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401.
Martin Brokate Stephen MacCarthy Alexander Pimenov Alexei Pokrovskii Dmitrii Rachinskii 《Environmental Modeling and Assessment》2011,16(4):313-333
Cyclic wetting and drying of soils due to changing weather conditions is characterised by a well-documented hysteresis in
the relationship between the pressure or matric potential and the water content in the soil. Hysteresis manifests itself through
a difference in drying and wetting curves. Its presence suggests that there is dissipation of energy associated with intermittent
wetting and drying of the soil, which can be released in the form of heat. In this paper, we discuss a model for evaluation
of the energy dissipation rate due to soil-moisture hysteresis. The model has three main ingredients: (a) a hysteresis constitutive
relationship between soil-water potential and moisture content in the soil, which is modelled by the Preisach operator; (b)
a lumped form of Darcy’s law assuming that the water flux is proportional to the difference of potentials in the soil and
on its surface; (c) a rainfall term governing the evolution of the outer potential, which is modelled by a periodic forcing
or a Poisson process. We propose a combination of analytic and numerical methods to evaluate the energy dissipation rate and
how it is affected by the variation of rain parameters, such as the frequency of arrivals of rain cells and their shape, intensity
and duration. 相似文献
402.
Gregory E. Schwarz Richard B. Alexander Richard A. Smith Stephen D. Preston 《Journal of the American Water Resources Association》2011,47(5):1151-1172
Schwarz, Gregory E., Richard B. Alexander, Richard A. Smith, and Stephen D. Preston, 2011. The Regionalization of National‐Scale SPARROW Models for Stream Nutrients. Journal of the American Water Resources Association (JAWRA) 47(5):1151‐1172. DOI: 10.1111/j.1752‐1688.2011.00581.x Abstract: This analysis modifies the parsimonious specification of recently published total nitrogen (TN) and total phosphorus (TP) national‐scale SPAtially Referenced Regressions On Watershed attributes models to allow each model coefficient to vary geographically among three major river basins of the conterminous United States. Regionalization of the national models reduces the standard errors in the prediction of TN and TP loads, expressed as a percentage of the predicted load, by about 6 and 7%. We develop and apply a method for combining national‐scale and regional‐scale information to estimate a hybrid model that imposes cross‐region constraints that limit regional variation in model coefficients, effectively reducing the number of free model parameters as compared to a collection of independent regional models. The hybrid TN and TP regional models have improved model fit relative to the respective national models, reducing the standard error in the prediction of loads, expressed as a percentage of load, by about 5 and 4%. Only 19% of the TN hybrid model coefficients and just 2% of the TP hybrid model coefficients show evidence of substantial regional specificity (more than ±100% deviation from the national model estimate). The hybrid models have much greater precision in the estimated coefficients than do the unconstrained regional models, demonstrating the efficacy of pooling information across regions to improve regional models. 相似文献
403.
404.
Clara Illi Josefine Koenigbauer Wolfgang Henrich Laura Fangmann Charlotte Reinhardt Sophia Ossmann Alexander Weichert 《黑龙江环境通报》2023,43(11):1459-1462
Germline pathogenic variants in isocitrate dehydrogenase 1 (IDH1) can lead to a rare neurodevelopmental disorder called metaphyseal chondromatosis with D-2-hydroxyglutaric aciduria, including severe skeletal and cerebral anomalies. To the best of our knowledge, no prenatal case of an IDH1 pathogenic variant has been reported in literature. Somatic sequence variants in IDH1/2 genes are described in distinct cancers, premalignant diseases and rare inherited metabolic disorders. Amniocentesis and further genetic testing including trio exome sequencing were performed due to suspicious findings on a second trimester routine prenatal ultrasound examination. The fetus was found to have growth restriction, cerebral abnormalities (ex vacuo hydrocephalus, cerebellar and vermian hypoplasia, corpus callosum dysgenesis), brachycephaly, narrow chest, persistent left superior vena cava, liver calcifications, hyperechogenic bowel, short tubular bones and joint contractures. A de novo heterozygous variant in the IDH1 gene was detected via trio exome sequencing. The prenatal diagnosis of a de novo pathogenic variant in IDH1 in a fetus with the described phenotype, obtained through trio exome sequencing, helped parents and providers with an informed decision making about pregnancy management. 相似文献
405.
Bauer Tatiana V. Pinskii David L. Minkina Tatiana M. Shuvaeva Victoria A. Soldatov Alexander V. Mandzhieva Saglara S. Tsitsuashvili Victoria S. Nevidomskaya Dina G. Semenkov Ivan N. 《Environmental geochemistry and health》2022,44(2):335-347
Environmental Geochemistry and Health - Modeling metal sorption in soils is of great importance to predict the fate of heavy metals and to assess the actual risk driven from pollution. The present... 相似文献
406.
