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Search Results: 1 - 10 of 133130 matches for " LI Ke-rang "
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Progress in the study on the relationship between global warming and wetland ecological system

FU Guo-bin,LI Ke-rang,

地理研究 , 2001,
Abstract: This paper reviews the recent progress in the study on the relationship between global warming and wetland ecological system from three aspects. (1) The wetlands are both sources and sinks of the major trace gases, such as CO2, CH4, N2O, NOx etc., hence they have a close relation with greenhouse effect and contribute a great deal to the global warming. (2) Global warming will affect the areal extent and distribution of wetlands——although at present it is impossible to estimate future areal size and distribution of wetlands from climate-change scenarios——and the cycling of carbon in wetlands. As a result some carbon-sequestering wetlands might change from CO2 sinks to sources due to a lowering of water table or temperature rise. The hydrological regime changes resulted from global warming and/or other disturbance that change the vegetation types in wetland areas will affect other wetland functions as well. (3) Wetlands are highly valued in many areas. The lack of data to fully address their responses to global warming/climate change calls for several areas of research in the future. These include site-specific experiments on the direct responses of trace gases on wetland ecological system, the feedback on climate by changes in trace gases flow from wetlands, models suitable for the study, comprehension study on this issue, and adaptation, conservation and rehabilitation of wetlands in response to global warming.
The progress in methodologies to study impacts of global climate change in China

LI Ke-rang,CHEN Yu-feng,

地理研究 , 1999,
Abstract: In this paper, the new progresses on research methodology of evaluating impacts of global Climate change in China are presented. They are experiments of laboratory, farmland field observation; methods of ice core tree-ring and historical writing; Studies of numerical models including static and dynamic model. At last, the indeterminacy and problems of existed and prospects are given.
Estimation of soil organic carbon reservoir in China

WANG Shao-qiang,ZHOU Cheng-hu,LI Ke-rang,ZHU Song-li,HUANG Fang-hong,

地理学报 , 2001,
Abstract: The paper respectively adopted physio-chemical properties of every soil stratum from 2473 soil profiles of the second national soil survey. The corresponding carbon content of soils is estimated by utilizing conversion coefficient 0.58. In the second soil survey, the total amount of soil organic carbon is about 924.18×108t and carbon density is about 10.53 kgC/m2 in China according to the area of 877.63×106 hm2 surveyed throughout the country. The spatial distribution characteristics of soil organic carbon in China is that the carbon storage increases when latitude increases in eastern China and the carbon storage decreases when longitude reduces in northern China. A transitional zone with great variation in carbon storage exists. Moreover, there is an increasing tendency of carbon density with decrease of latitude in western China. Soil circle is of great significance to global change, but with substantial difference in soil spatial distribution throughout the country. Because the structure of soil is inhomogeneous, it could bring some mistakes in estimating soil carbon reservoirs. It is necessary to farther resolve soil respiration and organic matter conversion and other questions by developing uniform and normal methods of measurement and sampling.
Modeling study of vegetation shoot and root biomass in China

HUANG Mei,JI Jin-Jun,CAO Ming-Kui,LI Ke-Rang,

生态学报 , 2006,
Abstract: 应用大气-植被相互作用模型AVIM2在0.1°×0.1°经纬度网格上估算了中国区域植被总生物量、地下和地上生物量以及根茎比的空间分布格局。研究了植被生物量和根茎比的空间分布与水热限制条件的关系。研究表明:中国植被总生物量、地下和地上生物量受水热条件影响明显,空间分布趋势基本相似,即在暖湿的东南和西南地区生物量大,而在干冷的西部地区生物量小。同类植被生物量的空间分布有显著区域差异,气温高、降水量大的区域植被生物量大;低温和干旱地区的植被生物量小。除灌木以外,植被生物量大小的空间分布受水分的影响大于温度。中国区域植被根茎比的空间分布存在明显区域差异,全国大致以大兴安岭、太行山、秦岭以及青藏高原东南侧一线为界线,界线东南植被根茎比较小;界线以西,植被根茎比较大。植被根茎比的空间分布与年平均气温、土壤湿度和年降水量显著反相关,水分因子对根茎比空间分布的影响大于温度。
Some facts about the effect of the meridional difference of sea surface temperature anomaly of North Pacific on the subtropical high

