oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 17 )

2018 ( 587 )

2017 ( 630 )

2016 ( 700 )

Custom range...

Search Results: 1 - 10 of 36903 matches for " 湿学发 "
All listed articles are free for downloading (OA Articles)
Page 1 /36903
Display every page Item
Diurnal variations of soil evaporation δ18O and factors affecting it in cropland in North China
华北平原农田土壤蒸发δ18O的日变化特征及其影响因素

YANG Bin,XIE Fu-Ti,WEN Xue-Fa,SUN Xiao-Min,WANG Jian-Lin,
杨斌
,谢甫绨,湿,孙晓敏,王建林

植物生态学报 , 2012,
Abstract: Aims The δ18O of soil evaporation (δE) is an important factor controlling the variations of atmospheric δ18O (δv), and it is also one of the key challenges of partitioning evapotranspiration into evaporation and transpiration components. δE is mostly simulated by the Craig-Gordon model, which is constrained by the δv of water vapor, the relative humidity (h), the equilibrium and kinetic factors and the δ18O of soil water (δs) at the evaporating front. Our objective is to investigate the diurnal variations of δE and factors affecting it. Methods We determined the δ18O of water vapor in a winter wheat-summer maize cropland based on the in-situ and continuous water vapor isotope ratio measurement system. We sampled soil water at different depths and analyzed it using the cryogenic vacuum distillation technique to acquire the δ18O of soil water at the evaporating front. Important findings During the growing period of winter wheat-summer maize, the diurnal variation of δE exhibited a bimodal pattern with peaks at 6:00 and 15:00. The h has a significant effect on the diurnal variation of δE in cropland ecosystems, and causes the Craig-Gordon model to be invalid under high humidity condition of h>95%. The in-situ and high resolution measurement of δv overcomes the uncertainty of using the local precipitation equilibrium method to evaluate δv, which improves the accuracy of δE. Different equilibrium factors have no significant influence on the accuracy of δE. Different kinetic factors, especially the canopy scale kinetic factor, influence the accuracy of δE significantly. The location of the evaporating front determines the h normalized to soil temperature and the δ18O of soil water directly and also influences the accuracy of δE significantly. Further research is needed to attain direct measurement of δE by combining isotope ratio infrared spectroscopy (IRIS) with the static chamber or dynamic chamber.
拉萨河流域未来降水情景预估
Projection of Future Precipitation in the Lhasa River Basin
 [PDF]

刘文丰, 徐宗,
Journal of Water Resources Research (JWRR) , 2012, DOI: 10.12677/JWRR.2012.14039
Abstract: 拉萨河流域是西藏地区政治、经济、文化中心,在全球气候变暖影响下,流域气候变化显著,针对拉萨河流域开展气候变化研究具有重要意义。本文基于气象站点实测数据和ERA-40MIROC3.2_medres大尺度网格数据,采用统计降尺度模型Automated Statistical Downscaling(ASD),对拉萨河流域日降水量进行降尺度研究,在此基础上分析了流域2046~2065年与2081~2100年降水量变化情景。结果显示:ASD模型能够较好地模拟流域降水基本特征,各站点的解释方差(R2)达到13%~22%,率定期与验证期的均方根误差(RMSE)分别控制在0.250.53以内。未来两个时期流域降水格局变化显著,年降水量将减少10.55%~17.25%
一种评估植被与气候变化对河川径流影响的方法
An Approach for Separating Relative Effects of Vegetation and Climate Changes on Watershed Hydrology
 [PDF]

, 王伟峰,
International Journal of Ecology (IJE) , 2015, DOI: 10.12677/IJE.2015.43009
Abstract:
科学评估植被与气候变化对河川径流的影响对造林或采伐规划、流域水资源管理、河流生物多样性及生境保护具有重要作用。它可以帮助我们理解与评估河流形态的变化、泥沙的迁移及水灾与旱灾的规律。文章介绍了国际上一种新的评估方法(Tomer-Schilling framework),并分析了其计算方法原理。最后,探讨了将该方法引入国内的可行性,以期为我国生态水文学的发展提供参考。
Scientific evaluation of vegetation and climate change impact on the runoff of afforestation or cutting planning, management of river basin water resources, rivers of biodiversity and habitat protection plays an important role. It can help us to understand and evaluate the change of river morphology, sediment migration and the laws of flood and drought. This paper introduces the international on a new assessment method (Tomer-Schilling framework), and analyses the calculation method for the principle. Finally, this paper discusses the feasibility of introducing the method of domestic, so as to provide reference for the development of ecological hydrology in China.
泥石流灾害国内外研究动态评述
Review on International Research Dynamic of Debris Flows Disaster
 [PDF]

