全文获取类型
收费全文 | 1644篇 |
免费 | 84篇 |
国内免费 | 8篇 |
专业分类
测绘学 | 60篇 |
大气科学 | 241篇 |
地球物理 | 433篇 |
地质学 | 603篇 |
海洋学 | 49篇 |
天文学 | 241篇 |
综合类 | 1篇 |
自然地理 | 108篇 |
出版年
2021年 | 21篇 |
2020年 | 42篇 |
2019年 | 26篇 |
2018年 | 71篇 |
2017年 | 62篇 |
2016年 | 86篇 |
2015年 | 73篇 |
2014年 | 78篇 |
2013年 | 120篇 |
2012年 | 46篇 |
2011年 | 61篇 |
2010年 | 73篇 |
2009年 | 80篇 |
2008年 | 42篇 |
2007年 | 56篇 |
2006年 | 55篇 |
2005年 | 30篇 |
2004年 | 23篇 |
2003年 | 34篇 |
2002年 | 34篇 |
2001年 | 29篇 |
2000年 | 30篇 |
1999年 | 22篇 |
1998年 | 18篇 |
1997年 | 31篇 |
1996年 | 20篇 |
1995年 | 25篇 |
1994年 | 22篇 |
1993年 | 17篇 |
1991年 | 20篇 |
1990年 | 17篇 |
1988年 | 11篇 |
1987年 | 13篇 |
1984年 | 14篇 |
1983年 | 22篇 |
1982年 | 13篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1978年 | 17篇 |
1977年 | 11篇 |
1976年 | 12篇 |
1975年 | 12篇 |
1974年 | 16篇 |
1973年 | 20篇 |
1972年 | 13篇 |
1971年 | 10篇 |
1970年 | 12篇 |
1969年 | 11篇 |
1968年 | 12篇 |
1965年 | 14篇 |
排序方式: 共有1736条查询结果,搜索用时 343 毫秒
991.
Often, we are faced with questions regarding past events and the answers are hidden in the historical text archives. The growing developments in geographic information retrieval and temporal information retrieval techniques have given new ways to explore digital text archives for spatio‐temporal data. The question is how to retrieve the answers from the text documents. This work contributes to a better understanding of spatio‐temporal information extraction from text documents. Natural language processing techniques were used to develop an information extraction approach using the GATE language processing software. The developed framework uses gazetteer matching, spatio‐temporal relationship extraction and pattern‐based rules to recognize and annotate elements in historical text documents. The extracted spatio‐temporal data is used as input for GIS studies on the time–geography context of the German–Herero resistance war of 1904 in Namibia. Related issues when analyzing the historical data in current GIS are discussed. Particularly problematic are movement data in small scale with poor temporal density and trajectories that are short or connect very distant locations. 相似文献
992.
Combining machine-learning topic models and spatiotemporal analysis of social media data for disaster footprint and damage assessment 总被引:1,自引:0,他引:1
Current disaster management procedures to cope with human and economic losses and to manage a disaster’s aftermath suffer from a number of shortcomings like high temporal lags or limited temporal and spatial resolution. This paper presents an approach to analyze social media posts to assess the footprint of and the damage caused by natural disasters through combining machine-learning techniques (Latent Dirichlet Allocation) for semantic information extraction with spatial and temporal analysis (local spatial autocorrelation) for hot spot detection. Our results demonstrate that earthquake footprints can be reliably and accurately identified in our use case. More, a number of relevant semantic topics can be automatically identified without a priori knowledge, revealing clearly differing temporal and spatial signatures. Furthermore, we are able to generate a damage map that indicates where significant losses have occurred. The validation of our results using statistical measures, complemented by the official earthquake footprint by US Geological Survey and the results of the HAZUS loss model, shows that our approach produces valid and reliable outputs. Thus, our approach may improve current disaster management procedures through generating a new and unseen information layer in near real time. 相似文献
993.
Hofmann Mandy Voigt Thomas Bittner Lucas Gärtner Andreas Zieger Johannes Linnemann Ulf 《International Journal of Earth Sciences》2018,107(3):913-932
International Journal of Earth Sciences - The Saxonian–Bohemian Cretaceous Basin (Elbsandsteingebirge, E Germany and Czech Republic, Elbtal Group) comprises Upper Cretaceous sedimentary rocks... 相似文献
994.
Kunz Barbara E. Manzotti Paola von Niederhäusern Brigitte Engi Martin Darling James R. Giuntoli Francesco Lanari Pierre 《International Journal of Earth Sciences》2018,107(1):203-229
International Journal of Earth Sciences - During the late Palaeozoic, lithospheric thinning in part of the Alpine realm caused high-temperature low-to-medium pressure metamorphism and partial... 相似文献
995.