Li Ke-rang,Chen Yong-shen,Liu Jun-feng and,

大气科学 , 1979,
Abstract: 本文在系统分析1951—1975年北太平洋海温距平特征及夏季西太平洋付高强度的基础上,得到如下主要结果:整个北太平洋海温距平基本上可以分为正型和负型两种类型。正型是指海温距平经向差为正,即南正北负或南区的距平值大于北区,负型反之。正型和负型各有很长的持续性、周期性和经常在春、秋发生转换的阶段性。此外,北太平洋海温距平经向差与付高之间存在非常密切的正相关,它们有共同的周期,同时付高比海温的变化落后3—7个月。在付高与海温相关普查的基础上,给出了用海温距平经向差予报付高趋势的拟合曲线。
Progress in the studies on carbon cycle in terrestrial ecosystem

TAO Bo,GE Quan-sheng,LI Ke-rang,SHAO Xue-mei,

地理研究 , 2001,
Abstract: The concentration of the atmospheric CO2, one of the most important greenhouse gases, is increasing since the beginning of industrialization from its pre-industrial value of 280ppmv to its present value of 366ppmv. It has been proved that human activities, including fossil fuel burning, cement production, and land-use change, have severely disrupted the model of the carbon cycle, thereby alter the climate system and affect the processes and mechanisms in terrestrial ecosystems. Understanding the consequences of these changes in the coming decades is critical for the formulation of political, economic, energy, and security policies. So recently,studies in carbon cycle have increasingly become a focus of global change and geo-science in the world. The terrestrial ecosystem,one of the most important parts of the global carbon cycle, is most complex and most greatly affected by human activities. This paper, combined with the latest reports related to carbon cycle in IGBP and IPCC, introduces some major carbon pools, namely, lithosphere, atmosphere, ocean,and terrestrial ecosystem,in the global carbon cycle and their sizes and characteristics. Furthermore, four major approaches, including inventories method, eddy covariance measurements, inverse modeling and model of carbon cycle, which have been used to evaluate the biosphere-atmospheric exchange of CO2in the terrestrial ecosystems,are introduced. Using inventories method we can get an estimate of the actual accumulation of carbon in terrestrial ecosystem. The eddy covariance approach can detect small changes in net CO2exchange between terrestrial ecosystems and the atmosphere over various time scales. Inverse modeling approach can be used to infer carbon sources or sinks based on 3-D atmospheric tracer transport models and CO2 records from the atmospheric observations, fossil fuel combustion and land use change. Model of carbon cycle is a powerful tool to estimate and evaluate the temporal and spatial patterns of carbon sources or sinks in various scales. The existing problems of using these four methods are also analyzed. Moreover, the uncertainties in terrestrial carbon process are analyzed particularly.Additionally,some problems unsettled in carbon cycle and development tendency are specified concisely.
Isoflurane Preconditioning Confers Cardioprotection by Activation of ALDH2
Xiao-E Lang, Xiong Wang, Ke-Rang Zhang, Ji-Yuan Lv, Jian-Hua Jin, Qing-Shan Li
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0052469
Abstract: The volatile anesthetic, isoflurane, protects the heart from ischemia/reperfusion (I/R) injury. Aldehyde dehydrogenase 2 (ALDH2) is thought to be an endogenous mechanism against ischemia-reperfusion injury possibly through detoxification of toxic aldehydes. We investigated whether cardioprotection by isoflurane depends on activation of ALDH2.Anesthetized rats underwent 40 min of coronary artery occlusion followed by 120 min of reperfusion and were randomly assigned to the following groups: untreated controls, isoflurane preconditioning with and without an ALDH2 inhibitor, the direct activator of ALDH2 or a protein kinase C (PKCε) inhibitor. Pretreatment with isoflurane prior to ischemia reduced LDH and CK-MB levels and infarct size, while it increased phosphorylation of ALDH2, which could be blocked by the ALDH2 inhibitor, cyanamide. Isolated neonatal cardiomyocytes were treated with hypoxia followed by reoxygenation. Hypoxia/reoxygenation (H/R) increased cardiomyocyte apoptosis and injury which were attenuated by isoflurane and forced the activation of ALDH2. In contrast, the effect of isoflurane-induced protection was almost abolished by knockdown of ALDH2. Activation of ALDH2 and cardioprotection by isoflurane were substantially blocked by the PKCε inhibitor. Activation of ALDH2 by mitochondrial PKCε plays an important role in the cardioprotection of isoflurane in myocardium I/R injury.
李克让 Li Ke-rang,陈永申 Chen Yong-shen,刘军风 Liu Jun-feng,等 et al
大气科学 , 1979, DOI: 10.3878/j.issn.1006-9895.1979.02.06
Abstract: 本文在系统分析1951—1975年北太平洋海温距平特征及夏季西太平洋付高强度的基础上,得到如下主要结果:整个北太平洋海温距平基本上可以分为正型和负型两种类型。正型是指海温距平经向差为正,即南正北负或南区的距平值大于北区,负型反之。正型和负型各有很长的持续性、周期性和经常在春、秋发生转换的阶段性。此外,北太平洋海温距平经向差与付高之间存在非常密切的正相关,它们有共同的周期,同时付高比海温的变化落后3—7个月。在付高与海温相关普查的基础上,给出了用海温距平经向差予报付高趋势的拟合曲线。

