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151.
Offshore–inshore and vertical distributional patterns of heteropod mollusks off leeward Oahu, Hawaii
Roger R. Seapy 《Marine Biology》2008,154(6):985-995
Replicated zooplankton tows were taken during day and night periods at neritic (1 nmi offshore) and oceanic (5 and 15 nmi
offshore) stations off the leeward side of Oahu, Hawaii during fall (September) and spring (April). Plankton samples were
obtained with a 1-m2 MOCNESS net system towed obliquely through seven depth strata to 80 m (neritic station) and eight depth strata to 200 m (oceanic
stations). Five more species were collected in April (17) than in September (12). During both months the number of species
decreased from the 15 to the 1 nmi stations; from 11 to 9 in September and 15 to 11 in April. Species diversity, as measured
by species accumulation (rarefaction) curves, was higher at the 15 than the 1 nmi stations during both months. Total nighttime
water column density in April was about double that in September. In September, the density decreased sevenfold from the 15
to 1 nmi stations, but in April densities were comparable among the three stations; mainly as a result of the shoreward increase
in density of Atlanta plana. The most abundant species in both months were A. plana, A. lesueuri, A. inflata, A. peroni, and Protatlanta souleyeti, which in combination accounted for 93% (September) and 91% (April) of the total nighttime water column densities. The vertical
ranges of six species were limited to the upper 100 m, and nocturnal migration was suggested for two (A. helicinoides during both months and A. turriculata in April). The ranges of the remaining 11 species extended to 160 or 200 m, and among them nocturnal migration was suggested
for five (A. plana, A. meteori and Pterotrachea hippocampus during both months, and A. peroni and Protatlanta soueleyti in April). 相似文献
152.
Zisheng Xing Charles P.-A. Bourque Fan-Rui Meng Roger M. Cox D. Edwin Swift Tianshan Zha Lien Chow 《Ecological modelling》2008
In this paper we present a simple hybrid gap-filling model (GFM) designed with a minimum number of parameters necessary to capture the ecological processes important for filling medium-to-large gaps in Flux data. As the model is process-based, the model has potential to be used in filling large gaps exhibiting a broad range of micro-meteorological and site conditions. The GFM performance was evaluated using “Punch hole” and extrapolation experiments based on data collected in west-central New Brunswick. These experiments indicated that the GFM is able to provide acceptable results (r2 > 0.80) when >500 data points are used in model parameterization. The GFM was shown to address daytime evolution of NEP reasonably well for a wide range of weather and site conditions. An analysis of residuals indicated that for the most part no obvious trends were evident; although a slight bias was detected in NEP with soil temperature. To explore the portability of the GFM across ecosystem types, a transcontinental validation was conducted using NEP and ancillary data from seven ecosystems along a north-south transect (i.e., temperature–moisture gradient) from northern Europe (Finland) to the Middle East (Israel). The GFM was shown to explain over 75% of the variability in NEP measured at most ecosystems, which strongly suggests that the GFM maybe successfully applied to forest ecosystems outside Canada. 相似文献
153.
The effects of landscape structure on space competition and alternative stable states 总被引:1,自引:0,他引:1
Many species that compete for space live on heterogeneous landscapes and interact at local scales. The quality, amount, and structure of landscapes may have considerable impact on the ability of species to compete or coexist, yet basic models of space competition do not include that level of detail. We model space competition between two species with positive feedback through recruitment facilitation, which creates the potential for alternative stable states to occur. We compare the predictions of a spatially implicit model with a simulation model that includes explicit space and landscape structure. We create structured landscapes in which we specify the amount of habitat and degree of fragmentation and ask how landscape structure, dispersal strategy, and scale affect the presence of alternative stable states, or bistability. We find that structured landscapes can reduce the range of parameter values that lead to bistability in our model, but they do not eliminate bistability. The type of landscape and the dispersal distance for each species also influence the amount of environmental change needed for abrupt community shifts to occur. Coexistence of the two competitors is possible under certain conditions when connectivity is low. Consequently, landscape structure may lead to considerable disparity between the predictions of simple models and actual dynamics on complex landscapes during environmental change. 相似文献
154.
Use of structured expert judgment to forecast invasions by bighead and silver carp in Lake Erie
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Marion E. Wittmann Roger M. Cooke John D. Rothlisberger Edward S. Rutherford Hongyan Zhang Doran M. Mason David M. Lodge 《Conservation biology》2015,29(1):187-197
Identifying which nonindigenous species will become invasive and forecasting the damage they will cause is difficult and presents a significant problem for natural resource management. Often, the data or resources necessary for ecological risk assessment are incomplete or absent, leaving environmental decision makers ill equipped to effectively manage valuable natural resources. Structured expert judgment (SEJ) is a mathematical and performance‐based method of eliciting, weighting, and aggregating expert judgments. In contrast to other methods of eliciting and aggregating expert judgments (where, for example, equal weights may be assigned to experts), SEJ weights each expert on the basis of his or her statistical accuracy and informativeness through performance measurement on a set of calibration variables. We used SEJ to forecast impacts of nonindigenous Asian carp (Hypophthalmichthys spp.) in Lake Erie, where it is believed not to be established. Experts quantified Asian carp biomass, production, and consumption and their impact on 4 fish species if Asian carp were to become established. According to experts, in Lake Erie Asian carp have the potential to achieve biomass levels that are similar to the sum of biomasses for several fishes that are harvested commercially or recreationally. However, the impact of Asian carp on the biomass of these fishes was estimated by experts to be small, relative to long term average biomasses, with little uncertainty. Impacts of Asian carp in tributaries and on recreational activities, water quality, or other species were not addressed. SEJ can be used to quantify key uncertainties of invasion biology and also provide a decision‐support tool when the necessary information for natural resource management and policy is not available. El Uso de Juicio Experto Estructurado para Predecir Invasiones de Carpas Asiáticas en el Lago Erie 相似文献
155.
