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301.
史静  肖仙桃  王鑫  白光祖  刘澜  吴秀平  章茵  李玉馨 《地质学报》2015,89(12):2433-2442
本文基于文献计量方法,以加拿大、澳大利亚、法国、德国、芬兰5国的地质调查机构2000~2014年发表的论文为统计对象,从产出论文数量和年度变化、主要研究领域和热点变化、国际合作和机构合作等方面,对5个机构的工作内容、科研发展态势进行判读,为国内地质调查机构的发展提供数据参考。  相似文献   
302.
303.
Shi  Feng  Yang  Bao  Linderholm  Hans W.  Seftigen  Kristina  Yang  Fengmei  Yin  Qiuzhen  Shao  Xuemei  Guo  Zhengtang 《Climate Dynamics》2020,54(7):3387-3404
Climate Dynamics - Tree growth trends can affect the interpretation of the response of tree-ring proxies (especially tree-ring width) to climate in the low-frequency band, which in turn may limit...  相似文献   
304.
隆林县石漠化地区发展金银花种植气候适应性分析   总被引:1,自引:0,他引:1  
以隆林县石漠化地区的气候条件为依据,采用比较分析方法,对金银花的气候生态规律和环境因子对金银花生长、产量的影响进行分析,找出其影响的气候指标。结果表明,隆林县石漠化地区金银花生长条件较好,西北部山区和南部高寒山区为适宜区,其它区域仅为次适宜区,为石漠化地区发展金银花种植提供气候依据。  相似文献   
305.
This paper presents a scenario-based study that investigates the interaction between sea-level rise and land subsidence on the storm tides induced fluvial flooding in the Huangpu river floodplain. Two projections of relative sea level rise (RSLR) were presented (2030 and 2050). Water level projections at the gauging stations for different return periods were generated using a simplified algebraic summation of the eustatic sea-level rise, land subsidence and storm tide level. Frequency analysis with relative sea level rise taken into account shows that land subsidence contributes to the majority of the RSLR (between 60 % and 70 %). Furthermore, a 1D/2D coupled flood inundation model (FloodMap) was used to predict the river flow and flood inundation, after calibration using the August 1997 flood event. Numerical simulation with projected RSLR suggests that, the combined impact of eustatic sea-level rise and land subsidence would be a significantly reduced flood return period for a given water level, thus effective degradation of the current flood defences. In the absence of adaptation measures, storm flooding will cause up to 40 % more inundation, particularly in the upstream of the river.  相似文献   
306.
A Regional Climate Chemistry Modeling System that employed empirical parameterizations of aerosol-cloud microphysics was applied to investigate the spatial distribution, radiative forcing (RF), and climate effects of black carbon (BC) over China. Results showed high levels of BC in Southwest, Central, and East China, with maximum surface concentrations, column burden, and optical depth (AOD) up to 14 μg?m?3, 8 mg?m?2, and 0.11, respectively. Black carbon was found to result in a positive RF at the top of the atmosphere (TOA) due to its direct effect while a negative RF due to its indirect effect. The regional-averaged direct and indirect RF of BC in China was about +0.81 and ?0.95 W?m?2, respectively, leading to a net RF of ?0.15 W?m?2 at the TOA. The BC indirect RF was larger than its direct RF in South China. Due to BC absorption of solar radiation, cloudiness was decreased by 1.33 %, further resulting in an increase of solar radiation and subsequently a surface warming over most parts of China, which was opposite to BC’s indirect effect. Further, the net effect of BC might cause a decrease of precipitation of ?7.39 % over China. Investigations also suggested large uncertainties and non-linearity in BC’s indirect effect on regional climate. Results suggested that: (a) changes in cloud cover might be more affected by BC’s direct effect, while changes in surface air temperature and precipitation might be influenced by BC’s indirect effect; and (b) BC second indirect effect might have more influence on cloud cover and water content compared to first indirect effect. This study highlighted a substantial role of BC on regional climate changes.  相似文献   
307.
彭小燕  杜银  丁裕国 《气象科技》2013,41(3):522-528
利用Voronoi\\Delaunay图模型影响范围和局部动态的特性,提出一种基于动态边界定量提取强降水过程空间非均匀分布特征的新方法,根据1959—2002年中国740站逐日降水资料,构建5日、10日两种时间尺度区域持续性年极端强降水过程序列,用以检验该方法的应用效果,并应用该方法分析了5日(10日)区域持续性年极端强降水过程空间非均匀分布特征及其演变规律。结果表明:与传统的数量统计方法和区域插值方法相比,该方法在强降水空间分布中心、过程内不同强度降水覆盖区域、降水集中区等的定量度量方面具有更高的分辨力和较好实际应用价值;气候趋势分析中在1959—2002年间,5日区域持续性年极端强降水过程出现日期有明显提前趋势。  相似文献   
308.
