全文获取类型
收费全文 | 162篇 |
免费 | 7篇 |
国内免费 | 2篇 |
专业分类
测绘学 | 1篇 |
大气科学 | 15篇 |
地球物理 | 44篇 |
地质学 | 46篇 |
海洋学 | 16篇 |
天文学 | 44篇 |
自然地理 | 5篇 |
出版年
2023年 | 1篇 |
2020年 | 2篇 |
2019年 | 1篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 3篇 |
2013年 | 9篇 |
2012年 | 7篇 |
2011年 | 18篇 |
2010年 | 5篇 |
2009年 | 9篇 |
2008年 | 8篇 |
2007年 | 8篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 7篇 |
2003年 | 7篇 |
2002年 | 11篇 |
2001年 | 4篇 |
2000年 | 1篇 |
1998年 | 1篇 |
1996年 | 1篇 |
1995年 | 4篇 |
1994年 | 3篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有171条查询结果,搜索用时 46 毫秒
41.
Removal of Pb^2+, Cu^2+, Zn^2+ and Cd^2+ from aqueous solutions by sorption on a natural phosphate rock (FAP) was investigated. The effects of the contact time and initial metal concentration were examined in the batch method. The percentage sorption of heavy metals from solution ranges generally between 50% and 99%. The amount of sorbed metal ions follows the order Cu〉Pb〉Cd〉Zn. Heavy metal immobilization was attributed to both surface complexation of metal ions on the surface of FAP grains and partial dissolution and precipitation of a heavy metal-containing phosphate. The very low desorption ratio of heavy metals further supports the effectiveness of FAP as an alternative and low-cost material to remove toxic Pb^2+, Cu^2+, Zn^2+ and Cd^2+ from polluted waters. 相似文献
42.
Sandro da Silva Fernandes 《Celestial Mechanics and Dynamical Astronomy》1995,63(3-4):375-408
Expansions of the functions (r/a)cos
jv and (r/a)m
sin
jv of the elliptic motion are extended to highly eccentric orbits, 0.6627 ... <e<1. The new expansions are developed in powers of (e–e*), wheree* is a fixed value of the eccentricity. The coefficients of these expansions are expressed in terms of the derivatives of Hansen's coefficients with respect to the eccentricity. The new expansions are convergent for values of the eccentricity such that |e–e*|<(e*), where the radius of convergence (e*) is the same of the extended solution of Kepler's equation. The new expansions are intrinsically related to Lagrange's series. 相似文献
43.
The effectiveness of high-resolution LiDAR data combined with PSInSAR data in landslide study 总被引:1,自引:0,他引:1
Andrea Ciampalini Federico Raspini William Frodella Federica Bardi Silvia Bianchini Sandro Moretti 《Landslides》2016,13(2):399-410
The spatial resolution of digital elevation models (DEMs) is an important factor for reliable landslide studies. Multi-interferometric techniques such as persistent scatterer interferometric synthetic aperture radar (PSInSAR) are used to evaluate the landslide state of activity and its ground deformation velocity, which is commonly measured along the satellite line of sight (LOS). In order to compare velocities measured by different satellites in different periods, their values can be projected along the steepest slope direction, which is the most probable direction of real movement. In order to achieve this result, DEM-derived products are needed. In this paper, the effectiveness of different DEM resolutions was evaluated in order to project ground deformation velocities measured by means of PSInSAR technique in two different case studies in the Messina Province (Sicily, southern Italy): San Fratello and Giampilieri. Three DEMs were used: (i) a 20-m resolution DEM of the Italian Military Geographic Institute (IGM), (ii) a 2-m resolution DEM derived from airborne laser scanning (ALS) light detection and ranging (LiDAR) data for the San Fratello 2010 landslide, and (iii) a 1-m resolution DEM derived from ALS LiDAR data for the area of Giampilieri. The evaluation of the applied method effectiveness was performed by comparing the DEMs elevation with those of each single permanent scatterer (PS) and projecting the measured velocities along the steepest slope direction. Results highlight that the higher DEM resolution is more suitable for this type of analysis; in particular, the PS located nearby the watershed divides is affected by geometrical problems when their velocities are projected along the steepest slope. 相似文献
44.
Decadal Climatic Anomalies in the Northern Adriatic Sea Inferred from a New Oceanographic Data Set 总被引:1,自引:0,他引:1
Abstract. In 1997, Artegiani et al. depicted for the first time the seasonal climatology of the Adriatic Sea; they used the ATOS data set, formed by 5540 oceanographic stations sampled over this continental basin from 1911 to 1980. Lately, two Italian institutes working on the Adriatic Sea for long time, IBM and IRPEM, merged their recent data sets for the northernmost part of the basin. This yielded 3600 new oceanographic stations, concentrated in an area where 809 ATOS stations were located. The new data were quality checked, and then a seasonal climatology was drawn up as a first analysis step. The new climatology differed significantly from the ATOS results; this could be explained, at least partially, by the climatic changes that have occurred on this area. For example, air temperature increased significantly over northern Italy starting from 1988. Variations of the observed air temperature and Po River runoff qualitatively agree with sea surface temperature and salinity variations. A preliminary computation of heat fluxes based on ECMWF reanalysis confirms an increased heat flux to the Northern Adriatic Sea starting from 1988. 相似文献
45.
