Dendrogeomorphic dating of rockfalls on low‐latitude,high‐elevation slopes: Rodadero,Iztaccíhuatl volcano,Mexico     

Markus Stoffel  Michelle Bollschweiler  Lorenzo Vázquez‐Selem  Osvaldo Franco‐Ramos  David Palacios 《地球表面变化过程与地形》2011,36(9):1209-1217

Dynamics and rates of rockfalls have been repeatedly studied in mountain environments with archival records as well as lichenometric, radiocarbon or dendrogeomorphic approaches. In this study, we test the potential of conifers growing at a low‐latitude, high‐elevation site as a dendrogeomorphic tool to reconstruct to calendar dates associated rockfall activity. Analysis is based on tree‐ring records of Mexican mountain pine (Pinus hartwegii Lindl.) growing at timberline [~4000 m above sea level (a.s.l.)] and at the runout fringe of a north–northeast (NNE)‐facing slope of the dormant Iztaccíhuatl volcano (Mexico), which is subject to frequent rockfalls. The potential and limitations of tree‐ring data are demonstrated based on 67 rockfall impacts dated in the increment‐ring series of 24 trees since ad 1836. While findings of this paper are site‐specific, the study clearly shows the potential of dendrogeomorphic approaches in extra‐Alpine, low‐latitude environments and for the understanding of rockfall processes in space and time. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

巴旦木春季低温霜冻灾害的气象指标分析     

陈丛敏 《沙漠与绿洲气象(新疆气象)》2014,8(1)

摘要：以3个当地主栽品种（莎车1号、莎车14号和莎车18号）为试材,在春季巴旦杏花蕾期至开花期,利用高精度冰箱进行花蕾、花朵和叶低温霜冻害模拟试验,结合历史灾情资料分析春季低温霜冻的强度与发生时段,确定巴旦杏晚霜冻冻害气象指标。结果表明,在开花期若遇到-4.0℃低温且持续2h,会出现轻度冻害;-4.0℃低温若持续4h,莎车1号（纸皮）、莎车14号（叶尔羌）和莎车18号（晚丰）三个品种均会发生冻害,减产幅度达到20%左右;若-6.0℃的低温霜冻持续达2h,三个品种都会发生严重冻害。  相似文献   

巴旦杏春季低温霜冻灾害气象指标分析   总被引：2，自引：0，他引：2  

陈丛敏  刘立宏  王东 《沙漠与绿洲气象(新疆气象)》2014,(1):57-60

以3个当地主栽品种（莎车1号、莎车14号和莎车18号）为试材,在春季巴旦杏花蕾期至开花期,利用高精度冰箱进行花蕾、花朵和叶低温霜冻害模拟试验,结合历史灾情资料分析春季低温霜冻的强度与发生时段,确定巴旦杏晚霜冻冻害气象指标。结果表明,在开花期若遇到-4．0℃低温且持续2h,会出现轻度冻害;-4．0℃低温若持续4h,莎车1号（纸皮）、莎车14号（叶尔羌）和莎车18号（晚丰）3个品种均会发生冻害,减产幅度达到20％左右;若-6．0℃的低温霜冻持续达2h,3个品种都会发生严重冻害。  相似文献   

Concentration of particulate organic nitrogen in the marlborough sounds,New Zealand (note)     

Philip Tortell 《新西兰海洋与淡水研究杂志》2013,47(3):539-541

Samples of particulate matter were analysed for nitrogen by the micro‐Kjeldahl technique in an attempt to obtain an indication of the food available for mussels. The small amounts of nitrogen available in the samples prevented the detection of seasonal variation by this method. The mean concentration of 11.8 μg‐at of nitrogen per litre obtained from this study compares favourably with data from mussel farming areas in Spain.  相似文献   

放射性肺损伤的CT分析     

李忠喜  徐凯  王绪  章龙珍 《CT理论与应用研究》2001,10(1):21-24

目的：分析放射性肺损伤的CT表现，评价其CT诊断价值。材料与方法：收集资料完整的放射性肺损伤病人160例，对其CT表现回顾性分析与平片表现进行比较。结果：160例首诊表现为放射性肺炎者66例，过渡期者40例，瘢痕期者54例。CT表现：急性放射性肺炎期表现为照射野内出现均匀的密度稍高影或仅表现为轻度的肺野透光度减低，过渡期表现为照射野内出现均匀的密度稍高影或仅表现为轻度的肺野透光度减低，过渡期表现为照射野内索条影夹杂小斑片影，瘢痕期表现为照射野内浓密的索条影及斑片影，范围缩小。CT显示急性放射性损伤平均较平片早1-2周，且对于隐秘部位病灶显示、各期区分、肺损伤与原发灶（或复发）区分CT明显较平片更容易、精确。结论：CT能明确显示放射性肺损伤的影像学表现及大体分明，具有较平片更高的敏感性，对临床有较好的指导与鉴别作用。  相似文献   

