矿物-水界面的表面离子化和络合反应模式   总被引：19，自引：1，他引：19  

魏俊峰  吴大清 《地球科学进展》2000,15(1):90-96

表面络合模式已广泛应用于研究矿物表面吸附和溶解反应,尤其是(氢)氧化物和层状铝硅酸盐矿物。表面官能团是矿物参与表面络合反应的基本单元,(氢)氧化物矿物只具有表面羟基,而层状铝硅酸盐矿物除表面羟基外还具有离子交换位。矿物的表面电荷由永久结构电荷、配位表面电荷和离解表面电荷组成,各种零表面电荷状态可由不同的零电荷点来表征。恒电容模式、双层模式和三层模式是3种最常用的表面络合模式,它们在双电层结构、表面反应(质子化反应和络合反应)、表面电荷与质量平衡方程及应用范围上存在着一些差异。  相似文献   

The solution of mixed boundary value problems with the reference ellipsoid as boundary   总被引：1，自引：0，他引：1  

Y. Jinghai  W. Xiaoping 《Journal of Geodesy》1997,71(8):454-460

In this paper we study the following mixed boundary value problem where is the reference ellipsoid, and T the disturbing potential. With the help of the variational principles of partial differential equations and the expression of ellipsoidal harmonic series, we give a linear system related to the coefficients of the ellipsoidal harmonic series. Hence the solution of the problem can be obtained in the form of ellipsoidal harmonic series, which supplies us an important theoretical basis for making use of data given by satellite altimetry measurements more efficiently. Received: 16 January 1996; Accepted: 22 January 1997  相似文献   

都市圈经济发展的主要原理及对兰州都市圈建设的启示   总被引：1，自引：0，他引：1  

吴文恒  牛叔文  董晓峰 《干旱区地理》2007,30(2):311-319

都市圈是经济发展到一定阶段的产物,发展经济是都市圈建立并不断完善的重要内容。以此为出发点,分析了距离衰减规律、万有引力原理、中心地理论、地域生产综合体理论、绝对优势与比较优势原理及网络结构理论等对都市圈建设的指导作用。以兰州都市圈为例,阐释了部分原理在实际建设中的应用:兰州都市圈的空间界定、经济发展功能分区及网络经济构建。  相似文献   

Urban niche dynamics of Kaifeng city     

Ding Shengyan  Li Zhiheng 《地理学报》2007,17(2):221-233

Niche theory is one of the most important ecological theories. It is widely applied to analyzing such phenomena as competition among, and evolution of, urban ecosystem func-tional modules. This paper describes a study concerning different functional modules of Kaifeng city urban ecosystem. Niche theory and techniques were used to analyze the changes of these functional modules in the period 1994–2003. The results showed that, in the period 1994–2003: (1) Niche value of the atmospheric environment and urban virescence modules increased, while niche value of the water environment and sound environment modules decreased; (2) niche value of the tertiary industry module increased, niche value of the secondary industry module decreased, while niche value of the primary industry module showed little change; and (3) niche value of the infrastructure, resource distribution, and production & social security modules increased, while niche value of the population module decreased. This study may contribute to macroscopic planning of urban functional modules, economic development, and environmental protection.  相似文献   

随机模型不正确对方差一致性检验统计量的影响   总被引：2，自引：1，他引：2  

刘长建张前恩  王玉成 《测绘学院学报》2004,21(2):85-86,92

当平差模型不正确时必然会影响平差结果及其统计性质。文中着重分析了在函数模型正确的前提下，采用不正确的随机模型对方差一致性检验统计量的影响，并给出了具体的影响公式。所得结果对进一步充实测量平差教学内容及实用中检验模型的正确性等方面具有一定的意义。  相似文献   

European vegetation during Marine Oxygen Isotope Stage-3     

Brian Huntley  Mary J.o AlfanoJudy R.M Allen  Dave PollardPolychronis C Tzedakis  Jacques-Louis de BeaulieuEberhard Grüger  Bill Watts 《Quaternary Research》2003,59(2):195-212

European vegetation during representative “warm” and “cold” intervals of stage-3 was inferred from pollen analytical data. The inferred vegetation differs in character and spatial pattern from that of both fully glacial and fully interglacial conditions and exhibits contrasts between warm and cold intervals, consistent with other evidence for stage-3 palaeoenvironmental fluctuations. European vegetation thus appears to have been an integral component of millennial environmental fluctuations during stage-3; vegetation responded to this scale of environmental change and through feedback mechanisms may have had effects upon the environment. The pollen-inferred vegetation was compared with vegetation simulated using the BIOME 3.5 vegetation model for climatic conditions simulated using a regional climate model (RegCM2) nested within a coupled global climate and vegetation model (GENESIS-BIOME). Despite some discrepancies in detail, both approaches capture the principal features of the present vegetation of Europe. The simulated vegetation for stage-3 differs markedly from that inferred from pollen analytical data, implying substantial discrepancy between the simulated climate and that actually prevailing. Sensitivity analyses indicate that the simulated climate is too warm and probably has too short a winter season. These discrepancies may reflect incorrect specification of sea surface temperature or sea-ice conditions and may be exacerbated by vegetation-climate feedback in the coupled global model.  相似文献   

