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801.
B. Miljevic K.E. Fairfull-Smith S.E. Bottle Z.D. Ristovski 《Atmospheric environment (Oxford, England : 1994)》2010,44(18):2224-2230
Reactive oxygen species (ROS) and related free radicals are considered to be key factors underpinning the various adverse health effects associated with exposure to ambient particulate matter. Therefore, measurement of ROS is a crucial factor for assessing the potential toxicity of particles. In this work, a novel profluorescent nitroxide, BPEAnit, was investigated as a probe for detecting particle-derived ROS. BPEAnit has a very low fluorescence emission due to inherent quenching by the nitroxide group, but upon radical trapping or redox activity, a strong fluorescence is observed. BPEAnit was tested for detection of ROS present in mainstream and sidestream cigarette smoke. In the case of mainstream cigarette smoke, there was a linear increase in fluorescence intensity with an increasing number of cigarette puffs, equivalent to an average of 101 nmol ROS per cigarette based on the number of moles of the probe reacted. Sidestream cigarette smoke sampled from an environmental chamber exposed BPEAnit to much lower concentrations of particles, but still resulted in a clearly detectible increase in fluorescence intensity with sampling time. It was calculated that the amount of ROS was equivalent to 50 ± 2 nmol per mg of particulate matter; however, this value decreased with ageing of the particles in the chamber. Overall, BPEAnit was shown to provide a sensitive response related to the oxidative capacity of the particulate matter. These findings present a good basis for employing the new BPEAnit probe for the investigation of particle-related ROS generated from cigarette smoke as well as from other combustion sources. 相似文献
802.
Kai-Chung Cheng Marian D. Goebes Lynn M. Hildemann 《Atmospheric environment (Oxford, England : 1994)》2010,44(16):2062-2066
The effect of foot traffic on indoor particle resuspension was evaluated by associating non-prescribed foot traffic with simultaneous size-resolved airborne particulate matter (PM) concentrations in a northern California hospital. Foot traffic and PM were measured every 15 min in a carpeted hallway over two 27-h periods. The PM concentration in the hallway was modeled based on the foot traffic intensity, including the previous PM concentration via an autocorrelation regression method based on the well-mixed box model. All 5 size ranges of PM, ranging from 0.75–1 μm to 5–7.5 μm, were highly correlated with foot traffic measurements for both monitoring periods (p < 0.001, R2 = 0.87–0.90). However, correlations during daytime hours were less significant than nighttime. Coefficients found via this autoregressive analysis can be interpreted to reveal (i) time-independent contributions of walking activities on PM levels for a specific location; and (ii) size-specific characteristics of the resuspended PM. 相似文献
803.
Kris A. G. Wyckhuys Robert J. O’Neil 《Environment, Development and Sustainability》2010,12(3):297-311
In subsistence farming systems of the developing world, adoption of resource-conserving practices such as integrated pest
management (IPM) is often strikingly low. This has partially been ascribed to researchers’ limited understanding of how technologies
develop at the interface of the systems’ social and ecological components. In Honduras (Central America), there exists concern
about limited adoption and diffusion of IPM technologies in certain smallholder production systems. In this study, we determine
social and ecological drivers of IPM adoption in subsistence maize production in the country’s hillside environment. Honduran
small-scale maize production is typified by a key insect pest (the fall armyworm, Spodoptera frugiperda) being partly kept at bay through action of a diverse natural enemy complex, including ants, social wasps, carabid beetles,
and spiders. Local agricultural landscapes, primarily shaped through shifting cultivation, provide key resources to maintain
this natural enemy diversity. These local ecological conditions and related natural enemy abundance strongly influence farmers’
agroecological knowledge and pest management practices. In the meantime, farmer practices are also affected by local communication
networks, which help validate and spread IPM concepts and technologies. Based on our findings, we advocate a holistic approach
to improve IPM extension through mapping of agroecological opportunities, visualization of regional patterns in farmer knowledge,
and associated priority setting. Local IPM capacity could be built through institutional strengthening and adaptive comanagement,
while IPM training should be linked with natural resource management initiatives. These approaches may eventually improve
the way IPM is delivered to small-scale farmers who operate in the ecologically diverse environments of the tropics. 相似文献
804.
805.
The effect of invertebrate predation pressure by the cladoceran Leptodora kindti on the population structure of Daphnia galeata and D. hyalina has been estimated by analyzing the occurrence frequency of the normal and spined morphotypes in Lake Baikal. It is shown
that the growth of L. kindti population density leads to an increase in the proportion of the spined morphotype, while that of that of the normal morphotype
decreases. 相似文献
806.
Sex-biased predation is thought to have important implications for sexual selection, sex allocation, and population dynamics (Magnhagen, 1991; Le-Galliard et al., 2005 for an example in lizards). Most studies found that males are subjected to higher predation pressure than females during the reproductive season (Korpimäki, 1985; Lodé et al., 2004; Christe et al., 2006; Costantini et al., 2007). In that period, males are very mobile, emit acoustic signals and exhibit brilliant colourations, which are needed to attract females but may make them more visible to predators. With regard to lizards, a recent study provided the first evidence that males of a lizard species may be preyed on more than females (Costantini et al., 2007). In the present study, we investigated whether there is sex-biased predation on two small lacertid species, the common wall lizard Podarcis muralis (Laurenti, 1768) and the Italian wall lizard Podarcis sicula (Rafinesque-Schmaltz, 1810), by Eurasian kestrels (Falco tinnunculus) during the reproductive season. We also examined whether (1) the rate of predation differed between species and (2) the rate of predation differed across years or among hunting habitats for each species. 相似文献
807.
