全文获取类型
收费全文 | 119篇 |
免费 | 8篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 2篇 |
地球物理 | 40篇 |
地质学 | 35篇 |
海洋学 | 4篇 |
天文学 | 20篇 |
综合类 | 2篇 |
自然地理 | 23篇 |
出版年
2024年 | 1篇 |
2023年 | 2篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 4篇 |
2016年 | 6篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 5篇 |
2012年 | 4篇 |
2011年 | 4篇 |
2010年 | 1篇 |
2009年 | 8篇 |
2008年 | 6篇 |
2007年 | 3篇 |
2006年 | 5篇 |
2005年 | 6篇 |
2004年 | 5篇 |
2003年 | 5篇 |
2002年 | 5篇 |
2001年 | 1篇 |
2000年 | 4篇 |
1999年 | 4篇 |
1998年 | 7篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1993年 | 2篇 |
1989年 | 2篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1924年 | 1篇 |
排序方式: 共有127条查询结果,搜索用时 15 毫秒
121.
M. Martin J. R. R. Ritter the CALIXTO working group 《Geophysical Journal International》2005,162(2):448-460
122.
U. Kolb A. R. King & H. Ritter 《Monthly notices of the Royal Astronomical Society》1998,298(2):L29-L33
We have measured central line strengths for a complete sample of early-type galaxies in the Fornax cluster, comprising 11 elliptical and 11 lenticular galaxies, more luminous than M B = −17. In contrast to the elliptical galaxies in the sample studied by González (and recently revisited by Trager) we find that the Fornax ellipticals follow the locus of galaxies of fixed age in Worthey's models and have metallicities varying from roughly solar to three times solar. The lenticular galaxies, however, exhibit a substantial spread to younger luminosity-weighted ages, indicating a more extended star formation history. We present measurements of the more sensitive indices: C4668 and HγA ; these confirm and reinforce the conclusions that the elliptical galaxies are coeval and that only the lenticular galaxies show symptoms of late star formation. The inferred difference in the age distribution between lenticular and elliptical galaxies is a robust conclusion as the models generate consistent relative ages using different age and metallicity indicators even though the absolute ages remain uncertain. The young luminosity-weighted ages of the S0s in the Fornax cluster are consistent with the recent discovery that the fraction of S0 galaxies in intermediate-redshift clusters is a factor of 2–3 lower than found locally, and suggest that a fraction of the cluster spiral galaxy population has evolved to quiescence in the 5-Gyr interval from z = 0.5 to the present. Two of the faintest lenticular galaxies in our sample have blue continua and strong Balmer-line absorption, suggesting starbursts ≲2 Gyr ago. These may be the low-redshift analogues of the starburst or post-starburst galaxies seen in clusters at z = 0.3, similar to the Hδ-strong galaxies in the Coma cluster. 相似文献
123.
Scattering parameters of the lithosphere below the Massif Central, France, from teleseismic wavefield records 总被引:1,自引:0,他引:1
Joachim R. R. Ritter Sergei A. Shapiro & Barbara Schechinger 《Geophysical Journal International》1998,134(1):187-198
Teleseismic P -wave recordings are analysed in the frequency range 0.3–6 Hz to derive structural (statistical) parameters of the lithosphere underneath the French Massif Central. For this we analyse differences in frequency-dependent intensities of the mean wavefield and the fluctuation wavefield. It is possible to discriminate a weak fluctuation regime of the wavefield in the frequency range below 1 Hz and a strong fluctuation regime starting above 1 Hz and continuing to higher frequencies. The observed wavefield fluctuations in the frequency range 0.3–3 Hz can be explained by scattering of the teleseismic P wave front at elastic inhomogeneities in the lithosphere. A statistical distribution of the inhomogeneities is assumed and the concept of random media is applied. The lithospheric structure under the Massif Central can be described as a 70 km thick heterogeneous layer with velocity fluctuations of 3–7 per cent and correlation lengths of the heterogeneities of 1–16 km. 相似文献
124.
Joachim R.R. Ritter 《Journal of Seismology》2002,6(4):477-486
The mechanical, automatically recording seismological instruments developed by Emil Wiechert in Göttingen at the beginning of the 20th century are still in use today. I comparethe recording characteristics of these seismographswith a modern, electrodynamic MARK L4-3D instrument. The frequency-dependent transfer functions are determined and used to restitute the`true' ground displacement. The displacement waveforms at the different instruments are well correlated at frequencies between 0.05 and 4.0 Hz.Amplitudes differ by a factor of less than two. This is sufficientfor the determination of seismological magnitudes which are defined on a logarithmicbasis. The timing accuracy is less favourable due to theslow recording speed on the smoked paper. However, relativetime differences within one second may be resolved, allowing the use of variousmodern seismological interpretation techniques. 相似文献
125.