Kinetics of microbial landfill methane oxidation in biofilters 总被引:1,自引:0,他引:1
A methane oxidizing biofilter system fitted to the passive venting system of a harbor sludge landfill in Germany was characterized with respect to the the methanotrophic population, methane oxidizing capacity, and reaction kinetics. Methanotrophic cell counts stabilized on a high level with 1.3 x 10(8) to 7.1 x 10(9) cells g dw(-1) about one year after first biofilter operation, and a maximum of 1.2 x 10(11) cells g dw(-1). Potential methane oxidizing activity varied between 5.3 and 10.7 microg h(-1) g dw(-1). Cell numbers correlated well with methane oxidation activities. Extrapolation of potential activities gave methane removal rates between 35 and 109 g CH4 h(-1) m(-3), calculated for 30 degrees C. Optimum temperature was 38 degrees C for freshly sampled biofilter material and 22 degrees C for a methanotrophic enrichment culture grown at 10 degrees C incubation temperature. Substrate kinetics revealed the presence of a low-affinity methane oxidizing community with a high Vmax of 1.78 micromol CH4 h(-1) g ww(-1) and a high K(M) of 15.1 microM. K(MO2) for methane oxidation was 58 microM. No substantial methane oxidizing activity was detected below 1.7-2.6 vol.-% O2 in the gaseous phase. Methane deprivation led to a decrease in methane oxidation activity within 5-9 weeks but could still be detected after 25 weeks of substrate deprivation and was fully restored within 3 weeks of continuous methane supply. Very high salt loads are leached from the novel biofilter material, expanded clay, yielding electric conductivity values of up to 15 mS cm(-1) in the leachate. Values > 6 mS cm(-1) were shown to depress methane consumption. Water retention characteristics of the material proved to be favourable for methane oxidizing systems with a gas permeable volume of 78% of bulk volume at field capacity water content. Correspondingly, no influence of water content on methane oxidation activity could be detected at water contents between 2.5 and 20 vol.-%. 相似文献
407.
408.
J.L.T. Pestana A.C. Alexander J.M. Culp D.J. Baird A.J. Cessna A.M.V.M. Soares 《Environmental pollution (Barking, Essex : 1987)》2009,157(8-9):2328-2334
Structural and functional responses of a benthic macroinvertebrate assemblage to pulses of the insecticide imidacloprid were assessed in outdoor stream mesocosms. Imidacloprid pulses reduced invertebrate abundance and community diversity in imidacloprid-dosed streams compared to control streams. These results correlated well with effects of imidacloprid on leaf litter decomposition and feeding rates of Pteronarcys comstocki, a stonefly, in artificial streams. Reductions in oxygen consumption of stoneflies exposed to imidacloprid were also observed in laboratory experiments. Our findings suggest that leaf litter degradation and single species responses can be sensitive ecotoxicological endpoints that can be used as early warning indicators and biomonitoring tools for pesticide contamination. The data generated illustrates the value of mesocosm experiments in environmental assessment and how the consideration of functional and structural endpoints of natural communities together with in situ single species bioassays can improve the evaluation and prediction of pesticide effects on stream ecosystems. 相似文献
409.
C. Alexander Brownlow 《Conservation biology》1996,10(2):390-396
Recent publications have reaffirmed that the red wolf ( Canis rufus ) is a hybrid of the coyote and the gray wolf. Besides the implications these results will likely have for future conservation efforts and allotment of resources through the Endangered Species Act for recovery of the red wolf, it is likely that broader consequences will be felt throughout the conservation community as species come under the scrutiny of a more powerful means of taxonomic identification. As molecular technology is refined in its ability to resolve taxonomic histories and uncertainties, it is likely that hybridization event(s) will be recognized in more species. This may be of particular importance for large carnivores, whose small population sizes make them susceptible to hybridization episodes with closely related, sympatric species. Because of negative perceptions, powerful antipredator advocates, conservation and resource constraints, and an enigmatic hybrid policy within the Endangered Species Act, how red-wolf taxonomy is decided by the U.S. Fish and Wildlife Service may affect the future of large carnivores in general. 相似文献
410.
David Alexander 《Disasters》1997,21(4):284-304
As part of a series of papers to mark the 21st year of publication of Disasters, it is opportune to consider some of the changes that have occurred in the field it has covered so diligently for the last two decades. The paper begins with a brief review of the major natural disasters during this period and assesses their impact. It then considers the problem of how to define two key concepts: natural disaster and vulnerability, which remains an open question. The latter is one of the key determinants of the former. Next comes a review of what has occurred in the disasters field since the journal began publication, including some notes on the rise in vulnerability, the information technology revolution and the dilemmas of hazard mitigation. The following two sections assess, respectively, what hoped-for developments did not occur during the period studied and what assets were lost in the name of progress. For example, on the theoretical front, academic over-specialisation has predominated, while on the practical side there has been insufficient transfer of technology to where it is needed. The paper concludes that analyses of disaster need to become more sophisticated and multi-disciplinary and must take account of several forms of context within which developments take place. 相似文献