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941.
942.
Agroecology of Birds in Organic and Nonorganic Farmland 总被引:4,自引:0,他引:4
Nancy A. Beecher Ron J. Johnson § James R. Brandle † Ronald M. Case Linda J. Young‡ 《Conservation biology》2002,16(6):1620-1631
943.
Ecobalance represents the basic principle for an environmental analysis and the starting point for the possibility of achieving improvements. Using the criteria related to both technology and ecology, this method has been expanded upon by IKP/PE and, over the course of many years, has proven to be a satisfactory method for those fields associated with industry and research. Data banks and software systems have been designed and are today applied in industry. An expansion of the holistic balancing to include the ‘social’ dimension is currently being developed by the IKP. Today, ecological decisions in technically and economically-associated areas are continuously being developed which place more emphasis on the preliminary developments than on a purely retrospective analysis. Aside from the continuous, further developments of these types of analysis with regard to never technical questions as well as the integration of newer aspects of optimization based on life cycle information (e.g. production balancing), the goal of further work includes the preparation of process-chain information in the respective in preliminary developments related to the design. The automobile industry consequently plays a significant role here, as was also the case in the initial transformation of methodology which was carried out in the 1990s. Finally, these developments are additionally motivated through the new ordinances presented to be employed throughout the entire EU. The responsibility attributed to a product over the course of its entire lifetime therefore plays a more prominent role. This is also reflected in ordinances like those related to the redemption of old automobiles or in the WEEE of the electronics industry (Directive on Waste Electrical and Electronic Equipment). 相似文献
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945.
Goal and Scope
Which impact does the use of non-energetic abiotic resources (ores, minerals, etc.) have in life cycles of energy systems based on biogenic and fossil fuels? Is this kind of resource use less or more environmentally harmful than the utilisation of energetic abiotic resources (mineral oil, natural gas, etc.) in the same life cycles? This paper aims at answering these questions. In Part 1, a methodology is presented and applied to the life cycles of selected energy systems. Part 2 presents and discusses the results.Methods
The applied methodology has been explained in the Part 1. For the assessment of energetic abiotic resource use, a widely recognised method is used. For the assessment of nonenergetic abiotic resource use, no overall recognised methodological approach exists. That is why for this aspect two different methods are exemplarily applied and compared with each other.Results and Conclusion
Results show that the two assessment approaches for non-energetic resource utilisation lead to qualitatively equal results. Nevertheless they differ considerably from each other in their absolute values. This makes obvious that there is still a need for further methodological research work on that issue. Nevertheless, both methodologies yield that the accumulated effect of ore and mineral use is considerably lower than the accumulated effect of fossil primary energy utilisation in all life cycles analysed. With the assumptions made, the use of non-energetic abiotic resources only plays a comparatively subordinate role in the environmental life cycle assessment of energy systems based on biogenic and fossil fuels.Recommendation and Perspective
Results suggest that an important resource-related impact of biomass and fossil fuel powered energy systems is caused by their consumption of fossil primary energy resources. The impact of non-energetic resource use can be neglected in comparison to that. At the same time, results also make clear that there is still a considerable need for further methodical research aiming at a standardised assessment methodology for the use of non-energetic abiotic resources. 相似文献946.
Martin R. Billingham Tiago Simões Thorsten B. H. Reusch Ester A. Serrão 《Marine Biology》2007,152(4):793-801
The spatial distribution of genetic variability depends on the spatial patterns of clonal and sexual reproduction, gene flow,
genetic drift and natural selection. Species with restricted dispersal may exhibit genetic structuring within populations
with immediate neighbours being close relatives, and may show differentiation among populations. Genetic structuring of a
species may have important genetic, evolutionary and ecological consequences including distance-dependent mating success.
In this study we used microsatellite markers to show that clones of Zostera marina in a population in the Ria Formosa, Portugal, were aggregated and covered distances of up to 3–4 m. Clones within 4 m of
each other exhibited significant and positive coancestry values, reflecting the limited seed dispersal of this species. Hand-pollinations
between near (0–10.9 m), intermediate (11–32 m) and far (15 km) individuals resulted in similar levels of seed set, although
the near pollinations had higher, although not statistically significant, levels of seed abortion during maturation. Seeds
from intermediate-distance pollinations had a significantly higher proportion of seeds germinate and shorter germination time
than both the near and far seeds. Similarly, the average number of seedlings produced per pollination, used as an overall
estimate of fitness, was significantly greater for the intermediate distance when compared to both near and far pollinations.
These results suggest that the genetic structuring observed may result in both inbreeding and outbreeding depression, which
gives rise to an intermediate optimal outcrossing distance. 相似文献
947.
Skin and stomach epithelia of the four suborders of nudibranch gastropods (Mollusca, Opisthobranchia) are characterized by
large intracellular ovoid disks, here called spindles. These spindles are an evolutionary novelty in the nudibranchs; in shell-less
sacoglossan species they are missing. We here examined whether the distribution and occurrence of the spindles is consistent
with the assumption of a protective role against discharging nematocysts of co-habiting and prey Cnidaria. Spindles were abundant
in epidermal cells of regions exposed to nematocysts, such as the cerata, the lips, the edges of lamellate rhinophores, the
surfaces of non-retractile gill-like organs, as well as in the stomach epithelium of eolid and dendronotacean species which
feed on Cnidaria. While cells packed with spindles almost exclusively formed the epidermis of eolid and arminacean species,
they were less numerous in the skin of dendronotacean and dorid species, where glandular cells predominated. The preponderance
of either glandular or spindle cells suggests a dual complementary defense strategy, on the one side the production of mucus
coats and aversive glandular secretions, on the other structural defensive devices that are cushion-like entities filled with
inert grains. 相似文献
948.
949.
950.
The distribution and diet of juvenile (<750 mm) Patagonian toothfish are described from four annual trawl surveys (2003–2006)
around the island of South Georgia in the Atlantic sector of the Southern Ocean. Recruitment of toothfish varies inter-annually,
and a single large cohort dominated during the four years surveyed. Most juveniles were caught on the Shag Rocks shelf to
the NW of South Georgia, with fish subsequently dispersing to deeper water around both the South Georgia and Shag Rocks shelves.
Mean size of juvenile toothfish increased with depth of capture. Stomach contents analysis was conducted on 795 fish that
contained food remains and revealed that juvenile toothfish are essentially piscivorous, with the diet dominated by notothenid
fish. The yellow-finned notothen, Patagonotothen guntheri, was the dominant prey at Shag Rocks whilst at South Georgia, where P. guntheri is absent, the dominant prey were Antarctic krill and notothenid fish. The diet changed with size, with an increase in myctophid
fish and krill as toothfish grow and disperse. The size of prey also increased with fish size, with a greater range of prey
sizes consumed by larger fish. 相似文献