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51.
电子政务空间辅助决策系统中数据库性能的优化   总被引:2,自引:1,他引:2  
栗斌  刘纪平  朱翊  石丽红 《测绘科学》2005,30(3):88-90,93
Oracle9i数据库系统是一个大型而复杂的运行系统,其运行效率对系统性能至关重要。本文从数据库结构、SQL语句和内存分配等三个方面对Oracle9i数据库性能的优化做了阐述,提出了一些原则和方法。  相似文献   
52.
广东博罗县小金河植物区系研究   总被引:1,自引:0,他引:1  
王英强  陈邦余 《热带地理》1995,15(4):350-361
本区计有野生维管束植物172科、532属、978种(包括变种、变型)。发现2新种,1新变种和3个广东新记录种。本区系的表征科为山茶科、壳斗科、桑科、芸香科、紫金牛科、樟科等,这些科大都是热带-亚热带分布式的,代表了本区系的性质。在属的地理成分中,本区以热带成分173属(占总数的35.2%)和热带-亚热带成分169属(占总数的34.4%)为主,说明了本区系具有由亚热带向热带过渡的南亚热带特征。本区与  相似文献   
53.
Hawai‘ian honeycreepers have undergone widespread extinction and population declines due to human disturbances, including habitat fragmentation, introduced predatory mammals, alien competitors, and introduced avian diseases. The Hawai‘i ‘amakihi (Hemignathus virens) is one of seven extant Hawai‘ian honeycreepers that, like all other native honey‐creepers, vanished from the low‐elevation native forests on the island of Hawai‘i due to these disturbances. But recent observations indicate that ‘amakihi have begun to recolonize low‐elevation forests in eastern Hawai‘i. In this article we discuss the current abundance of Hawai‘ian ‘amakihi in a suburban habitat on the island of Hawai‘i. We also examine the ‘amakihi's relative preference for native or exotic vegetation. Recolonization in low‐elevation habitats underscores the importance of the remaining native forests. However, concurrent with this recolonization, eastern Hawai‘i is undergoing a residential building boom that has resulted in increased deforestation and forest fragmentation. Thus the future of honeycreepers is uncertain, given the widespread environmental changes taking place in eastern Hawai‘i.  相似文献   
54.
基于J2EE的数字预案查询系统研究   总被引:1,自引:0,他引:1  
简要介绍了城市公共安全应急平台的建设背景;详细论述了公共安全应急平台数字预案查询系统的建设,提出了基于J2EE的数字预案查询系统建设方案;展示了该数字预案查询系统的界面。  相似文献   
55.
56.
基于SGM100i和最新月球重力场模型GLGM-3比较,分析了月球自由空气重力异常和月球大地水准面起伏。利用SGM100i绘制了月球垂线偏差及其分量的全月分布图,并分析了垂线偏差与月球地形特征、质量分布之间的相关性,发现利用垂线偏差反演得到的月球地形、质量分布均与实际情况一致。  相似文献   
57.
Environmental planning is an arena of policy making in which formal public deliberation is among the most extensive. At the same time, environmental disputes can also be among the most resistant to resolution, often becoming entangled in issues that some describe as “intangible”. The discourse is largely structured by regulatory frameworks, such as environmental impact assessment laws and procedures, which focus primarily on operational rights (what one can or cannot do where and when) and tangible impacts on the physical or natural environment. A comparative case study of mariculture in Hawai‘i reveals that a large measure of public concerns focused on collective choice rights (who has a right to make which decisions on behalf of whom) and the more intangible impacts to the social or cultural environment. These concerns are often nested in a historic context that has implications for the social processes that they create. The findings from this study imply a need for more structured or systematic ways to deliberate issues of collective choice rights alongside operational rights within the larger process of environmental planning.  相似文献   
58.
