Parameters of “Macromaturity” (PMM): novel rank and type related indices from chemical degradation of macromolecular network of coals     

Ph. Blanc  P. Albrecht   《Organic Geochemistry》1991,17(6)

Benzene polycarboxylic acids formed upon oxidative degradation of the macromolecular network of a set of French coals with ruthenium tetroxide are proposed as the basis of new coal rank indices. Their distribution probably reflects the degree of condensation of the polyaromatic subunits occurring in the network of the coals. This feature is illustrated in the case of the benzene tetracarboxylic acids. Application of these molecular indices to Gondwana coals, as well as to maceral concentrates indicates that they are also type related. They could prove particularly useful in the case of coals or kerogens having undergone secondary alteration processes.  相似文献   

钼矿石中氧化钼的浸取条件研究   总被引：1，自引：0，他引：1  

王成 《岩矿测试》1992,11(3):243-245

以Cu~(2+)-稀HCl混合溶液为MoO_3的选择性溶剂,Cu~(2+)能有效地消除酸溶硫化物溶解时产生的H_2S对MoO_3测定的干扰。选用催化极谱法测Mo可进一步简化操作手续,提高测定灵敏度。所拟方法用于一般钼矿石物相分析,尤其对含酸溶硫化物较多的矿石均能得到满意的结果。  相似文献   

Nanociliates of the order Prostomatida: Their relevance in the microbial food web of a mesotrophic lake     

Ruben Sommaruga  Roland Psenner 《Aquatic Sciences - Research Across Boundaries》1993,55(3):179-187

Two nanociliates of the order Prostomatida,Pseudobalanion planctonicum (12–18 µm) andUrotricha furcata (12–21 µm), were found to be the most abundant ciliates in the epilimnion of Piburger See, a small mesotrophic lake. Temperature and food availability were the main factors controlling the sudden increase in abundance, which reached a maximum of 101 cell ml^–1 at the beginning of summer. During their exponential development in numbers and biomass, a strong decrease in chlorophylla and in the abundance of phytoplankton, especiallyRhodomonas, was observed. We assume, therefore, thatPseudobalanion planctonicum andUrotricha furcata together with rotifers, mainlyPolyarthra dolichoptera, are able to reduce the phytoplankton biomass in the upper epilimnion to the same level as found during the clearwater phase. Preliminary results of grazing on bacteria suggest that these nanociliates are omnivorous, although their impact on bacterial assemblages was low (3.1% of the standing stock grazed per day). Feeding on the base of the food web combined with their high abudance at certain times makes them an important link for higher trophic levels. This study constitutes the second report onPseudobalanion as an important component of the microbial food web in lakes.  相似文献   

Incipient vortex size-dependent evolution of tropical disturbances Part II — Some governing processes     

R. Koteswar Rao  P. Goswami 《Journal of Earth System Science》1994,103(4):449-468

Recently it was shown (Goswami and Rao 1993) that the process of intensification of tropical disturbances depends on the size of the incipient vortex in a rather nonlinear fashion. Among vortices of size ranging from 100 to 450 km (radius), embedded in the same large scale condition, it is the vortex with size about 250 km that intensifies to the most severe system. These results also showed a strong correspondence between the maximum intensity reached and the initial (3–6 hour) low level convergence field near the centre. The purpose of the present work is to identify the process(es) responsible for this scale selective intensification of tropical disturbances. It is proposed that diffusion is likely to play a crucial role in bringing about this selective intensification. In the present work a series of experiments with an axisymmetric numerical model of tropical cyclone (Wada’s model) is carried out to determine the relative roles of horizontal diffusion of momentum, moisture, heat and vertical diffusion. The results show that diffusion significantly affects the process of intensification and scale selection. While moderate diffusion does not alter the magnitude of intensification significantly, the scale selection is quite sensitive to the strength of diffusion. Interestingly, these diffusion processes, of momentum, moisture, heat and vertical do not affect the scale selection in the same fashion. The scale selection process turns out to be a result of a combined effect of these diffusion processes. However, no single diffusion process alone can give rise to a sharp selection of scale at the size of 250 km.  相似文献   

