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31.
In most birds, natal dispersal is female-biased, but the selective pressures leading to this pattern have rarely been explored
with comprehensive data on lifetime reproductive success. In territorial birds, the benefit of philopatry should be higher
for males than for females when males establish territories for which knowledge about the local environment is important.
As females may use male characteristics for mate choice, and hence indirectly for territory choice, the benefit from the direct
knowledge of the local environment may be lower for females than males. We tested this hypothesis using data from a long-term
study of group living corvids, the Siberian jays (Perisoreus infaustus). In this species, the socially dominant offspring delay dispersal while the sub-dominant offspring leave the family group
directly after reaching independence. Our results show that natal dispersal distance (a proxy for local knowledge) was related
to sex and dispersal timing (a proxy for “quality”): Females and early dispersers traveled further on average than males and
delayed dispersers. Furthermore, dispersal distance and timing were negatively related to the number of recruits produced
over an individual’s lifetime in males, but not in females. Hence, the results support the hypothesis that the female-biased
natal dispersal found in this and other bird species may come about through higher lifetime reproductive success of philopatric
males than females. 相似文献
32.
A simulation model has been developed that predicts numbers and phenology of a population of codling moth, Cydia pomonella (L.), in an apple orchard. The model is a general insect population model based on the interative-cohort technique. It operates at two time scales: a fine time scale (1 h) for temperature-dependent physiological processes, and a coarse time scale (1 day) for population processes. The population is divided into a specifiable number of stages, and each stage is described by four process functions, which may be of any convenient mathematical form, and may differ among stages. Each stage is divided into cohorts of individuals born or emerged on the same day, and individuals within a cohort are considered probabilistically identical. The model simulates the processes of development, transition among stages, and mortality by using probability distributions representing these processes, and incorporates the effects of pesticides on mortality of the insect. Model output was evaluated by comparison with records of pheromone trap catches of codling moths in commercial apple orchards in North Carolina. The model predicts timing of the first spring flight well, depending on the initial age distribution used. Time between peaks of numbers of adults in the model is about 15 days longer than the observed period between flight peaks in orchards. Sensitivity analysis indicates that this discrepancy may be related to differences between measured ambient temperature and tree canopy temperature. The sensitivities of numbers of insects produced by the model, and timing of peaks in numbers present were determined for each of the parameters in the model. The parameters with greatest effect on the model output were those which control the locations of developmental rate functions and survival functions on the temperature scale. In the model, pesticides had a much larger effect on numbers of adults present than records of moths caught in pheromone traps indicate actually occurred, suggesting that moths caught in traps in commercial orchards where effective pesticides are applied may be largely immigrants. 相似文献
33.
Luis Antonio Bojórquez-Tapia Peter F. Ffolliott D. Phillip Guertin 《Environmental management》1990,14(3):317-324
The current Mexican environmental law provides the legal basis for comprehensive land-use planning. Under the law, development
of natural ecosystems must combine goals, policies, and practices towards the sustainable use of natural resources and the
protection of biological diversity. Thus, ecosystem manipulation must be able to counter fragmentation of natural ecosystems
and isolation of natural reserves, while providing for human needs. Assessment of the potential of natural ecosystems and
management impacts are required. Multiple-resource simulation is an assessment and land-use planning tool that permits managers
and decision makers to comply with the law, providing a flexible, user-oriented system that can meet the needs of managers,
conservationists, and researchers. A multiple-resource model and an example of how it can be applied to meet planning needs
is presented for discussion. 相似文献
34.
Indirect Effects of Feral Horses on Estuarine Communities 总被引:1,自引:1,他引:1
Phillip S. Levin ‡ Julie Ellis Rachel Petrik Mark E. Hay† 《Conservation biology》2002,16(5):1364-1371
35.
Titanium dioxide (TiO2) is a widely used white pigment. TiO2 production in 2006 was about 1,400,000 metric tons in the USA. The two major processes to manufacture TiO2 are the chloride process and the sulfate process. Currently, the TiO2 industry finds the waste generated in the chloride process less than the waste generated in the sulfate process in its present design, despite generating large quantities of process-related carbon dioxide and carbon monoxide. As a consequence, the sulfate process appears less economical, notably due to the production of green vitriol, FeSO4·7H2O, as a major waste. Here, we describe a more sustainable sulfate process based on an earlier study on thermal decomposition of iron(II) sulfates. In the sustainable sulfate process, FeSO4·7H2O waste is used for greener production of sulfuric acid, H2SO4, used in turn for the digestion of ilmenite. Theoretical and actual yields of waste byproducts per metric ton of TiO2 produced are used to show the environmental and economic advantages of the sustainable sulfate process. 相似文献
36.
Sharon L. Forbes David A. Cohen Ross Cullen Stephen D. Wratten Joanna Fountain 《Journal of Cleaner Production》2009,17(13):1195-1199
Previous research has suggested that consumers are becoming increasingly concerned by the effects of conventional agricultural food production practices on human health and environmental wellbeing. This study sought to understand whether environmentally sustainable practices in the vineyard would equate to advantages in the wine marketplace. Structured questionnaires were used to ascertain the views of wine consumers in Christchurch, New Zealand. The findings of this study indicate that consumers have a strong demand for wine which is produced using “green” production practices. Consumers believe that the quality of sustainable wine will be equal to or better than conventionally produced wine, and they are prepared to pay a higher price for this wine. 相似文献
37.
Ceratium tripos dominated a multi-species dinoflagellate patch in the sub-surface chlorophyll maximum in August 1978 on the Southern California shelf. The specific growth rate () ofC. tripos averaged 0.25 d-1. Patch length was about 45 km along the shelf. Several members of the subsurface dinoflagellate assemblage were also present in surface samples, but only during the daytime. These apparent vertical migrators includedProrocentrum micans, C. furca, Gonyaulax polyedra and other less common forms. The growth ofC. tripos in the California patch is compared with that in aC. tripos patch off New York in 1976. 相似文献
38.
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40.
Phillip Cassey Golo Maurer Camille Duval John G. Ewen Mark E. Hauber 《Behavioral ecology and sociobiology》2010,64(10):1711-1720
Studies of avian eggshell coloration have been a long-standing research focus in behavioral evolutionary ecology. Museum collections
have provided a widely used resource because they allow efficient sampling across broad temporal, geographical, and taxonomic
ranges, even for species that are rare and for which sampling in the wild is ethically or practically unwarranted. We used
reflectance spectrophotometry across the avian visual spectrum to compare eggshell color of specimens of the song thrush (Turdus philomelos) in two museums (Natural History Museum, UK and Auckland Museum, New Zealand) with each other and with eggshells collected
fresh in New Zealand. These data enabled us to test the effects of source and storage in different museums, as well as time
since collection, across four metrics of eggshell coloration: blue-green and ultraviolet chroma, overall brightness, and the
spectral coefficient of variation. Variation within an egg, within a clutch, and among clutches, was similar between the two
museum datasets but different from those of fresh eggs. We found significant differences in all four metrics between the collections,
and that fresh eggshells reflected stronger in the blue-green wavelength than in museum eggs. This difference is most likely
due to different preservation techniques and storage histories. Furthermore, an effect of time since collection was only apparent
in the blue-green chroma and was higher in more recent museum eggshell samples. Our results support the use of historic museum
samples in intraspecific studies of shell coloration providing that efforts are made to compare specimens, which were collected
during similar periods. 相似文献