全文获取类型
收费全文 | 1297篇 |
免费 | 60篇 |
国内免费 | 23篇 |
专业分类
测绘学 | 30篇 |
大气科学 | 144篇 |
地球物理 | 324篇 |
地质学 | 418篇 |
海洋学 | 122篇 |
天文学 | 217篇 |
综合类 | 9篇 |
自然地理 | 116篇 |
出版年
2024年 | 4篇 |
2023年 | 8篇 |
2022年 | 9篇 |
2021年 | 21篇 |
2020年 | 27篇 |
2019年 | 33篇 |
2018年 | 37篇 |
2017年 | 52篇 |
2016年 | 39篇 |
2015年 | 38篇 |
2014年 | 56篇 |
2013年 | 82篇 |
2012年 | 40篇 |
2011年 | 74篇 |
2010年 | 62篇 |
2009年 | 89篇 |
2008年 | 78篇 |
2007年 | 68篇 |
2006年 | 67篇 |
2005年 | 47篇 |
2004年 | 51篇 |
2003年 | 39篇 |
2002年 | 29篇 |
2001年 | 25篇 |
2000年 | 28篇 |
1999年 | 20篇 |
1998年 | 18篇 |
1997年 | 23篇 |
1996年 | 20篇 |
1995年 | 21篇 |
1994年 | 14篇 |
1993年 | 11篇 |
1992年 | 9篇 |
1991年 | 10篇 |
1990年 | 11篇 |
1989年 | 7篇 |
1988年 | 7篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 9篇 |
1984年 | 6篇 |
1983年 | 11篇 |
1982年 | 5篇 |
1981年 | 8篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1892年 | 6篇 |
排序方式: 共有1380条查询结果,搜索用时 15 毫秒
201.
Kevin Romig 《The Journal of geography》2017,116(4):180-184
Significant changes in textbook publishing are at college instructors' door. Textbook representatives are directed to mesmerize potential clients with eye-catching displays and statements about digital literacy of the next generation of college students. Based on a one-year pilot study, in 2014–2015, of an electronic textbook, this commentary shares real experiences with the digital tools, contextualizes the shift in textbook publishing and research on student outcomes, and provides insight in navigating through the Brave New World of digital texts and adaptive learning tools. 相似文献
202.
Kevin Keenan 《Urban geography》2017,38(6):927-950
This paper expands the values-vulnerability nexus for studying urban vulnerability to terrorism. Gender is among the most salient social structures affecting a person’s interpretation of risk, and urban geographers have demonstrated that gender also deeply affects the experience of urban life. However, the values that shape urban vulnerability to terrorism have been conceptualized more broadly, usually focusing on the underpinning economic organization of cities that terrorists exploit rather than on concepts such as gender. As a result, the role of gender in understanding societal responses to terrorism—specifically risk perception and preparedness—is underdeveloped, including in the 2008 US National Survey of Disaster and Preparedness, which sought to understand Americans’ responses to terrorism. This paper outlines a gender values–vulnerability nexus for studying terrorism. Using interview data from Boston, Massachusetts conducted before and after the 15 April 2013 Boston Marathon attacks, I demonstrate that gender deeply affected how Bostonians learned about and responded to terrorism. The gender values–vulnerability nexus explores the role of gendered political, social, economic, and geographical dimensions in urban vulnerability to terrorism. The role of gender has the potential to substantially increase vulnerability for urban populations, particularly given gender-similar social networks and urban contexts that continue to yield different experiences for men and women. The implications of these findings may signal challenges for urban emergency managers, public safety officials, and ordinary people in American cities. 相似文献
203.
Financialization and urban politics: expanding the optic 总被引:1,自引:1,他引:0
Kevin Ward 《Urban geography》2017,38(1):1-4
204.
