全文获取类型
收费全文 | 192篇 |
免费 | 3篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 19篇 |
大气科学 | 22篇 |
地球物理 | 49篇 |
地质学 | 54篇 |
海洋学 | 24篇 |
天文学 | 6篇 |
综合类 | 1篇 |
自然地理 | 22篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 3篇 |
2019年 | 3篇 |
2018年 | 1篇 |
2016年 | 2篇 |
2015年 | 8篇 |
2014年 | 1篇 |
2013年 | 19篇 |
2012年 | 9篇 |
2011年 | 15篇 |
2010年 | 10篇 |
2009年 | 11篇 |
2008年 | 11篇 |
2007年 | 12篇 |
2006年 | 5篇 |
2005年 | 4篇 |
2004年 | 8篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 6篇 |
1977年 | 4篇 |
1974年 | 2篇 |
1952年 | 1篇 |
排序方式: 共有197条查询结果,搜索用时 15 毫秒
91.
92.
Brian Mills Dan Unrau Carla Parkinson Brenda Jones Jennifer Yessis Kelsey Spring Laurel Pentelow 《Natural Hazards》2008,47(2):157-183
This article summarizes research completed to assess the risk of lightning-related injuries and fatalities in Canada. Although
lightning mortality has declined significantly over the past century, it remains a common meteorological hazard that regularly
kills and injures. Based on an analysis of media reports, vital statistics, hospital admission and emergency room visit records,
and fire loss data, the authors estimate that on average about 9–10 lightning-related deaths and 92–164 injuries occur each
year in Canada. The distribution of casualties reflects current provincial population and cloud-to-ground lightning densities.
Consistent with similar studies in other developed nations, most lightning-related fatalities and injuries in Canada occur
during the June-August summer season, coincident with peak lightning, and during the Thursday-Saturday period, most likely
related to higher rates of participation in outdoor activities. The majority of victims are male, less than 46 years old,
and engaged in outdoor recreational activities when injured or killed in a lightning incident. Media reports used in the study
were found to underestimate both lightning mortality (36%) and morbidity (20–600%).
相似文献
Brian MillsEmail: |
93.
A monitoring system that uses applied geomatics techniques, including videogrammetry and terrestrial laser scanning, has been developed in order to investigate the dynamic behaviour of as-built membrane roof structures. To accommodate the problems involved in measuring such roof structures, examples of which include uniform surface texture and unreachable height, the system adopts a non-contact targeting methodology to substitute for traditional control techniques. In-house software was developed for processing the acquired video imagery in order to produce a sequential surface model of the membrane. This paper firstly reports on experiments conducted to demonstrate that the monitoring system was capable of measuring representative test structures with a precision of better than ±1 mm. To prove the feasibility and transferability of the system, videogrammetric monitoring campaigns were subsequently performed at a real-world test site where two different types of membrane structure were observed. The sequential 3D surface models that were generated allowed the displacement of the membrane surfaces to be investigated over a period, during which the range of the movement reached over 20 mm. The information acquired from the system is proving to be of great value to structural engineers involved in research and development of such membrane structures. 相似文献
94.
95.
96.
K. Mills P. Gell J. Gergis P. J. Baker C. M. Finlayson P. P. Hesse 《Australian Journal of Earth Sciences》2013,60(5):561-571
The management of the water resources of the Murray-Darling Basin (MDB) has long been contested, and the effects of the recent Millennium drought and subsequent flooding events have generated acute contests over the appropriate allocation of water supplies to agricultural, domestic and environmental uses. This water-availability crisis has driven demand for improved knowledge of climate change trends, cycles of variability, the range of historical climates experienced by natural systems and the ecological health of the system relative to a past benchmark. A considerable volume of research on the past climates of southeastern Australia has been produced over recent decades, but much of this work has focused on longer geological time-scales, and is of low temporal resolution. Less evidence has been generated of recent climate change at the level of resolution that accesses the cycles of change relevant to management. Intra-decadal and near-annual resolution (high-resolution) records do exist and provide evidence of climate change and variability, and of human impact on systems, relevant to natural-resource management. There exist now many research groups using a range of proxy indicators of climate that will rapidly escalate our knowledge of management-relevant, climate change and variability. This review assembles available climate and catchment change research within, and in the vicinity of, the MDB and portrays the research activities that are responding to the knowledge need. It also discusses how paleoclimate scientists may better integrate their pursuits into the resource-management realm to enhance the utility of the science, the effectiveness of the management measures and the outcomes for the end users. 相似文献
97.
