全文获取类型
收费全文 | 72篇 |
免费 | 3篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 5篇 |
地球物理 | 19篇 |
地质学 | 34篇 |
海洋学 | 8篇 |
天文学 | 4篇 |
自然地理 | 3篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2019年 | 1篇 |
2018年 | 2篇 |
2017年 | 2篇 |
2016年 | 1篇 |
2015年 | 2篇 |
2012年 | 1篇 |
2011年 | 6篇 |
2010年 | 2篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 6篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2003年 | 4篇 |
2002年 | 3篇 |
2001年 | 4篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1998年 | 1篇 |
1996年 | 2篇 |
1995年 | 1篇 |
1993年 | 1篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1986年 | 2篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1981年 | 2篇 |
排序方式: 共有75条查询结果,搜索用时 15 毫秒
11.
Paul F. Green Rob Westaway D.A.C. Manning Paul L. Younger 《Proceedings of the Geologists' Association. Geologists' Association》2012,123(3):450-463
The Cenozoic landscape development of Britain remains relatively poorly understood. On the one hand, ‘plumists’ have tried to explain the present-day topography as a consequence of effects of the Iceland mantle plume during the Palaeocene-Eocene British Tertiary Igneous Province (BTIP) magmatism, with little or no subsequent modification. On the other hand, abundant evidence exists from fluvial and marine terraces and superimposed karstic levels for significant vertical crustal motions during the Quaternary, which clearly has nothing to do with any mantle plume. To shed light on this issue, we present the first publication of data that constrain the Cenozoic thermal history of the North Pennine uplands of northern England, from apatite fission-track analysis of drill cuttings from the Eastgate Borehole in Weardale, in the western part of County Durham. Our results indicate ~650 m of regional denudation since the latest Oligocene/Early Miocene, plus the ~400 m of localized entrenchment that has created the modern Weardale valley. Before the latest Oligocene/Early Miocene, but following the BTIP magmatism, the crust in this region experienced significant cooling, mainly due to a decrease in the geothermal gradient from ~55 to 61 °C km?1 to the present 38 °C km?1, along with ~300 ± 200 m of denudation. Although significant BTIP magmatism occurred in northern England, it thus had only a limited net effect; the crust experienced dramatic heating, but cooled back to its original thermal state within, at most, a few tens of millions of years. We suggest that this rapid cooling effect resulted from westward flow of relatively cold material within the mobile lower-crustal layer, driven by the lateral pressure gradient induced by earlier heating effects and effects of surface processes. Whatever topography developed during the Palaeogene, as a direct result of these heating effects, underplating at the base of the crust, and the associated modest denudation, was presumably also short-lived; significant changes to the crustal thickness, and thus to the topography, can be envisaged as a consequence of subsequent lower-crustal flow. 相似文献
12.
McKay CP Grunthaner FJ Lane AL Herring M Bartman RK Ksendzov A Manning CM Lamb JL Williams RM Ricco AJ Butler MA Murray BC Quinn RC Zent AP Klein HP Levin GV 《Planetary and Space Science》1998,46(6-7):769-777
The MOx instrument was developed to characterize the reactive nature of the martian soil. The objectives of MOx were: (1) to measure the rate of degradation of organics in the martian environment; (2) to determine if the reactions seen by the Viking biology experiments were caused by a soil oxidant and measure the reactivity of the soil and atmosphere: (3) to monitor the degradation, when exposed to the martian environment, of materials of potential use in future missions; and, finally, (4) to develop technologies and approaches that can be part of future soil analysis instrumentation. The basic approach taken in the MOx instrument was to place a variety of materials composed as thin films in contact with the soil and monitor the physical and chemical changes that result. The optical reflectance of the thin films was the primary sensing-mode. Thin films of organic materials, metals, and semiconductors were prepared. Laboratory simulations demonstrated the response of thin films to active oxidants. 相似文献
13.
Jenni E. Sherriff Keith N. Wilkinson Poppy Harding Hayley Hawkins Rhys G. O. Timms Daniel S. Adler Emily J. Beverly Simon P. E. Blockley Boris Gasparyan Christina J. Manning Darren Mark Samvel Nahapetyan Katie J. Preece 《第四纪科学杂志》2022,37(1):6-27
The significance of the southern Caucasus in understanding Pleistocene hominin expansions is well established. However, the palaeoenvironments in which Palaeolithic occupation of the region took place are presently poorly defined. The Hrazdan river valley, Armenian Highlands, contains a rich Palaeolithic record alongside Middle Pleistocene volcanic, fluvial and lacustrine strata, and thus offer exciting potential for palaeoenvironmental reconstruction. We present the first results of sedimentological, geochemical, tephrostratigraphical and biological (diatoms) study of the sequence of Bird Farm 1, located in the central part of the valley. These data show six phases of landscape development during the interval 440–200 ka. The sequence represents the first quantitative Pleistocene diatom record from the Armenian Highlands and the southern Caucasus, and indicates the persistence of a deep, stratified lacustrine system, with evidence for changing lake productivity that is tentatively linked to climate. Furthermore, major element chemical characterization of visible and crypto-tephra horizons in the sequence enables the first stages of the development of a regional tephrostratigraphy. Together, the evidence from Bird Farm 1 demonstrates the importance of lacustrine archives in the region for palaeoenvironmental reconstruction and highlights the potential for linkages between archives on both a local and regional scale. 相似文献
14.
