋氧同位素记录比西南石笋氧同位素记录晚了约100年。因此,庙洞石笋氧同位素记录与西南石笋氧同位素记录中显示的缓慢减弱-快速增强模式不同,2.8 ka事件在辽东石笋氧同位素记录中表现为快速减弱-突然增强的变化模式,与太阳活动代用指标一致变化,支持太阳活动是2.8 ka弱季风事件驱动因子的观点。庙洞石笋氧同位素快速响应太阳活动的变化特征,说明其动力学机制可能是太阳活动减弱导致北半球高纬度地区温度降低,然后通过大气"遥相关"作用影响东亚夏季风。  相似文献   
577.
绕月探测工程的初步科学成果   总被引:11,自引:0,他引:11       下载免费PDF全文
嫦娥一号是我国发射的第一个月球轨道探测器, 是中国月球探测工程“绕”、“落”、“回”发展战略的第一步. 嫦娥一号于2007年10月24日在西昌卫星发射中心成功发射, 2009年3月1日受控落月于52.36°E, 1.50°S的丰富海区域, 在轨运行495天, 比预期一年的工作寿命延长4个多月, 一共获得了1.37 TB的原始科学探测数据, 在此基础上目前已生产出约4 TB科学应用数据产品. 通过对这些科学探测数据的初步分析和应用研究, 已经获得了包括“中国首次月球探测工程全月球影像图”在内的一系列科学成果, 圆满实现了预期的各项科学目标, 为推动我国月球科学和天体化学的研究和后续月球探测工程的开展奠定了重要基础.  相似文献   
578.
:针对2008年初的南方雨雪冰冻灾害,以受灾严重的广东南岭山区为研究区域,采用面向对象的方法进行森林植被破坏遥感检测研究,首先得到林地分布图,然后用K均值聚类法进行基于对象NDVI差值的森林受灾程度分级,得到灾害等级地图,最后用分带统计法对灾害的空间分布形态进行了分析.林地提取的总体精度为95.33%,灾害分级的总体精度为87.27%,Kappa系数为80.74%.灾害空间分析表明:高程上,600~1 600 m主要为重度、中度受灾;600~1 300 m,高程越高,受灾比例越大;1 300~1 600 m,比例有所下降;400 m以下和1 600 m以上主要为轻度受灾;坡度上,随着坡度的增大,重度、中度受灾比例有所增加,但差异并不十分明显;坡向上,各级灾害比例几乎没有差别.  相似文献   
579.
Estivation, hibernation, and starvation are indispensable inactive states of sea cucumbers Apostichopus japonicus in nature and in culture ponds. Generally, temperature is the principal factor that induces estivation or hibernation in the sea cucumber. The present study provided insight into the physiological adaptations of A. japonicus during the three types of inactivity (hibernation, estivation, and starvation) by measuring the oxygen consumption rates (Vo2) and biochemical compositions under laboratory conditions of low (3°C), normal (17°C) and high (24°C) temperature. The results show that the characteristics of A. japonicus in dormancy (hibernation and estivation) states were quite different from higher animals, such as fishes, amphibians, reptiles, and mammals, but more closely resembled a semi-dormant state. It was observed that the shift in the A. japonicus physiological state from normal to dormancy was a chronic rather than acute process, indicated by the gradual depression of metabolic rate. While metabolic rates declined 44.9% for the estivation group and 71.7% for the hibernation group, relative to initial rates, during the 36 d culture period, metabolic rates were not maintained at constant levels during these states. The metabolic depression processes for sea cucumbers in hibernation and estivation appeared to be a passive and an active metabolic suppression, respectively. In contrast, the metabolic rates (128.90±11.70 μg/g h) of estivating sea cucumbers were notably higher (107.85±6.31 μg/g h) than in starving sea cucumbers at 17°C, which indicated that the dormancy mechanism here, as a physiological inhibition, was not as efficient as in higher animals. Finally, the principle metabolic substrate or energy source of sea cucumbers in hibernation was lipid, whereas in estivation they mainly consumed protein in the early times and both protein and lipid thereafter.  相似文献   
580.
LA-ICP-MS工作参数优化及在锆石U-Pb定年分析中的应用   总被引:6,自引:4,他引:2  
将激光器(LA)和电感耦合等离子体质谱仪(ICP-MS)联用避免了溶液分析繁琐、耗时的前处理操作,减少了样品制备过程中可能带来的污染,同时又具备分析成本低、测试速度快、分析数据精度高等优势。本文将LA与ICP-MS联接使用,通过激光能量密度和剥蚀频率组合来讨论较低的元素分馏效应,同时匹配RF功率、采样深度、载气及He气流速等主要工作参数以获得较高的元素信号灵敏度和稳定性,从而得到仪器最优工作参数组合,建立了可靠的锆石U-Pb定年方法。通过对锆石标样91500、GJ-1及Ple2ovic互测结果表明,其206Pb/238U加权平均年龄分别为1063.9±6.0 Ma(2σ,n=20)、600.3±2.6 Ma(2σ,n=27)及337.6±1.7 Ma(2σ,n=20),测试结果准确度和精度均在1%范围内,与前人报道的误差范围一致。使用优化后的仪器参数对来自鄂东南铜绿山矿区石英正长闪长玢岩岩体中的实际锆石样品进行测试,获得其206Pb/238U年龄与前人研究结果基本一致,表明本法能准确地对锆石进行定年分析。  相似文献   
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