全文获取类型
收费全文 | 203篇 |
免费 | 6篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 14篇 |
地球物理 | 57篇 |
地质学 | 83篇 |
海洋学 | 20篇 |
天文学 | 13篇 |
综合类 | 1篇 |
自然地理 | 14篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 7篇 |
2019年 | 4篇 |
2018年 | 10篇 |
2017年 | 5篇 |
2016年 | 9篇 |
2015年 | 12篇 |
2014年 | 8篇 |
2013年 | 9篇 |
2012年 | 8篇 |
2011年 | 12篇 |
2010年 | 14篇 |
2009年 | 16篇 |
2008年 | 14篇 |
2007年 | 7篇 |
2006年 | 10篇 |
2005年 | 6篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有211条查询结果,搜索用时 15 毫秒
71.
In the upwelling area along the Namibian coast of SW-Africa sulphur discolorations were investigated to study the impact of hydrogen sulphide on the ecosystem using satellite imagery. The formation of colloidal sulphur in the upper water layer results from the oxidation of hydrogen sulphide. The occurrence of sulphur plumes as well as their temporal and spatial development was investigated in relation to the driving meteorological and oceanographic conditions. Because of the sporadic occurrence of sulphur events and the limited number of ship-borne investigations in that area remote sensing of ocean colour is the only method to follow these phenomena continuously and synoptically. In the past the sulphur plumes were studied by true colour images derived from ocean colour satellite data like sea-viewing wide field of view sensor or moderate resolution imaging spectroradiometer and identified by their typical milky turquoise discoloration. 相似文献
72.
We characterized the abundance and species composition of sessile and mobile epifaunal assemblages in the York River, a tributary
of the Chesapeake Bay, U.S., during the summer hypoxia seasons in 1996 and 1997. We collected communities on artificial substrates
in two areas of the river that have historically experienced different exposure to hypoxia. Despite frequent hypoxic stress,
epifauna formed dense communities in both areas. Dominant species comprised a range of phyla and included the polychaetesPolydora cornuta andSabellaria vulgaris, the bryozoansMembranipora tenuis andConopeum tenuissimum, the tunicateMolgula manhattensis, the barnacleBalanus improvisus, the anemoneDiadumene leucolena, and the hydroidsEctopleura dumortieri andObelia bicuspidata. Common mobile species included the nudibranchsCratena kaoruae andDoridella obscura, the amphipodsMelita nitida andParacaprella tenuis, the polychaeteNereis succinea, and the flatwormStylochus ellipticus. We found few differences in species composition between the two areas, even though one area usually experienced lower oxygen
concentrations during hypoxic events, suggesting that hypoxia does not exclude any epifaunal species, in the York River. We
did find differences between the two study areas in percent cover and abundance of some species. While tunicates, hydroids,
and anemones were equally abundant in both areas during both study years, bryozoans and the polychaeteS. vulgaris were more abundant in the area with gereally higher oxygen, suggesting that they may be less tolerant of hypoxic stress.
The polychaeteP. cornuta was more abundant in the area that usually had lower oxygen. These results suggest that many epifaunal species have high
hypoxia tolerance, and most epifaunal species found in the lowr York River are able to survive in hypoxic areas. Epifaunal
species are not necessarily more susceptible to hypoxia than infaunal species in the York River. Epifaunal communities in
areas with brief hypoxic episodes and moderate hypoxia (0.5–2 mg O2 I−1) can persist with little change in species composition, and with few changes in abundance, as oxygen concentrations fall. 相似文献
73.
74.
75.