广东冬季寒害对香蕉产量的影响   总被引：6，自引：0，他引：6  

刘玲  高素华  黄增明 《气象》2003,29(10):46-50

广东丰富的气候资源有利于香蕉生产的发展，但冬季寒害仍可使香蕉生产遭受重大损失，即使冬季最温暖的粤西南亦难幸免。阐述了广东香蕉寒害发生的情况，对几次突出的冬季寒害及其危害进行分析。严重影响广东香蕉主产区的寒害虽然平均约5年左右一遇，但是20世纪90年代寒害出现较频繁，加上反季节种植的春夏蕉由于经济效益较高，种植面积迅速扩大，使得其抽蕾或花芽分化在冬季，造成香蕉遭受寒害的几率增大，对香蕉产量影响很大。为此，广东香蕉生产的发展要重视寒害、风害及市场变化带来的风险，必须因地因时制宜，合理布局，搞好防灾减灾。  相似文献   

Estimating Injury and Loss of Life in Floods: A Deterministic Framework   总被引：3，自引：3，他引：3  

Edmund Penning-Rowsell  Peter Floyd  David Ramsbottom  Suresh Surendran 《Natural Hazards》2005,36(1-2):43-64

This paper presents an outline methodology and an operational framework for assessing and mapping the risk of death or serious harm to people from flooding, covering death and physical injuries as a direct and immediate consequence of deep and/or fast flowing floodwaters (usually by drowning), and deaths and physical injuries associated with the flood event (but occurring in the immediate aftermath). The main factors that affect death or injury to people during floods include flow velocity, flow depth, and the degree to which people are exposed to the flood. The exposure potential is related to such factors as the “suddenness” of flooding (and amount of flood warning), the extent of the floodplain, people’s location on the floodplain, and the character of their accommodation. In addition, risks to people are affected by social factors including their vulnerability and behaviour. A methodology is described for estimating the likely annual number of deaths/injuries. This is based on defining zones of different flood hazard and, for each zone, estimating the total number of people located there, the proportion that are likely to be exposed to a flood, and the proportion of those exposed who are likely to be injured or killed during a flood event. The results for each zone are combined to give an overall risk for each flood cell and/or community. The objective of the research reported here is to develop a method which could be applied using a map-based approach in which flood risks to people are calculated and displayed spatially for selected areas or communities. The information needed for each part of the process is described in the paper, and the further research to provide the required information is identified.  相似文献   

CT在急诊脑血管病和脑外伤诊断上的应用     

李安敏  任自强 《CT理论与应用研究》1997,6(4):46-48

本文总结回顾了ＣＴ在７８例急性脑外伤和脑血管病中应用，认为ＣＴ在帮助临床上定位，定性诊断中具有重要价值，为临床正确诊断和治疗手段上提供了客观准确的依据。  相似文献   

新疆棉花延迟型冷害指标试验研究   总被引：5，自引：0，他引：5  

李新建  唐凤兰  杨举芳  陈丛敏  邹陈  刘辉 《沙漠与绿洲气象(新疆气象)》2007,1(2):44-46

通过对北疆乌兰乌苏、莫索湾及南疆莎车2003—2004年两年棉花分期播种资料的分析研究,得到:新疆延迟型冷害与≥10℃活动积温相关最好。籽棉产量与≥10℃积温有极显著正相关。≥10℃活动积温是新疆延迟型冷害的优良指标。当以相对减产量确定延迟型冷害的积温级别时,还应考虑当地正常的产量。  相似文献   

东胜气田致密砂岩气藏钻井储层保护研究及应用          下载免费PDF全文

冯永超 《探矿工程》2022,49(5):118-126

东胜气田上古生界下石盒子组为致密砂岩储层,部分区域储层物性好,具备不压裂自然建产潜能,钻井过程中存在井壁失稳及储层损害问题,各因素叠合造成的储层伤害阻碍了气层的产能释放。为进一步提升储层自然建产能力和增加单井产量,在储层渗透率恢复率的基础上,通过储层伤害影响因素分析,引入钻井液侵入深度定量化评价方法,深化了储层伤害机理认识,明确了低密度、无土相、低失水和强封堵的钻井液对策,室内优选了防水锁剂和致密承压复合暂堵剂,优化形成了无土相复合暂堵高酸溶钻井液,储层渗透率恢复率提高至91.11%,泥浆侵入深度降低46.28%。形成的钻井液在锦66井区推广应用,平均单井产量提升11%,并实现3口井自然建产,进一步提高东胜气田致密砂岩储层高效勘探开发的效果。  相似文献