共查询到19条相似文献，搜索用时 531 毫秒
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一、加入世界贸易组织对我国矿产资源产业的影响 我国自2001年11月7日正式加入世界贸易组织,至今已经一年。一年来,世界贸易组织各项规则的实施对我国矿产资源的产品贸易和服务贸易产生的效果及深层次影响已初见端倪。总结一年来的情况,对于做好加入世界贸易组织过渡期的工作和今后工作的顺利开展具有重要意义。 相似文献
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60~100 km低电离层对无线电传播、测量具有重大影响。IRI2016作为目前最新的国际参考电离层模型,研究其提供的电子密度在高度60~100 km的精度具有重要实际意义。本文以廊坊中频雷达(位于中纬度地区)提供的电子密度资料(2014—2016年)为基准,利用偏差、绝对差、相关系数、相对偏差和Lomb-Scargle周期图方法,定量分析了IRI2016模型电子密度在中纬度地区60~100 km高度范围内的精度特征。结果表明,在中纬度地区60~100 km高度范围内:①电子密度偏差、绝对差、相对偏差与季节有密切关系,在高度86~100 km,随高度增加均快速增大;相关系数同样与季节有密切关系,但随高度增加表现出增大、减小的交替变化特征;②IRI2016模型电子密度精度与太阳活动、地磁条件有关,在太阳活动低年、磁宁静条件下的电子密度精度最高;③中频雷达和IRI2016模型电子密度在82~84 km均显著(通过90%显著性检验)含有准全日潮汐波、准8 h重力波,同时IRI2016模型还显著含有准半日潮汐波,而中频雷达未显著含有准半日潮汐波;在86~92 km均显著含有准全日潮汐波、准半日潮汐波,无准8 h重力波;④中频雷达、IRI2016模型电子密度在同一高度层显著含有的波周期及功率谱存在差异,不同高度层之间显著含有的波周期及功率谱也存在差异;⑤对于高度82~92 km的中频雷达、IRI2016模型电子密度变化特征,准全日潮汐波均为主要作用,准8 h重力波在82 km为次要作用,而准半日潮汐波在86~92 km为次要作用。 相似文献
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塔吉克斯坦矿业投资环境 总被引：2，自引：0，他引：2
一、经济发展 2001年8月17日,塔吉克斯坦总理阿·阿基洛夫在塔独立10周年国家经济研讨会上说,“最近4年,塔吉克斯坦国内生产总值增长了20％,其中工业生产增长了23％,农产品增长了12.5％。”今年上半年,塔经济继续保持良好的发展势头。阿基洛夫强调,塔政府今后经济战略的主要目标是:消 相似文献
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当今世界仍不太平,研究国际冲突对人类社会的进步和发展具有重要的意义。利用Cite Space可视化文献分析工具对1946—2016年的Web of Science数据库中国际冲突研究的12 035篇文献进行分析,研究结果直观地展示了发文时间分布、主要发文国家、主要发文机构、核心期刊等,揭示了国际冲突研究领域由理论探讨战争发生机制、理论研究政治体制与国际冲突的关系到定量研究的演进路径,指出引发国际冲突原因、特征及其解决是当前的研究热点,地理要素、非国家行为体、国际法等与国际冲突的关系及对其影响是今后需重点关注的方面。为更好地了解国际冲突研究领域基础及研究进展提供了有价值的参考。 相似文献
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国际制图协会(ICA)第21届国际制图研讨会和第12届代表大会 总被引：3，自引：0，他引：3
国际制图协会(International Cartographic Association,简称ICA,亦译国际地图学协会)是世界地图制图学界权威的学术组织,其宗旨是促进国际间地图制图学的发展,加强国际间技术合作和技术交流。它的任务是推进地图制图学的研究,鼓励和协调这一领域的科研活动,包括国际间的协作、技术和文献的交流,促进地图制图学教育的发展,推动地图制图学的科普工作,组织地图制图学的国际学术讨论会、讲座、培训和技术展览会等,并参加其他国际学术组织的有关会议和活动。中国测绘学会于1980年加入了ICA,现为四级会员。中国积极参加并主办ICA的各项活动,在ICA中发挥了积极的作用与影响。武汉大学胡毓钜先生曾担任两届ICA副主席、国家基础地理信息中心李莉女士于1999年当选为ICA副主席。国家测绘局和中国测绘学会2001年8月在北京成功举办第20届国际制图大会,在国际制图界造成了空前的影响。 相似文献
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在科学技术飞速发展的当今世界,技术贸易已成为商品贸易中的极为重要的组成部份。而技术的输出与引进,又是技术贸易中的相辅相成的两个方面。世界各国在引进别国先进技术的同时,为扩大国际市场,都竟相采取鼓励本国人将其发明向外国申请专利的战略决策。甚至象日本这样一些靠引进技术立国的国家,近年来也竭力向外输出专利技术,以期扭转进出口不平衡的局面。例如日本仅在一九七九年前,就向美国这一个国家申请过专利14,009件。可见,技术的输出与引进,在国际经济交往中,两者是不可偏废的。 相似文献
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针对GIS国际顶级期刊《International Journal of Geographic Information Science》,辅以《ComputersGeosciences》2001~2010年10 a来发表的文献进行统计,找出我国与美国、加拿大、德国等发达国家的差距,总结我国论文的作者、机构等分布特征,了解分析GIS技术国内外10 a来的发展动态和趋势,为我国地球空间信息技术发展提供参考和依据。 相似文献
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Sike Li 《International Journal of Digital Earth》2018,11(2):195-211
Cropland is one of the essential elements of our ecological systems for producing agricultural products. In developing countries, urban expansion is a frequently appearing phenomena, which is a type of land cover land use (LCLU) change. This change can drastically alter the features on the land surface including croplands. It can lead to detrimental consequences which has considerable effects on the social-ecological systems when croplands are lost. Argentina is an extremely agricultural intense developing country, and Buenos Aires province is a top agricultural production site and has been urbanizing during the last 30 years. Thus studying and analyzing the metropolitan area of this province will contribute to our understanding of the relationship between urban expansion and its effect on croplands. So far, no research has used measurable quantitative methodologies on the Buenos Aires metropolitan region (BAMR) to reveal the relationship between urbanization and cropland. By using 30-meter resolution Landsat images of June 1985 and July 2015, this study finds urban land has expanded from 937.16?km2 to 1835.47?km2, and 30.28% of the new urban lands comes from existing croplands. 相似文献
