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501.
Virtual Field Geologic Trip System (VFGTS) constructed by the technique of visualization can efficiently present geologic field information and widely used in the field of geologic education. This paper introduces the developing thinking of VFGTS and discusses the main implement processes. Building VFGTS mainly includes systemically gathering of field geological data, the building of virtual geological world, and displaying of virtual geologic world and human-computer interaction. 相似文献
502.
Debris flows introduced in landslide deposits under rainfall conditions: The case of Wenjiagou gully 总被引:4,自引:2,他引:4
Debris flows often occur in landslide deposits during heavy rainstorms. Debris flows are initiated by surface water runoff and unsaturated seepage under rainfall conditions. A physical model based on an infinitely long, uniform and void-rich sediment layer was applied to analyze the triggering of debris-flow introduced in landslide deposits. To determine the initiation condition for rainfall-induced debris flows, we conducted a surface water runoff and saturated-unsaturated seepage numerical program to model rainfall infiltration and runoff on a slope. This program was combined with physical modeling and stability analysis to make certain the initiation condition for rainfall-introduced debris flows. Taking the landslide deposits at Wenjiagou gully as an example, the initiation conditions for debris flow were computed. The results show that increase height of surface-water runoff and the decrease of saturated sediment shear strength of are the main reasons for triggering debris-flows under heavy rainfall conditions. The debris-flow triggering is affected by the depth of surface-water runoff, the slope saturation and shear strength of the sediment. 相似文献
503.
Climate warming-induced upward shift of Moso bamboo population on Tianmu Mountain, China 总被引:2,自引:0,他引:2
Xin-zhang Song Chang-hui Peng Guo-mo Zhou Hong Jiang Wei-feng Wang Wen-hua Xiang 《山地科学学报》2013,10(3):363-369
Although increasing attention has been paid to upward shift of plant species in altitude as a response to global warming, research on this phenomenon at low altitudinal and low latitudinal zones did not receive enough attention. In this study, an investigation was carried out to test the relationship between the upward spread of Moso bamboo (Phyllostachys pubescens) along altitudinal gradient and the increasing air temperature over the past decade within the Tianmu Mountain region, situated in southeastern China. Results showed that the peak elevation of Moso bamboo population establishment rose by an average of 9.8 m (±2.7 m) during the past decade and significant correlation existed with mean annual temperature (P < 0.0001, n = 339) but not with annual precipitation (P = 0.7, n = 339), indicating that the upward shift of Moso bamboo along altitudinal gradients was driven primarily by warming temperatures. This upward shift could potentially reduce biodiversity by altering the species composition of the ecosystem. However, there is also the potential for increased carbon sequestration capacity of local forest systems, which would produce an additional carbon sink to combat rising atmospheric CO2 concentrations and future global warming. 相似文献
504.
针对环境中痕量的间甲苯酚用一般仪器很难直接分析测定的问题,提出将分散液液微萃取技术与气相色谱联用测定环境水样中间甲苯酚的新方法.实验考察了影响分散液液微萃取效率的因素,包括萃取剂种类和用量、分散剂种类和用量、萃取时间、离心时间和盐度等,确定了最佳萃取条件为:200μL氯苯(萃取剂)和2.5mL丙酮(分散剂)混匀后,快速注入水样,室温静置8min,以3000r/min离心8rain,吸取1μL沉积相进行气相色谱分析.实验结果为:在最佳的萃取条件下,间甲苯酚的富集倍数为98.7倍,方法的线性范围为0.05~50mg/L,检出限为4.2μg/L(S/N=3),相对标准偏差为5.64%.将方法用于实际水样的测定,水样的加标回收率在86%~~122%,相对标准偏差(RSD)为3.3%~7.3%(n=3),实验表明该方法操作简便快速、成本低、环境友好,可用于实际水样的测定. 相似文献
505.
��̬������С����ģ�͵������㷨 总被引:4,自引:2,他引:4
????????????????????????????????????????????????????С????????в???????,?????????????С???????????????????????????????????Tikhonov?????????????????????С??????????????????????????????????????????????Э????????????????????Fredholm???????????????????????????С????????????????????? ???????????????????????й????????????????????????????? 相似文献
506.
The increasing use of pharmaceuticals has become a major environmental issue in China.The presence of antibiotics in water may have deleterious effects on non-target aquatic organisms such as microalgae.In this study,a cyanobacterium and an alga species in surface waters,Microcystis aeruginosa and Chlamydomonas microsphaera,were exposed to 0,0.1,0.5,1.0,2.0,5.0,10.0,and 20.0 mg/L of oxytetracycline dihydrate(OXY) and sulfamethoxazole(SMZ) for 96 h to determine the effects of these antibiotics on the growth and surface morphology.Moreover,the photosynthetic activity and the contents of superoxide dismutase(SOD),malondialdehyde(MDA),and protein were measured to examine the biochemical characteristics of M.aeruginosa and C.microsphaera under OXY and SMZ stress.The effects of both antibiotics on the growth of both species were concentration-dependent and characterized by low-dose stimulation and high-dose inhibition.C.microsphaera was more sensitive to both antibiotics than M.aeruginosa was.The algal cell membranes of both species disintegrated after exposure to a high concentration of OXY.All of the physiological parameters measured in this study were relatively stable at low concentrations of OXY and SMZ.After exposure to high concentrations of OXY and SMZ,photosynthetic activity decreased significantly,whereas lipid peroxidation and the abundance of SOD,MDA,and protein increased significantly.Thus,low-dose antibiotics may increase algal blooms in eutrophic waters. 相似文献
507.
为解决湖南省建设用地审批红线空间数据问题,保障新增建设项目顺利上报审批,并支撑湖南省建设用地批后监管业务,研究建设用地审批红线空间数据清理、核查、整合处理的技术方法,并以安仁县为例进行验证。经试验,结合研究的技术方法解决了安仁县2009—2019年形成的批地问题图斑的问题,在全省范围可推广。 相似文献
508.
509.
510.
周定文 《成都信息工程学院学报》1990,(4)
本文将冷岛视为一个负的扰动加热源,即冷源,用小扰动方法求出了冷岛效应的分析解,给出了解例,并与热岛效应的结果作了对比分析。 相似文献