Martino Marelli David Salvetti Fabio Gastaldello Simona Ghizzardi Silvano Molendi Andrea De Luca Alberto Moretti Mariachiara Rossetti Andrea Tiengo 《Experimental Astronomy》2017,44(3):297-308
XMM-Newton is the direct precursor of the future ESA ATHENA mission. A study of its particle-induced background provides therefore significant insight for the ATHENA mission design. We make use of ~12 years of data, products from the third XMM-Newton catalog as well as FP7 EXTraS project to avoid celestial sources contamination and to disentangle the different components of the XMM-Newton particle-induced background. Within the ESA R&D AREMBES collaboration, we built new analysis pipelines to study the different components of this background: this covers time behavior as well as spectral and spatial characteristics. 相似文献
46.
Teresa Mineo Simone Lotti Silvano Molendi Simona Ghizzardi 《Experimental Astronomy》2017,44(3):287-296
Soft protons constitute an important source of background in focusing X-ray telescopes, as Chandra and XMM-Newton experience has shown. The optics in fact transmit them to the focal plane with efficiency similar to the X-ray photon one. This effect is a good opportunity to study the environment of the Earth magnetosphere crossed by the X-ray satellite orbits, provided that we can link the spectra detected by the instruments with the ones impacting on the optics. For X-ray photons this link has the form of the so-called response matrix that includes the optics effective area and the energy redistribution in the detectors. Here we present a first attempt to produce a proton response matrix exploiting ray-tracing and GEANT4 simulations with the final aim to be able to analyse XMM-Newton soft proton data and link them to the external environment. If the procedure is found to be reliable, it can be applied to any future X-ray missions to predict the soft particles spectra impacting on the focal plane instruments. 相似文献
47.
David Salvetti Martino Marelli Fabio Gastaldello Simona Ghizzardi Silvano Molendi Andrea De Luca Alberto Moretti Mariachiara Rossetti Andrea Tiengo 《Experimental Astronomy》2017,44(3):309-320
We present an accurate characterization of the particle background behaviour on XMM-Newton based on the entire EPIC archive. This corresponds to the largest EPIC data set ever examined. Our results have been obtained thanks to the collaboration between the FP7 European program EXTraS and the ESA R&D ATHENA activity AREMBES. We used as a diagnostic an improved version of the diagnostic which compares the data collected in unexposed region of the detector with the region of the field of view in the EPIC-MOS. We will show that the in Field-of-View excess background is made up of two different components, one associated to flares produced by soft protons and the other one to a low-intensity background. Its origin needs to be further investigated. 相似文献
48.
49.
ABSTRACTThe critical need for hydrological observations in support of water resources management, particularly during extreme events, has transformed traditional methods of hydrological data management. This transformation has given rise to a framework of e-monitoring the hydrological cycle, the aim of which is to improve understanding of the nature of water. New trends in data science, coupled with increasing technological evolution, make the new generation of data systems more agile and responsive to the needs and expectations for efficient and effective data sharing and service delivery. The WMO Hydrological Observing System was designed around the integration of observations, data exchange, research, data processing, modelling and forecasting, in such a way that societal needs for disaster risk reduction, improved sustainability of environmental resources, climate resilience and economic growth can be effectively met. With its implementation of conceptual functionalities for sustainable data management, the WHOS operational architecture is hydrology’s system for the future. 相似文献
50.
Bonacci S Browne MA Dissanayake A Hagger JA Corsi I Focardi S Galloway TS 《Marine pollution bulletin》2004,49(5-6):445-455
Marine environments are continuously being threatened by a large number of xenobiotics from anthropogenic sources. Even in sparsely populated and relatively pristine areas, such as Antarctica, hazardous chemicals can pose a serious environmental problem. The main aims of the present study were to (1) validate and optimize an analytical technique utilizing a microtitre-plate photometer to ascertain background levels of esterase activities in the Antarctic bivalve Adamussium colbecki, (2) carry out in situ monitoring of esterase activities to assess any potential environmental impacts of the Italian Scientific Antarctic Base "Terra Nova Bay" on the surrounding marine area. Results showed the presence of organophosphorous-sensitive cholinesterase (ChE) and carboxylesterase (CbE) activities in the gills of A. colbecki and optimal assay conditions were comparable with those found for bivalve species from temperate areas. A higher sensitivity of ChE versus acetylthiocholine activity in A. colbecki to chlorpyrifos compared to species from temperate areas may also be inferred. The in situ study indicated no differences in the environmental quality of the three study sites located around the Italian Base. 相似文献