河南省城市职能结构的有序推进   总被引：12，自引：2，他引：12  

徐晓霞 《地域研究与开发》2003,22(3):31-35

文章首先根据河南城市的产业结构和行业区位熵将河南城市进行职能类型的划分；然后对此进行分析并找出河南城市职能结构存在的问题；最后结合国际、国内形势提出了河南省城市职能结构有序推进的对策。  相似文献   

Artificial Neural Networks for Mineral-Potential Mapping: A Case Study from Aravalli Province,Western India   总被引：1，自引：0，他引：1  

Porwal  Alok  Carranza  E. J. M.  Hale  M. 《Natural Resources Research》2003,12(3):155-171

This paper describes a GIS-based application of a radial basis functional link net (RBFLN) to map the potential of SEDEX-type base metal deposits in a study area in the Aravalli metallogenic province (western India). Available public domain geodata of the study area were processed to generate evidential maps, which subsequently were encoded and combined to derive a set of input feature vectors. A subset of feature vectors with known targets (i.e., either known mineralized or known barren locations) was extracted and divided into (a) a training data set and (b) a validation data set. A series of RBFLNs were trained to determine the network architecture and estimate parameters that mapped the maximum number of validation vectors correctly to their respective targets. The trained RBFLN that gave the best performance for the validation data set was used for processing all feature vectors. The output for each feature vector is a predictive value between 1 and 0, indicating the extent to which a feature vector belongs to either the mineralized or the barren class. These values were mapped to generate a predictive classification map, which was reclassified into a favorability map showing zones with high, moderate and low favorability for SEDEX-type base metal deposits in the study area. The method demarcates successfully high favorability zones, which occupy 6% of the study area and contain 94% of the known base metal deposits.  相似文献   

Plant functional types and climate along a precipitation gradient in temperate grasslands, north-east China and south-east Mongolia   总被引：1，自引：0，他引：1  

Jian Ni 《Journal of Arid Environments》2003,53(4):501-516

Using data from three field surveys along a precipitation gradient of temperate grasslands in north-east China (the Northeast China Transect, NECT) and south-east Mongolia, the spatial distribution of six plant functional types (PFTs): C₃ species, C₄ species, grasses, shrubs, forbs and succulents and their relationships with climate were analysed. The spatial distribution of different PFTs varies in different regions and in different grassland types of the study area. The species richness in each PFT also has different relationships with climate (significantly or not). Generally, the number of C₃ species, C₄ species, grasses and forbs have positive relationships with precipitation and aridity. Shrubs have negative relationship with precipitation and aridity. Succulents were found to have no relationship with precipitation and aridity. Shrubs, grasses and forbs have stronger relationships with precipitation than C₃ and C₄ species. The relationships between C₃ species, forbs and aridity are more significant than with precipitation. On a regional basis, the combined effect of precipitation and temperature, the aridity, is more significantly correlated with the distribution of C₃ species and forbs, which are more dominant in the study area, than with C₄ species, grasses and succulents.  相似文献   

Effective Emergency Transportation for Saving Human Lives     

Yasuko Kuwata  Shiro Takada 《Natural Hazards》2004,33(1):23-46

To save lives immediately after a catastrophic earthquake occurs, it is essential for an urban transportation system to retain its functional performance in order to carry injured people to hospitals. Recent seismic assessment studies have mostly been based on cost-benefit analyses, carried out in monetary terms that are reasonable for long-term considerations. However, many problems of seismic risk management still remain. For example, attributing a monetary value to a human life is considered impossible. Also, requirements for functioning of a transportation system are different in the period immediately after an earthquake. This paper concentrates on how to assess the importance of an urban transportation system as it relates to saving human life, and what system enhancements should be made to improve performance. This paper proposes a risk assessment method for the functional reliability of a transportation system immediately after an earthquake. In that period, system malfunction adversely affects the saving of lives as a result of time delays when moving injured people to medical facilities. A system dynamics simulation of transporting injured people is incorporated in the method, which uses two assessment approaches to evaluate the differences of cumulative injured people who receive medical care. In deciding on the destination of medical facility in the simulation, two ways of deciding are addressed; one uses information only on the road network, and the other uses information on both road network and hospital availability. Results of an application to an actual target area show the most vulnerable road links and differences of the two decision-making processes. A way to mitigate the loss due to damage to road links is examined. The paper also summarizes future developments in advanced information technology for emergency transportation systems.  相似文献