YU Li,CAO Ming-Kui,TAO Bo,LI Ke-Rang,DONG Wen-Jie,LIU Hong-Bin,LIU Chang-You,
,【曹明奎】,陶 波,李克让,董文杰,刘洪滨,刘长友

植物生态学报 , 2008,
Abstract: 陆地生态系统对气候变化的响应及其脆弱性评价研究是当前全球变化领域的重要内容之一。该研究在生态系统过程模型的基础上,耦合了潜在植被对气候变化的动态响应,模拟气候变化对潜在植被分布格局和生态系统主要功能的影响,以潜在植被的变化次数和变化方向定义植被分布对气候变化的敏感性和适应性,以生态系统功能特征量的年际变率及其变化趋势定义生态系统功能对气候变化的敏感性和适应性,进而对生态系统的脆弱性进行定量评价,分析不同气候条件下我国陆地生态系统的脆弱性分布格局及其区域特点。结果表明,我国自然生态系统气候脆弱性的总体特点为南低北高、东低西高,气候变化将会增加系统的脆弱性。采用政府间气候变化委员会排放情景特别报告国内和区域资源情景,即IPCC-SRES-A2气候情景进行的预测模拟表明,到21世纪末我国不脆弱的生态系统比例将减少22%左右,高度脆弱和极度脆弱的生态系统所占的比例较当前气候条件下分别减少1.3%和0.4%。气候变化对我国陆地生态系统的脆弱性分布格局影响不大。不同气候条件下,高度脆弱和极度脆弱的自然生态系统主要分布在我国内蒙古、东北和西北等地区的生态过渡带上及荒漠-草地生态系统中。总体而言,华南及西南大部分地区的生态系统脆弱性将随气候变化而有所增加,而华北及东北地区则有所减小。
Joint DOD DOA and Polarization Estimation for MIMO Radar with Electromagnetic Vector Sensors
基于矢量传感器MIMO雷达的DOD DOA和极化联合估计算法

Wang Ke-rang,Zhu Xiao-hua,He Jin,

电子与信息学报 , 2012,
Abstract: The issue of joint estimation of Direction Of Departure (DOD), Direction Of Arrive (DOA) and polarization for MIMO radar with electromagnetic vector sensors is investigated. A novel bistatic MIMO radar system with multiple transmit sensors and multiple receive electromagnetic vector sensors is proposed. Three joint parameter estimation algorithms, which are, respectively, termed as four-dimensional MUSIC, ESPRIT and iterative one-dimensional (1D) MUSIC, are presented. The iterative 1D-MUSIC algorithm first uses the internal structure of the vector sensors to obtain a set of initialize DOA estimates, and then two 1D-MUSIC searches are employed to get the DOD and DOA estimates in succession, finally a polarization ESPRIT algorithm is proposed for polarization estimation. The iterative 1D-MUSIC algorithm is suitable for irregular array geometry, imposes less constraints on the receive array geometries, and requires no two-dimensional or high-dimensional searching. Moreover, this algorithm can improve the DOA estimation performance by extending the array aperture. The CRB for the issue under consideration is also derived. Simulations show that the estimation accuracy of the iterative 1D-MUSIC algorithm is closest to the CRB, compared with those of the previous two algorithms.
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