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991.
Alan J Krupnick Wallace E Oates Eric Van De Verg 《Journal of Environmental Economics and Management》1983,10(3):233-247
After examining the properties of several alternative forms of marketable permit systems for the control of air pollution, this paper proposes a system of pollution offsets as the most promising approach. Under the pollution-offset scheme, sources of emissions are free to trade emissions permits subject to the constraint of no violations of the predetermined air-quality standard at any receptor point. The paper shows that the pollution-offset system has the capacity to achieve the predetermined standards of air quality at the minimum aggregate abatement cost, while making comparatively modest demands both on the sources and on the administering agency. 相似文献
992.
Echinocardium cordatum (Pennant, 1777) were collected in Normandy, France, in March and November 1985. The grooved frontal ambulacrum of the burrowing echinoid E. cordatum functions in transferring surface sediment from the apex to the mouth of the echinoid. Particles that fall down the burrow's chimney accumulate between the spines of the apical tuft and are taken over by specialized groove spines. Due to the slope of the groove and the type of floor spines it harbours, four successive regions can be recognized, namely the adapical region, the fasciolar region, the ambital region, and the adoral region. As a general rule aboral floor spines (i.e. club-shaped, golf-club-shaped, and isodiametric spines) function in gathering particles while propelling them mouthwards; they simultaneously embed particles in a mucous string. The oral floor spines (i.e. spatulated spines) function in hauling and guiding the mucous string towards the peribuccal area of the echinoid. Once facing the peribuccal area, particles are picked up by the peribuccal tube feet that either transfer them into the esophagus or scrape them out against the peribuccal spines. Spine-retained particles are either sucked up by the pumping action of the esophagus or fall to the burrow's floor where the tube feet may pick them up again. Together the apical tuft, the frontal groove, and the peribuccal area form an efficient food-collecting system that transfers trapped surface particles from the echinoid apex down to the mouth. Compared to that of most other spatangoids the frontal ambulacrum of E. cordatum is highly specialized. Such specialization is related to colonization of fine sediment, as is the occurrence of a chimney linking the burrow to the sediment surface. Actually the burrow's chimney is the only route for oxygen and food supply; it acts as a real ecological umbilical cord for spatangoids buried in fine sediment. 相似文献
993.
Iztok Arčon Arnold Pastrello Laura Catalano Maria De Nobili Pierpaolo Cantone Liviana Leita 《Environmental Chemistry Letters》2006,4(4):191-194
The fate of cyanides in soil is strongly influenced by the formation of Fe cyanides, which can interact with organic and inorganic colloids and precipitate as stable compounds. Scarce information is available on the capacity of humic acids to interact with cyano-complexes and thus affect the leaching and prevent the risk of contamination of watertable. Here we show that interaction between humic acids (HAs) and ferricyanide complex led to a formation of ferricyanide-humo micelles, and that the interaction did not imply changes in the original structure of ferricyanide complex. 相似文献
994.
S. I. C. O. Santos L. De Neve J. T. Lumeij M. I. Förschler 《Behavioral ecology and sociobiology》2007,61(9):1499-1506
The assessment of plumage colouration has become a common procedure in many ornithological studies, especially after the discovery
of differences between avian and human visual systems, namely the avian ability to perceive ultraviolet wavelengths. There
are many techniques available for plumage colour assessment. Nevertheless, unidirectional reflectance spectrometry seems actually
to be the method of choice and is used in most studies. The active avian visual communication skills, the physical characteristics
of the plumage surface and the birds’ body shape prompted us to study plumage colouration with different angles of incidence
and observation by bidirectional reflectance spectrometry. In this study, we explore the effect of different angles of incidence
and observation, on a single plane of incidence, on the reflectance spectrometric assessment of five differently coloured
body regions of the blue fronted Amazon parrot (Amazona aestiva). Measurements were made using a AVS-USB2000 spectrometer with a DH-2000 light source and two different reflection probes
(bifurcated fibre optic probe and a specially designed fibre holder). The results of this study illustrate clear angle dependence
of colour parameters in differently coloured non-iridescent plumage regions of the blue fronted Amazon parrot. Our results
may have direct implications on the observed transmitted information of display and its associated predation risk (trade-off)
in birds, but also in other animals. Moreover, the results show that unidirectional reflectance spectrometry alone may be
a rather limited procedure to quantify and compare true colour of a complex surface such as birds’ plumage. Therefore, slight
but behavioural important characteristics of plumage pattern may remain undiscovered with this method. 相似文献
995.
