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31.
Side-by-side comparisons of polycyclic aromatic hydrocarbon (PAH) concentrations in resident blue mussels (Mytilus trossulus) and in semi-permeable membrane devices (SPMDs) were made at four sites in Prince William Sound, Alaska. SPMDs were deployed for approximately 30 days on the surface of the beach sediment at three tidal elevations on each shore and in 0.5 m deep open pits in the middle intertidal zone. Total PAH (TPAH) concentrations in mussels and in SPMDs were correlated, but the PAH compositions were different. The lower molecular weight PAH were relatively more abundant in the SPMDs than in the mussels at oiled and HA sites. TPAH concentrations in SPMDs deployed in pits and mussels collected adjacent to those pits at oiled sites were higher than in SPMDs and mussels from non-pitted SPMD locations approximately 3-15 m from the pits. Pitting released buried oil making its PAH bioavailable. SPMDs deployed in the supratidal zone (+4.0 m tidal elevation) were exposed to atmospheric contaminants for a large fraction of the deployment time and accumulated primarily pyrogenic (combustion-sourced) PAH from the atmosphere. The SPMD strips supplied by the manufacturer contained significant amounts (approximately 125 ng/strip) of primarily alkylated 2-3 ring PAH. These blank levels make SPMDs unsuitable for shoreline assessments when environmental PAH concentrations are low. Consequently, where available, mussels are recommended for use in assessments of the bioavailability of buried oil residues sequestered in intertidal sediments following an oil spill. Mussels are the preferred monitoring tool when the assessments involve food-chain effects. At locations where the absence of mussels necessitates the use of SPMDs or other passive sampling devices, their limitations need to be carefully considered in the interpretation of results. 相似文献
32.
Following the Amoco Cadiz crude oil spill in March 1978, marine animals in coastal and estuarine environments along the north shore of Brittany, France became heavily contaminated with crude oil. The resident benthic fauna in the oil-impacted area which survived the spill were severely stressed by the pollution. The objectives of our investigation were to document long-term trends in petroleum hydrocarbon contamination and sublethal stress in oysters and plaice from the estuaries, Aber Benoit and Aber Wrac'h. Oysters in the estuaries accumulated aliphatic and aromatic petroleum hydrocarbons to high levels and remained heavily contaminated for the duration of the 27 month investigation. Plaice, on the other hand, retained only low concentrations of petroleum hydrocarbons in muscle and liver tissue. Nevertheless, the oysters exhibited very few histopathologic and biochemical responses to the oil, whereas the plaice from the estuaries exhibited a variety of sublethal histopathologic and biochemical alterations. 相似文献
33.
The hydrocarbon composition of seawater samples collected within a subsurface oil-rich layer in the southwest North Atlantic Ocean (Sargasso Sea) during February–March, 1978, has been examined in detail. Chromatograms generated through gas chromatographs/mass spectrometry (GC/MS) analyses of saturated and aromatic hydrocarbons are characterized by a narrow unresolved envelope (UCM or unresolved complex mixture) containing isoprenoids as major resolved peaks, suggesting a petroleum source which has undergone moderate biodegradative weathering. Distributions of terpanes, steranes and polycyclic aromatic hydrocarbons corroborate the inferred fossil origin. Stable carbon isotopic compositions (δ13C) suggest that the source of these hydrocarbons is enriched in 13C in comparison with most petroleums. The results support the previous suggestions (Harvey et al., 1979) that this layer is part of a massive submarine oil seep originating somewhere on the Venezuelan shelf, although its origin cannot be attributed to seepage of a specific oil formation. 相似文献
34.
C. Boehm H. Mathis J. Devriendt J. Silk 《Monthly notices of the Royal Astronomical Society》2005,360(1):282-287
We address the degree and rapidity of generation of small-scale power over the course of structure formation in cosmologies where the primordial power spectrum is strongly suppressed beyond a given wavenumber. We first summarize the situations where one expects such suppressed power spectra and point out their diversity. We then employ an exponential cut-off, which characterizes warm dark matter (WDM) models, as a template for the shape of the cut-off and focus on damping scales ranging from 106 to 109 h −1 M⊙ . Using high-resolution simulations, we show that the suppressed part of the power spectrum is quickly (re)generated and catches up with both the linear and the non-linear evolution of the unsuppressed power spectrum. From z = 2 onwards, a power spectrum with a primordial cut-off at 109 h −1 M⊙ becomes virtually indistinguishable from an evolved cold dark matter (CDM) power spectrum. An attractor such as that described in Zaldarriaga, Scoccimarro & Hui for power spectra with different spectral indices also emerges in the case of truncated power spectra. Measurements of z ∼ 0 non-linear power spectra at ∼100 h −1 kpc cannot rule out the possibility of linear power spectra damped below ∼109 h −1 M⊙ . Therefore, WDM or scenarios with similar features should be difficult to exclude in this way. 相似文献
35.
Alexandria B. Boehm Kevan M. Yamahara Sarah P. Walters Blythe A. Layton Daniel P. Keymer Rachelle S. Thompson Karen L. Knee Matt Rosener 《Estuaries and Coasts》2011,34(5):925-936
This study quantifies dissolved inorganic nitrogen (DIN), soluble reactive phosphorous (SRP), and microbial pollutant inputs
to a tropical embayment, Hanalei Bay, Kaua'i, Hawai'i from rural watersheds during two field excursions during non-storm conditions.
