全文获取类型
收费全文 | 495篇 |
免费 | 13篇 |
国内免费 | 1篇 |
专业分类
测绘学 | 6篇 |
大气科学 | 39篇 |
地球物理 | 103篇 |
地质学 | 207篇 |
海洋学 | 62篇 |
天文学 | 43篇 |
自然地理 | 49篇 |
出版年
2023年 | 3篇 |
2022年 | 2篇 |
2021年 | 9篇 |
2020年 | 6篇 |
2019年 | 6篇 |
2018年 | 11篇 |
2017年 | 7篇 |
2016年 | 19篇 |
2015年 | 13篇 |
2014年 | 10篇 |
2013年 | 38篇 |
2012年 | 20篇 |
2011年 | 19篇 |
2010年 | 18篇 |
2009年 | 28篇 |
2008年 | 30篇 |
2007年 | 26篇 |
2006年 | 32篇 |
2005年 | 13篇 |
2004年 | 17篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 13篇 |
2000年 | 11篇 |
1999年 | 5篇 |
1998年 | 15篇 |
1997年 | 4篇 |
1996年 | 8篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 5篇 |
1992年 | 7篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1982年 | 2篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 2篇 |
1969年 | 1篇 |
排序方式: 共有509条查询结果,搜索用时 515 毫秒
1.
Nicolaj K. Larsen Laura B. Levy Astrid Strunk Anne Sofie Sndergaard Jesper Olsen Torben L. Lauridsen 《Boreas: An International Journal of Quaternary Research》2019,48(3):551-562
Local glaciers and ice caps (GICs) comprise only ~5.4% of the total ice volume, but account for ~14–20% of the current ice loss in Greenland. The glacial history of GICs is not well constrained, however, and little is known about how they reacted to Holocene climate changes. Specifically, in North Greenland, there is limited knowledge about past GIC fluctuations and whether they survived the Holocene Thermal Maximum (HTM, ~8 to 5 ka). In this study, we use proglacial lake records to constrain the ice‐marginal fluctuations of three local ice caps in North Greenland including Flade Isblink, the largest ice cap in Greenland. Additionally, we have radiocarbon dated reworked marine molluscs in Little Ice Age (LIA) moraines adjacent to the Flade Isblink, which reveal when the ice cap was smaller than present. We found that outlet glaciers from Flade Isblink retreated inland of their present extent from ~9.4 to 0.2 cal. ka BP. The proglacial lake records, however, demonstrate that the lakes continued to receive glacial meltwater throughout the entire Holocene. This implies that GICs in Finderup Land survived the HTM. Our results are consistent with other observations from North Greenland but differ from locations in southern Greenland where all records show that the local ice caps at low and intermediate elevations disappeared completely during the HTM. We explain the north–south gradient in glacier response as a result of sensitivity to increased temperature and precipitation. While the increased temperatures during the HTM led to a complete melting of GICs in southern Greenland, GICs remained in North Greenland probably because the melting was counterbalanced by increased precipitation due to a reduction in Arctic sea‐ice extent and/or increased poleward moisture transport. 相似文献
2.
Seismic data combined with core analysis of the northwesternmost exploration well on the Norwegian continental margin, well 7316/5-1, has been used to map and discuss the genesis of three well-defined sand ridges. The sand ridges have a NE-SW to N-S orientation and are of Late Pliocene age. The dimensions of the ridges are: height 40 m, length 2–4 km and width 0.5–1 km.In relation to the glaciation models of the Barents Sea, the position of well 7316/5-1, and especially information from a core that penetrated one of the sand ridges, provide important information. The ridges are not, in themselves, diagnostic for grounded glaciers at the margin of the Barents Sea shelf during the Late Pliocene, although the presence of pebbles in a cored section of the ridges may represent ice-dropped material. Whether the possible influx of glaciogenic material is related to local or regional glaciations on the Barents Shelf remains to be evaluated. 相似文献
3.
Sediment successions in coastal cliffs around Mezen Bay, southeastern White Sea, record an unusually detailed history of former glaciations, interstadial marine and fluvial events from the Weichselian. A regional glaciation model for the Weichselian is based on new data from the Mezen Bay area and previously published data from adjacent areas. Following the Mikulinian (Eemian) interglacial a shelf‐centred glaciation in the Kara Sea is reflected in proglacial conditions at 100–90 ka. A local ice‐cap over the Timan ridge existed between 75 and 65 ka. Renewed glaciation in the Kara Sea spread southwestwards around 60 ka only, interrupted by a marine inundation, before it advanced to its maximum position at about 55–50 ka. After a prolonged ice‐free period, the Scandinavian ice‐sheet invaded the area from the west and terminated east of Mezen Bay about 17 ka. The previously published evidence of a large ice‐dammed lake in the central Arkhangelsk region, Lake Komi, finds no support in this study. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
4.
Davide Lenaz Henrik Skogby Francesco Princivalle 《Geochimica et cosmochimica acta》2008,72(2):475-479
Four nearly pure MgAl2O4 spinels, of both natural and synthetic occurrence, have been studied by means of X-ray single crystal diffraction and FTIR spectroscopy in order to detect their potential OH content. Absorption bands that can be assigned to OH incorporated in the spinel structure were only observed in spectra of a non-stoichiometric synthetic sample. The absorption intensity of two bands occurring at 3350 and 3548 cm−1 indicate an OH content of 90 ppm H2O. Based on correlations of OH vibrational frequencies and O-H?O distances, the observed absorption bands correspond to O-H?O distances of 2.77 and 2.99 Å, respectively, which is close to the values obtained by the structure refinements for VIO-Ounsh (2.825 Å) and IVO-O (3.001 Å). This indicates that one probable local position for hydrogen incorporation is the oxygens coordinating a vacant tetrahedral site. The present spectra demonstrate that the detection limit for OH in Fe-free spinels is in the range 10-20 ppm H2O. However, at appreciable Fe2+ levels, the detection of OH bands becomes hampered due to overlap with strong absorption bands caused by electronic d-d transitions in Fe2+ in the tetrahedral position. 相似文献
5.
Controlling geological and hydrogeological processes in an arsenic contaminated aquifer on the Red River flood plain,Vietnam 总被引:1,自引:0,他引:1
6.
7.
8.
9.
Regional variation in maturation of sandeels in the North Sea 总被引:1,自引:0,他引:1
10.
Climatic effects on plankton and productivity on the Faroe Shelf 总被引:1,自引:0,他引:1
Hansen Bogi; Eliasen Solva K.; Gaard Eilif; Larsen Karin M.H. 《ICES Journal of Marine Science》2005,62(7):1224-1232