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191.
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At 8 wk intervals, from December 1975 through March 1978, we took a census of the infaunal benthic invertebrates at a natural petroleum seep near Santa Barbara, California, USA and at an area nearby where no fresh petroleum occurred in the sediments. Both sites had in common 72% of the populations representing over 90% of the individuals, strongly suggesting that the two sites are part of the same community. At the petroleum seep there were higher densities of individuals in many populations (60%), but no dramatic difference in diversity (Shannon-Wiener or dominance-diversity). The seep populations tended to be more variable from one sampling period to the next, possibly due, at least in part, to large larval settlements there. The most abundant populations at the seep site were dominated by deposit feeders (14 of the 15 species considered), especially oligochaetes which are extremely rare at the comparison site. The discussion includes a hypothesis of trophic enrichment of the seep populations by bacterial growth stimulated by fresh petroleum. 相似文献
194.
Invertebrates harbouring endosymbiotic chemoautotrophic bacteria are widely distributed in a variety of reducing marine habitats,
including deep-sea hydrothermal vents. Bathymodiolids are dominants of the biomass at geochemically distinct vent sites of
the Mid Atlantic Ridge (MAR) and thus are good candidates to study biological processes in response to site-specific conditions.
To satisfy their nutritional requirements, these organisms depend to varying extent on two types of chemoautotrophic symbionts
and on filterfeeding. The quantitative relationships of the nutritional modes are poorly understood. Using enzyme cytochemistry,
electron microscopy and X-ray microanalysis, the structural and functional aspects of the cellular equipment necessary for
lysosomal digestion was studied. We provide evidence for the following: (1) the basis of intracellular digestion of symbionts
in Bathymodiolus azoricus from two geochemically distinct vent sites was not mainly in the large lysosomal bodies as previously thought (based on the
membranous content resembling bacteria); (2) senescent bacteria are autolysed, possibly by bacterial acid phosphatase, that
is more likely a cell cycling of the symbionts rather than an active lysosomal digestion by the host; (3) the consistent absence
of hydrolases may indicate the improper use of the name “lysosome” for large vesicles at the base of the gill bacteriocytes
(4) nutrient transfer in B. azoricus, therefore, may more likely be accomplished through leaking of metabolites from the symbiont to the host, not excluding lysosomal
resorption of dead bacteria as an auxiliary strategy for organic molecule transfer; (5) evidence is provided for microvillar
transfer of substances from the seawater that may indicate filter-feeding, in non-symbiotic ciliated gill cells of mussels
from Lucky Strike; (6) two types of lysosomal vesicles can be distinguished in digestive cells based on their enzymatic content
and their elemental composition. 相似文献
195.
Katrina Davis Marit Kragt Stefan Gelcich Steven Schilizzi David Pannell 《Conservation biology》2015,29(1):226-237
Marine fish stocks are in many cases extracted above sustainable levels, but they may be protected through restricted‐use zoning systems. The effectiveness of these systems typically depends on support from coastal fishing communities. High management costs including those of enforcement may, however, deter fishers from supporting marine management. We incorporated enforcement costs into a spatial optimization model that identified how conservation targets can be met while maximizing fishers’ revenue. Our model identified the optimal allocation of the study area among different zones: no‐take, territorial user rights for fisheries (TURFs), or open access. The analysis demonstrated that enforcing no‐take and TURF zones incurs a cost, but results in higher species abundance by preventing poaching and overfishing. We analyzed how different enforcement scenarios affected fishers’ revenue. Fisher revenue was approximately 50% higher when territorial user rights were enforced than when they were not. The model preferentially allocated area to the enforced‐TURF zone over other zones, demonstrating that the financial benefits of enforcement (derived from higher species abundance) exceeded the costs. These findings were robust to increases in enforcement costs but sensitive to changes in species’ market price. We also found that revenue under the existing zoning regime in the study area was 13–30% lower than under an optimal solution. Our results highlight the importance of accounting for both the benefits and costs of enforcement in marine conservation, particularly when incurred by fishers. Justificación de los Costos de Aplicación en la Asignación Espacial de Zonas Marinas 相似文献
196.
Bugueño-Carrasco Sebastián Monteil Hélène Toledo-Neira Carla Sandoval Miguel Ángel Thiam Abdoulaye Salazar Ricardo 《Environmental science and pollution research international》2021,28(19):23753-23766
Environmental Science and Pollution Research - In this study, the simultaneous degradation of antibiotics (ampicillin, sulfamethazine, and tetracycline; and non-steroidal anti-inflammatories... 相似文献
197.
