全文获取类型
收费全文 | 2554篇 |
免费 | 264篇 |
国内免费 | 434篇 |
专业分类
测绘学 | 260篇 |
大气科学 | 99篇 |
地球物理 | 328篇 |
地质学 | 1453篇 |
海洋学 | 291篇 |
天文学 | 11篇 |
综合类 | 190篇 |
自然地理 | 620篇 |
出版年
2024年 | 16篇 |
2023年 | 36篇 |
2022年 | 93篇 |
2021年 | 136篇 |
2020年 | 126篇 |
2019年 | 119篇 |
2018年 | 87篇 |
2017年 | 105篇 |
2016年 | 88篇 |
2015年 | 98篇 |
2014年 | 141篇 |
2013年 | 126篇 |
2012年 | 140篇 |
2011年 | 128篇 |
2010年 | 102篇 |
2009年 | 130篇 |
2008年 | 158篇 |
2007年 | 123篇 |
2006年 | 154篇 |
2005年 | 137篇 |
2004年 | 144篇 |
2003年 | 125篇 |
2002年 | 95篇 |
2001年 | 86篇 |
2000年 | 91篇 |
1999年 | 75篇 |
1998年 | 59篇 |
1997年 | 45篇 |
1996年 | 58篇 |
1995年 | 49篇 |
1994年 | 50篇 |
1993年 | 25篇 |
1992年 | 16篇 |
1991年 | 23篇 |
1990年 | 18篇 |
1989年 | 12篇 |
1988年 | 6篇 |
1987年 | 10篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1982年 | 4篇 |
1981年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有3252条查询结果,搜索用时 15 毫秒
71.
72.
讨论空间应用的一种面向问题的表达方法与实现机制。为解决空间应用的描述问题,在建立时空一体化空间数据模型基础上,定义了对SQL进行扩展的时空复合查询语言,实现了对空间应用问题的非过程化描述;研究复杂空间应用的表达问题,讨论时空复合查询语言的限制,并在语言中引入流机制,通过空间应用问题的组合实现更为复杂的空间应用,并支持空间数据分布式计算;最后给出若干空间应用实例及其面向问题的表达。 相似文献
73.
74.
This paper calls for more analysis of contemporary transnational linguistic movements. Geographers have hitherto focused on linguistic problems within states and paid less attention to issues that arise as languages, notably English, are used internationally across state boundaries. It does this by examining a conflict that arose when forces integrating the supranational European Single Market space came into conflict with a Member State's determination to protect the linguistic 'integrity' of its national territory. This conflict would appear to be a precursor of similar ones to come as languages increasingly compete in a linguistic market within an integrating Europe and a globalizing world. 相似文献
75.
人类世可持续发展背景下的远程耦合框架及其应用 总被引:1,自引:1,他引:1
在全球一体化进程不断加深的背景下,国家与地区之间的联系日益紧密,产生了一系列跨国家、跨地区、多尺度的社会—经济—环境影响,远程耦合(Telecoupling,社会、经济、环境的远距离相互作用)科学概念和综合框架的提出为解决上述问题提供了新方法和新途径。为更好促进远程耦合综合框架的正确使用和规范推广,本文系统解析了远程耦合综合框架,厘清各组成部分的定义和功能,梳理了框架的应用现状;通过对3个中国典型案例的阐释,展示了远程耦合综合框架的使用方法、结果分析及由此得出的科学意义和政策价值;最后描述了远程耦合综合框架使用中需要重点关注的问题,并对其应用前景进行了展望。远程耦合综合框架的推广应用有助于以跨国家、跨地区、多尺度的视角,重新审视多个人类与自然耦合系统的相互作用,揭示隐藏的远距离地理空间作用的科学价值,服务于有关政策的制定和实施,促进全球社会、经济、环境的可持续发展。 相似文献
76.