Colin Beier James Mills Patrick McHale Charles T. Driscoll Myron J. Mitchell 《水文研究》2021,35(8):e14328
Located in the Adirondack Mountains of northern New York State, Huntington Wildlife Forest (HWF) is a 6000-ha research and education facility operated by SUNY ESF (State University of New York, College of Environmental Science and Forestry) with continuous long-term monitoring (LTM) programs spanning over six decades. One of the ‘cradles’ of acid rain research in North America, HWF was in the first cohort of National Atmospheric Deposition Program (NADP) sites beginning in 1978. HWF is currently the only location (NY-20) in New York with the full suite of NADP programs in operation, including atmospheric mercury speciation (AMNet), along with EPA CASTNET. Nearby to NY-20 at HWF, Arbutus Lake and its forested watershed have been the focus of intensive LTM since installation of v-notch weirs at the lake outlet and inlet in 1991 and 1994, respectively. Discharge at these locations has been monitored continuously at 15-min intervals since 1999. Lake outlet water chemistry samples were collected starting in 1983. Weekly sampling of water chemistry at both weirs began in 1995 and was expanded to include two headwater streams and groundwater wells in 2007. More recently, LTM programs at HWF have been augmented by participation in the PhenoCam Network since 2008, collection of high-resolution LiDAR in 2009, and installation of a precision NY Mesonet weather station in 2016. In 2018, we installed sensor networks that continuously monitor soil microclimate and snow depth. Lastly, we improved data access via a new website ( www.adk-ltm.org ) where users can create custom queries and visualize outputs. 相似文献
98.
Mountain regions throughout the world face intense development pressures associated with recreational and tourism uses. Despite these pressures, much of the research on bio‐geophysical impacts of humans in mountain regions has focused on the effects of natural resource extraction. This paper describes findings from the first 3 years of a study examining high elevation watershed processes in a region undergoing alpine resort development. Our study is designed as a paired‐watershed experiment. The Ranch Brook watershed (9·6 km2) is a relatively pristine, forested watershed and serves as the undeveloped ‘control’ basin. West Branch (11·7 km2) encompasses an existing alpine ski resort, with approximately 17% of the basin occupied by ski trails and impervious surfaces, and an additional 7% slated for clearing and development. Here, we report results for water years 2001–2003 of streamflow and water quality dynamics for these watersheds. Precipitation increases significantly with elevation in the watersheds, and winter precipitation represents 36–46% of annual precipitation. Artificial snowmaking from water within West Branch watershed currently augments annual precipitation by only 3–4%. Water yield in the developed basin exceeded that in the control by 18–36%. Suspended sediment yield was more than two and a half times greater and fluxes of all major solutes were higher in the developed basin. Our study is the first to document the effects of existing ski area development on hydrology and water quality in the northeastern US and will serve as an important baseline for evaluating the effects of planned resort expansion activities in this area. Published in 2007 by John Wiley & Sons, Ltd. 相似文献
99.
Plumboselite, ideally Pb3O2(SeO3), is a new selenite (IMA2010?C028) from the Tsumeb mine, Namibia. It occurs as fibres on clausthalite and is also associated with smithsonite, mimetite and vaterite. Plumboselite occurs in subparallel to divergent clusters of thin, flattened, colourless fibres up to 0.3?mm in length, but not exceeding 5???m in width and 2???m in thickness. The fibres are elongated parallel to [001] and flattened on {010}, with {010} the only form observed. The crystals have a dull to adamantine lustre and a white streak. The tenacity is brittle and the Mohs hardness is estimated to be between 2 and 3. Plumboselite crystals are optically biaxial with parallel extinction and are length fast in all orientations. The Gladstone-Dale relationship predicts n av?=?2.115. The high indices of refraction and small crystal size prevented the determination of other optical properties. The calculated density is 7.814?g/cm3. The empirical formula (based on 5 O atoms) is Pb2.92Ca0.01Se1.03O5. Plumboselite is orthorhombic, space group Cmc21, a?=?10.5384(11), b?=?10.7452(13), c?=?5.7577(7) ?, V?=?651.98(12) ?3 and Z?=?4. The five strongest lines in the powder X-ray diffraction pattern are [d obs in ?/(I)/hkl]: 3.155/(100)/221; 1.956/(26)/042,402; 2.886/(22)/311,002; 1.713/(21)/223; 2.691/(17)/040. The crystal structure was solved from single-crystal X-ray diffraction data and refined to R 1?=?0.0371 on the basis of 200 unique reflections with F o?>?4??F. The structure is based on double [O2Pb3] chains of edge-sharing oxo-centered [OPb4] tetrahedra along c, between which are sited SeO3 triangles. The two independent Pb2+ atoms and the Se4+ atom have sterochemically active lone electron pairs. 相似文献
100.