15.
J.P. Manning D.J. McGillicuddy Jr. N.R Pettigrew J.H. Churchill L.S. Incze 《Continental Shelf Research》2009
Two-hundred and twenty seven satellite-tracked drifters were deployed in the Gulf of Maine (GoM) from 1988 to 2007, primarily during spring and summer. The archive of tracks includes over 100,000 km logged thus far. Statistics such as transit times, mean velocities, response to wind events, and preferred pathways are compiled for various areas of the coastal GoM. We compare Lagrangian flow with Eulerian estimates from nearby moorings and evaluate drifter trajectories using Ekman theory and 3-D ocean circulation models. 相似文献
16.
17.
We develop a parametric fit to the results of a detailed magnetohydrodynamic (MHD) study of the response of ion escape rates (O+, and ) to strongly varied solar forcing factors, as a way to efficiently extend the MHD results to different conditions. We then use this to develop a second, evolutionary model of solar forced ion escape. We treat the escape fluxes of ion species at Mars as proportional to the product of power laws of four factors - that of the EUV flux Reuv, the solar wind particle density Rρ, its velocity (squared) Rv2, and the interplanetary magnetic field pressure RB2, where forcing factors are expressed in units of the current epoch-averaged values. Our parametric model is: , where ?(i) is the escape flux of ion i. We base our study on the results of just six provided MHD model runs employing large forcing factor variations, and thus construct a successful, first-order parametric model of the MHD program. We perform a five-dimensional least squares fit of this power law model to the MHD results to derive the flux normalizations and the indices of the solar forcing factors. For O+, we obtain the values, 1.73 × 1024 s−1, 0.782, 0.251, 0.382, and 0.214, for ?0, α, β, γ, and δ, respectively. For , the corresponding values are 1.68 × 1024 s−1, −0.393, 0.798, 0.967, and 0.533. For , they are 8.66 × 1022 s−1, −0.427, 1.083, 1.214, and 0.690. The fit reproduces the MHD results to an average error of about 5%, suggesting that the power laws are broadly representative of the MHD model results. Our analysis of the MHD model shows that by itself an increase in REUV enhances O+ loss, but suppresses the escape of and , whereas increases in solar wind (i.e., in , and RB2, with Reuv constant) favors the escape of heavier ions more than light ions. The ratios of escaping ions detectable at Mars today can be predicted by this parametric fit as a function of the solar forcing factors. We also use the parametric model to compute escape rates over martian history. This second parametric model expresses ion escape functions of one variable (per ion), ?(i) = ?0(i)(t/t0)−ξ(i). The ξ(i) are linear combinations of the epoch-averaged ion escape sensitivities, which are seen to increase with ion mass. We integrate the and oxygen ion escape rates over time, and find that in the last 3.85 Gyr, Mars would have lost about mbars of , and of water (from O+ and ) from ion escape. 相似文献
18.
Karl T. Bates Peter L. Falkingham David Hodgetts James O. Farlow Brent H. Breithaupt Mike O'Brien Neffra Matthews William I. Sellers & Phillip L. Manning 《Geology Today》2009,25(4):134-139
Public engagement and the promotion of science to a wider non-academic audience form an integral role of the professional scientist in the twenty-first century. The high level of public interest in palaeontology means that the Earth's prehistoric past can provide an important medium through which to communicate information concerning contemporary scientific issues. Here we explain how modern computer techniques can be used to enhance public understanding of complex palaeontological issues. 相似文献
19.
The behaviour of tungsten in granitic melt-vapour systems 总被引:9,自引:0,他引:9
An experimental study has been carried out to determine the effect of solution composition on the partitioning behaviour of
tungsten in granitic melt-vapour systems at 800° C and 1 kbar. With chloride and phosphate solutions, tungsten partitions
strongly into the aqueous phase, whereas with fluoride, carbonate and borate solutions, and water alone, tungsten partitions
in favour of the melt. With chloride solutions, the fluid/melt partition coefficients (K
D) for W show a marked positive correlation with chloride concentration, and suggest that at low chloride concentrations W-Cl
complexes with low Cl∶W ratios (such as associated equivalents of (WO3)2C1−) may be present. In contrast, at higher chloride concentrations complexes with high Cl∶W ratios (such as WOCl4, WCl6 and associated ionic equivalents) may predominate. With phosphate solutions, K
D shows little variation with phosphate concentration, and phosphorus heteropolytungstates (such as H3[PW12O40]) may be present. There is no evidence to suggest that fluoride, carbonate or borate complexes of tungsten are important
under the experimental conditions: the data for these compositions can be interpreted assuming that isopolytungstates (such
as H6[H2W12O40]) are present. Within high temperature hydrothermal solutions tungsten may be transported principally as isopolytungstates
and heteropolytungstates in addition to chloride complexes, and this may, in part, account for the common association of apatite
and arsenopyrite with scheelite and wolframite in tungsten deposits. 相似文献
20.