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101.
102.
Hugh J. Barclay 《Ecological modelling》1980,11(3):167-177
Four different models of pest populations under control by the release of sterile individuals are examined to determine whether or not the release of pesticides in conjunction with steriles would further reduce the pest population equilibrium. It is found that single species without interactions with other species would generally have their equilibria reduced more with the release of both sterile individuals and pesticides than with the release of only steriles. As biotic interactions become more important, however, the feasibility of releasing pesticides in a sterile release programme becomes less sure and more dependent on the nature of the population regulation of the species involved. In particular, when predation on the pest species is heavy, the sterile release programme is likely to be hindered by the release of pesticides as well. 相似文献
103.
104.
105.
Hugh Clout 《Journal of Environmental Planning and Management》1984,27(2):84-92
Over the past thirty years Bordeaux's politicians and planners have played critical roles in both changing and conserving the inner environments of one of France's most attractive provincial cities. A succession of urban policies has been implemented to attempt to halt depopulation, economic decline and environmental degradation in the inner city. These policies reflect changing emphasis in national planning for urban areas and have ranged from slum clearance and total renovation in the Mériadeck district, to a recent more socially aware set of approaches that attempt to rehabilitate inner‐city housing and promote neighbourhood well‐being in the district of Saint Michel. Investment in architectural conservation continues apace and both private and public capital is being directed to improving housing stock in the inner city. Attempts to revitalise economic activities have achieved modest success but more socially orientated policies prove difficult to implement. 相似文献
106.
107.
Summary Brown (Acanthiza pusilla), buff-rumped (A. reguloides) and striated thronbills (A. lineata) were studied over three years in eucalypt forest in northern New South Wales. All three are small, sexually monomorphic insectivores. A. pusilla is a shrub-feeder, reguloides a bark and ground forager and lineata gleans from eucalypt leaves. A. reguloides and lineata show a two-tiered social organization with territorial clans in the non-breeding season which split up into breeding pairs or groups of 3 or 4. Non-breeding birds feed nestlings and fledglings, and after reformation of the clan adults feed fledglings belonging to other groups. Females tend to disperse more than males before the next breeding season, males tend to stay and help. A. pusilla breeds in pairs, with no helpers, defends year-round territories and expels juveniles a few months after they fledge. We discuss possible reasons why A. pusilla is not cooperative whereas the other two species are. It seems not to be due to greater adult survival and habitat saturation in the latter two, nor to reduced seasonal fluctuations in food. We propose that a major factor is the low risk of dispersing relative to staying at home in pusilla compared with the other two species. 相似文献
108.
To determine whether solicitation by blue-footed booby chicks accurately encodes their need for food, we independently manipulated
the body condition and recent food ingestion of singleton chicks and recorded three measures of begging. Variations in the
three measures of begging covaried only partially, but in general, chicks begged more intensely when they were in poor body
condition and also when suffering recent food deprivation. Effects of body condition and recent food deprivation on begging
were broadly additive, although deprived chicks in poor condition failed to beg more intensely than those in good condition.
Protracted short-term deprivation may create such a high level of need that the body condition component of need becomes temporarily
unimportant. Parents more frequently fed chicks that begged more intensely, chicks in poor condition, and chicks suffering
food deprivation. Deprived chicks in poor condition received more food than deprived chicks in normal condition even though
they did not beg more intensely, possibly because parents responded not only to current begging but also to begging earlier
in the day, or to other cues to body condition. These results support the hypothesis that begging of boobies represents honest
signaling of need. 相似文献
109.
The degradation photoproducts of the fungicide fenarimol obtained from irradiation of aqueous solutions with sunlight were characterised. The photoproducts resulting from samples with different exposure times were extracted and separated using chromatographic techniques. Seven main photoproducts were detected using high performance liquid chromatography with a photodiode array detector, gas chromatography with mass spectrometry detector and Fourier transform infrared spectroscopy. Structures are suggested for possible photoproducts based on the characterisation results, minimum energy geometry of the parent compound, and the mass spectral behaviour of fenarimol. These correspond to the compounds with m/z 328 (three structural isomers (a), (b) and (c)), m/z 294 (two structural isomers (a) and (b)), m/z 292, 278 and 190. Of the various major products detected, the isomer 328(a) is seen to be particularly unstable under the action of sunlight. The most stable photoproducts are found to be those with m/z 294(a), 278 and 190. However, upon prolonged solar irradiation all of these break down to produce polar, low molecular weight compounds. Comparison with our own and other results on fenarimol photolysis indicate significant solvent effects on the process. The combination of these structural characterisation results and previous data from spectroscopic and photodegradation kinetics studies allows us to suggest some possible mechanisms for the photodegradation of fenarimol under sunlight. 相似文献
110.
Efficiency,costs and trade-offs in marine reserve system design 总被引:1,自引:0,他引:1
Romola?R.?StewartEmail author Hugh?P.?Possingham 《Environmental Modeling and Assessment》2005,10(3):203-213
With marine biodiversity conservation the primary goal for reserve planning initiatives, a site's conservation potential is
typically evaluated on the basis of the biological and physical features it contains. By comparison, socio-economic information
is seldom a formal consideration of the reserve system design problem and generally limited to an assessment of threats, vulnerability
or compatibility with surrounding uses. This is perhaps surprising given broad recognition that the success of reserve establishment
is highly dependent on widespread stakeholder and community support. Using information on the spatial distribution and intensity
of commercial rock lobster catch in South Australia, we demonstrate the capacity of mathematical reserve selection procedures
to integrate socio-economic and biophysical information for marine reserve system design. Analyses of trade-offs highlight
the opportunities to design representative, efficient and practical marine reserve systems that minimise potential loss to
commercial users. We found that the objective of minimising the areal extent of the reserve system was barely compromised
by incorporating economic design constraints. With a small increase in area (<3%) and boundary length (<10%), the economic
impact of marine reserves on the commercial rock lobster fishery was reduced by more than a third. We considered also how
a reserve planner might prioritise conservation areas using information on a planning units selection frequency. We found
that selection frequencies alone were not a reliable guide for the selection of marine reserve systems, but could be used
with approaches such as summed irreplaceability to direct conservation effort for efficient marine reserve design. 相似文献