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51.
Aleksey Sidorchuk 《地球表面变化过程与地形》2006,31(11):1329-1344
52.
The impact of tidal wave on a permeable shore consisting of porous material results in groundwater table lying above the average sea level. This effect, stemming from the nonlinearity of the process of seawater flow in the soil, is referred to as pumping effect. 相似文献
53.
T. V. Berezhnykh O. Yu. Marchenko N. V. Abasov V. I. Mordvinov 《Geography and Natural Resources》2012,33(3):223-229
We examine the formation patterns of the low-water periods 1976?C1982 and 1996?C2011 for the Selenga river. One of the immediate reasons for the low-water periods under consideration is the attenuation of the circulation in the zone of convergence of monsoon flows and mid-latitude flows over Mongolia and North China. Unlike the low-water periods of the preceding decades, a decrease in precipitation amounts during the current low-water period is taking place concurrently with large-scale climatic changes. 相似文献
54.
Doklady Earth Sciences - Based on the data of atomic modeling, the different schemes of isomorphic incorporation of Cr3+ ions into the crystal structures of CaSiO3 and MgSiO3 were tested in the... 相似文献
55.
Kazuyuki Saito Sergei Marchenko Vladimir Romanovsky Amy Hendricks Nancy Bigelow Kenji Yoshikawa John Walsh 《Boreas: An International Journal of Quaternary Research》2014,43(3):733-749
A high‐resolution map of potential frozen ground distribution in NE Asia (90–150°E, 25–60°N) at the period of the Last Permafrost Maximum (LPM, c. 21 000 years ago) was dually reconstructed by means of a statistical classification using air freezing and thawing indices and a topographical downscaling using a digital relief model (ETOPO1). Background LPM climate data were derived from global climate model simulations of the Paleoclimate Model Intercomparison Project, Phase II (PMIP2). The reconstructed LPM map shows the southward shift of the southern limit of climate‐driven permafrost by 400–1500 km, with the greatest advance in the western sector (90–110°E), encompassing an area from central Siberia to most of the Altai area. The advance of environmentally conditional permafrost and seasonally frozen ground was greatest in the eastern sector (110–150°E), with an average shift of about 450 km. The descent of the lower limit of LPM alpine permafrost was in the range of 400–800 m. A comparison of the reconstructed map with published literature shows that this method, simplistically constructed yet effectively recognizing seasonality, continentality and topography, captures local features better than more elaborate methods. The sensitivity examination of a constant atmospheric lapse rate shows that altitudes of 2000–5000 m a.s.l. were most sensitive, though with only a limited effect on overall LPM distribution. 相似文献
56.
The estimation of the Earth’s gravitational potential energy E was obtained for different density distributions and rests
on the expression E = − (Wmin + ΔW) derived from the conventional relationship for E. The first component Wmin expresses minimum amount of the work W and the second component ΔW represents a deviation from Wmin interpreted in terms of Dirichlet’s integral applied on the internal potential. Relationships between the internal potential
and E were developed for continuous and piecewise continuous density distributions. The global 3D density model inside an
ellipsoid of revolution was chosen as a combined solution of the 3D continuous distribution and the reference PREM radial
piecewise continuous profile. All the estimates of E were obtained for the spherical Earth since the estimated (from error
propagation rule) accuracy σE of the energy E is at least two orders greater than the ellipsoidal reduction and the contribution of lateral density inhomogeneities
of the 3D global density model. The energy E contained in the 2nd degree Stokes coefficients was determined. A good agreement
between E = EGauss derived from Gaussian distribution and other E, in particular for E = EPREM based on the PREM piecewise continuous density model and E-estimates derived from simplest Legendre-Laplace, Roche, Bullard
and Gauss models separated into core and mantle only, suggests the Gaussian distribution as a basic radial model when information
about density jumps is absent or incomplete. 相似文献
57.
Liang Zhao Huijun Jin Chuanchuan Li Zhijiu Cui Xiaoli Chang Sergey S. Marchenko Jef Vandenberghe Tingjun Zhang Dongliang Luo Dongxin Guo Gengnian Liu Chaolu Yi 《Boreas: An International Journal of Quaternary Research》2014,43(3):688-698
Recent investigations into relict periglacial phenomena in northern and western China and on the Qinghai–Tibet Plateau provide information for delineating the extent of permafrost in China during the Late Pleistocene. Polygonal and wedge‐shaped structures indicate that, during the local Last Glacial Maximum (LLGM, between ~35 and 10.5 ka BP), the southern limit of latitudinal permafrost in northern China advanced southward at least to ~38–40°N in the east and to ~37–39°N in the west. This represents an advance of about 5–10° of latitude beyond present‐day permafrost limits. The lower limits of elevationally controlled permafrost on the Qinghai–Tibet Plateau and its peripheries were about 1000 m lower: this permafrost was largely continuous during the LLGM. This suggests a cooling of between 4 and 10°C, or more. This paper discusses the extent of permafrost during the LLGM and presents maps that have been constructed on the basis of extensive and integrative analysis of all reliable and pertinent data. The results indicate that the extent of LLGM permafrost in China was between ~3.8 and 4.3×106 km2. This is 80 to 100% more than that of ~2.15×106 km2 in the 1970s, and 120 to ~150% more than that of ~1.75×106 km2 today. 相似文献
58.
We present some results of observations on the X-raytransients XTE J1859+226 and XTE J1118+480 by means of the 0.7-metretelescope at the Kalinenkov Astronomical Observatory of Nikolaev StateUniversity. The observations of XTE J1859+226 were obtained inNovember 1999 and April 2000. The observations of theXTE J1118+480 started in April 2000. The light curves are presented here. 相似文献
59.
Jef Vandenberghe Hugh M. French Aldar Gorbunov Sergei Marchenko Andrey A. Velichko Huijun Jin Zhijiu Cui Tingjun Zhang Xudong Wan 《Boreas: An International Journal of Quaternary Research》2014,43(3):652-666
This paper accompanies a map that shows the extent of permafrost in the Northern Hemisphere between 25 and 17 thousand years ago. The map is based upon existing archival data, common throughout the Northern Hemisphere, that include ice‐wedge pseudomorphs, sand wedges and large cryoturbations. Where possible, a distinction is made between areas with continuous permafrost and areas where permafrost is either spatially discontinuous or sporadic. The associated mean annual palaeo‐temperatures that are inferred on the basis of present‐day analogues increase understanding of the possible changes in permafrost extent that might accompany current global warming trends. Areas with relict permafrost and areas that were formerly exposed due to lower sea level (submarine permafrost) are also mapped. Mapping is mostly limited to lowland regions (areas approximately <1000 m a.s.l.). Striking features that appear from the map are (i) the narrow permafrost zone in North America, which contrasts with the broader LPM permafrost zone in Eurasia (that may be related to different snow thickness or vegetation cover), (ii) the zonal extent of former LPM permafrost (that may reflect sea‐ice distribution), which contrasts with the present‐day pattern of permafrost extent (especially in Eurasia) and (iii) the relatively narrow zones of LPM discontinuous permafrost (that may indicate strong temperature gradients). 相似文献
60.
The coastal zone of the sea is a boundary domain between seawater and land, making most processes within it to show specific features. Seawater can penetrate into aquifers in the land part of the shore through the underwater part of the sea–shore interface and move over considerable distances from the shoreline, mixing with fresh groundwater. This process is of critical importance for the construction of oil and gas pipelines in permafrost areas. 相似文献