铜绿微囊藻(Microcystic aeruginosa var. major)胞外酸性多糖的分离、纯化及其理化特性   总被引：15，自引：5，他引：10  

梅秋红  缪月秋  张成武  陆长梅  吴国荣 《湖泊科学》2005,17(4):322-326

通过研究太湖湖鲚的年龄结构、食物组成,结合太湖鱼类渔获量统计和环境检测资料,分析了1973-2002年间太 湖湖鲚渔获量变化的规律、原因及与生物环境间的相互关系．结果表明：1994年后湖鲚渔获量正以平均年增1430t 的速度 上升;种群中0~ 个体占99．04±2．21%(2003年)、99．08±0．80%(2004年);而0~ 湖鲚主要以浮游动物为食,其中枝角 类占食物总个数的89．77．80±13．69%．分析发现：湖鲚渔获量与 TIN、TN、COD 间的正相关关系均达到显著水平;与翘嘴 红鲌、银鱼产量间的负相关关系达到极显著水平;种群低龄化趋势加剧与捕捞强度不断升高相一致;浮游动物现存量有随 湖鲚渔获量升高而降低的趋势．  相似文献   

电感耦合等离子体质谱法测定二氧化铀和八氧化三铀粉末中的杂质元素   总被引：4，自引：0，他引：4  

郭冬发  武朝辉  黄秋红  裴玲云  李振涛 《铀矿地质》1999,15(3):177-180

本文简述了等离子体质谱法测定二氧化铀和八氧化三铀粉末中的硼、钛、钒、钼、铬、锌、镉等７个痕量元素的方法。本方法采用ＴＢＰ萃取色层分离铀基体后,用高分辨等离子体质谱仪（ＩＣＰ－ＭＳ）测定多个痕量元素,测定下限达１×１０－９ｇ／ｇ,测定的相对标准偏差小于１５％。核工业１４个实验室比对试验结果表明,本方法结果准确可靠  相似文献   

Tectonic implications of the subduction of the Kyushu-Palau Ridge beneath the Kyushu,southwest Japan     

Chenglong Xia  Yanpeng Zheng  Baohua Liu  Qingfeng Hua  Long Ma  Xianfeng Li  Qiuhong Xie 《海洋学报(英文版)》2021,40(3):70-83

The Kyushu-Palau Ridge(KPR), a remnant arc on the Philippine Sea Plate(PSP), is subducting beneath the Kyushu, southwest Japan. Influenced by the subducting KPR, the Kyushu subduction zone corresponding to the KPR is significantly different from Shikoku subduction zone in terms of gravity anomalies, seismicity, the stress state, and the subducting slab morphology. Significant negative free-air and Bouguer gravity anomalies are observed in a prolonged area of KPR, southeast of the Miyazaki Plain, indicating that this is where KPR overlaps the overriding plate. The gravity anomaly in this area is much lower than that in other areas where the inferred KPR extends, suggesting that the subduction of the buoyant KPR may cause the lower mantle density to decrease.More earthquakes have occurred in Hyuga-nada region where the KPR subducts than in Shikoku forearc and other areas in the Kyushu forearc, indicating that the subduction of the KPR enhances the local coupling between the subducting and overriding plates. The centroid moment tensor(CMT) mechanism of earthquakes shows that stress is concentrated in the accumulated crust beneath the Kyushu forearc corresponding to the KPR, and the shallow thrusting events in the obducting plate are caused by the KPR subduction. The buoyant KPR, with a large volume of low-density sediments, was responsible for the differences of the subduction depth and dip angle of the subducting Philippine Sea(PS) slab between northern Kyushu and Shikoku. The seismic gaps and the sudden change of the dipping angle of the subducting PS slab indicate that slab tear may have occurred along the west side of the KPR beneath southwest Kyushu. A two-tear model was proposed, and the subduction of the buoyant KPR was believed to play an important role in the slab tear.  相似文献   

