全文获取类型
收费全文 | 193篇 |
免费 | 16篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 3篇 |
大气科学 | 21篇 |
地球物理 | 69篇 |
地质学 | 54篇 |
海洋学 | 12篇 |
天文学 | 43篇 |
综合类 | 2篇 |
自然地理 | 7篇 |
出版年
2023年 | 1篇 |
2022年 | 4篇 |
2021年 | 7篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 11篇 |
2017年 | 9篇 |
2016年 | 11篇 |
2015年 | 11篇 |
2014年 | 9篇 |
2013年 | 6篇 |
2012年 | 6篇 |
2011年 | 12篇 |
2010年 | 6篇 |
2009年 | 13篇 |
2008年 | 15篇 |
2007年 | 9篇 |
2006年 | 9篇 |
2005年 | 5篇 |
2004年 | 3篇 |
2003年 | 9篇 |
2002年 | 7篇 |
2001年 | 6篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1984年 | 1篇 |
1978年 | 1篇 |
1976年 | 1篇 |
1973年 | 3篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1970年 | 3篇 |
1969年 | 5篇 |
1965年 | 1篇 |
1962年 | 1篇 |
1960年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有211条查询结果,搜索用时 46 毫秒
61.
Angelo Minissale Mohamed A. Mattash Orlando Vaselli Franco Tassi Ismail N. Al-Ganad Enrico Selmo Nasr M. Shawki Dario Tedesco Robert Poreda Abdassalam M. Ad-Dukhain Mohammad K. Hazzae 《Applied Geochemistry》2007
Most thermal springs of continental Yemen (about 65 emergences at 48 sampling sites) and a couple of fumaroles and boiling water pools have been sampled and analyzed for chemical and isotopic composition in the liquid phase and the associated free-gas phase. Whatever the emergence, all the water discharges have an isotopic signature of meteoric origin. Springs seeping out from high altitudes in the central volcanic plateau show a prevalent Na–HCO3-composition, clearly affected by an anomalous flux of deep CO2 deriving from active hydrothermal systems located in the Jurassic Amran Group limestone sequence and/or the Cretaceous Tawilah Group, likely underlying the 2000–3000 m thick volcanic suite. At lower elevations, CO2 also affects the composition of some springs emerging at the borders of the central volcanic plateau. 相似文献
62.
A finite-volume numerical model is employed to investigate the adaptation of the atmospheric boundary layer to a change in
the underlying surface roughness, such as that existing in the transition from land to the free surface of a water body. Numerical
results are validated by comparison with neutral stratification atmospheric data and compared with the internal boundary-layer
(IBL) heights computed using a number of existing empirical formulae. The numerical analysis allows an extension of the fetch
range in which the existing formulae, calibrated only by comparison with short fetch data, may be applied. An argument is
offered that the spatial variability of the water surface roughness should be also taken into account for the IBL development
over the surface of a water body. 相似文献
63.
Salvatore Giammanco Massimo Ottaviani Enrico Veschetti 《Pure and Applied Geophysics》2007,164(12):2523-2547
Data for major, minor and trace elements in groundwaters from Mt. Etna volcano collected in 1994, 1995 and 1997 were analyzed
using Cluster Analysis (CA). Two groups of sampling sites were identified (named clusters A and B), mainly on the basis of
their different salinity and content of dissolved CO2. The highest levels of both of these parameters were observed in the sites of cluster A, located in the lower south-western
and central eastern flanks of the volcano. For both of the statistical groups CA was repeated, taking into account the mean
values of each parameter in time, and the results allowed us to recognize four distinct groups of parameters for each group
of sites on the basis of their temporal patterns. Four different types of temporal patterns were recognized: concave, convex,
increasing, decreasing. The observed changes were basically interpreted as a result of the different response of dissolved
chemical elements to changes in the aqueous environment and/or in their solubility/mobility in water due to different rates
of input of magmatic gases to Etna’s aquifers. The main changes occurred in 1995, when Etna’s volcanic activity resumed after
a two-year period of rest. The temporal changes of the majority of the studied parameters (water temperature, water conductivity,
Eh, pH, Al, Mg, B, Ca, Cl−, Hg, Mn, Mo, Na, Ni, Se, Si, Sr, Cr Zn and pCO2) were not cluster-dependent, therefore they were not apparently affected by differences in water salinity between the two
groups of sampling sites. A limited number of parameters (Ti, K, Li, HCO3−, As, Fe, SO42−, Cu and V), however, manifested different behaviors, depending on the cluster of sites to which they belonged, thus suggesting
their apparent dependency on water salinity. 相似文献
64.
65.
66.
Anita Mohan Bhola N. Dwivedi Enrico Landi 《Journal of Astrophysics and Astronomy》2000,21(3-4):407-411
Using spectra obtained from the SUMER (Solar Ultraviolet Measurements of Emitted Radiation) spectrograph on the spacecraft
SOHO (Solar and Heliospheric Observatory), we investigate the height dependence of electron density, temperature and abundance
anomalies in the solar atmosphere. In particular, we present the behaviour of the solar FIP effect (the abundance enhancement
of elements with first ionization potential < 10 eV in the corona with respect to photospheric values) with height
above an active region observed at the solar limb, with emphasis on the so-called transition region lines. 相似文献
67.
