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441.
Rossano Piazza Ana Carolina Ruiz-Fernández Mauro Frignani Roberta Zangrando Luca Giorgio Bellucci Ivo Moret Federico Páez-Osuna 《Environmental Geology》2008,54(7):1537-1545
Concentrations of polychlorinated biphenyls (PCBs) and polycyclic aromatic hydrocarbons (PAHs) were measured in 13 surficial
sediment samples collected at three lacustrine locations in the surroundings of Mexico City and four coastal areas of the
States of Sinaloa, Sonora, Oaxaca and Veracruz. Total PCB concentrations span the interval 3.18–621 ng g−1. The highest values (63.7–621 ng g−1) were found in Mexico City, which is a highly anthropogenically impacted area, whereas low concentrations (3.18–12.9 ng g−1) were characteristic of seven places, some of them subject to intense hydrodynamics. In these latter cases, values increase
by 18–73 times if normalised against the fine fraction (silt plus clay) content in sediment. Two samples from Mexico City
exceed the ERM (Effect Range Median) guidelines and are likely to cause adverse effects. Samples contain only lower chlorinated
PCBs (mainly 2-, 3- and 4-CB), thus suggesting that the most used PCB commercial mixture was Aroclor 1242. The homologue composition
of the sample taken close to the nuclear power plant of Laguna Verde is identical to this commercial mixture. PAHs in the
same samples have relatively low concentrations (14.9–287 ng g−1), well below ERL (Effect Range Low) guidelines. The composition of PAH mixtures accounts for the influence of both petrogenic
and pyrolitic sources, with these latter prevailing at some places in Mexico City. 相似文献
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447.
Fiorani Luca Santoro Simone Parracino Stefano Maio Giovanni Nuvoli Marcello Aiuppa Alessandro 《Natural Hazards》2016,83(1):21-29
Volcanic gases give information on magmatic processes. In particular, anomalous releases of carbon dioxide precede volcanic eruptions. Up to now, this gas has been measured in volcanic plumes with conventional measurements that imply the severe risks of local sampling and can last many hours. For these reasons and for the great advantages of laser sensing, the thorough development of volcanic lidars has been undertaken at ENEA (Italian National Agency for New Technologies, Energy and Sustainable Economic Development). In fact, lidar profiling allows one to scan remotely volcanic plumes in a fast and continuous way, and with high spatial and temporal resolution. A differential absorption lidar instrument will be presented in this paper: BILLI (BrIdge voLcanic LIdar). It is based on injection-seeded Nd:YAG laser, double-grating dye laser, difference frequency mixing and optical parametric amplifier. BILLI is funded by the ERC (European Research Council) project BRIDGE (BRIDging the gap between Gas Emissions and geophysical observations at active volcanos). It scanned the gas emitted by Pozzuoli Solfatara (Naples, Italy) and Stromboli Volcano (Sicily, Italy) during field campaigns carried out from October 13 to 17, 2014, and from June 24 to 29, 2015, respectively. Carbon dioxide concentration maps were retrieved remotely in few minutes in the crater areas. To our knowledge, it is the first time that carbon dioxide in a volcanic plume is retrieved by lidar. This result represents the first direct measurement of this kind ever performed on active volcanos and shows the high potential of laser remote sensing in early detection of volcanic hazard. 相似文献
448.
Livelihoods, fire and policy in eastern Indonesia 总被引:2,自引:0,他引:2
Indonesian legislation calls for a zero-burning policy. This approach to fire management is largely in response to significant negative impacts on the economy and the environment, not only in Indonesia but also the neighbouring region, that result annually from peat fires in Kalimantan and Sumatra. In this context, the present paper investigates the local use and management of fire in Flores and Sumba islands in eastern Indonesia. Our appraisals show that people's livelihoods depend on fire to maintain grasslands and, therefore, that the national policy and legislation for zero-burning is inappropriate and needs to be revised. This follows from the fact that not all fires cause damage and are unwanted. Through a series of rapid rural appraisal interviews, we found that the fires in grasslands are often lit intentionally to maintain the grasslands that local people use to sustain a variety of livelihood activities such as cattle rearing, hunting and farming. Although fires can damage or destroy remnant dry forests in eastern Indonesia, in order to be effective, future policy formulations need to account for this human livelihood dimension and the geographic variation in fuels, climate and land use. 相似文献
449.
Territorial disparities, natural resource distribution, and land degradation: a case study in southern Europe 总被引:1,自引:0,他引:1
The aim of this paper is to analyse the territorial disparities in some socio-economic and environmental factors involved
in land degradation (LD) processes in a dry Mediterranean region. A simplified framework in which ecological and economic
factors may increase inequality in natural resource distribution along the elevation gradient and accelerate LD is illustrated.
To test at a local scale if territorial disparities observed in such factors have increased in the last period, we studied
changes in LD sensitivity over thirty years in Latium, central Italy, a region prone to soil degradation phenomena. An estimate
of LD sensitivity at the municipality level was obtained through a synthetic index (ISD) composed by three partial indicators
analysing respectively climate and soil conditions (CLI), land use characteristics (LAN), and human pressure (POP). ISD and
the three partial indicators were computed separately for 1970 and 2000. The divergence in LD sensitivity among coastal and
inland areas significantly increased over the study period. In the former zones, median ISD increased with a reduction in
score variability among municipalities; the reverse pattern was observed in the latter zones. Differences in ISD score among
the elevation gradient are especially due to human factors affecting land use changes and agriculture intensification. New
findings to be achieved in the context of human impacts on the environment as an original contribution to the study of LD
at a local scale were finally delineated. 相似文献
450.
In this paper, a scenario for the early evolution of the Jurassic oceanic Liguria-Piemonte basin is sketched. For this purpose,
four selected examples of ophiolite sequences from the Northern Apennines and Corsica are described and analyzed. In the External
Ligurian units (Northern Apennines), the ocean–continent transition of the Adria plate was characterized by a basement made
up of subcontinental mantle and lower continental crust, covered by extensional allochthons of upper crust. Both, the basement
rocks and the extensional allochthons are cut by basaltic dikes and covered by basalts and pelagic deposits. The conjugate
ocean–continent transition of the Corsica margin, represented by the Balagne nappe (Corsica), was composed of mantle peridotites
and gabbros covered by basaltic flows and minor breccias, that in addition include continent-derived clasts. By contrast,
the innermost (i.e., closest to the ocean) preserved area observed in the Internal Ligurian (Northern Apennines) and Inzecca
(Corsica) units consists of former morphological highs of mantle peridotites and gabbros, bordered by small basins where the
basement is covered by a volcano-sedimentary complex, characterized by ophiolitic breccias and cherts interlayered with basaltic
flows. The overall picture resulting from our reconstructions suggests an asymmetric architecture for the Liguria-Piemonte
basin with a central area bounded by two different transition zones toward the continental margins. This architecture can
be interpreted as the result of a rifting process whose development includes a final stage characterized by passive, asymmetric
extension of the lithosphere along an east-dipping detachment fault system. 相似文献