Pia Mukherjee Andrew R. Liddle 《Monthly notices of the Royal Astronomical Society》2008,389(1):231-236
We use Bayesian model selection tools to forecast the Planck satellite's ability to distinguish between different models for the re-ionization history of the Universe, using the large angular scale signal in the cosmic microwave background polarization spectrum. We find that Planck is not expected to be able to distinguish between an instantaneous re-ionization model and a two-parameter smooth re-ionization model, except for extreme values of the additional re-ionization parameter. If it cannot, then it will be unable to distinguish between different two-parameter models either. However, Bayesian model averaging will be needed to obtain unbiased estimates of the optical depth to re-ionization. We also generalize our results to a hypothetical future cosmic variance limited microwave anisotropy survey, where the outlook is more optimistic. 相似文献
126.
Maria Pia Di Mauro Jørgen Christensen-Dalsgaard Lucio Paternò 《Astrophysics and Space Science》2003,284(1):229-232
We investigate properties of the internal structure of HR2021, better known as Hydri, a G2 IV subgiant with mass close to solar and for which observations by Bedding et al. (2001) have shown the presence of solar-like oscillations.We have computed models of Hydri,based on updated global parameters,and compared the computed frequencies for the models with the observed oscillation spectrum. 相似文献
127.
The Palaeoproterozoic Kristineberg VMS deposit, Skellefte district, northern Sweden, part I: geology
Hans Årebäck Timothy J. Barrett Stig Abrahamsson Pia Fagerström 《Mineralium Deposita》2005,40(4):351-367
The Kristineberg volcanic-hosted massive sulphide (VMS) deposit, located in the westernmost part of the Palaeoproterozoic
Skellefte district, northern Sweden, has yielded 22.4 Mt of ore, grading 1.0% Cu, 3.64% Zn, 0.24% Pb, 1.24 g/t Au, 36 g/t
Ag and 25.9% S, since the mine opened in 1941, and is the largest past and present VMS mine in the district. The deposit is
hosted in a thick pile of felsic to intermediate and minor mafic metavolcanic rocks of the Skellefte Group, which forms the
lowest stratigraphic unit in the district and hosts more than 85 known massive sulphide deposits. The Kristineberg deposit
is situated lower in the Skellefte Group than most other deposits. It comprises three main ore zones: (1) massive sulphide
lenses of the A-ore (historically the main ore), having a strike length of about 1,400 m, and extending from surface to about
1,200 m depth, (2) massive sulphide lenses of the B-ore, situated 100–150 m structurally above the A-ore, and extending from
surface to about 1,000 m depth, (3) the recently discovered Einarsson zone, which occurs in the vicinity of the B-ore at about
1,000 m depth, and consists mainly of Au–Cu-rich veins and heavily disseminated sulphides, together with massive sulphide
lenses. On a regional scale the Kristineberg deposit is flanked by two major felsic rock units: massive rhyolite A to the
south and the mine porphyry to the north. The three main ore zones lie within a schistose, deformed and metamorphosed package
of hydrothermally altered, dominantly felsic volcanic rocks, which contain varying proportions of quartz, muscovite, chlorite,
phlogopite, pyrite, cordierite and andalusite. The strongest alteration occurs within 5–10 m of the ore lenses. Stratigraphic
younging within the mine area is uncertain as primary bedding and volcanic textures are absent due to strong alteration, and
tectonic folding and shearing. In the vicinity of the ore lenses, hydrothermal alteration has produced both Mg-rich assemblages
(Mg-chlorite, cordierite, phlogopite and locally talc) and quartz–muscovite–andalusite assemblages. Both types of assemblages
commonly contain disseminated pyrite. The sequence of volcanic and ore-forming events at Kristineberg is poorly constrained,
as the ages of the massive rhyolite and mine porphyry are unknown, and younging indicators are absent apart from local metal
zoning in the A-ores. Regional structural trends, however, suggest that the sequence youngs to the south. The A- and B-ores
are interpreted to have formed as synvolcanic sulphide sheets that were originally separated by some 100–150 m of volcanic
rocks. The Einarsson zone, which is developed close to the 1,000 m level, is interpreted to have resulted in part from folding
and dislocation of the B-ore sulphide sheet, and in part from remobilisation of sulphides into small Zn-rich massive sulphide
lenses and late Au–Cu-rich veins. However, the abundance of strongly altered, andalusite-bearing rocks in the Einarsson zone,
coupled with the occurrence of Au–Cu-rich disseminated sulphides in these rocks, suggests that some of the mineralisation
was synvolcanic and formed from strongly acidic hydrothermal fluids.
Editorial handling: P. Weihed 相似文献