Hawai‘i's agricultural landscape was previously dominated by large monocrop plantations of sugar cane and pineapple, but following a sweeping series of plantation closures beginning at the end of the twentieth century, that era has concluded. The last spatial assessment of Hawai‘i's agricultural footprint was completed in 1980, during the active plantation period. Here we present the results of a 2015 statewide assessment of the commercial crop footprint for Hawai‘i, based on World-View 2 satellite imagery and supporting datasets. We analyzed changes relative to the 1980 baseline on both a statewide and regional basis, to better understand how Hawai‘i's agricultural system has evolved in the post-plantation era. Sugar cane and pineapple saw dramatic reductions during this period, collectively losing more acres (257,000) than were planted for all crops combined (152,000) in 2015. Idle plantation lands and past plantation-era investments in irrigation and other infrastructure have created opportunities for other types of agriculture, despite rising land values, new and existing tropical diseases, and other challenges. Seed crops, primarily for genetically modified corn trials, were the second largest crop in 2015 (24,000 acres) despite having no mapped footprint in 1980. Commercial forestry, also absent in 1980, covered 23,000 acres in 2015. Macadamia nut, coffee, and diversified agriculture also all saw significant gains in their footprints, with coffee plantings increasing >250% during this period. Despite these gains, the Hawaiian Islands continue to have an extremely low degree of self-reliance for food production. The Oahu plain, adjacent to the major population center of Honolulu, has the most potential for considerably increasing the production of local produce, but without changes in consumption patterns and significant efforts to protect agricultural land from development, any increases in local food production will continue to be incremental. The post-plantation agricultural landscape in Hawaii is smaller, more diversified, and more nimble than it was in 1980, reflecting inter-island geographic differences in land use, history, and ownership. Mapping and assessing spatial changes in agricultural activity over time can provide valuable insights for decision-makers and communities as they continue to define what agriculture should look like in the post-plantation era. Our results suggest that Hawai‘i's agricultural landscape and overall production capability will continue to contract without substantial changes in policy and practice.  相似文献   
59.
Armed with a scholarship to find an answer to the question “What is geography?” Simion Mehedin?i's studies took him to continental Europe's three main centers of geographic thought: Paris, Berlin, and Leipzig. We explore how his innovative ideas flourished, especially in Leipzig under Ratzel. The first Romanian geographer, Mehedin?i, must be credited with having defined geography as a science of mutual relationships between geospheres. This thinking reached its pinnacle in two complex books, Terra and Ethnos, the contents of which we synthetically explore. We also trace the unfavorable historical and geopolitical conditions that led to this pioneering work being little recognized worldwide.  相似文献   
60.
Two key figures analyzed in Donna Haraway’s monograph, Primate Visions: Gender Race and Nature in The World of Modern Science (1989) warrant further analysis in the emerging cyber politics of environmental conservation. These figures are Koko, a female lowland gorilla born in the San Francisco Zoo and her companion Dr. Francine (Penny) Patterson, a developmental psychologist who taught Koko how to communicate with a modified form of American Sign Language (ASL). Nine years after Haraway’s initial analysis, Koko and Patterson became early examples of conservation-related Web 2.0 engagement with their unprecedented inter-species America Online chat room encounter with 7811 member participants. Today, Koko has a Twitter account (@kokotweets), a Facebook page, a YouTube channel and a website where users watch videos of Koko celebrating birthdays and donate to ‘distant’ conservation projects. One project site is a gorilla reserve in Cameroon and another is a former pineapple plantation turned private nature preserve in Maui, Hawai’i. Inspired by recent analytical work in animal geographies and feminist political ecology, this article explores complex landscapes of caring, aging and conservation in a time of proliferating social media engagement from colonized sites of enduring privilege. The article argues that new media adds layers of violence, disciplinary techniques and co-dependence to the aging bodies, caring practices and landscapes that Koko, Patterson and others inhabit in California and in the proposed physical spaces of a repurposed pineapple field in Maui.  相似文献   
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