Marina?Silva?PaezEmail author Dani?Gamerman Victor?De?Oliveira 《Environmental and Ecological Statistics》2005,12(2):169-193
In this work we present a Bayesian analysis in linear regression models with spatially varying coefficients for modeling and inference in spatio-temporal processes. This kind of model is particularly appealing in situations where the effect of one or more explanatory processes on the response present substantial spatial heterogeneity. We describe for this model how to make inference about the regression coefficients and response processes under two scenarios: when the explanatory processes are known throughout the study region, and when they are known only at the sampling locations. Using a simulation experiment we investigate how parameter inference and interpolation performance are affected by some features of the data and prior distribution that is used. The proposed methodology is used to model the dataset on PM10 levels in the metropolitan region of Rio de Janeiro presented in Paez and Gamerman (2003). 相似文献
996.
The effects of Asian Dust on particulate matter fractionation in Seoul,Korea during spring 2001 总被引:1,自引:0,他引:1
The concentrations of three different fractions of particulate matter (PM) including PM2.5, PM10, and TSP were determined concurrently during March-May 2001. Measurements of three PM fractions were made at hourly intervals from four different observatory sites located within the city boundary of Seoul. On the basis of this study, we attempted to describe relationships between the occurrences of the Asian Dust (AD) event and its influences on the PM distribution characteristics. The results of our study demonstrated distinct differences between concentrations of PM fractions at AD and non-AD (NAD) periods. The increase of PM observed during the AD episode appeared to be dominated by the coarse, rather than fine, fraction of PM. In addition, it was found that TSP/PM10 ratios were almost constant, while the coarse/fine or TSP/PM2.5 ratios changed noticeably between AD and NAD periods. In most cases, differences in environmental conditions between AD and NAD periods were prominent and proven to be statistically significant. Moreover, the regression relationships between PM and N-oxides indicate that the source processes governing PM levels between the AD and NAD period can be different. The overall results of our analysis were hence helpful enough to distinguish competing processes in AD and NAD periods, while suggesting indirectly the possible control of different source processes on PM fractionation. 相似文献
997.
Wilshusen JH Hettiaratchi JP De Visscher A Saint-Fort R 《Environmental pollution (Barking, Essex : 1987)》2004,129(2):305-314
Oxygen concentration plays an important role in the regulation of methane oxidation and the microbial ecology of methanotrophs. However, this effect is still poorly quantified in soil and compost ecosystems. The effect of oxygen on the formation of exopolymeric substances (EPS) is as yet unknown. We studied the effect of oxygen on the evolution of methanotrophic activity. At both high and low oxygen concentrations, peak activity was observed twice within a period of 6 months. Phospholipid fatty acid analysis showed that there was a shift from type I to type II methanotrophs during this period. At high oxygen concentration, EPS production was about 250% of the amount at low oxygen concentration. It is hypothesized that EPS serves as a carbon cycling mechanism for type I methanotrophs when inorganic nitrogen is limiting. Simultaneously, EPS stimulates nitrogenase activity in type II methanotrophs by creating oxygen-depleted zones. The kinetic results were incorporated in a simulation model for gas transport and methane oxidation in a passively aerated biofilter. Comparison between the model and experimental data showed that, besides acting as a micro-scale diffusion barrier, EPS can act as a barrier to macro-scale diffusion, reducing the performance of such biofilters. 相似文献
998.
A fungal strain capable of utilizing metsulfuron-methyl as sole carbon and energy sources was isolated from a metsulfuron-methyl treated soil. The degradation characteristics of metsulfuron-methyl by this fungal strain were investigated in liquid culture and soil. More than 79% of metsulfuron-methyl at concentrations of 0.10 mgl(-1), 1.0 mgl(-1) and 10.0 mgl(-1) in pure culture was degraded by strain MD after incubation for 7 days, whereas only 5.6%, 8.6% and 13.1% of metsulfuron-methyl were degraded at levels of 0.10 mgl(-1), 1.0mgl(-1) and 10.0 mgl(-1) in the controls, respectively. The incorporation of strain MD into soil was found to substantially increase the degradation of metsulfuron-methyl. Degradation was 7.5 and 3.8 times faster in strain MD amended soils than in sterilized and fresh soils. The results show that addition of the isolated strain MD enhances degradation of metsulfuron-methyl in water and soil. 相似文献
999.
1000.
Leverett R. Smith Thomas M. Holsen Noel C. Ibay Ronald M. Block Anthony B. De Leon 《Chemosphere》1985,14(9):1383-1389
We have studied the acute toxicity of fluoride ion to , , and juvenile . LC50 values varied with species and (due to precipitation) initial water hardness. Exposure to elevated fluoride levels in water resulted in increased blood fluoride levels in . 相似文献