全文获取类型
收费全文 | 209篇 |
免费 | 10篇 |
国内免费 | 6篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 9篇 |
地球物理 | 68篇 |
地质学 | 94篇 |
海洋学 | 30篇 |
天文学 | 6篇 |
综合类 | 2篇 |
自然地理 | 14篇 |
出版年
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 5篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 10篇 |
2013年 | 12篇 |
2012年 | 14篇 |
2011年 | 12篇 |
2010年 | 16篇 |
2009年 | 23篇 |
2008年 | 15篇 |
2007年 | 10篇 |
2006年 | 9篇 |
2005年 | 15篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1996年 | 2篇 |
1990年 | 1篇 |
1986年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有225条查询结果,搜索用时 15 毫秒
91.
92.
The oblique and diachronous collision of the Apennine-Maghrebian Chain with the Apulian (in the north-east) and Pelagian (in
the south) continental forelands, has determined the characteristic arcuate structure of this orogen. The effects of Plio-Pleistocene
deformation of the Calabrian Arc have been analysed on the basis of available reflection seismic profiles and using local
time-structural maps reconstructed along the main structures. During this period, internal sectors of the Tertiary chain migrated
forward on the oceanic Ionian foreland, and were cut by important strike-slip systems. These last have an orientation approximately
coincident with that of the migration of the front, allowing differential movement of the different sectors of the arc, towards
the weakly buoyant Ionian oceanic domain. The dataset suggests a clear connection between the development of the strike-slip
systems cutting the chain and the direction of tectonic transport, towards the East during Late Messinian/Early Pliocene time,
to the ESE during Late Pliocene/Early Pleistocene time, finally to the SSE during the Middle/Late Pleistocene to Present,
showing a clockwise rotation in well defined stages during the kinematic evolution of the chain. The origin of the Strait
of Messina during the different phases is also interpreted in the context of the analysed regional tectonic setting. 相似文献
93.
Carla Roncoli Norman Breuer David Zierden Clyde Fraisse Kenneth Broad Gerrit Hoogenboom 《Climatic change》2012,113(3-4):1113-1121
This article illustrates how a wildfire risk forecast evolved iteratively based on stakeholder consultations. An assessment based on phone interviews indicates that such forecasts can assist fire management decisions, such as deployment of human, financial, and material resources and management of forest, timber, and habitats, and public safety. But careful attention to communication, collaboration, and capacity building is key to realizing this potential. 相似文献
94.
Influences of temperature and nutrients on Synechococcus abundance and biomass in the southern Mid-Atlantic Bight 总被引:1,自引:0,他引:1
Synechococci are small (<1 μm) coccoid prokaryotes that play a significant ecological role in microbial food webs and are important contributors to carbon and nitrogen biogeochemical cycles. Under funding from NOAA and NASA, we developed a time series observatory to understand the seasonal variability of Synechococcus and other phytoplankton. Our goal is to understand the distribution and relative contribution of Synechococcus to the carbon cycle and how they relate to nutrients and temperature. Synechococcus in the southern Mid-Atlantic Bight exhibited a clear seasonal abundance pattern in both inshore and offshore waters—peaking in abundance (11×104 cells ml−1) during warm periods of summer. Synechococci were numerically important during periods of stratification when waters were warm and macronutrients were low. Using a simple algorithm to convert cellular volume to cellular carbon using image analysis, we estimated that Synechococcus cellular carbon ranged from 0.1 to 1.5 pg C per cell and was most significant compared to total particulate carbon in the summer peaking at ∼25% of the total carbon available. No direct correlations were found between Synechococcus abundance and nitrate, nitrite, ammonium, phosphate, and silicate. However, inshore Synechococcus abundance peaked at 104 cells ml−1 when nitrogen concentrations were lowest. Our results suggest that Synechococcus is adapted to warm temperatures and are capable of demonstrating rapid growth during summer when macronutrients are limiting. The ability of Synechococcus to take advantage of high summer temperatures, low nutrient concentrations and low light levels allows them to maintain a picoplankton community during periods of low detritus and nanophytoplankton is nutrient limited. Temperature-dependence is important in altering the size spectrum of the phytoplankton community and affects the carbon cycle on the Mid Atlantic Bight. 相似文献
95.
96.
The prevalence of toxicopathic liver lesions in English sole (Pleuronectes vetulus) was determined along a presumed gradient of chemical contamination in Vancouver Harbour, Canada. Fish were captured from five sites in or near Vancouver Harbour, British Columbia, Canada. No toxicopathic lesions were observed in fish examined at the reference site (Howe Sound outside Vancouver Harbour), or at the outer harbour site. In contrast, 20-23% of the fish from three sites located in the central harbour, Indian Arm and Port Moody Arm had one or more types of toxicopathic lesions. Likewise, aromatic hydrocarbon (AH) metabolites measured in bile exhibited a gradient in levels from lower concentrations at the reference site to significantly higher levels in fish from Indian Arm and Port Moody Arm harbour sites. The occurrence of toxicopathic liver lesions was statistically associated with concentrations of AHs measured in sediment and AH metabolite levels measured in bile. 相似文献
97.
Carla J. Potter 《Geo-Marine Letters》1982,2(3-4):243-246
Large quantities of raw geotechnical data presently exist in the individual collections of institutions and agencies throughout
the world. In order to increase the usefulness of this vast amount of data to the scientific community, the National Geophysical
Data Center (NGDC) intends to develop a comprehensive data bank for geotechnical information to be located at NGDC, along
with a common format for the exchange of geotechnical information. This format would facilitate not only the transfer of geotechnical
information between researchers, but also simplify the exchange and development of computer software with which to manipulate
the data. 相似文献
98.
Abstract. Distribution patterns of epiphytic hydroids of seagrass ( Posidonia occanica and Cymodocea nodosa ) beds were studied in the 'Stagnone', a moderately hypcrhaline lagoon in Sicily. The role of water movement in determining the spatial and temporal zonation of epiphytic hydroids and their morpho-physiological variations is evaluated. Remarks on systematics arc also included. 相似文献
99.
100.
Riccardo Cattaneo-Vietti Giancarlo Albertelli Giorgio Bavestrello Carlo Nike Bianchi Carlo Cerrano Mariachiara Chiantore Laura Gaggero Carla Morri Stefano Schiaparelli 《Marine Ecology》2002,23(S1):65-77
Abstract. Biomineralogy, as the complex of interactions at different levels (cell, organism, species, and community) between organisms and minerals, may play a significant role in the spatial distribution and structure of marine communities. For instance, a negative influence of quartz has been underlined on the Mediterranean benthic communities, which show a species-poorer structure in quartz-rich environments. Excluding the role of quartz, the aim of this work is to verify whether the composition of various mineralogical substrata can affect a hard-bottom benthic community. In the Ligurian Sea, the Levanto area shows an astonishing complex of substrata with different petrographic characters: in a few kilometres, sandstones, serpentinites, gabbros, and basalts occur in geometric association. Consequently, this area represents a suitable frame for this type of study. Herein, algal photophilic assemblages growing on the four mineralogical substrata show significant differences in number of species and percentage cover or abundance. This suggests a significant influence of rock mineral composition on the hard bottom community. Therefore, rock composition must be taken into account for a better understanding of the processes at the basis of hard-bottom community development and diversity. 相似文献