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157.
Bernardino Murilo Martins Alves Paulo Roger Lopes de Santo Fernanda Benedet Niemeyer Júlia Carina Leal Rafael Marques Pereira 《Environmental science and pollution research international》2021,28(22):27655-27665
Environmental Science and Pollution Research - Imidacloprid is one of the most commercialized insecticides in agriculture in the world, with a broad spectrum of action. However, little is known... 相似文献
158.
Tony Svejcar Chad Boyd Kirk Davies Matthew Madsen Jon Bates Roger Sheley Clayton Marlow David Bohnert Mike Borman Ricardo Mata-Gonzàlez John Buckhouse Tamzen Stringham Barry Perryman Sherman Swanson Kenneth Tate Mel George George Ruyle Bruce Roundy Chris Call Kevin Jensen Karen Launchbaugh Amanda Gearhart Lance Vermeire John Tanaka Justin Derner Gary Frasier Kris Havstad 《Environmental management》2014,53(6):1035-1038
In a previous article, Beschta et al. (Environ Manag 51(2):474–491, 2013) argue that grazing by large ungulates (both native and domestic) should be eliminated or greatly reduced on western public lands to reduce potential climate change impacts. The authors did not present a balanced synthesis of the scientific literature, and their publication is more of an opinion article. Their conclusions do not reflect the complexities associated with herbivore grazing. Because grazing is a complex ecological process, synthesis of the scientific literature can be a challenge. Legacy effects of uncontrolled grazing during the homestead era further complicate analysis of current grazing impacts. Interactions of climate change and grazing will depend on the specific situation. For example, increasing atmospheric CO2 and temperatures may increase accumulation of fine fuels (primarily grasses) and thus increase wildfire risk. Prescribed grazing by livestock is one of the few management tools available for reducing fine fuel accumulation. While there are certainly points on the landscape where herbivore impacts can be identified, there are also vast grazed areas where impacts are minimal. Broad scale reduction of domestic and wild herbivores to help native plant communities cope with climate change will be unnecessary because over the past 20–50 years land managers have actively sought to bring populations of native and domestic herbivores in balance with the potential of vegetation and soils. To cope with a changing climate, land managers will need access to all available vegetation management tools, including grazing. 相似文献
159.
Wild and Scenic Rivers provide a host of psychological, social, ecological, and economic benefits to local communities. In
this study, we use data collected from recreational users of two Wild and Scenic Rivers to examine perceptions of the benefits
provided by the rivers to local communities. Our purposes are (1) to determine if similar perceptions of community benefits
exist across the two rivers, (2) to determine if individuals’ proximity to the rivers are related to the benefits they perceive,
(3) to determine if individuals’ prior recreation experience on the river is related to variations in perceived benefits,
(4) to determine if users’ sociodemographic characteristics are related to perceived community benefits, and (5) to determine
if the influence of these characteristics on perceived community benefits is similar across the two resource areas. Perceived
benefits were found to be analogous across both rivers as individuals consistently ranked ecological/affective benefits as
well as tangible benefits similarly. Recreationists living further from the river ranked ecological and affective benefits
as significantly less important than those individuals living closer to the river. Women perceived the community benefits
produced by the resource areas to be significantly more important when compared to men. Significant relationships were also
found between perceived benefits and recreationists’ previous use of the river, their age, and their level of education. With
the exception of resource proximity and prior use history, the effects of user characteristics on perceived community benefits
were not statistically different across the two rivers. These findings imply similar patterns of perceived community benefits
exist across distinct resource areas and that the relationships between user characteristics and perceived benefits are also
similar across the study rivers. 相似文献
160.
Deterministic, size-structured models are widely used to describe consumer-resource interactions. Such models typically ignore potentially large random variability in juvenile development rates. We present simple representations of this variability and show five approaches to calculating the model parameters for Daphnia pulex interacting with its algal food. Using our parameterized models of growth variability, we investigate the robustness of a recently proposed stabilizing mechanism for Daphnia populations. Growth rate variability increases the range of enrichments over which small-amplitude cycles or quasi-cycles occur, thus increasing the plausibility that the underlying mechanism contributes to the prevalence of small-amplitude cycles in the field and in experiments. More generally, our approach allows us to relate commonly available information on variance of development times to population stability. 相似文献