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731.
732.
George Rapp James D. Allert Barbara W. Liukkonen Judith A. Ilse Orie L. Loucks Gary E. Glass 《Environment international》1985,11(5):425-440
The relationship between lake sensitivity to atmospheric acidic inputs and the neutralization capacity of watersheds is examined for 267 lakes in northeastern Minnesota. Three water chemistry/sensitivity measures (color, sulfate, and alkalinity) are correlated with variables representative of precipitation and sulfate inputs, hydrology, and the acid neutralization capacity of various watershed components. An ordinal scale for ranking bedrock and surficial deposit neutralization capacity is presented. The watershed variables found to account for the largest percentages of the variability in measured color, sulfate, and alkalinity levels are determined. Color is strongly related to the presence of peat or marsh and hydrologic renewal time, whereas sulfate is primarily related to atmospheric deposition, evaporative concentration, bedrock type, and the presence of coniferous forest. Variation in alkalinity is the most difficult of the water chemistry measures to explain; for headwater lakes, atmospheric sulfate input, water renewal time, the presence of deciduous forest, and the weatherability of underlying bedrock determine much of its variability. The results illustrate important averaging properties of watersheds from small headwater systems to large drainages and the difficulty in obtaining correlations for some water quality measures (e.g., alkalinity) when some variables, such as soils and land cover, are available only as large-area averages. 相似文献
733.
Craig S. Hieber Stimson R. Wilcox Jay Boyle George W. Uetz 《Behavioral ecology and sociobiology》2002,53(1):51-60
Earlier studies have shown that the sarcophagid fly Arachnidomyia lindae is the principal egg-sac predator of the colonial orb-weaving spider Metepeira incrassata, and that risk of egg-sac loss increases with group size. Observations of specialized behaviors for attack (flies) and defense (spiders) suggest that this predator-prey relationship may incorporate elements of ploy and counterploy behavior. Here we explore this relationship in detail and test hypotheses regarding efficacy of attack and defense behaviors. Egg-sac guarding by the spider includes defensive behaviors specific to this fly predator, which were observed during experimental "attacks" with tethered A. lindae, but not with similar presentations of non-predatory Musca domestica. Experimental studies also show that Metepeira incrassata recognizes this predatory fly by airborne cues (i.e., the signature frequency of wing-beats), and can distinguish between this predator and other flies (potential prey) on the basis of wing-beat frequency differences. Removal of female spiders results in a significantly higher probability of unguarded egg-sacs being parasitized, demonstrating the adaptive value of spider defensive behaviors. We also present evidence that A. lindae utilizes a behavioral ploy for circumventing spider guarding behavior (aggressive mimicry - producing vibrations of captured prey in the web), and that Metepeira incrassata, in turn, exhibits a counter-ploy behavior (signal thread cutting) to eliminate this potentially distracting vibratory information. While previous studies have shown that this colonial web-building spider uses a number of general attack-abatement mechanisms against a diversity of predators and parasitoids, results of this study suggest that selection pressures from a highly specialized predator may also result in evolution of predator-specific prey responses. 相似文献
734.
Hans Schreier Sandra Brown George Kennedy Pravakar B. Shah 《Environmental management》1991,15(6):815-822
A GIS-based land evaluation model was developed to determine the food, feed, and fuelwood sufficiency of all districts in
Nepal. Resource surpluses or deficits were calculated for each district for 1981, the year for which the national land resource
data were available. Of the three resources, feed supplies were found to be the most critical. Feed deficits occurred in 57%
of all districts in 1981, while food and fuelwood deficits occurred in less than 10% of all districts. Different scenarios
were carried out for the year 2000 to estimate the magnitude of future resource deficits, assuming resource use and yields
in Nepal remain constant in the face of growing population and livestock numbers. Linking resource data with spreadsheet and
GIS systems provides a new way to understand and evaluate resources at the district and national levels. To more fully capture
the usefulness of this approach, information on rates of change in productivity and land use is needed. 相似文献
735.