Fracturing and fluid‐flow during post‐rift subsidence in carbonates of the Jandaíra Formation,Potiguar Basin,NE Brazil
下载免费PDF全文
![点击此处可从《Basin Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Giovanni Bertotti Kevin Bisdom Brigit Oskam Hubert B. Vonhof Francisco H. R. Bezerra Caroline L. Cazarin 《Basin Research》2017,29(6):836-853
Pervasive fracture networks are common in many reservoir‐scale carbonate bodies even in the absence of large deformation and exert a major impact on their mechanical and flow behaviour. The Upper Cretaceous Jandaíra Formation is a few hundred meters thick succession of shallow water carbonates deposited during the early post‐rift stage of the Potiguar rift (NE Brazil). The Jandaíra Formation in the present onshore domain experienced <1.5 km thermal subsidence and, following Tertiary exhumation, forms outcrops over an area of >1000 km2. The carbonates have a gentle, <5?, dip to the NE and are affected by few regional, low displacement faults or folds. Despite their simple tectonic history, carbonates display ubiquitous open fractures, sub‐vertical veins, and sub‐vertical as well as sub‐horizontal stylolites. Combining structural analysis, drone imaging, isotope studies and mathematical modelling, we reconstruct the fracturing history of the Jandaíra Formation during and following subsidence and analyse the impact fractures had on coeval fluid flow. We find that Jandaíra carbonates, fully cemented after early diagenesis, experienced negligible deformation during the first few hundreds of meters of subsidence but were pervasively fractured when they reached depths >400–500 m. Deformation was accommodated by a dense network of sub‐vertical mode I and hybrid fractures associated with sub‐vertical stylolites developed in a stress field characterised by a sub‐horizontal σ1 and sub‐vertical σ2. The development of a network of hybrid fractures, rarely reported in the literature, activated the circulation of waters charged in the mountainous region, flowing along the porous Açu sandstone underlying the Jandaíra carbonates and rising to the surface through the fractured carbonates. With persisting subsidence, carbonates reached depths of 800–900 m entering a depth interval characterised by a sub‐vertical σ1. At this stage, sub‐horizontal stylolites developed liberating calcite which sealed the sub‐vertical open fractures transforming them in veins and preventing further flow. During Tertiary exhumation, several of the pre‐existing veins and stylolites opened and became longer, and new fractures were created typically with the same directions of the older features. The simplicity of our model suggests that most rocks in passive margin settings might have followed a similar evolution and thus display similar structures. 相似文献
205.
206.
207.
208.
209.
Julia CURIO Yongren CHEN Reinhard SCHIEMANN ANDrew G.TURNER Kai Chi WONG Kevin HODGES Yueqing LI 《大气科学进展》2018,35(8):965-980
Tibetan Plateau vortices(TPVs) are mesoscale cyclones originating over the Tibetan Plateau(TP) during the extended summer season(April–September).Most TPVs stay on the TP,but a small number can move off the TP to the east.TPVs are known to be one of the main precipitation-bearing systems on the TP and moving-off TPVs have been associated with heavy precipitation and flooding downstream of the TP(e.g.,in Sichuan province or over the Yangtze River Valley).Identifying and tracking TPVs is difficult because of their comparatively small horizontal extent(400–800 km) and the limited availability of soundings over the TP,which in turn constitutes a challenge for short-term predictions of TPV-related impacts and for the climatological study of TPVs.In this study,(i) manual tracking(MT) results using radiosonde data from a network over and downstream of the TP are compared with(ii) results obtained by an automated tracking(AT) algorithm applied to ERA-Interim data.Ten MT-TPV cases are selected based on method(i) and matched to and compared with the corresponding AT-TPVs identified with method(ii).Conversely,ten AT-TPVs are selected and compared with the corresponding MT-TPVs.In general,the comparison shows good results in cases where the underlying data are in good agreement,but considerable differences are also seen in some cases and explained in terms of differences in the tracking methods,data availability/coverage and disagreement between sounding and ERA-Interim data.Recommendations are given for future efforts in TPV detection and tracking,including in an operational weather forecasting context. 相似文献
210.