全文获取类型
| 收费全文 | 166篇 |
| 免费 | 18篇 |
| 国内免费 | 13篇 |
专业分类
| 测绘学 | 25篇 |
| 大气科学 | 15篇 |
| 地球物理 | 46篇 |
| 地质学 | 72篇 |
| 海洋学 | 9篇 |
| 天文学 | 19篇 |
| 综合类 | 6篇 |
| 自然地理 | 5篇 |
出版年
| 2022年 | 4篇 |
| 2021年 | 3篇 |
| 2020年 | 8篇 |
| 2019年 | 4篇 |
| 2018年 | 4篇 |
| 2017年 | 15篇 |
| 2016年 | 9篇 |
| 2015年 | 10篇 |
| 2014年 | 8篇 |
| 2013年 | 8篇 |
| 2012年 | 11篇 |
| 2011年 | 16篇 |
| 2010年 | 9篇 |
| 2009年 | 10篇 |
| 2008年 | 6篇 |
| 2007年 | 13篇 |
| 2006年 | 10篇 |
| 2005年 | 5篇 |
| 2004年 | 2篇 |
| 2003年 | 7篇 |
| 2002年 | 4篇 |
| 2001年 | 12篇 |
| 2000年 | 3篇 |
| 1999年 | 2篇 |
| 1998年 | 2篇 |
| 1997年 | 1篇 |
| 1995年 | 2篇 |
| 1994年 | 3篇 |
| 1993年 | 1篇 |
| 1992年 | 1篇 |
| 1990年 | 2篇 |
| 1988年 | 1篇 |
| 1976年 | 1篇 |
排序方式： 共有197条查询结果，搜索用时 15 毫秒
101.
102.
As a new remote sensing technology, the global navigation satellite system (GNSS) reflection signals can be used to collect the information of ocean surface wind, surface roughness and sea surface height. Ocean altimetry based on GNSS reflection technique is of low cost and it is easy to obtain large amounts of data thanks to the global navigation satellite constellation. We can estimate the sea surface height as well as the position of the specular reflection point. This paper focuses on the study of the algorithm to determine the specular reflection point and altimetry equations to estimate the sea surface height over the reflection region. We derive the error equation of sea surface height based on the error propagation theory. Effects of the Doppler shift and the size of the glistening zone on the altimetry are discussed and analyzed at the same time. Finally, we calculate the sea surface height based on the simulated GNSS data within the whole day and verify the sea surface height errors according to the satellite elevation angles. The results show that the sea surface height can reach the precision of 6 cm for elevation angles of 55° to 90°, and the theoretical error and the calculated error are in good agreement. 相似文献
103.
The (U–Th)/He dating method was applied to fluorite of the La Azul fluorspar deposit, Taxco mining district, Mexico. Ages of ten U-rich (4–94 g/g) samples range from 30 to 33 Ma (mean 32±2 Ma, 1). This age range is interpreted as the time of primary fluorite precipitation and is close to the K/Ar age of sericite from a small fluorspar deposit (Los Tréboles) in the same area, and the K/Ar age of the nearby volcanic succession, which is thought to be the main source of fluorine in both deposits. This age is also in concordance with the very few published ages of epithermal deposits in southern Mexico. The dating of fluorite by other methods, particularly for young samples, is a difficult task. We believe that the (U–Th)/He method, which has been applied before to thermochronological studies of apatite, zircon, titanite and hematite, can be used as a tool for direct dating of fluorite with microgram per gram levels of uranium and thorium.Editorial handling: B. Lehmann 相似文献
104.
