全文获取类型
收费全文 | 2616篇 |
免费 | 363篇 |
国内免费 | 414篇 |
专业分类
测绘学 | 176篇 |
大气科学 | 282篇 |
地球物理 | 461篇 |
地质学 | 1026篇 |
海洋学 | 340篇 |
天文学 | 22篇 |
综合类 | 138篇 |
自然地理 | 948篇 |
出版年
2024年 | 8篇 |
2023年 | 31篇 |
2022年 | 83篇 |
2021年 | 108篇 |
2020年 | 101篇 |
2019年 | 136篇 |
2018年 | 91篇 |
2017年 | 115篇 |
2016年 | 128篇 |
2015年 | 115篇 |
2014年 | 157篇 |
2013年 | 201篇 |
2012年 | 163篇 |
2011年 | 177篇 |
2010年 | 147篇 |
2009年 | 136篇 |
2008年 | 137篇 |
2007年 | 139篇 |
2006年 | 158篇 |
2005年 | 165篇 |
2004年 | 147篇 |
2003年 | 127篇 |
2002年 | 98篇 |
2001年 | 66篇 |
2000年 | 68篇 |
1999年 | 75篇 |
1998年 | 45篇 |
1997年 | 55篇 |
1996年 | 40篇 |
1995年 | 39篇 |
1994年 | 33篇 |
1993年 | 27篇 |
1992年 | 18篇 |
1991年 | 11篇 |
1990年 | 7篇 |
1989年 | 5篇 |
1988年 | 8篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有3393条查询结果,搜索用时 15 毫秒
951.
G217天山公路典型泥石流沟危险性评价研究 总被引:2,自引:0,他引:2
泥石流是新疆天山公路的主要地质灾害之一。在泥石流危险度评价模式的基础上,结合泥石流对公路的作用特点及危害程度,建立了天山公路泥石流危险度评价理论体系。此理论在天山公路泥石流危险度评价中得到了很好的验证。同时,此理论体系对公路泥石流危险度量化指标和分级评判标准,具有极大的使用价值。运用灰色关联法进行天山公路典型泥石流沟危险度计算后发现,其计算值离异程度小,可靠性强,结果较为理想。这些评价参数最终为泥石流病害治理提供了一个很好的指导。 相似文献
952.
青藏铁路工作条件艰苦、工期紧、任务重、质量要求高,利用当代工程测量、GPS、航空摄影测量和计算机应用等领域的研究成果减少野外作业工作量,提高勘测设计成果的再利用率,缩短勘测设计周期势在必行。通过对青藏线格拉段勘测设计中应用勘测设计计算机一体化技术的情况进行总结,并对进一步实施工作提出了建议,旨在对今后工作有一定的参考价值。 相似文献
953.
The spatial and temporal distributions of rain-on-snow (ROS) events across the Canadian Arctic Archipelago (CAA) remain poorly understood owing to their sporadic nature in time and space. This situation motivated the development of remote sensing detection algorithms. This paper uses a large meteorological dataset across the CAA to adapt an existing ROS-detection algorithm developed in a previous study by our group. Results highlight the spatial distribution and evolution of ROS occurrences reported since 1985 at 14 weather stations across the CAA. Results show that >600 ROS events were inventoried since 1985, for which >70% were classified as pure rain (liquid form) and 30% as mixed precipitation (solid/liquid). Of the pure rain events, 75% occurred during spring, 14% during fall, 8% during summer and <1% during winter. Such events can have significant impacts on ungulate grazing conditions through the creation of ice layers, causing serious problems for caribou calf survival, especially during the migration period. This paper introduces an adaptation for larger scale Arctic application of a detection algorithm (sensitivity analysis on the detection threshold) with an error of ~5%. The validation, however, remains limited due to a short study period and limited number of sites. 相似文献
954.
Sustainable river management requires strong participation from technical and nontechnical experts. However, in many cases, the nontechnical element is lacking. This paper explores possibilities for participation that can emerge from a reorientation toward dialog. This reorientation is supported by a sociogeomorphological approach, which encourages recognition of the physical and social coproduction of a fluvial landscape, including a history of colonization and landscape degradation. Recognition of this sociogeomorphic context invited dialog with stakeholders involved in river management, which revealed opportunities for improving relationships in river management. The paper argues that dialog supports building interpersonal relationships as a basis for river management, where relationships could replace “stakes” as a structure for participation. Following reorientation, relationship development and maintenance, through dialog, emerges as a key activity of environmental management. Because dialog happens at the interpersonal scale, a relational approach has potential implications for researchers, practitioners, and stakeholders in many fields of environmental management. 相似文献
955.
Making Space for Failure in Geographic Research 总被引:1,自引:0,他引:1
The idea that field research is an inherently “messy” process has become widely accepted by geographers in recent years. There has thus far been little acknowledgment, however, of the role that failure plays in doing human geography. In this article we push back against this, arguing that failure should be recognized as a central component of what it means to do qualitative geographical field research. This article seeks to use failure proactively and provocatively as a powerful resource to improve research practice and outcomes, reconsidering and giving voice to it as everyday, productive, and necessary to our continual development as researchers and academics. This article argues that there is much value to be found in failure if it is critically examined and shared, and—crucially—if there is a supportive space in which to exchange our experiences of failing in the field. 相似文献
956.
日本旅游地理学的百年传统与演进 总被引:1,自引:0,他引:1
以日本出版的旅游地理学著作和主要地理类学术期刊刊载的旅游地理学相关论文为线索,总结和述评日本旅游地理研究的历史演进与特点。日本旅游地理学经历了近一个世纪的研究历程,学科发展始终与其社会发展及旅游方式的阶段性变迁相应。经历第二次世界大战前的萌芽,旅游大众化时代的学科初创与成长后,已步入了旅游个性化时代的多元发展期,在传承与创新中逐渐形成了自身的研究特色,并确立了独立分支学科的地位。基于区域地理(地志学)视角,偏重微观空间尺度的旅游地实证研究已沉淀成为日本旅游地理学的研究特色。同时,旅游发展形势与学术研究的转向对日本旅游地理学研究视角、研究方法、学际和国际交流方面也提出了新的要求。而比较成熟的旅游地区域研究方法与研究范式、代际传承实践对中国旅游地理学研究具有一定的启示与借鉴意义。 相似文献
957.
958.
TAOWei ZHONGWen-hui HONGYan 《中国地理科学(英文版)》2005,15(2):173-178
1IN T R O D U C T IO N Urban tourismisa broad concept includingallkindsof recreationaalctivitietshattakeplaceincitie.s With the development of post-industrializat,i oncomprehen sive strengthofcitieshas been enhanced, and theimprove- ment of urban environm… 相似文献
959.
The development of any analytical method should have to experience at least four stages: its initial status, growth, mature and declining. However, although the regional input-output analysis has been widely applied for more than forty years, it is still one of the most important approach in regional economic analysis and forecast at present in the world. This is due to the never ended modifications and its great potentials. In this paper, we review the historical development of the regional input-output analysis. 相似文献
960.
胡亚辉 《地球科学与环境学报》1989,(1)
解析测图仪和机助测图系统以及数字地面模型(D.T.M.)数据库,可以按照人们的意图去调用地图信息,提供各种地质、地貌等数据和图件。 我国已有一定数量的进口带有D、T,M。数据库的解析测图仪,但在不规则地区进行随机点的高程内插却殊不多见,本文根据自己的实践,提出一些方法,以便充分发挥仪器作用。 相似文献