Differently colored natural Brazilian andalusite crystals heat-treated under reducing and oxidizing conditions were analyzed
by optical spectroscopy. The intensity of a broad intense band at around 20,500 cm−1 in the optical absorption spectra of all color zones of the sample is proportional to the product of Ti- and Fe-concentrations
and herewith proves its attribution to electronic Fe2+/Ti4+ IVCT transition. The band is strictly E||c-polarized, causing an intense red coloration of the samples in this polarization. The polarization of the Fe2+/Ti4+ IVCT band in andalusite, E||c, shows that the electronic charge-transfer process takes place in Al–O octahedral groups that share edges with neighbors
on either side, forming chains parallel to the c-axis of the andalusite structure. Under thermal treatments in air, the first noticeable change is some intensification of
the band at 800°C. However, at higher temperatures its intensity decreases until it vanishes at 1,000°C in lightly colored
zones and 1,100°C in darkly colored ones. Under annealing in reducing conditions at 700 and 800°C, the band also slightly
increases and maintains its intensity at treatments at higher temperatures up to 1,000°C. These results demonstrate that weakening
and disappearance of the Fe2+/Ti4+ IVCT band in spectra of andalusite under annealing in air is caused by oxidization of Fe2+ to Fe3+ in IVCT Fe2+/Ti4+-pairs. Some intensification of the band at 800°C is, most probably, due to thermally induced diffusion of Fe2+ and Ti4+ in the structure that leads to aggregation of “isolated” Ti4+ and Fe2+ ions into Fe2+–Ti4+-pairs. At higher temperatures, the competing process of Fe2+ → Fe3+ oxidation overcomes such “coupling” and the band continues to decrease. The different thermal stability of the band in lightly
and darkly colored zones of the samples evidence some self-stabilization over an interaction of Fe2+/Ti4+-pairs involved in IVCT process. 相似文献
76.
Martin Danišík Jaroslav Kadlec Christoph Glotzbach Anett Weisheit István Dunkl Milan Kohút Noreen J. Evans Monika Orvošová Brad J. McDonald 《Swiss Journal of Geoscience》2011,104(2):285-298
A combination of four thermochronometers [zircon fission track (ZFT), zircon (U–Th)/He (ZHe), apatite fission track (AFT)
and apatite (U–Th–[Sm])/He (AHe) dating methods] applied to a valley to ridge transect is used to resolve the issues of metamorphic,
exhumation and topographic evolution of the Nízke Tatry Mts. in the Western Carpathians. The ZFT ages of 132.1 ± 8.3, 155.1 ± 12.9,
146.8 ± 8.6 and 144.9 ± 11.0 Ma show that Variscan crystalline basement of the Nízke Tatry Mts. was heated to temperatures
>210°C during the Mesozoic and experienced a low-grade Alpine metamorphic overprint. ZHe and AFT ages, clustering at ~55–40
and ~45–40 Ma, respectively, revealed a rapid Eocene cooling event, documenting erosional and/or tectonic exhumation related
to the collapse of the Carpathian orogenic wedge. This is the first evidence that exhumation of crystalline cores in the Western
Carpathians took place in the Eocene and not in the Cretaceous as traditionally believed. Bimodal AFT length distributions,
Early Miocene AHe ages and thermal modelling results suggest that the samples were heated to temperatures of ~55–90°C during
Oligocene–Miocene times. This thermal event may be related either to the Oligocene/Miocene sedimentary burial, or Miocene
magmatic activity and increased heat flow. This finding supports the concept of thermal instability of the Carpathian crystalline
bodies during the post-Eocene period. 相似文献
77.
78.
79.
We focus on Swiss earthquakes in antiquity and the early medieval period before A.D. 1000. We have information on less than
half a dozen earthquakes within this era, since written records for the first half of the first millennium A.D. are minimal,
and there is little hope of finding more written evidence for earthquakes. Furthermore, interpreting the documents at hand
is somewhat complex. For the 6th century Gregory of Tours in Historia Francorum gives hints of a rockslide near the castle Tauredunum (Le Grammont) in the Swiss canton Valais, an event that has been considered in the literature as caused by an earthquake. The Carolingian period (ca. 750–950) included the rise of some very important cultural centers in various parts of today’s Switzerland. For
instance, the ecclesiastical culture in St. Gallen generated a remarkable number of written records, which survived for our
use in a unique manner. From the 9th and 10th centuries, we have evidence for earthquakes in the years 849, 867, 902, and
944. However, information on them remains so scarce that their location and intensity are generally difficult to assess. Nevertheless,
the finding of a new document - a memoir written by the abbot of Reichenau - offers some insight into the A.D. 849 event and
its reportedly aftershocks.
相似文献
Monika GislerEmail: |
80.
Santosh Sapkota Saurav Sarup Khadka Gautam Sabin Karki Monika Adhikari Binod Mishra Roshan Kumar Klausner Virginia Dhungana Beni Madhav 《Geomagnetism and Aeronomy》2022,62(1-2):125-137
Geomagnetism and Aeronomy - Electrodynamical coupling between the solar wind’s plasma and the Earth’s magnetosphere creates geomagnetic disturbances recorded on the ground. This work... 相似文献