Linnemann Ulf Pidal Agustín Pieren Hofmann Mandy Drost Kerstin Quesada Cecilio Gerdes Axel Marko Linda Gärtner Andreas Zieger Johannes Ulrich Jens Krause Rita Vickers-Rich Patricia Horak Jana 《International Journal of Earth Sciences》2018,107(3):885-911
International Journal of Earth Sciences - In the Cadomian orogen of the NE Bohemian Massif and of SW Iberia, a post-Gaskiers glacial event dated at c. 565 Ma has been detected. Such... 相似文献
996.
Zentilli Marcos Maksaev Victor Boric Ricardo Wilson Jessica 《International Journal of Earth Sciences》2018,107(3):1097-1126
International Journal of Earth Sciences - The MMH porphyry type copper–molybdenum deposit in northern Chile is the newest mine in the Chuquicamata District, one of largest copper... 相似文献
997.
Diann J. Prosser Jessica L. Nagel Shay Howlin Paul R. Marbán Daniel D. Day R. Michael Erwin 《Estuaries and Coasts》2018,41(1):207-222
In many coastal regions throughout the world, there is increasing pressure to harden shorelines to protect human infrastructures against sea level rise, storm surge, and erosion. This study examines waterbird community integrity in relation to shoreline hardening and land use characteristics at three geospatial scales: (1) the shoreline scale characterized by seven shoreline types: bulkhead, riprap, developed, natural marsh, Phragmites-dominated marsh, sandy beach, and forest; (2) the local subestuary landscape scale including land up to 500 m inland of the shoreline; and (3) the watershed scale >500 m from the shoreline. From 2010 to 2014, we conducted waterbird surveys along the shoreline and open water within 21 subestuaries throughout the Chesapeake Bay during two seasons to encompass post-breeding shorebirds and colonial waterbirds in late summer and migrating and wintering waterfowl in late fall. We employed an Index of Waterbird Community Integrity (IWCI) derived from mean abundance of individual waterbird species and scores of six key species attributes describing each species’ sensitivity to human disturbance, and then used this index to characterize communities in each subestuary and season. IWCI scores ranged from 14.3 to 19.7. Multivariate regression model selection showed that the local shoreline scale had the strongest influence on IWCI scores. At this scale, percent coverage of bulkhead and Phragmites along shorelines were the strongest predictors of IWCI, both with negative relationships. Recursive partitioning revealed that when subestuary shoreline coverage exceeded thresholds of approximately 5% Phragmites or 8% bulkhead, IWCI scores decreased. Our results indicate that development at the shoreline scale has an important effect on waterbird community integrity, and that shoreline hardening and invasive Phragmites each have a negative effect on waterbirds using subestuarine systems. 相似文献
998.
Tobias Diehl John Clinton Nicolas Deichmann Carlo Cauzzi Philipp Kästli Toni Kraft Irene Molinari Maren Böse Clotaire Michel Manuel Hobiger Florian Haslinger Donat Fäh Stefan Wiemer 《Swiss Journal of Geoscience》2018,111(1-2):221-244
This report summarizes the seismicity in Switzerland and surrounding regions in the years 2015 and 2016. In 2015, the Swiss Seismological Service detected and located 735 earthquakes in the region under consideration. With a total of 20 earthquakes of magnitude ML ≥ 2.5, the seismic activity of potentially felt events in 2015 was close to the average of 23 earthquakes over the previous 40 years. Seismic activity was above average in 2016 with 872 located earthquakes of which 31 events had ML ≥ 2.5. The strongest event in the analyzed period was the ML 4.1 Salgesch earthquake, which occurred northeast of Sierre (VS) in October 2016. The event was felt in large parts of Switzerland and had a maximum intensity of V. Derived focal mechanisms and relative hypocenter relocations of aftershocks image a SSE dipping reverse fault, which likely also hosted an ML 3.9 earthquake in 2003. Another remarkable earthquake sequence in the Valais occurred close to Sion with four felt events (ML 2.7–3.2) in 2015/16. We associate this sequence with a system of WNW-ESE striking fault segments north of the Rhône valley. Similarities with a sequence in 2011, which was located about 10 km to the NE, suggest the existence of an en-echelon system of basement faults accommodating dextral slip along the Rhône-Simplon line in this area. Another exceptional earthquake sequence occurred close to Singen (Germany) in November 2016. Relocated hypocenters and focal mechanisms image a SW dipping transtensional fault segment, which is likely associated with a branch of the Hegau-Bodensee Graben. On the western boundary of this graben, micro-earthquakes close to Schlattingen (TG) in 2015/16 are possibly related to a NE dipping branch of the Neuhausen Fault. Other cases of earthquakes felt by the public during 2015/16 include earthquakes in the region of Biel, Vallorcine, Solothurn, and Savognin. 相似文献
999.
1000.