全文获取类型
收费全文 | 559篇 |
免费 | 12篇 |
专业分类
测绘学 | 17篇 |
大气科学 | 26篇 |
地球物理 | 127篇 |
地质学 | 205篇 |
海洋学 | 17篇 |
天文学 | 140篇 |
自然地理 | 39篇 |
出版年
2021年 | 4篇 |
2019年 | 11篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 7篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 14篇 |
2012年 | 13篇 |
2011年 | 9篇 |
2010年 | 10篇 |
2009年 | 29篇 |
2008年 | 18篇 |
2007年 | 15篇 |
2006年 | 20篇 |
2005年 | 19篇 |
2004年 | 15篇 |
2003年 | 11篇 |
2002年 | 15篇 |
2001年 | 10篇 |
2000年 | 5篇 |
1999年 | 11篇 |
1998年 | 6篇 |
1997年 | 13篇 |
1996年 | 6篇 |
1995年 | 16篇 |
1994年 | 23篇 |
1993年 | 11篇 |
1992年 | 10篇 |
1991年 | 16篇 |
1990年 | 13篇 |
1989年 | 9篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 10篇 |
1985年 | 8篇 |
1984年 | 14篇 |
1983年 | 16篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 14篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1977年 | 12篇 |
1975年 | 8篇 |
1974年 | 7篇 |
1973年 | 14篇 |
1971年 | 6篇 |
1963年 | 3篇 |
1956年 | 3篇 |
排序方式: 共有571条查询结果,搜索用时 15 毫秒
51.
52.
This study is concerned with the influence of the glacial-isostatic adjustment caused by the last Pleistocene deglaciation
on the present-day sea level. The viscoelastic deformation caused by the time-variable ice and ocean loads is simulated by
computing the resulting perturbations for a spherical, self-gravitating, incompressible, Maxwell-viscoelastic earth model.
The associated variation of the earth rotation is described in terms of the Liouville equation, which is solved by means of
the MacCullagh formulae. This allows the determination of the vertical displacement and geoid height and, thus, the solution
of the sea-level equation. We test several viscosity and ice models and evaluate them by comparison of the computed response
with the Holocene relative sea-level record. Using the optimum combination of viscosity and ice models, we then estimate the
influence of the last Pleistocene deglaciation on the tide-gauge measurements. A comparison between the observational and
residual linear trends for the tide-gauge measurements shows a significant reduction of the variance and geographical variability
for the latter, in particular for the formerly ice-covered regions of North America and Scandinavia. The favoured value determined
for the global mean sea-level rise is (1.46±0.2) mm a−1. 相似文献
53.
Helmut Wolf 《Journal of Geodesy》1963,37(2):149-163
Ohne Zusammenfassung
Communication présentée à l'Assemblée générale de l'Association Internationale de Géodésie (Helsinki 1960). 相似文献
54.
55.
The organic analysis of the murchison meteorite 总被引:1,自引:0,他引:1
The organic compounds released from the Murchison carbonaceous chondrite following vaporization-pyrolysis at 150, 300 and 430°C were investigated. The total organic yield was 272 ppm and consisted of n-alkanes, alkenes, aromatic hydrocarbons and thioaromatics. The composition and yield at all three temperatures are compared with those obtained by an identical analysis on another carbonaceous chondrite, Allende, and two terrestrial rocks.Comparison of compounds released by 150°C volatilization of Murchison and Allende reveals remarkable similarities, suggesting commonality in the processes responsible for their formation. The origin of the organic compounds found can be explained in terms of the Fischer-Tropsch synthesis followed by partial equilibration of the primary products. However, problems concerning the relationship between types of carbonaceous chondrites remain unresolved. 相似文献
56.
Wolf Tietze Gerhard Kortum W. R. Mead T. K. Poiker C. Paddick George Kish A. Njøs H. Mensching V. Haarmann Uzo M. Igbozurike M. M. Yoshino Mushtaqur Rahman Lage Wahlström J. Connell Kazimierz Dziewonski Wayland R. Swain J. Humlum G. W. Lüttig Haruko Kishimoto Mai Britt E. Mørk 《GeoJournal》1982,6(3):270-280
57.
58.
This study demonstrates that oxalate has a strong inhibiting effect onFe-catalyzed S(IV) oxidation by oxygen in aqueous solution. While thepseudo-first order rate constant of S(IV) oxidation was determined to be1.6 × 103 M-1 s-1 in experimentswithout oxalate, the oxidation of S(IV) was totally inhibited at a molarconcentration ratio of iron:oxalate = 1:5 at an oxalate concentration of 4M. Under these conditions, the Fe(II)/Fe(III) ratio remained nearlyconstant during the observed reaction time. The determined rate constants wereindependent of the initial oxidation state of iron. However, with increasingconcentrations of oxalate, a longer induction period is observed forexperiments with iron initially in the Fe(II) oxidation state. 相似文献
59.
We review the historical, geological, tide-gauge, GPS and gravimetric evidence advanced in favour of, or against, continuing
land uplift around Hudson Bay, Canada. We also reanalyse the tide-gauge and GPS data for Churchill using longer time series
than those available to previous investigators. The dependence of the mean rate of relative sea-level change obtained from
the tide-gauge record on the length and mid-epoch of the observation interval considered is investigated by means of a newly
developed linear-trend analysis diagram. For studying the shorter-period variability of the tide-gauge record, the wavelet
transform is used. The mean rate of land uplift obtained from GPS is based on a new analysis using IGS solutions of GFZ. To
include the post-glacial land uplift, sea-level indicators from the Churchill region representing the relative sea-level history
during the past 8000 years are also used. Finally, the values of the four observables are jointly inverted in terms of mantle
viscosity. The optimum values are ~3.2 × 1020 Pa s and ~1.6 × 1022 Pa s for the upper- and lower-mantle viscosities, respectively. 相似文献
60.
In 1988, four states in the northeastern USA commissioned a study to address land use changes in the Northern Forest, 26 million acres of temperate and boreal forest extending from Maine to eastern New York State. Against a backdrop of economic destabilization and concerns regarding social and ecological implications of a real estate boom, the sustained deliberative dialogue catalyzed by this study has come to rely heavily on the ambiguous concept of “working forest.” To clarify political and environmental dynamics in the region, we analyzed how people respond to and seek to capitalize on the interpretive flexibility of the term working forest. We combine an analysis of socio-political discourses of working forest based on a structured literature review with an assessment of local peoples’ definitions of working forest based on a survey conducted in a pair of contrasting New York State communities. The first study site represents an amenity-oriented community (i.e. a place where the forest supports a service economy including recreation and tourism) and the other study site represents a timber-dependent community. By linking data from community-level analysis to data derived from a general analysis of forest politics, we seek to develop a more robust perspective. By comparing discourses across differently structured communities, we investigate how local forest politics are mediated by local economic development processes. Our study empirically illustrates contested and geographically uneven processes of social construction of environment and rural development in a region confronting pressures of globalization. Results indicate that timber harvesting is a heavily privileged management objective, as a logic of ‘the forest that pays is the forest that stays’ dominates. Environmental politics in the region, and perhaps more generally, increasingly conforms to a form of pragmatism in which economic opportunities structure conservation planning and investment. 相似文献