We employ land cover analysis and a suite of nucleic acid fecal source tracking markers (host-specific Bacteroidales and human enterovirus) to identify sources of pollutants to the bay. The highest concentrations of DIN and SRP are in streams
draining watersheds with large areas of cultivated land, suggesting fertilizer is a source of these nutrients to the streams
and coastal waters. Pollutant areal loading correlates with the fractions of urban and cultivated land cover. Microbial source
tracking indicates the presence of human, pig, and ruminant feces in the streams. This work provides preliminary evidence
that human development affects loading of DIN, SRP, and microbial pollutants to tropical coastal waters; further study is
needed to confirm this. Additionally, results point to a mix of microbial pollutant sources. 相似文献
36.
Assessment of ECMWF-derived tropospheric delay models within the EUREF Permanent Network 总被引:1,自引:0,他引:1
The Global Positioning System (GPS) observations from the EUREF Permanent Network (EPN) are routinely analyzed by the EPN
analysis centers using a tropospheric delay modeling based on standard pressure values, the Niell Mapping Functions (NMF),
a cutoff angle of 3° and down-weighting of low elevation observations. We investigate the impact on EPN station heights and
Zenith Total Delay (ZTD) estimates when changing to improved models recommended in the updated 2003 International Earth Rotation
and Reference Systems Service (IERS) Conventions, which are the Vienna Mapping Functions 1 (VMF1) and zenith hydrostatic delays
derived from numerical weather models, or the empirical Global Mapping Functions (GMF) and the empirical Global Pressure and
Temperature (GPT) model. A 1-year Global Positioning System (GPS) data set of 50 regionally distributed EPN/IGS (International
GNSS Service) stations is processed. The GPS analysis with cutoff elevation angles of 3, 5, and 10° revealed that changing
to the new recommended models introduces biases in station heights in the northern part of Europe by 2–3 mm if the cutoff
is lower than 5°. However, since large weather changes at synoptic time scales are not accounted for in the empirical models,
repeatability of height and ZTD time series are improved with the use of a priori Zenith Hydrostatic Delays (ZHDs) derived
from numerical weather models and VMF1. With a cutoff angle of 3°, the repeatability of station heights in the northern part
of Europe is improved by 3–4 mm. 相似文献
37.
The Acoustic Tracking Array Platform (ATAP) is a marine science programme that monitors the movements and migrations of inshore marine animals along the South African coastline. Acoustically tagged animals are monitored by an expanded network of approximately 100 automated data-logging acoustic receivers moored at strategic node sites, from Cape Point in the west to the South Africa–Mozambique border in the east. During five years since its inception, in 2011, the ATAP has achieved outstanding progress in terms of the numbers of animals and the variety of species tagged. To date, the ATAP has yielded over 2.6 million detections from more than 700 acoustically tagged animals, representing 27 different species from 20 families, including the African penguin Spheniscus demersus, fishery-at-risk species (e.g. dusky kob Argyrosomus japonicus) and iconic elasmobranchs (e.g. white shark Carcharodon carcharias). Following a period of considerable equipment loss in 2014, refinement of the receiver network was required and the deeper receivers at each site were decommissioned without influencing the integrity of the nationwide array. The platform, managed by the South African Institute for Aquatic Biodiversity, ultimately represents a low-cost method of collecting long-term data that currently benefits approximately 25 researchers from 14 organisations. Case studies are presented to expose the opportunities provided by the ATAP, which will undoubtedly yield new discoveries and provide a greater understanding of the movement patterns and migrations of a wide variety of inshore marine and estuary-associated species. 相似文献
38.
Eric A. Crecelius John H. Trefry Margarete S. Steinhauer Paul D. Boehm 《Environmental Geology》1991,18(1):71-79
Increased development and changing climate have enhanced global interest in the Arctic Ocean and adjacent seas. Using a large, 3-yr data base, we have determined the distribution of trace metals in sediments from the inner shelf of the western Beaufort Sea. Metal concentrations in these sediments reflect pristine conditions, consistent with those for most coastal areas in the Arctic and with predictions based on average continental crust. Geographic variations in metal values are primarily related to sediment grainsize distribution. However, grain-size patterns are a complex function of several variables including source areas, ice and water movement, as well as physical and chemical weathering. Future identification of any metal contamination in Beaufort Sea sediments will be simplified by understanding the predictable natural patterns. 相似文献
39.
40.
Nicholas B. Handler Adina Paytan Christopher P. Higgins Richard G. Luthy Alexandria B. Boehm 《Estuaries and Coasts》2006,29(5):860-870
To elucidate relationships between land cover and water quality along the central California coast, we collected monthly samples
from 14 coastal waterway outlets representing various degrees of human development. Sites were distributed between three salinity
categories, freshwater, estuarine, and marine, to better understand land cover-water quality relationships across a range
of coastal aquatic ecosystems. Samples were analyzed for fecal indicator bacteria (FIB), dissolved nutrients, stable nitrogen
isotopes in particulate organic matter, and chlorophylla (chla). Sediment samples from 11 sites were analyzed for the concentration of the anthropogenic organic contaminant perfluorooctane
sulfonate and its precursors (ΣPFOS). While the data indicated impairment by nutrient, microbial, and organic contaminants
at both agricultural and urban sites, the percentage of agricultural land cover was the most robust indicator of impairment,
showing significant correlations (p<0.05) to FIB, nutrient, chla, and ΣPFOS levels. FIB densities were strongly influenced by salinity and were highest at sites dominated by agriculture
and urbanization. Nutrient levels and chla correlated to both agricultural and urban land use metrics as well. Positive correlations among FIB, nutrients, chla, and ΣPFOS suggest a synergy between microbial, nutrient, and organic pollution. The results emphasize the importance of
land management in protecting coastal water bodies and human health, and identify nutrient, microbial, and organic pollution
as prevalent problems in coastal California water bodies. 相似文献