, 陈志,
Open Journal of Nature Science (OJNS) , 2015, DOI: 10.12677/OJNS.2015.34027
Abstract:
在众多的地质灾害里,泥石流属于破坏力比较强的一种,它不仅对当地的地质环境造成永久性破坏,还严重影响到当地居民的生产和生活。因此,开展泥石流的相关研究非常必要。本文以文献计量学方法为基础,从泥石流灾害相关概念出发,评述了国内外泥石流研究的最新动态,并对今后该研究领域的重要发展方向进行了分析,以期为我国泥石流灾害的科学治理提供理论指导。
In many geological disasters, debris flows is a kind of relatively strong destructive power, which not only causes permanent damage to the local geological environment, but also seriously affects the production and life of local residents. Therefore, to carry out related research of debris flows is very necessary. In this paper, based on bibliometric methods, and according to the related concepts of debris flows, we reviewed the latest research dynamic of debris flows at home and abroad, and analyzed the important development direction for future research in the field in order to provide theoretical guidance for the scientific management of debris flows in our country.
大腿蓟马科首次在我国记录
韩运,张广
昆虫学报 , 1981,
Abstract:
分离变量法解三维的分数阶扩散-波动方程的初边值问题
,
福州大学学报(自然科学版) , 2007,
Abstract: 考虑在有限区间上三维的时间分数阶扩散-波动方程的初边值问题.当时间分数阶导数的阶α从0变到2时,解的性态变化从慢的扩散到传统的扩散,再到混合扩散-波动.利用分离变量法,分别导出三维的非齐次时间分数阶扩散方程和非齐次时间分数阶扩散-波动方程的初边值问题的基本解.
应用矿物学未来和发展――第十一届国际应用矿物学大会综述
,
矿物岩石 , 2014,
Abstract: 以“应用矿物学未来和发展”为主题的第十一届国际应用矿物学大会于2013年7月8~10日在绵阳召开,会议发表的技术报告内容涉及环境与医用矿物学、工业矿物、生物矿物学与生物材料、先进材料、工艺矿物学、矿业与冶金、矿物结构与表面、矿物与微生物的相互作用、固体废物处理与资源化等9个方面。
同步发电机的串级非线性PID励磁控制
国陈
电力系统自动化 , 1999,
Abstract: 将一种非线性PID控制方法和串级控制思想引入发电机的励磁控制。跟踪—微分器和基于非线性度α变换组成的非线性PID控制,改善了常规PID控制器受一点线性化影响产生的稳定范围局限性。串级控制有效地实现了功角稳定和机端电压稳定的统一。通过对单机无穷大系统的数值仿真表明,该励磁控制方式鲁棒性强,控制品质好,有利于提高系统的暂态稳定性。
黄河三角洲ndvi与albedo时空分布规律
,徐宗
人民黄河 , 2008,
Abstract: ?采用modis科学组l3级产品,详细分析了黄河三角洲地区ndvi和albedo的时空分布规律,结果表明:①该产品具备相当高的精度,基本反映了研究区的植被覆盖和地表反照率的变化规律,并与土地利用变化情况吻合较好;②modis地表反照率对黄河三角洲地区具有一定的适用性;③黄河三角洲地区人类活动特别是农业耕作的季节性更替对ndvi的年内变化影响显著;④黄河三角洲地区的albedo也具有明显的季节性变化,但其变化规律要比ndvi复杂得多.
气孔导度对co2浓度变化的模拟及其生理机制
王建林?,*?
生态学报 , 2010,
Abstract: 基于气孔运动的生理生化机制重点进行了气孔导度(gs)对co2浓度变化的响应机制分析,并推导得到气孔导度(gs)对co2浓度变化响应模型,并以9种植物进行了模型验证。结果表明:随着co2浓度的升高,气孔导度会逐渐降低,且下降的幅度会随着co2浓度的升高而逐渐减弱。气孔导度对co2浓度(cs)变化的响应模型可以表达为gs=gmax/(1+cs/cs0),其中式中gmax是最大气孔导度和cs0是实验常数。该模型较好地模拟了气孔导度随co2浓度变化的规律,模型参数具有明确的生理意义,与jarvis模型和ball-berry模型相比,该模型如何实现多种环境因子的耦合有待进一步突破。另外,模型是在短期改变叶片co2浓度的条件下得出的,在co2浓度长期胁迫下的适用性也有待进一步确认。
Page 1 /36903
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.