A. V. Artem’ev 《Russian Journal of Ecology》2010,41(5):418-421
On the basis of long-term studies on the ecology of pied flycatcher in Karelia, it has been shown that male nonparticipation
in nestling feeding is due to the course of postnuptial molt rather than to the mode of mating relationships, as it was considered
previously. This is confirmed by the results of selective capture of birds that have stopped to feed their brood. It is suggested
that reduction of parental care is associated with changes in the hormonal balance of molting birds. 相似文献
808.
Resident Motivations and Willingness-to-Pay for Urban Biodiversity Conservation in Guangzhou (China)
The monetary assessment of biodiversity measures the welfare damages brought by biodiversity losses and the cost-benefit analysis
of conservation projects in a socio-economic context. The contingent valuation method could include motivational factors to
strengthen economic analysis of nature conservation. This study analyzed Guangzhou residents’ motivations and willingness-to-pay
(WTP) for an urban biodiversity conservation program in the National Baiyun Mountain Scenic Area (BMSA). The peri-urban natural
site, offering refuge to some endemic species, is under increasing development pressures for recreational and residential
use. A questionnaire survey was conducted in the Guangzhou metropolitan area during June to October 2007. We interviewed face-to-face
720 stratified sampled households to probe residents’ attitudes towards the city’s environmental issues, motivations for urban
nature conservation, and WTP for biodiversity conservation. Principal component analysis identified five motivational factors,
including environmental benefit, ecological diversity, nature-culture interaction, landscape-recreation function, and intergenerational
sustainability, which illustrated the general economic values of urban nature. Logistic regression was applied to predict
the probability of people being willing to pay for the urban biodiversity conservation in BMSA. The significant predictors
of WTP included household income and the factor nature-culture interaction. The median WTP estimated RMB149/household (about
US$19.5/household) per year and an aggregate of RMB291 million (approximately US$19.5/household) per year and an aggregate of RMB291 million (approximately US38.2 million) annually to support the urban
conservation project. Including public motivations into contingent valuation presents a promising approach to conduct cost-benefit
analysis of public projects in China. 相似文献
809.
Carbon Storage in Soil Size Fractions Under Two Cacao Agroforestry Systems in Bahia, Brazil 总被引:1,自引:0,他引:1
Emanuela F. Gama-Rodrigues P. K. Ramachandran Nair Vimala D. Nair Antonio C. Gama-Rodrigues Virupax C. Baligar Regina C. R. Machado 《Environmental management》2010,45(2):274-283
Shaded perennial agroforestry systems contain relatively high quantities of soil carbon (C) resulting from continuous deposition
of plant residues; however, the extent to which the C is sequestered in soil will depend on the extent of physical protection
of soil organic C (SOC). The main objective of this study was to characterize SOC storage in relation to soil fraction-size
classes in cacao (Theobroma cacao L.) agroforestry systems (AFSs). Two shaded cacao systems and an adjacent natural forest in reddish-yellow Oxisols in Bahia,
Brazil were selected. Soil samples were collected from four depth classes to 1 m depth and separated by wet-sieving into three
fraction-size classes (>250 μm, 250–53 μm, and <53 μm)—corresponding to macroaggregate, microaggregate, and silt-and-clay
size fractions—and analyzed for C content. The total SOC stock did not vary among systems (mean: 302 Mg/ha). On average, 72%
of SOC was in macroaggregate-size, 20% in microaggregate-size, and 8% in silt-and-clay size fractions in soil. Sonication
of aggregates showed that occlusion of C in soil aggregates could be a major mechanism of C protection in these soils. Considering
the low level of soil disturbances in cacao AFSs, the C contained in the macroaggregate fraction might become stabilized in
the soil. The study shows the role of cacao AFSs in mitigating greenhouse gas (GHG) emission through accumulation and retention
of high amounts of organic C in the soils and suggests the potential benefit of this environmental service to the nearly 6
million cacao farmers worldwide. 相似文献
810.
Forest policymakers, public lands managers, and scientists in the Pacific Northwest (USA) seek ways to evaluate the landscape-level
effects of policies and management through the multidisciplinary development and application of spatially explicit methods
and models. The Interagency Mapping and Analysis Project (IMAP) is an ongoing effort to generate landscape-wide vegetation
data and models to evaluate the integrated effects of disturbances and management activities on natural resource conditions
in Oregon and Washington (USA). In this initial analysis, we characterized the spatial distribution of forest and range land
development in a four-county pilot study region in central Oregon. The empirical model describes the spatial distribution
of buildings and new building construction as a function of population growth, existing development, topography, land-use
zoning, and other factors. We used the model to create geographic information system maps of likely future development based
on human population projections to inform complementary landscape analyses underway involving vegetation, habitat, and wildfire
interactions. In an example application, we use the model and resulting maps to show the potential impacts of future forest
and range land development on mule deer (Odocoileus hemionus) winter range. Results indicate significant development encroachment and habitat loss already in 2000 with development located
along key migration routes and increasing through the projection period to 2040. The example application illustrates a simple
way for policymakers and public lands managers to combine existing data and preliminary model outputs to begin to consider
the potential effects of development on future landscape conditions. 相似文献