Vasconcelos Pedro Hermano M. Camelo André Luiz M. de Lima Ari Clecius A. do Nascimento Hélio O. Vidal Carla B. do Nascimento Ronaldo F. Lopes Gisele S. Longhinotti Elisane 《Environmental science and pollution research international》2021,28(7):8012-8021
Environmental Science and Pollution Research - Chemometric tools are powerful strategies to efficiently optimize many processes. These tools were employed to optimize a fast-solid phase... 相似文献
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199.
Scott G. Davis Peter C. Hinze Olav R. Hansen Kees van Wingerden 《Journal of Loss Prevention in the Process Industries》2011,24(6):837-846
The hazards of dust explosions prevailing in plants are dependent on a large variety of factors that include process parameters, such as pressure, temperature and flow characteristics, as well as equipment properties, such as geometry layout, the presence of moving elements, dust explosion characteristics and mitigating measures. A good dust explosion risk assessment is a thorough method involving the identification of all hazards, their probability of occurrence and the severity of potential consequences. The consequences of dust explosions are described as consequences for personnel and equipment, taking into account consequences of both primary and secondary events.While certain standards cover all the basic elements of explosion prevention and protection, systematic risk assessments and area classifications are obligatory in Europe, as required by EU ATEX and Seveso II directives. In the United States, NFPA 654 requires that the design of the fire and explosion safety provisions shall be based on a process hazard analysis of the facility, process, and the associated fire or explosion hazards. In this paper, we will demonstrate how applying such techniques as SCRAM (short-cut risk analysis method) can help identify potentially hazardous conditions and provide valuable assistance in reducing high-risk areas. The likelihood of a dust explosion is based on the ignition probability and the probability of flammable dust clouds arising. While all possible ignition sources are reviewed, the most important ones include open flames, mechanical sparks, hot surfaces, electric equipment, smoldering combustion (self-ignition) and electrostatic sparks and discharges. The probability of dust clouds arising is closely related to both process and dust dispersion properties.Factors determining the consequences of dust explosions include how frequently personnel are present, the equipment strength, implemented consequence-reducing measures and housekeeping, as risk assessment techniques demonstrate the importance of good housekeeping especially due to the enormous consequences of secondary dust explosions (despite their relatively low probability). The ignitibility and explosibility of the potential dust clouds also play a crucial role in determining the overall risk.Classes describe both the likelihood of dust explosions and their consequences, ranging from low probabilities and limited local damage, to high probability of occurrence and catastrophic damage. Acceptance criteria are determined based on the likelihood and consequence of the events. The risk assessment techniques also allow for choosing adequate risk reducing measures: both preventive and protective. Techniques for mitigating identified explosions risks include the following: bursting disks and quenching tubes, explosion suppression systems, explosion isolating systems, inerting techniques and temperature control. Advanced CFD tools (DESC) can be used to not only assess dust explosion hazards, but also provide valuable insight into protective measures, including suppression and venting. 相似文献
200.
Evaluating the potential for overpressures from the ignition of an LNG vapor cloud during offloading 总被引:1,自引:0,他引:1
Filippo Gavelli Scott G. Davis Olav R. Hansen 《Journal of Loss Prevention in the Process Industries》2011,24(6):908-915
Ignition of natural gas (composed primarily of methane) is generally not considered to pose explosion hazards when in unconfined and low- or medium-congested areas, as most of the areas within LNG regasification facilities can typically be classified. However, as the degrees of confinement and/or congestion increase, the potential exists for the ignition of a methane cloud to result in damaging overpressures (as demonstrated by the recurring residential explosions due to natural gas leaks). Therefore, it is prudent to examine a proposed facility’s design to identify areas where vapor cloud explosions (VCEs) may cause damage, particularly if the damage may extend off site.An area of potential interest for VCEs is the dock, while an LNG carrier is being offloaded: the vessel hull provides one degree of confinement and the shoreline may provide another; some degree of congestion is provided by the dock and associated equipment.In this paper, the computational fluid dynamics (CFD) software FLACS is used to evaluate the consequences of the ignition of a flammable vapor cloud from an LNG spill during the LNG carrier offloading process. The simulations will demonstrate different approaches that can be taken to evaluate a vapor cloud explosion scenario in a partially confined and partially congested geometry. 相似文献