Maquiladoras, manufacturing plants that primarily assemble foreign components for reexport, are located in concentrations
along the northern frontier of the US/Mexico border. These plants process a wide variety of materials using modern industrial
technologies within the context of developing world institutions and infrastructure. Hazardous waste generation by maquiladoras
represents a critical environmental management issue because of the spatial concentration of these plants in border municipalities
where the infrastructure for waste management is nonexistent or poor. These border municipalities contain rapidly increasing
populations, which further stress their waste handling infrastructure capacities while exposing their populations to greater
contaminant risks. Limited empirical knowledge exists concerning hazardous waste types and generation rates from maquiladorsas.
There is no standard reporting method for waste generation or methodology for estimating generation rates at this time. This
paper presents a method that can be used for the rapid assessment of hazardous waste generation. A first approximation of
hazardous waste generation is produced for maquiladoras in the three municipalities of Nogales, Sonora, Mexicali, Baja California,
and Cd. Juarez, Chihuahua, using the INVENT model developed by the World Bank. In addition, our intent is to evaluate the
potential of the INVENT model for adaptation to the US/Mexico border industrial situation. The press of border industrial
development, especially with the recent adoption of the NAFTA, make such assessments necessary as a basis for the environmental
policy formulation and management needed in the immediate future. 相似文献
736.
George J. Moosburner Eric F. Wood 《Journal of the American Water Resources Association》1980,16(6):971-978
ABSTRACT: Land use planning in rapidly developing areas can serve as an effective tool for minimizing water quality impacts on ground water supplies. A land use management model applied to Jackson Township of the New Jersey Pine Barrens was developed. The management model consisted of a simulation model for the transport of nitrates from septic tank systems through the aquifer and a multiobjective, goal programming optimization model to determine population density restrictions using 208 areawide planning population projections. Results showed that growth may have to be curtailed in several areas of Jackson Township and that current population projections over the next 30 years may result in unacceptably high nitrate concentrations downgradient of Jackson Township. The management framework provides a flexible approach to land use planning. 相似文献
737.
738.
The thermal behavior of dilute (5000-50 ppm) solutions of tri- and tetrachlorobenzene in mineral oil, silicone oil, and tetrachloroethylene (TCE) has been investigated. Although pyrolyses or combustion of neat chlorobenzenes readily forms significant yields of PCDDs/PCDFs, corresponding treatment of dilute solutions was generally non-productive. This result is consistent with the proposition that, under the conditions studied, the rate-limiting step for PCDD/PCDF formation is bimolecular in chlorobenzene. In contrast, earlier studies of PCBs implied a rate-limiting step that was unimolecular in chloroaromatics. Combustion of dilute solutions of chlorobenzenes in tetrachloroethylene did produce detectable concentrations of PCDF; this result reflects combination of chlorobenzene and TCE- or TCE-derived species. 相似文献
739.
Thomas A. Gasiewicz Ellen C. Henry Raymond B. Baggs George Rucci Arnold Schecter 《Chemosphere》1986,15(9-12)
The temporal - and dose-related characteristics of hepatic enzymes induced and toxic responses elicited in the hamster by 2,3,7,8-tetrachlorodibenzo-
-dioxin were examined. The results demonstrate a dissociation of the induction of these hepatic enzymes from TCDD-elicited lethality, but not necessarily hepatic damage, in this species. Furthermore, the hyperthyroidism observed is suggestive of a role of these hormones in the relatively insensitive nature of this species to TCDD treatment. 相似文献
740.
Zalidis GC Takavakoglou V Panoras A Bilas G Katsavouni S 《Environmental management》2004,34(6):875-886
Lake Karla, Greece, was almost completely drained in 1962 both to protect surrounding farmlands from flooding and to increase agricultural area. Loss of wetland functions and values resulted in environmental, social, and economic problems. A number of restoration plans were proposed to address these problems. The plan approved by the government in the early 1990s proposed construction of a 4200-ha reservoir solely to improve water storage and flood attenuation functions. However, the Ramsar Scientific and Technical Review Panel states that the primary goal of any restoration project is to create resilient and sustainable ecosystems, as measured on a human timescale, in order to improve the ecological character and enhance the socioeconomic role that the wetland plays in the watershed. This study utilizes Ramsar guidelines for sustainable restoration of Lake Karla. Eight additional restoration measures are proposed based on functional analysis of the wetland to enhance additional wetland functions and support multiple values for humans and nature. 相似文献