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Monitoring agricultural land cover is highly relevant for global early warning systems such as ASAP (Anomaly hot Spots of Agricultural Production), because it represents the basis for detecting production deficits in food security assessment. Given the significant inconsistencies among existing land cover datasets, there is a need to obtain a more accurate representation of the spatial distribution and extent of agricultural area in Africa. In this research, we explore a fusion approach that combines the strength of individual datasets and minimises their limitations. Specifically, a semi-automatic method is developed, relying on multi-criteria analysis (MCA) complemented with manual fine-tuning using the best-rated datasets, to generate two hybrid and static agricultural masks – one for cropland and another for grassland. Following a comprehensive selection of land cover maps, each dataset is evaluated at country level according to five criteria: timeliness, spatial resolution, comparison with FAO statistics, accuracy assessment and expert evaluation. A sensitivity analysis is performed, based on an evaluation of the impact of weight settings on the resulting land cover. The proposed methodology is capable of improving agricultural characterisation in Africa. As a result, two static masks at 250 m spatial resolution for the nominal year 2016 are provided. 相似文献
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李宇 《测绘与空间地理信息》2021,44(1):73-76,81
研究水稻分布的时空演变特征及驱动机制,对优化农业生产结构至关重要。基于植被物候变化特征、地表水变化特征结合方法识别水稻的空间分布,获取了2001—2017年东北水稻空间分布图,并进行了水稻的时空演变特征及驱动机制研究。研究表明,2001—2017年东北地区水稻呈先略减后直线上升的特点,2017年水稻种植面积约300万hm 2,约为2001年的2倍,增加面积主要分布在黑龙江省的三江平原农垦模式的耕地区域。东北地区水稻种植面积扩张约90%分布在低海拔、距水体较近区域。气温变暖、农业技术的发展、水稻总产值的上涨及农业税减免、稻谷最低收购价等系列惠农政策的实施,促进了东北地区水稻种植面积的大幅扩张。这些发现为将来更加深刻探讨水稻分布对自然-人为因素的响应提供了基础。 相似文献
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Minakshi P.K. Sharma Amandeep Kaur Vanita Shalley 《Journal of the Indian Society of Remote Sensing》2005,33(1):63-68
This study reveals the temporal changes in the land use/land cover of district Ludhiana from the years 1970 to 2001 and reports
on the change that has occurred in land use/land cover as a result of change in cropping pattern. The changes were analysed
through the data obtained from statistical abstract 1969–70, False Colour Composite (FCC) of IRS-IC LISS-III satellite data
of March 2001 and ground truth. There has been a decrease in agricultural land by 2100 ha. but still it occupies 83.76% of
the total geographical area (TGA). The wasteland shows a declining trend whereas forest cover has increased from 1.07 to 2.71%
of TGA. Area under non-agricultural uses has increased from 10.13 to 12.50% of TGA. There has also been a great change in
the cropping pattern of the district. Crops such as groundnut, gram and cotton have nearly disappeared and wheat and rice
dominate the region. This change has substantially resulted in the decrease of area under wastelands. 相似文献
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以富锦市为研究区域,运用地理信息系统、土地资源学、土地利用规划学的知识,并结合景观生态学的相关知识,对该区域垦区与农区的耕地配置模式进行对比分析,着重从垦殖率、耕地内部数量结构、空间分布特征、斑块特征、居民点等方面探讨二者耕地配置模式的异同。结果表明:农区垦殖率为81.94%,高于垦区的70.64%;农区的水田、旱地面积相差悬殊,旱地面积接近于水田的7倍;农区、垦区水旱混合区分别占耕地总面积的13.28%和36.15%;农区水田斑块为10.81ha,小于垦区的21.38ha。最后为土地整治项目提出了一些参考建议,旨在促进农业现代化发展。 相似文献