MATTHEW C. LaFEVOR 《Geographical review》2012,102(2):202-224
The discovery, extraction, and monopolistic control of key natural resources was a priority of New Spain's colonial administration. Managing the region's abundant resources, however, often proved difficult for the Spanish Crown. Human and environmental challenges impeded protoindustrial growth and development, and monopolistic control of resources often met resistance. In this article I examine these processes in the context of New Spain's little‐known monopoly on sulphur—a yellow, powdery mineral the Crown jealously guarded as its own. Sulphur was critical for gunpowder and explosives production, yet the Crown often failed to produce enough of it to meet the growing demand by its military and the silver blast‐mining industry. Colonial documents reveal administrators’ attempts to improve sulphur production through reform measures, which included advising sulphur miners on how to discover sulphur deposits and, eventually, how to develop their mines. Efforts to improve sulphur production were moderately successful, although the process was messy and inefficient. 相似文献
77.
Head/Tail Breaks: A New Classification Scheme for Data with a Heavy-Tailed Distribution 总被引:2,自引:0,他引:2
Bin Jiang 《The Professional geographer》2013,65(3):482-494
This article introduces a new classification scheme—head/tail breaks—to find groupings or hierarchy for data with a heavy-tailed distribution. The heavy-tailed distributions are heavily right skewed, with a minority of large values in the head and a majority of small values in the tail, commonly characterized by a power law, a lognormal, or an exponential function. For example, a country's population is often distributed in such a heavy-tailed manner, with a minority of people (e.g., 20 percent) in the countryside and the vast majority (e.g., 80 percent) in urban areas. This new classification scheme partitions all of the data values around the mean into two parts and continues the process iteratively for the values (above the mean) in the head until the head part values are no longer heavy-tailed distributed. Thus, the number of classes and the class intervals are both naturally determined. I therefore claim that the new classification scheme is more natural than the natural breaks in finding the groupings or hierarchy for data with a heavy-tailed distribution. I demonstrate the advantages of the head/tail breaks method over Jenks's natural breaks in capturing the underlying hierarchy of the data. 相似文献
78.
Sara Beth Keough 《Urban geography》2013,34(8):1169-1196
Between 2000 and 2010, the population of the city of Fort McMurray, Alberta increased by 80%, mainly due to the expansion of oil extraction projects and subsidiary industries. Population growth of this magnitude has significant consequences for city planning. While Fort McMurray struggles to keep up with enormous numbers of in-migrants, the cost of living in the city has skyrocketed. Using interviews with city planners and field experience in the city, in this paper I examine the current challenges faced by urban planners in Fort McMurray against the backdrop of global economic decision-making, corporate influence, and commodity dynamics. While the recession of 2008 gave city planners some breathing room, they still struggle with gathering accurate census information and predicting population growth, providing affordable housing, and balancing short-range planning with their long-term goals. Attempts by city planners to address these challenges could provide a contemporary model for urban planning in rapidly growing, resource-dependent communities. 相似文献
79.
《The Professional geographer》2013,65(4):428-436
Recognized for years as a major environmental disruption, El Niño generated intense public interest in 1982–1983. During its last occurrence, this phenomenon, which develops in the tropical Pacific and usually affects rimlands of the Pacific basin, exceeded its boundaries and its effects were transmitted to continental North America, Europe, Africa and East Asia. Notwithstanding its vast areal extent, the interest of geographers in El Niño events, past and recent, has been comparatively less than that demonstrated by natural scientists and ecologists: little has been accomplished to place these climatic-ecological crises within global perspective. Lessons from El Niño include the acknowledgement of new concepts of climatic transitivity, ocean dynamics and energy exchanges that must find a place within the conceptual wealth of geography if this science intends to keep up with the rapid progress of other geosciences. 相似文献
80.
历史时期中国重大自然灾害时空分异特征(英文) 总被引:4,自引:0,他引:4
Based on historical documents and records this paper analyzes the characteristics of frequency and distribution of major disasters that took place in the history of China. The findings show that occurrences of different types of disasters varied and spatial pattern at provincial level are significantly different as well. The results also indicate that there is a strong relationship between type of disasters and spatial distribution and that the spatial pattern of losses was not the same as that of the frequency. The reasons are: (1) the hazard-formative environments which, to a large extent, determine the spatial pattern of the disasters are significantly different; (2) the losses caused by natural disasters were closely related to the concentration of economy and population. Number of deaths was usually large in areas where agriculture, culture and business were relatively developed. The spatial pattern of disaster losses is an evitable result of uneven economic development in the history of China. 相似文献