氟硼酸根离子选择性电极测定沉积物中的硼          下载免费PDF全文

张秀梅 《地质科学》1988,(1):92-96

本文建立了氟硼酸根离子选择性电极测定沉积物中的硼。在建立本方法过程中,做了各种干扰条件实验,得到了满意的分析结果。实验中不用溴甲酚绿,效果很好,可延长电极寿命。实验证明,本法较比色法简单、快速、干扰少,而且不需大型仪器设备,可测定0.000x—0.x%的硼。  相似文献   

Effects of Grazing on the Grassland Vegetation Community Characteristics in Inner Mongolia     

GUO Caiyun  ZHAO Dongsheng  ZHENG Du  ZHU Yu 《资源与生态学报(英文版)》2021,12(3):319-331

The continuous increase of livestock production in Inner Mongolia has caused severe degradation of the grassland ecosystems in recent years. Previous grazing experiments have shown a wide range of vegetation responses between the biome types on a global scale, but there is still a lack of sufficient studies to discern the relative responses of a given biome type. We conducted a meta-analysis of vegetation coverage (VC), plant density (PD), total biomass (TB), above-ground biomass (AGB), under-ground biomass (UGB) and Shannon-Weaver Index (SI) in different grassland types in Inner Mongolia obtained under conditions of different grazing intensities and durations. The results showed that grazing decreased VC, TB, AGB, UGB, and PD significantly. Compared to the global and national average values, the negative effects of grazing to steppe biomass in Inner Mongolia were higher than that on the global scale, while less pronounced than that in China. TB of the meadow steppe in Inner Mongolia increased by 40% under moderate grazing intensity and duration because of compensatory growth. SI of the desert and meadow steppe showed negative linear relationships with the grazing intensity in Inner Mongolia. The percentage changes in AGB, PD, and SI to grazing showed quadratic relationships with the mean annual temperature of the experimental year. With increasing mean annual precipitation, the negative effects of grazing on UGB and SI first decreased and then increased, with that of VC and grazing showing a cubic relationship.  相似文献   

围封对退化沙质草地植物群落的影响   总被引：1，自引：1，他引：0  

熊炳桥  赵丽娅  高丹丹 《中国沙漠》2018,38(2):324-328

对科尔沁沙地围封草地和放牧草地群落的种类组成、结构和多样性等特征进行比较研究。结果表明：（1）围封草地盖度、密度、地上生物量、高度均优于放牧草地（P<0.01）。与放牧相比,围封使植被盖度、密度、高度和地上生物量分别提高了237%、429%、77%和218%,植物群落结构得到明显改善。（2）与放牧草地相比,围封草地物种数增加了69%,多年生草本、灌木类种数和重要值均高于放牧草地。放牧草地的优势植物种依次是大果虫实（Corispermum macrocarpum）、狗尾草（Setaria viridis）、差巴嘎蒿（Artemisia halodendron）,重要值占72%;而围封草地优势植物种依次是达乌里胡枝子（Lespedeza davurica）、糙隐子草（Cleistogenes squarrosa）、虎尾草（Chloris virgate）和画眉草（Eragrostis pilosa）,重要值占57%,大果虫实、狗尾草和差巴嘎蒿逐渐处于群落的次要地位,取而代之的是与其环境条件相匹配的优质豆科和禾本科植物。围封使物种组成多样化,科属组成复杂化,优势物种发生了变化,群落结构和功能得到改善,沙地植被得以恢复。（3）围封草地的Shannon-Wiener指数、Simpson指数、Margalef指数、均匀度指数均大于放牧草地。围封增加了群落的物种多样性,群落的稳定性得以提高。  相似文献   

选择相关速度分析方法在VTI 介质中的应用     

李轶彬  王德利  徐世博 《世界地质》2013,32(3):590-597

To identify weak primaries in the presence of strong multiples is a challenge in conventional velocity spectra． Selective-correlation,an approach that can enhance the resolving of velocity analysis,is introduced, and extended to anisotropic media． Noting that the peaks of primaries submerged along the flank of the coherence peak of a strong multiples can be clearly identified in conventional spectrum comparing the velocity spectra obtained by this two approaches on synthetic data ,we conclued that selective-correlation keeps a higher resolution than conventional velocity analysis does． This process not only maintained the advantage of conventional velocity analysis, but also improveed manipulation． It matches the conventional velocity analysis on computational expense．  相似文献   

The potential of spectral mixture analysis to improve the estimation accuracy of tropical forest biomass     