基于GIS的中国历代诗词地名提及的时空格局与归因     

孙林艳  刘亮  田涵  苟思敏  钱秋红  李加安  彭秀华  彭文甫  刘寅  邹亚国 《地理信息世界》2018,(4):29-35

中国历代诗人创作的大量诗词时常提及的地名是诗人空间感知的自然流露。研究历代诗人创作诗词涉及的地名,有助于认识中国历史地理环境的变化过程。目前少有研究涉及这一范围,分析也有待深入。本研究基于GIS技术,以中国历代著名诗词为数据源,提取地名3 657个,按朝代先后分为9组,应用最近邻指数、核密度、平均中心、标准差椭圆等点分布模式分析算法,研究其时空格局及原因。结果表明:(1)时间上,历代空间感知重心存在绕历史总重心逆时针旋转的趋势,靠后朝代的感知格局除反映自身外还受到过往朝代的叠加影响。(2)空间上,中国诗人空间感知呈核心—轴线—背景面格局,核心是诗人的常住地,轴线是诗人在常住地间流动留下的迁徙轨迹,背景面是核心和轴线围成的弱感知区。(3)诗人的生命历程决定其空间感知,而个人的生命历程又处于社会历史大环境之中,因此,历代诗人的空间感知时空格局与中国经济、政治、文化重心时空格局基本一致。这一研究对分析中国历史重心的转移有参考意义。  相似文献   

青藏高原及其周边地区降水的水汽来源变化研究进展          下载免费PDF全文

汤秋鸿  刘宇博  张弛  苏凤阁  李颖  高艳红  李文弘  陈德亮 《大气科学学报》2020,43(6):1002-1009

近几十年来,随着全球气候变暖,青藏高原降水整体呈现增加趋势,气候暖湿化趋势明显;与此同时,位于青藏高原东南缘的中国西南地区整体上呈现暖干化趋势,干旱事件频发。探讨青藏高原及其周边地区降水的水汽来源变化、揭示降水趋势性变化的原因已经成为当前研究热点。本文评述了近年来青藏高原降水的水汽来源研究,重点关注青藏高原变湿、西南地区变干的水汽来源变化原因以及青藏高原南北水汽来源差异,讨论了尚未解决的科学问题,展望了未来研究方向。现有研究表明,青藏高原以西的西风带控制区蒸散发贡献的水汽整体呈现减少趋势,青藏高原以南和以东的季风控制区蒸散发贡献的水汽整体呈现增加趋势,上述水汽源区贡献变化导致了青藏高原及其周边不同区域降水趋势性变化的差异。展望未来,水汽来源分析的模型和数据需要进一步验证及减少不确定性,青藏高原下垫面和蒸散发变化对周边地区降水的影响机制研究有待加强,全球变化与青藏高原降水水汽来源变化的关系尚需深入分析。  相似文献   

北京地区蚊虫密度变化气象预测方法研究     

姜江  叶彩华  刘美德  尤焕苓  乔媛  夏江江  佟颖  张勇  阎婷  李秋红  刘婷  周小洁  曾晓芃 《气象科技》2022,50(4):584-593

本文利用蚊虫密度监测数据及气象资料,分析了2009—2019年北京市及其14个区的蚊虫密度与气象条件间的关系,并基于多元回归、支持向量机和随机森林3种经典的机器学习回归方法进行了蚊虫密度预测。结果表明：北京地区蚊虫密度呈周期性的波动,各区多年平均值在0.35~2.54只/(灯·h)之间,高峰值集中出现在7月中旬到8月中旬,与北京地区气温最高和降水最集中的时期非常吻合。采用机器学习方法,尝试了4种输入因子方案,并利用均方根误差和平均绝对百分误差两种方法进行预测效果检验,显示蚊虫数据相对较稳定的地区,如平谷、门头沟、大兴、海淀等地,预测效果相对更优。在3种方法中,支持向量机方法对2019年5月下旬的预测效果非常好,而多元回归与随机森林的预测效果则在2019年5—10月整体上表现得更为稳定。  相似文献   

