全文获取类型
收费全文 | 193篇 |
免费 | 7篇 |
国内免费 | 17篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 16篇 |
地球物理 | 52篇 |
地质学 | 113篇 |
海洋学 | 11篇 |
天文学 | 8篇 |
自然地理 | 16篇 |
出版年
2018年 | 1篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 3篇 |
2014年 | 5篇 |
2013年 | 23篇 |
2012年 | 4篇 |
2011年 | 1篇 |
2010年 | 5篇 |
2009年 | 5篇 |
2008年 | 4篇 |
2007年 | 11篇 |
2006年 | 3篇 |
2005年 | 11篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 6篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 8篇 |
1996年 | 22篇 |
1995年 | 2篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1971年 | 1篇 |
1970年 | 3篇 |
1968年 | 3篇 |
1967年 | 3篇 |
1965年 | 2篇 |
1964年 | 1篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1928年 | 1篇 |
排序方式: 共有217条查询结果,搜索用时 31 毫秒
81.
82.
A palaeoecological study of the mites (Acari) from a Lateglacial deposit at Usselo (The Netherlands)
JAAP SCHELVIS BAS VAN GEEL 《Boreas: An International Journal of Quaternary Research》1989,18(3):237-243
The distribution of the remains of mites in the Lateglacial (Late Weichselian) type section at Usselo (The Netherlands) is presented. The division of the sequence into (sub-)zones, based upon combined palaeo-botanical and palaeoentomological studies, is shown, as well as the approximate age based on 14 C determinations. The present habitats of the species are in agreement with the reconstruction of the local vegetational succession Four species of mites, three oribatids and one uropodid, have not previously been recorded as subfossils. 相似文献
83.
R. S. W. VAN DE WAL M. WILD J. DE WOLDE 《Tellus. Series B, Chemical and physical meteorology》2001,53(1):94-102
This paper focuses on the rôle of accumulation and cloudiness changes in the response of the Greenland ice sheet to global warming. Changes in accumulation or cloudiness were often neglected, or coupled to temperature changes. We used model output on temperature, precipitation and cloudiness from a GCM (ECHAM4 T106). The GCM output was used to drive the Greenland model that exists of a vertically averaged ice flow model, coupled to a 1D surface energy balance model that calculates the ablation. Variables are temperature, accumulation and cloudiness. Sensitivity experiments with this model show that changes in accumulation are very important for the ice sheet mass balance, whereas cloudiness is of secondary importance. If the Greenland model is forced by the GCM output, the Greenland model is found to contribute 70% less to sea level rise after 70 years than is indicated by the results presented in the IPCC report. This large discrepancy is mainly due to the fact that the enhanced ablation is strongly compensated by increased accumulation. Comparing the result obtained here with changes in mass balance derived directly from the same general circulation model, indicates a 20% larger contribution to sea level. This increase is due to changes in ice flow, and a different method for the ablation calculation. 相似文献
84.
AARNOUT VAN DELDEN 《地球,A辑:动力气象学与海洋学》2000,52(4):380-390
The process of hydrostatic adjustment to horizontally homogeneous heating in a stably stratified atmosphere of arbitrary thermal structure is investigated in the limit of small perturbations. A linear differential equation is derived for the vertical pressure distribution in the final balanced state. Solutions of this equation are compared with the time dependent solution which is found by numerically integrating the equations in time. During the process of hydrostatic adjustment acoustic‐buoyancy oscillations are generated. The amplitudes of these oscillations become so great that static instability is generated at heights above 100 km, depending on where and how abruptly the heat is added. As a crude representation of the unstable breakdown and damping of these waves, Rayleigh damping is introduced. If the associated damping coefficient in the upper atmosphere is sufficiently large (greater than the Brunt Väisälä frequency), the oscillations vanish. Below a height of about 50 km the steady state predicted by the above mentioned differential equation is reached approximately in 10 min. 相似文献
85.
The paleoenvironmental evolution of a Dutch deltaic swamp forest area during the mid-Holocene was strongly governed by a general rise of water level (bound to postglacial sea-level rise) and by fluctuations in this water-level rise. A phasing of this 2,000 years period shows alternation of closed swamp forest on the one hand, and (fluvio-) lacustrine environment with swamp forest islands on the other. The refined scale of investigation permits bird's-view landscape reconstructions. These also show how attractive the area was for neolithic fishermen. 相似文献
86.
87.
C. H. VAN DER BOGERT P. H. SCHULTZ J. G. SPRAY 《Meteoritics & planetary science》2003,38(10):1521-1531
Abstract— High speed friction experiments have been performed on the ordinary chondrites El Hammami (H5, S2) and Sahara 97001 (L6, S3) using an axial friction‐welding apparatus. Each sample was subjected to a strain rate of 103 to 104 s?1, which generated 250 to 500 μm‐deep darkened zones on each sample cube. Thin section analyses reveal that the darkened areas are composed of silicate glass and mineral fragments intermingled with dispersed submicron‐size FeNi and FeS blebs. Fracturing of mineral grains and the formation of tiny metallic veins define the extent of deformation beyond the darkened shear zone. These features are not present in the original meteorites. The shear zones and tiny veins are quite similar to certain vein systems seen in naturally deformed ordinary chondrites. The experiments show that shock deformation is not required for the formation of melt veins and darkening in ordinary chondrites. Therefore, the presence of melt veins and darkening does not imply that an ordinary chondrite has undergone severe shock deformation. In fact, high strain rate deformation and frictional melting are especially important for the formation of veins at low shock pressures. 相似文献
88.
89.
SEAN J. FITZSIMONS ERIC A. COLHOUN GUUS VAN DE GEER ROBERT S. HILL 《Boreas: An International Journal of Quaternary Research》1990,19(1):1-15
Interpretation of weathered glacial and interglacial deposits in the lower King Valley suggests that the Early Pleistocene Thureau Formation is conformably overlain by the Regency Formation. Pollen analysis of the Regency Formation provides evidence of a new climatic stage, the Regency Interglacial. The interglacial deposit consists of humified peat overlain by drifted wood and leaves. The pollen analysis shows a transition from montane scrub rainforest to lowland temperate rainforest dominated by Lagarostrobos franklinii, Nothofagus cunninghamii and Phyllocladus aspleniifolius. Trace quantities of the species Quintinia psi-latispora and Gothanipollis perplexus , now both extinct in Tasmania, were also recorded. On the basis of intense chemical weathering and correlation with sediments that have a reversed magnetization the weathered glacial deposits of the Thureau Formation are thought to be older than 730,000 B.P. The eroded interglacial deposit rests on the weathered deposits and is buried by outwash gravels of the David Formation, which was deposited during an ice advance of the Middle Pleistocene Henty Glaciation (c. 150,000 B.P.). Comparison of the Regency site with a site 2 km to the south at Baxter Rivulet shows that the unconformity between the interglacial deposit and the overlying outwash gravel represents the erosion of the evidence for the Middle Pleistocene Moore Glaciation. 相似文献
90.