Tyas Mutiara Basuki  Andrew K. Skidmore  Patrick E. van Laake  Iris van Duren  Yousif A. Hussin 《国际地球制图》2013,28(4):329-345

A main limitation of pixel-based vegetation indices or reflectance values for estimating above-ground biomass is that they do not consider the mixed spectral components on the earth's surface covered by a pixel. In this research, we decomposed mixed reflectance in each pixel before developing models to achieve higher accuracy in above-ground biomass estimation. Spectral mixture analysis was applied to decompose the mixed spectral components of Landsat-7 ETM+ imagery into fractional images. Afterwards, regression models were developed by integrating training data and fraction images. The results showed that the spectral mixture analysis improved the accuracy of biomass estimation of Dipterocarp forests. When applied to the independent validation data set, the model based on the vegetation fraction reduced 5–16% the root mean square error compared to the models using a single band 4 or 5, multiple bands 4, 5, 7 and all non-thermal bands of Landsat ETM+.  相似文献   

THE ORAL HISTORY OF GEOGRAPHY∗     

《The Professional geographer》2013,65(4):430-435

Book Reviewed in this article:

Latin America: Case Studies. Richard G. Boehm and Sent Visser

Locality and Rurality: Economy and Society in Rural Regions. Tony Bradley And Philip Lowe

The City and the Grassroots. Manuel Castells

Geopolitics and Conflict in South America. Quarrels among Neighbors. Jack Child

Post-Industrial America: A Geographical Perspective. David Clark

Coastal Research: UK Perspectives. Malcolm W. Clark

A Rural Policy for the EEC? Hugh Clout

Peasant Agriculture in Assam: A Structural Analysis. M. M. Das.

Environmental Change and Tropical Geomorphology. I. Douglas and T. Spencer

Advances in Abandoned Settlement Analysis: Application to Prehistoric Anthrosols in Colombia, South America. Robert C. Eidt

Measuring Culture. Jonathan L. Gross and Steve Rayner

North America: A Human Geography. Paul Guinness and Michael Bradshaw

A Geographical Bibliography for American Libraries. Chauncy D. Harris et al.

Geography and the Urban Environment: Progress in Research and Applications, Vol. VI. D. T. Herbert and R. J. Johnston

Changes in Global Climate: A Study of the Effect of Radiation and Other Factors During the Present Century. K. Ya. Kondrat'ev.

Rural Development and the State: Contradictions and Dilemmas in Developing Countries. David A. M. Lea and D. P. Chaudhri

The Martial Metropolis: U.S. Cities in War and Peace. Roger W. Lotchin

The Climate of the Earth. Paul E. Lydolph.

Weather and Climate. Paul E. Lydolph.

Spatial Divisions of Labor: Social Structures and the Geography of Production. Doreen Massey.

Panorama of the Soviet Union. N. Mikhailov.

Soviet Armenia. K. S. Demirchian.

USSR: Geography of the Eleventh Five-Year Plan Period. K. Spidchenko.

Planung und Verwirklichung der Wiener Ringstrassenzone (Planning and Materialization of the Ringstrasse-Zone of Vienna). Kurt Mollik, Hermann Reining, Rudolf Wurzer.

The American West Transformed: The Impact of the Second World War Gerald D. Nash.

An Overview of the Survey of Income and Program Participation. Dawn Nelson, David McMillen, and Daniel Kasprzyk.

Phenomenology, Science and Geography: Spatiality and the Human Sciences. John Pickles.

Biological Diversification in the Tropics. Ghillean T. Prance

Die Wanderviehwirtschaft im gebirgigen Westen der U.S.A. und ihre Auswirkungen im Naturraum. Gisbert Rinschede.

Social and Economic Aspects of Radioactive Waste Disposal: Considerations for Institutional Management

World-Wide Weather. K. Takahashi

Coastal Geomorphology in Australia. B. G. Thom

Settlement System in Rural India: A Case Study of the Lower Ganga-Yamuna Doab. Ram Chandra Tiwari.

Computer Programming for Geographers. David J. Unwin and John A. Dawson.

Late Quaternary Environments of the Soviet Union. A. A. Velichko, ed. H. E. Wright, Jr. and C. W. Barnosky

Ethics in Planning. Martin Wachs  相似文献