全文获取类型
收费全文 | 869篇 |
免费 | 51篇 |
国内免费 | 9篇 |
专业分类
测绘学 | 53篇 |
大气科学 | 65篇 |
地球物理 | 213篇 |
地质学 | 287篇 |
海洋学 | 81篇 |
天文学 | 140篇 |
综合类 | 7篇 |
自然地理 | 83篇 |
出版年
2023年 | 4篇 |
2022年 | 6篇 |
2021年 | 29篇 |
2020年 | 12篇 |
2019年 | 19篇 |
2018年 | 34篇 |
2017年 | 35篇 |
2016年 | 49篇 |
2015年 | 31篇 |
2014年 | 27篇 |
2013年 | 56篇 |
2012年 | 42篇 |
2011年 | 45篇 |
2010年 | 42篇 |
2009年 | 59篇 |
2008年 | 45篇 |
2007年 | 44篇 |
2006年 | 38篇 |
2005年 | 23篇 |
2004年 | 44篇 |
2003年 | 29篇 |
2002年 | 21篇 |
2001年 | 21篇 |
2000年 | 28篇 |
1999年 | 15篇 |
1998年 | 12篇 |
1997年 | 8篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 3篇 |
1993年 | 7篇 |
1991年 | 8篇 |
1990年 | 5篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1984年 | 6篇 |
1983年 | 12篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1973年 | 2篇 |
1972年 | 2篇 |
1967年 | 1篇 |
排序方式: 共有929条查询结果,搜索用时 15 毫秒
1.
2.
Tom Horlick-Jones 《GeoJournal》1995,37(3):329-334
Cities like London, New York and Los Angeles possess complex urban environments that, despite their technological sophistication, present their citizens with a multiplicity of risks. This paper presents a discussion of the effects of physical and social trends on the creation of risk and vulnerability to hazard in such cities. The interplay between physical hazards and perceived risks in late modern, or Risk, urban societies is considered, and the impact of this process on adjustment to hazard. 相似文献
3.
Mark E Bailey and Tom Ray give an overview of the National Astronomy Meeting in Dublin, where record numbers of astronomers went to talk, listen and network. 相似文献
4.
We used multivariate statistical techniques to analyse the distributions of surface sediment chironomid assemblages with respect to surface-water temperature, and an additional set of 27 environmental variables, in 30 freshwater lakes of northern Fennoscandia. Our study transect spans boreal coniferous forest to subarctic tundra and includes a steep temperature gradient. Canonical correspondence analysis (CCA) with forward selection and associated Monte Carlo permutation tests revealed that there were statistically significant (P<0.05) relationships between chironomid distributions and two environmental variables, namely lakewater temperature and maximum lake depth. A constrained CCA with temperature as the only predictor variable suggested that the relationship between lakewater temperature and chironomid composition was sufficiently robust for developing a weighted-averaging (WA) based quantitative inference model that will allow palaeotemperature reconstructions using subfossil chironomid remains preserved in lake sediments. 相似文献
5.
6.
7.
M. Julleh Jalalur Rahman Rumana Yeasmin Tom McCann 《Journal of the Geological Society of India》2016,88(6):705-710
Mineralogical and chemical investigations (<2μm clay separates) of shale samples from the Neogene-age Surma Group obtained from four wells (Habiganj-11, Shahbazpur-1, Titas-11, Titas-15) in the Bengal basin, Bangladesh, were carried out in order to reveal the clay mineral composition as reservoir exploration and exploitation requires a good understanding of the clay minerals. The samples were analyzed by X-ray diffraction (XRD), scanning electron microscope (SEM) and X-Ray fluorescence spectrometry (XRF). Mineralogically, the sub-surface Surma Group shales comprise predominantly quartz, plagioclase, illite, chlorite, kaolinite, with lesser amounts of K-feldspar, dolomite and smectite, and minor to trace amounts of calcite, siderite and pyrite. The chemical composition of the <2 μm clay separates also suggests an illite and chlorite-rich composition. With increasing burial depth, the Surma Group shales are enriched in illite. The gradual decreasing of the smectite clays with depth and ultimate disappearance at greater depths (≥ 3000 m) may have been responsible for the presence of the diagenetic illite. Based on the mineralogical composition it is most likely that the illite-chlorite associations together with quartz and feldspar were predominantly detrital in origin and thus reflect the presence of a rapidly-rising source terrain not subjected to intense weathering. 相似文献
8.
9.
During the late Paleozoic Oslo rifting event, the SW part of the Baltic Shield was penetrated by mantle-derived magmas from a depleted lithospheric or sublithospheric source. Along the way to their final emplacement, these magmas may have interacted with a heterogeneous continental crust, consisting of a mosaic of continental terranes, each with its unique composition and internal crustal history. Information on radiogenic isotope ratios and trace element distributions in the Precambrian terranes surrounding the rift can be used to define characteristic crustal components. These components may be used as endmembers in petrogenetic modelling of the Oslo Rift magmatic system. Based on available data, six endmember components can be identified, and (semi) quantitatively characterized in terms of Sr, Nd and Pb isotopes and selected trace elements. Data on the distribution of rock-types along the rift flanks allow estimates to be made of the relative importance of the components in different parts of the rift. Combining these data with petrological information may allow a realistic understanding of crust–magma interaction in the Oslo Rift magmatic system. 相似文献
10.