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Research making use of satellite data for land change science has developed in the last decades. However, analysis of land use has not developed with the same speed as development of new satellite sensors and available land cover data. Improvement of land use analysis is possible, but more advanced methods are needed which make it possible to link image data to analysis of land use functions. To make this linking possible, variable which affect farmer's long term decisions must be taken into account in analysis as well as the relative importance of the landscape itself.A GIS-based tool for the measurement of local spatial context in satellite data is presented in this paper and used to explore the relationship between land covers present in satellite data and land use represented in official databases. By the use of the developed tool, a land configuration image (LCI) over the Siljan area in northern Sweden was produced and used for analysis. The results are twofold. First, the produced LCI holds new information about variables that are relevant for the interpretation of land use. Second, the comparison with statistics of agricultural production shows that production in the study area varies depending on the relative land configuration. Villages consisting of relatively large-scale arable fields and less diverse landscape are less diverse in production than villages which consist of smaller-scale and more heterogonous landscapes. The result is especially relevant for land use studies and policymakers working on environmental and agricultural policies. We conclude that local spatial context is an endogenous variable in the relation between landscape configuration and agricultural land use. 相似文献
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The Mumbai-Navi Mumbai cities (Bombay and New Bombay) are among the highest populated cities in the country. The population pressure has caused drastic landuse change in the last seventy years. Multi-date data from SOI topographical maps and Landsat TM digital data have been used to study the landuse change. The change has been quantified using A GIS It was observed that 55% reduction in forest/agricultural land, while a 300% increase in built-up land has taken place in the last seventy years. This has affected the natural drainage system of the cities, causing flooding during monsoons. The quantum of draînage basin area and stream length, in the ten basins which drain the area, under influence of built-up land was found by using a map overlay of the drainage network map and landuse map of 1994. The results shed light on the extent of drainage network disruption within these two neighbouring cities. 相似文献
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In this study, an empirical model for predicting urban evapotranspiration (ET) is examined for the Phoenix metropolitan area that is in a subtropical desert climate using in situ ET measurements from a local flux tower and remotely sensed moderate-resolution imaging spectroradiometer land products. Annual ET maps of Phoenix are then created for the period from 2001 to 2015 using the empirical model developed. A time-series trend analysis is finally performed using predicted ET maps to discover the spatio-temporal patterns of ET changes during the study period. Results suggest that blue-sky albedo and land surface temperature are two statistically significant variables explanatory to model urban ET for Phoenix. Areas that have experienced significant increases of ET are highly spatially clustered, and are mainly found on the outskirts of the city, while areas of decreasing ET are generally associated with highly developed areas, such as downtown Phoenix. 相似文献