Sutter's Mill is a regolith breccia composed of both heavily altered clasts and more reduced xenoliths. Here, we present a detailed investigation of fragments of SM18 and SM51. We have characterized the water content and the mineralogy by infrared (IR) and thermogravimetric analysis (TGA) and the structure of the organic compounds by Raman spectroscopy, to characterize the secondary history of the clasts, including aqueous alteration and thermal metamorphism. The three methods used in this study suggest that SM18 was significantly heated. The amount of water contained in phyllosilicates derived by TGA is estimated to be approximately 3.2 wt%. This value is quite low compared with other CM chondrites that typically range from 6 to 12 wt%. The infrared transmission spectra of SM18 show that the mineralogy of the sample is dominated by a mixture of phyllosilicate and olivine. SM18 shows an intense peak at 11.2 μm indicative of olivine (Fig. 1). If we compare SM18 with other CM and metamorphosed CM chondrites, it shows one of the most intense olivine signatures, and therefore a lower proportion of phyllosilicate minerals. The Raman results tend to support a short‐duration heating hypothesis. In the ID/IG versus FWHM‐D diagram, SM18 appears to be unusual compared to most CM samples, and close to the metamorphosed CM chondrites Pecora Escarpment (PCA) 91008 and PCA 02012. In the case of SM51, infrared spectroscopy reveals that olivine is less abundant than in SM18 and the 10 μm silicate feature is more similar to that of moderately altered CM chondrites (like Murchison or Queen Alexandra Range [QUE] 97990). Raman spectroscopy does not clearly point to a heating event for SM51 in the ID/IG versus FWHM‐D diagram. However, TGA analysis suggests that SM51 was slightly dehydrated as the amount of water contained in phyllosilicates is approximately 3.7 wt%, which is higher than SM18, but still lower than phyllosilicate water contents in weakly altered CM chondrites. Altogether, these results confirm that fragments with different secondary histories are present within the Sutter's Mill fall. The dehydration that is clearly observed for SM18 is attributed to a short‐duration heating based on the similarity of its Raman spectra to that of PCA 91008. Because of the brecciated nature of Sutter's Mill and the presence of adjacent clasts with different thermal histories, impacts that can efficiently fragment and heat porous materials are the preferred heat source.  相似文献   
309.
We determined the abundances and enantiomeric compositions of amino acids in Sutter's Mill fragment #2 (designated SM2) recovered prior to heavy rains that fell April 25–26, 2012, and two other meteorite fragments, SM12 and SM51, that were recovered postrain. We also determined the abundance, enantiomeric, and isotopic compositions of amino acids in soil from the recovery site of fragment SM51. The three meteorite stones experienced terrestrial amino acid contamination, as evidenced by the low d/l ratios of several proteinogenic amino acids. The d/l ratios were higher in SM2 than in SM12 and SM51, consistent with rain introducing additional l‐ amino acid contaminants to SM12 and SM51. Higher percentages of glycine, β‐alanine, and γ‐amino‐n‐butyric acid were observed in free form in SM2 and SM51 compared with the soil, suggesting that these free amino acids may be indigenous. Trace levels of d +l‐ β‐aminoisobutyric acid (β‐AIB) observed in all three meteorites are not easily explained as terrestrial contamination, as β‐AIB is rare on Earth and was not detected in the soil. Bulk carbon and nitrogen and isotopic ratios of the SM samples and the soil also indicate terrestrial contamination, as does compound‐specific isotopic analysis of the amino acids in the soil. The amino acid abundances in SM2, the most pristine SM meteorite analyzed here, are approximately 20‐fold lower than in the Murchison CM2 carbonaceous chondrite. This may be due to thermal metamorphism in the Sutter's Mill parent body at temperatures greater than observed for other aqueously altered CM2 meteorites.  相似文献   
310.
The Sutter's Mill (SM) carbonaceous chondrite is a regolith breccia, composed predominantly of CM2 clasts with varying degrees of aqueous alteration and thermal metamorphism. An investigation of presolar grains in four Sutter's Mill sections, SM43, SM51, SM2‐4, and SM18, was carried out using NanoSIMS ion mapping technique. A total of 37 C‐anomalous grains and one O‐anomalous grain have been identified, indicating an abundance of 63 ppm for presolar C‐anomalous grains and 2 ppm for presolar oxides. Thirty‐one silicon carbide (SiC), five carbonaceous grains, and one Al‐oxide (Al2O3) were confirmed based on their elemental compositions determined by C‐N‐Si and O‐Si‐Mg‐Al isotopic measurements. The overall abundance of SiC grains in Sutter's Mill (55 ppm) is consistent with those in other CM chondrites. The absence of presolar silicates in Sutter's Mill suggests that they were destroyed by aqueous alteration on the parent asteroid. Furthermore, SM2‐4 shows heterogeneous distributions of presolar SiC grains (12–54 ppm) in different matrix areas, indicating that the fine‐grained matrix clasts come from different sources, with various thermal histories, in the solar nebula.  相似文献   
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