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21.
The recent growth of interest in sustainable development has led to the incorporation of the concept into policy making at a variety of scales. In all cases particular emphasis is placed upon the local scale as the focus for the implementation of policy and initiatives and especially upon local authorities as the major contributor to this process. There has been little assessment, however, of the extent to which local authorities either can, or are, undertaking such initiatives. This paper examines: the potential role that local authorities can play in integrating economic development and the environment; the forms of response and initiatives that are currently in place, drawing upon survey evidence from urban local authorities in England and Wales; and some of the limits to local authority action.  相似文献   
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Abstract:  Rainbow smelt ( Osmerus mordax ) have invaded many North American lakes, often resulting in the extirpation of native fish populations. Yet, their invasion is incipient and provides the rationale for identifying ecosystems likely to be invaded and where management and prevention efforts should be focused. To predict smelt presence and absence, we constructed a classification-tree model based on habitat data from 354 lakes in the native range for smelt in southern Maine. Maximum lake depth, lake area, and Secchi depth (surrogate measure of lake productivity) were the most important predictors. We then used our model to identify lakes vulnerable to invasion in three regions outside the smelt's native range: northern Maine (52 of 244 lakes in the non-native range), Ontario (4447 of 8110), and Wisconsin (553 of 5164). We further identified a subset of lakes with a strong potential for impact (potential–impact lakes) based on the presence of fish species that are affected by rainbow smelt. Ninety-four percent of vulnerable lakes in the non-native range in Maine are also potential–impact lakes, as are 94% and 58% of Ontario and Wisconsin's vulnerable lakes, respectively. Our modeling approach can be applied to other invaders and regions to identify invasion-prone ecosystems, thus aiding in the management of invasive species and the efficient allocation of invasive species mitigation and prevention resources.  相似文献   
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Abstract:  Changes in temperature, precipitation, and other climatic drivers and sea-level rise will affect populations of existing native and non-native aquatic species and the vulnerability of aquatic environments to new invasions. Monitoring surveys provide the foundation for assessing the combined effects of climate change and invasions by providing baseline biotic and environmental conditions, although the utility of a survey depends on whether the results are quantitative or qualitative, and other design considerations. The results from a variety of monitoring programs in the United States are available in integrated biological information systems, although many include only non-native species, not native species. Besides including natives, we suggest these systems could be improved through the development of standardized methods that capture habitat and physiological requirements and link regional and national biological databases into distributed Web portals that allow drawing information from multiple sources. Combining the outputs from these biological information systems with environmental data would allow the development of ecological-niche models that predict the potential distribution or abundance of native and non-native species on the basis of current environmental conditions. Environmental projections from climate models can be used in these niche models to project changes in species distributions or abundances under altered climatic conditions and to identify potential high-risk invaders. There are, however, a number of challenges, such as uncertainties associated with projections from climate and niche models and difficulty in integrating data with different temporal and spatial granularity. Even with these uncertainties, integration of biological and environmental information systems, niche models, and climate projections would improve management of aquatic ecosystems under the dual threats of biotic invasions and climate change.  相似文献   
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Allozyme-based genetic distances were used to determine the distinctness of six species of cave crayfish from the Ozark Plateau in Missouri, Arkansas, and Oklahoma. One of the cave species is in the subgenus Erebicambarus and the others are in Jugicambarus . Four of the six species are very rare and are found in only one to three known sites each. In addition, most populations of all the species are presumed to be small; rarely are more than a few individuals observed. A chela (claw) was collected from sixty individuals representing the six species, including all known populations of the four rare species. Variability and distance estimates were based on 20 presumptive gene loci. Population samples with identical genotypes were pooled. Thirteen loci were polymorphic, but average heterozygosity was low (H= 1%) compared to epigean crayfish species. Pairwise genetic distances within Jugicambarus ranged from D = 0.051 to 0.522, and mean distance between subgenera was D = 0.676. The underground water systems in Ozark caves are defined by discreet recharge zones. Groundwater pollution threatens the stability of cave ecosystems, including the survival of cave crayfish. If restoration of threatened or extirpated populations becomes necessary, a database of genetic variability and relatedness estimates for known populations of all the species will aid decisions about numbers and sources of individuals for propagation or transfer.  相似文献   
