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1.
MEI Li TONG Siqin YIN Shan BAO Yuhai HUANG Xiaojun ALATENG Tuya WANG Yongfang GUO Enliang YUAN Zhihui NASHUN Dalai GAO Suriguga LIU Xinyi YE Zhigang 《地理学报(英文版)》2023,33(1):169-194
Water use efficiency (WUE) is an important variable to explore coupled relationships in carbon and water cycles. In this study, we first compared the spatial variations of annual gross primary productivity (GPP) and evapotranspiration (ET) using four GPP and ET products. Second, we selected the products closest to the flux towers data to estimate WUE. Finally, we quantitatively analyzed the impact of climate change and soil water content on WUE. The results showed that: (1) Four GPP and ET products provided good performance, with GOSIF-GPP and FLDAS-ET exhibiting a higher correlation and the smallest errors with the flux tower data. (2) The spatial pattern of WUE is consistent with that of GPP and ET, gradually decreasing from the northeast to the southwest. Higher WUE values appeared in the northeast forest ecosystem, and lower WUE values occurred in the western Gobi Desert, with a value of 0.28 gC m?2 mm?1. The GPP and ET products showed an increasing trend, while WUE showed a decreasing trend (55.15%) from 2001 to 2020. (3) The spatial relationship between WUE and driving factors reveal the variations in WUE of Inner Mongolia are mainly affected by soil moisture between 0 and 10 cm (SM0-10cm), vapor pressure deficit (VPD), and precipitation, respectively. (4) In arid regions, VPD and precipitation exhibit a major influence on WUE. An increase in VPD and precipitation has a negative and positive effect on WUE, with threshold values of approximately 0.36 kPa and 426 mm, respectively. (5) In humid regions, SM0-10cm, VPD, SM10-40cm, and SM40-100cm exert a significant impact on WUE, especially SM0-10cm, and weakens with increasing soil depths, these differences may be related to physiological structure and living characteristics of vegetation types in different climate regimes. Our results emphasize the importance of VPD and soil moisture in regional variability in WUE. 相似文献
2.
Guojiang?WanEmail author Jing’an?Chen Siqin?Xu Fengchang?Wu P.?H.?Santschi 《中国科学D辑(英文版)》2005,48(4):484-496
The fundamental assumption of 210Pb sediment dating is the stable flux of 210Pbex, which was derived from atmosphere and then transferred into sediments via lake water. When the sedimentation rate is relatively
constant, the 210Pbex activity in sediments will be exponentially reduced with sedimentation age. 210Pbex in lake water is incorporated into sediments mainly via organic particulates. If the sedimentation flux of organic matter
in lake water is suddenly increased, 210Pbex will be significantly deposited and then transferred into sediments. On the one hand such sudden purification effect is obviously
unfit for the fundamental assumption of 210Pb dating; on the other hand, the sudden enhancement of 210Pbex flux would be indicative of the conspicuous variation of primary productivity of lake water. This problem will be discussed
in accordance with the variation trend of 210Pbex in the vertical profile of recent sediments of Lake Chenghai, Yunnan Province. The sediment core was collected from the deep-water
area of Lake Chenghai in June 1997. The vertical profile of 137Cs activity is characterized by a tree-peak pattern. This profile gave reliable ages, and also showed the stability of sediment
accumulation in the recent ten years. The vertical profile of 210Pbex activity displays a specific distribution of peaks, and is similar to the vertical profile of Corg. This phenomenon seems to be related to the mechanism of constraining the transfer of 210Pbex into lake sediments. The average atomic ratios of Horg/Corg and Corg/Norg in Lake Chenghai sediments are 5.51 and 7.04, respectively, indicating that the organic matter was predominantly derived