Multidecadal variability of the Tonle Sap Lake flood pulse regime     

Aifang Chen  Junguo Liu  Matti Kummu  Olli Varis  Qiuhong Tang  Ganquan Mao  Jie Wang  Deliang Chen 《水文研究》2021,35(9):e14327

Tonle Sap Lake (TSL) is one of the world's most productive lacustrine ecosystems, driven by the Mekong River's seasonal flood pulse. This flood pulse and its long-term dynamics under the Mekong River basin's (MRB) fast socio-economic development and climate change need to be identified and understood. However, existing studies fall short of sufficient time coverage or concentrate only on changes in water level (WL) that is only one of the critical flood pulse parameters influencing the flood pulse ecosystem productivity. Considering the rapidly changing hydroclimatic conditions in the Mekong basin, it is crucial to systematically analyse the changes in multiple key flood pulse parameters. Here, we aim to do that by using observed WL data for 1960–2019 accompanied with several parameters derived from a Digital Bathymetry Model. Results show significant declines of WL and inundation area from the late 1990s in the dry season and for the whole year, on top of increased subdecadal variability. Decreasing (increasing) probabilities of high (low) inundation area for 2000–2019 have been found, in comparison to the return period of inundation area for 1986–2000 (1960–1986). The mean seasonal cycle of daily WL in dry (wet) season for 2000–2019, compared to that for 1986–2000, has shifted by 10 (5) days. Significant correlations and coherence changes between the WL and large-scale circulations (i.e., El Niño-Southern Oscillation (ENSO), Pacific Decadal Oscillation (PDO) and Indian Ocean Dipole (IOD)), indicate that the atmospheric circulations could have influenced the flood pulse in different time scales. Also, the changes in discharge at the Mekong mainstream suggest that anthropogenic drivers may have impacted the high water levels in the lake. Overall, our results indicate a declining flood pulse since the late 1990s.  相似文献   

特长公路隧道信号控制逻辑分析     

赵忠杰  仝秋红 《地球科学与环境学报》1999,21(2)

以一条特长公路隧道为例,按照分区控制的思路,研究了其信号设置的方法、防灾控制时的信号逻辑、控制手段及其实施。  相似文献   

New speices of Late Mesozoic wood fossils from southeastern Mongolia     

DING Qiuhong  FU Xiaoping  LI Yong  ZHANG Wu . Shengyang Center of Geological Survey  China Geological Survy Bureau  Shenyang  China  . Shenzhen Fairy Lake Botanical Garden  Shenzhen  Guangdong 《东北亚地学研究》2011,(2)

Three new species of fossil woods are reported from the Upper Jurassic to Lower Cretaceous in southeastern Mongolia,including Protaxodioxylon mongolense sp. nov. Circoporoxylon mongolense sp. nov. Protocircoporoxylon mongolense sp. nov. The anatomical characters of three new species are described in detail.  相似文献   

双重眼壁台风大风降水对比分析          下载免费PDF全文

罗秋红梁碧玲  何夏江 《气象科技》2005,33(3):209-213,i001

通过利用多普勒雷达图、OLR日平均场、环境场和比湿场等资料对7514(ELSIE)、7908(HOPE)、0313(Dujuan)号台风进行对比诊断分析。结果表明3个双重眼壁台风都有规则和紧凑的螺旋云带，外围的云带范围小、副高强盛、登陆前850hPa西南风没加强等等，都是造成台风风大而且影响范围广，降水量偏少的原因；OLR场分布与降水场分布的同时对应关系很好，OLR低中心最终没移至陆上，因此陆上降水偏少；台风OLR低中心移向陆地的地点与强降水中心基本相符；登陆时台风中心比湿值、等值线的梯度越大、移速的越慢，则降水时间越长、雨强越大。降水越集中。  相似文献