TANG Liangjie JIA Chengzao PI Xuejun CHEN Suping WANG Zhiyu XIE Huiwen . Key Laboratory for Hydrocarbon Accumulation of Education Ministry Beijing China . Basin & Reservoir Research Center University of Petroleum Beijing China . PetroChina Company Limited Beijing China . Tarim Oilfield Company PetroChina Company Ltd. Kurle China . Department of Geology University of Petroleum Beijing China 《中国科学D辑(英文版)》2004,47(10):886-895
It is indicated that the salt beds have a bearingupon the hydrocarbon accumulation more than 80%discovered oil-gas reserves of the world[1]. The saltbeds can change the occurrence of overlying horizons,forming various structural traps[2,3]. The salt bed itselfis the most effective caprocks. The deposits ofhigh-saliniferous environment may have favorablepetroleum-generating conditions[4]. The salt beds withlow specific thermal conductivity may result in highergeothermal gradient of sub-salt str… 相似文献
105.
GPS Solutions - Global and local positioning systems (LPS) make use of nonlinear equations systems to calculate coordinates of unknown points. There exist several methods, such as Sturmfels’... 相似文献
106.
Graczyk Dariusz Pińskwar Iwona Kundzewicz Zbigniew W. Hov Øystein Førland Eirik J. Szwed Małgorzata Choryński Adam 《Theoretical and Applied Climatology》2017,129(1-2):459-471
Theoretical and Applied Climatology - On the basis of temperature observations at 60 meteorological stations in Poland, changes in the indices associated with the presence of extremely high air... 相似文献
107.
108.
109.
Zbigniew W. Kundzewicz Mikołaj Piniewski Abdelkader Mezghani Tomasz Okruszko Iwona Pińskwar Ignacy Kardel Øystein Hov Mateusz Szcześniak Małgorzata Szwed Rasmus E. Benestad Paweł Marcinkowski Dariusz Graczyk Andreas Dobler Eirik J. Førland Joanna O’Keefe Adam Choryński Kajsa M. Parding Jan Erik Haugen 《Acta Geophysica》2018,66(6):1509-1523
The present paper offers a brief assessment of climate change and associated impact in Poland, based on selected results of the Polish–Norwegian CHASE-PL project. Impacts are examined in selected sectors, such as water resources, natural hazard risk reduction, environment, agriculture and health. Results of change detection in long time series of observed climate and climate impact variables in Poland are presented. Also, projections of climate variability and change are provided for time horizons of 2021–2050 and 2071–2100 for two emission scenarios, RCP4.5 and RCP8.5 in comparison with control period, 1971–2000. Based on climate projections, examination of future impacts on sectors is also carried out. Selected uncertainty issues relevant to observations, understanding and projections are tackled as well. 相似文献
110.
Effects of transport and insertion of radio frequency identification (RFID) transponders on resistance and shape of natural and synthetic pebbles: applications for riverine and coastal bedload tracking 
下载免费PDF全文
下载免费PDF全文 RFID transponders, especially low‐frequency Passive Integrated Transponders (PIT tags), are now commonly used for assessing bedload mobility in gravel‐bed rivers. Early studies reported high PIT tag recovery rates in small streams, but recovery rates in larger systems remain low. Explanatory factors for low recovery rates have been identified, but only antenna detection ranges and clustering effects have been precisely characterized. Burial below detection limit and dispersion beyond the study site have been indirectly estimated, and PIT tag destruction is assumed to be negligible. In this study, we quantified the resistance of natural limestone pebbles equipped with PIT tags as related to tag insertion methods and distance travelled in an annular flume. We then compared the performance of these natural pebbles with synthetic pebbles made of polyurethane resin and corundum. Creation of synthetic pebbles makes it possible to test bigger transponders with a greater detection range and no clustering effects, bypassing the existing constraints of RFID tracking. We found that breakage of limestone particles leading to PIT tag destruction is far too rare to explain low recovery rates in situ. Further, breakage is more affected by initial pebble characteristics than by PIT tag insertion method. Synthetic pebbles are more sensitive to attrition, but less likely to break. Natural and synthetic pebbles show slight differences in mobility patterns, transport distances, and abrasion resistances. One of the two synthetic pebbles travelled faster than the other three indicating that mobility is not only related to density but also potentially to shape. To address clustering and detection range issues, we equipped synthetic pebbles with AIT‐tags (Active Integrated Transponders). These were tested for integrity and transponder endurance and show great promise for future applications. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献