from the remains of endogenic algae. In terms of the three-stage evolutionary characteristics of organic matter in sediments,
i.e., “deposition-de-composition-accumulation”, the sedimentation fluxes (F(Corg)) of organic carbon (Corg) since 1970 were calculated by modeling. The sedimentation fluxes of 210Pbex (F(210Pbex)) in different years display good synchronous relations with the sedimentation flux of organic carbon (F(Corg)), especially in the years of 1972–1974 and 1986–1989. The variation of F(Corg) led to the variation of F(210Pbex); the variation of F(210Pbex) reflects, to some extent, the historical variation of lake productivity. 相似文献
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目的：探讨艾灸阳明经穴对变应性鼻炎（AR）大鼠行为学的改变及改善AR情感反应可能的作用环节。方法：将30只SD大鼠随机分为空白组、AR模型组及艾灸阳明经穴组（艾灸组）,每组各10只,采用卵清蛋白致敏方法制作AR大鼠模型。观察大鼠鼻部症状以及躯体行为学的改变来评估情感变化;观察鼻黏膜组织病理改变;酶联免疫吸附测定法（ELISA）检测血清总免疫球蛋白E（sIgE）、白细胞介素4（IL-4）及干扰素（IFN-γ）含量;分离大鼠脑海马区组织免疫组织化学检测神经肽P物质（SP）、星形胶质细胞（GFAP）和小胶质细胞（OX-42）的蛋白表达,并进行比较。结果：与空白组比较,AR模型组大鼠搔鼻、流涕次数明显增多,行为学评分显著升高（P<0.01）;鼻黏膜上皮破坏明显,纤毛脱落,腺体增生及水肿,黏膜上皮深面固有层可见大量嗜酸性粒细胞（EOS）浸润;血清sIgE、IL-4含量升高（P<0.01）、IFN-γ含量下降（P<0.01）,SP、GFAP、OX-42蛋白表达升高（P<0.01）;与AR模型组比较,艾灸组大鼠搔鼻、流涕频次明显减少,行为学评分改善（P<0.05）;鼻黏膜上皮损伤、纤毛紊乱程度、腺体增生及水肿有所改善,黏膜下EOS数量减少（P<0.05）;血清sIgE、IL-4含量显著下降（P<0.05）、IFN-γ含量上升（P<0.05）,OX-42、GFAP、SP蛋白表达明显改善（P<0.05）。结论：AR组大鼠致敏后的鼻部症状及躯体行为学表现可能与鼻部致敏后激活了海马区情感行为相关的炎症介质有关,导致海马区神经胶质细胞炎症反应的发生。艾灸阳明经穴能显著改善AR情感反应,此效应可能通过下调AR大鼠脑内海马区炎性反应水平,减少神经胶质细胞过度活化而发挥作用。 相似文献
4.
旋涡星系中恒星形成对旋涡结构的影响 总被引：1，自引：0，他引：1
本文利用N体数值模拟方法,讨论了旋涡星系中恒星形成对旋涡结构的维持作用。在假定恒星是在一定密度区域中形成以及恒星诞生率为1.0M_⊙/年的情况下,模拟结果表明,旋涡图象的维持时间是未考虑恒星形成模型的2.3倍。 相似文献
5.
研究干旱变化的特征,有利于预防干旱发生.利用1961～2016年内蒙古境内的气温、降水数据计算得到不同时间尺度的标准化降水蒸散指数,结合趋势分析法、Mann-Kendall突变检验法和消除趋势波动(DFA)分析法,分析不同时间尺度干旱演变趋势及未来干旱预测.结果表明:①内蒙古年际干旱呈现增加趋势,1995年发生突变,由湿润转变为干旱.总体上,内蒙古地区呈现东部干旱程度加重,而西部减缓的趋势.轻旱发生频率较高,且东南部干旱的发生较多.②春、夏和秋季存在明显变干及突变趋势,且突变年份不一致,而冬季有不太明显的变湿趋势.春、夏和秋季干旱发生较为严重且范围较广.③在未来,内蒙古地区干旱将保持现有趋势,干旱仍持续一段时间. 相似文献
6.
Over the past two decades, migration from Mainland China (MC) to Australia has become increasingly significant. In contrast to previous migrant waves, post-2000 MC-born migrants in Australia are more likely to be highly skilled and/or financially independent, and often migrate under skilled, business and investment visa programs. Though scholarship has explored various facets of MC-born migrants’ settlement in Australian cities, the spatial dynamics of settlement, and change over time associated with these shifts in socio-economic profile, have remained unexplored. This paper draws on three census periods, and employs a local indicator of spatial autocorrelation together with a geographically weighted regression. We conclude that the settlement patterns of MC-born migrants in Australia do not follow the ‘straight-line’ assumptions of spatial assimilation theory, nor are they tied explicitly to socio-economic factors in the majority of capital cities. Instead, the settlement patterns of MC-born migrants vary by city: Sydney and Melbourne display the most spatially segmented settlement patterns; while Adelaide and Perth exhibit increasing levels of concentration as the number of MC-born migrants grows. Results indicate that while MC-born migrants are somewhat likely to cluster at the early stage of group formation, within-group spatial patterns are articulated by social attributes as the group grows in size and significance in a metropolitan context. 相似文献
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目的：观察四君子汤加减联合阿帕替尼治疗老年晚期胃癌脾胃气虚证患者的临床效果及不良反应情况。方法：将60例老年晚期胃癌脾胃气虚证患者随机分为治疗组和对照组,每组各30例。对照组口服阿帕替尼治疗,治疗组在对照组的基础上加服四君子汤加减治疗。观察2组的近期疗效、KPS评分,治疗组用药前后CEA、CA199、CA72-4水平变化,2组免疫功能及不良反应情况。结果：治疗组患者客观缓解率和疾病控制率分别为56.67%、93.33%,优于对照组的30.00%、66.67%,2组比较,差异有统计学意义（P<0.05）。2组患者KPS评分治疗前后组内比较及治疗后组间比较,差异均有统计学意义（P<0.05）。治疗组CEA、CA199、CA72-4水平治疗后较治疗前明显下降（P<0.01）。对照组CD4+、CD4+/CD8+水平治疗后较治疗前升高;治疗组CD3+、CD4+、CD4+/CD8+水平较治疗前升高,且治疗组CD3+、CD4+水平升高幅度优于对照组,差异均有统计学意义（P<0.05）。治疗组不良反应如白细胞减少、乏力、蛋白尿、血压升高等发生情况明显低于对照组,差异均有统计学意义（P<0.05）。结论：四君子汤加减联合阿帕替尼治疗老年晚期胃癌脾胃气虚证患者效果较单用阿帕替尼为优,可有效降低CEA、CA199、CA72-4水平,提高患者免疫功能,且不良反应发生率低,值得临床推广。 相似文献
8.