We present a geoid solution for the Weddell Sea and adjacent continental Antarctic regions. There, a refined geoid is of interest, especially for oceanographic and glaciological applications. For example, to investigate the Weddell Gyre as a part of the Antarctic Circumpolar Current and, thus, of the global ocean circulation, the mean dynamic topography (MDT) is needed. These days, the marine gravity field can be inferred with high and homogeneous resolution from altimetric height profiles of the mean sea surface. However, in areas permanently covered by sea ice as well as in coastal regions, satellite altimetry features deficiencies. Focussing on the Weddell Sea, these aspects are investigated in detail. In these areas, ground-based data that have not been used for geoid computation so far provide additional information in comparison with the existing high-resolution global gravity field models such as EGM2008. The geoid computation is based on the remove–compute–restore approach making use of least-squares collocation. The residual geoid with respect to a release 4 GOCE model adds up to two meters and more in the near-coastal and continental areas of the Weddell Sea region, also in comparison with EGM2008. Consequently, the thus refined geoid serves to compute new estimates of the regional MDT and geostrophic currents. 相似文献
68.
We present some algebraic and numerical simulations of the stable boundary layer. We also discuss the problem of the existence
of a critical Richardson number (Ri), beyond which the turbulence is suppressed. We compare the results of a second-order algebraic model with those of a third-order
numerical model and, to this purpose, numerical simulations of a wind-tunnel flow, which is characterized by various Richardson
numbers, were performed. As far as the second-order model is concerned, solutions, for the Richardson number greater than
any critical value, can be obtained by modifying the time scales of the second-order equation pressure correlation terms in
order to account for a buoyancy damping factor. We show that using a third-order model allows the same results (no critical
Richardson number) to be obtained without modifications to the time scales. It is suggested that the non-locality, accounted
for by the third-order moments, could allow the turbulence to persist also for Ri > 1. 相似文献
69.
Global and regional ocean carbon uptake and climate change: sensitivity to a substantial mitigation scenario 总被引:1,自引:0,他引:1
Marcello Vichi Elisa Manzini Pier Giuseppe Fogli Andrea Alessandri Lavinia Patara Enrico Scoccimarro Simona Masina Antonio Navarra 《Climate Dynamics》2011,37(9-10):1929-1947
Under future scenarios of business-as-usual emissions, the ocean storage of anthropogenic carbon is anticipated to decrease because of ocean chemistry constraints and positive feedbacks in the carbon-climate dynamics, whereas it is still unknown how the oceanic carbon cycle will respond to more substantial mitigation scenarios. To evaluate the natural system response to prescribed atmospheric ??target?? concentrations and assess the response of the ocean carbon pool to these values, 2 centennial projection simulations have been performed with an Earth System Model that includes a fully coupled carbon cycle, forced in one case with a mitigation scenario and the other with the SRES A1B scenario. End of century ocean uptake with the mitigation scenario is projected to return to the same magnitude of carbon fluxes as simulated in 1960 in the Pacific Ocean and to lower values in the Atlantic. With A1B, the major ocean basins are instead projected to decrease the capacity for carbon uptake globally as found with simpler carbon cycle models, while at the regional level the response is contrasting. The model indicates that the equatorial Pacific may increase the carbon uptake rates in both scenarios, owing to enhancement of the biological carbon pump evidenced by an increase in Net Community Production (NCP) following changes in the subsurface equatorial circulation and enhanced iron availability from extratropical regions. NCP is a proxy of the bulk organic carbon made available to the higher trophic levels and potentially exportable from the surface layers. The model results indicate that, besides the localized increase in the equatorial Pacific, the NCP of lower trophic levels in the northern Pacific and Atlantic oceans is projected to be halved with respect to the current climate under a substantial mitigation scenario at the end of the twenty-first century. It is thus suggested that changes due to cumulative carbon emissions up to present and the projected concentration pathways of aerosol in the next decades control the evolution of surface ocean biogeochemistry in the second half of this century more than the specific pathways of atmospheric CO2 concentrations. 相似文献
70.
Domenico Pileggi David Rossi Enrico Lunedei Dario Albarello 《Bulletin of Earthquake Engineering》2011,9(6):1839-1854
The problem of seismic characterization of rock-mass or stiff-soil outcrops by the use of passive seismic prospecting techniques
is discussed. Difficulties in the application of this kind of procedure in the presence of rugged morphology, high surface
wave velocities and low ambient vibration powers, typical of stiff-soil/rock-mass sites are examined. A methodology to face
these problems is here proposed, which is based on the strict synergy of detailed geologic surveys and application of robust
seismic prospecting techniques, jointly considering single-station and multi-station tools. The application of this approach
for the characterization of a number of sites belonging to the Italian Accelerometric Network is described, focusing on two
representative case histories. 相似文献