目的：探讨艾灸足三里对变应性鼻炎（AR）大鼠鼻黏膜免疫功能的影响。方法：将40只SD大鼠随机分为正常组、模型组、对照组和治疗组,每组10只。采用卵清蛋白致敏法制备AR大鼠模型。造模成功后对照组与治疗组进行艾灸治疗,正常组、模型组只捆绑不艾灸,疗程14 d。观察4组行为学评分,鼻黏膜组织病理情况,分泌性免疫球蛋白A（sIgA）、CD4+、CD8+表达水平。结果：治疗后,治疗组的行为学评分较模型组降低,差异有统计学意义（P<0.05）;治疗后,正常组、治疗组嗜酸性粒细胞、鼻咽冲洗液sIgA表达及CD4+、CD8+水平与模型组比较,差异均有统计学意义（P<0.05或P<0.01）。结论：艾灸足三里可改善AR大鼠行为学评分及鼻黏膜组织病理情况,降低嗜酸性粒细胞数,并能下调鼻黏膜sIgA、CD4+、CD8+表达,这可能是其治疗AR的免疫机制之一。 相似文献
9.
通常认为黔西南和黔南地区二叠纪栖霞组之下的一套陆缘碎屑岩地层,是石炭纪-二叠纪冈瓦纳大陆冰盖发育鼎盛时期大幅度海平面下降期间的沉积。最新研究表明,石炭纪-二叠纪冈瓦纳冰川是由多次不连续的冰川事件构成的。因此恢复该套以陆源碎屑岩为主地层的形成环境和堆积过程,探讨其成因与冈瓦纳冰川发育的关系,具有非常重要的科学意义。本研究查明了黔西南地区该套陆源碎屑岩的地层厚度和砂泥比值空间变化规律。在此基础上,选取碎屑岩发育最好的普安龙吟剖面开展沉积体系与成因研究。结果表明,沙子塘组主要是碳酸盐沉积体系,龙吟组和包磨山组主要为浅海陆棚三角洲沉积体系,梁山组以滨岸陆源碎屑沉积体系为主;二叠纪早期黔西南地区的陆棚相泥岩形成于冰川消融导致的海平面快速上升期间,三角洲沉积体系形成于海平面晚期高位域期间,而不是形成于冈瓦纳冰川增长期间的低位域沉积。冈瓦纳冰川的推进和消融是龙吟剖面二叠纪早期地层发育样式的主控因素。 相似文献
10.
运用经验正交函数（EOF）和交叉小波变换法,分析了湖南省1981―2013 年月蒸发量的时空分布特征及其与月平均气温之间的非线性交互关系。月蒸发量的EOF 分解表明：前3 个空间模态的累计贡献率达77.9%。其中EOF1（63.4%）揭示了湖南省月蒸发量最主要的时空分布特征呈东西反向型,体现出月蒸发量与高程之间存在一定的负相关性;EOF2（8.5%）具有正负位相频繁交替的时间系数,反映了更为复杂的时空变化特征;EOF3（6.0%）的值自西北向东南呈“＋、-、＋”分布。然后,分别选用洪江、桑植和新晃站作为3 个空间模态的代表站点,并计算出各站点的月蒸发量与月平均气温之间的交叉小波谱和小波一致性,结果表明：两者之间的相关性在8~16个月的时间尺度下最强,且其相位角均为0°,说明气温对蒸发量的影响在该时间尺度下最为显著且不存在时滞效应,但在＜8 个月和＞16 个月的时间尺度下,强相关性的出现频率和分布以及相位角的方向沿时间轴均呈现出较大的差异性。 相似文献