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This study was conducted to examine adsorption of pesticides bifenthrin, carbosulfan, λ-cyhalothrin, cypermethrin, endosulfan, parathion methyl, monocrotophos and 4-nitrophenol by sandy clay loam (S.C.L) and sandy loam (S.L) soils (with varying organic content). There was no significant difference between the observed soil water partitioning coefficient values (K d) derived from linear and nonlinear Freundlich isotherms. Adsorption of pesticides on S.C.L soils was higher than those on S.L soils. K d values showed significant correlations (r 2?=?0.8???0.99 and 0.65???0.97) with soil organic carbon content (OC) and weak correlations (r 2?=?0.2???0.29 and 0.1???0.18) with clay contents of S.C.L and S.L soil at p?≤?0.05, respectively for all pesticides (except monocrotophos). Observed K oc values (soil-water partitioning constants based on the organic C fraction of the soil) were in accordance with the literature values of Wauchope and Tomlin with a maximum deviation of less than 0.5 log units. Ten Quantitative Property-Property Relationships (QPPR) among water solubility, n-octanol water coefficient (K ow) and K oc were proposed for studied pesticides except monocrotophos. The models were considered acceptable when predicted-observed difference for log?K ow and log?K oc were ≤?0.3 and ≤?0.5?log units, respectively, during the validation procedure. This work indicates that the log?K oc derived from the log Kow, from some of existing relationships, may be a fair predictor where observed values (i.e., K d and K oc) are not available. Furthermore, predicted leaching potential by groundwater ubiquity scores (GUS) equation was solved by using observed K oc values and literature reported half lives of pesticides. GUS ranked the mobility of nonvolatile compounds i.e., bifenthrin, λ-cyhalothrin, cypermethrin and endosulfan extremely low; methyl parathion very low; 4-nitrophenol low; carbofuran and monocrotophos very high in S.C.L and S.L soils, respectively. Results discussed in this paper provide background to prioritize pesticides or chemical groups that should be evaluated under field conditions with regard to their leaching potential to groundwater in arid climates.  相似文献   
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Abstract:  Within the last 30 years, five endemic bird species of the Alaka'i Swamp, Kaua'i, Hawai'i, have likely gone extinct. We documented population trends of the remaining avifauna in this time period to identify a common pattern in the Hawaiian Islands: decline of native species and expansion of introduced species. We conducted bird surveys over 100 km2 of the Alaka'i and Kōke'e regions of Kaua'i in March–April 2000 to estimate population size, distribution, and range limits of seven native and six introduced forest birds. We compared the results with four previous surveys conducted over the last 30 years. Five of the seven native species we studied have fared well, maintaining sizeable populations (>20,000 individuals) and unchanged or increasing numbers. The endemic 'Akikiki ( Oreomystis bairdi ), however, declined from 6296 (SE ± 1374) to 1472 (SE ± 680) individuals and exhibited range contraction from 88 to 36 km2. The 'I'iwi ( Vestiaria coccinea ) also experienced a decline and contraction, though not as severe. Populations of several introduced forest birds are increasing, but all species, excluding the Japanese White-eye ( Zosterops japonicus ), were at low numbers (<5,500 individuals in survey area). One introduced species, the Japanese Bush-Warbler ( Cettia diphone ) recently invaded, whereas another, the Red-billed Leiothrix ( Leiothrix lutea ), has been extirpated. Two hurricanes in the past 20 years appear to have most strongly affected nectarivores and may have contributed to the decline or extinction of several other species. Overall, native bird populations on Kaua'i have exhibited species-specific responses to limiting factors. Although most native populations appear stable, the extant native avifauna is vulnerable as a result of limited distributions and the potential for widespread habitat degradation.  相似文献   
30.
Abstract: Conservation development projects combine real‐estate development with conservation of land and other natural resources. Thousands of such projects have been conducted in the United States and other countries through the involvement of private developers, landowners, land trusts, and government agencies. Previous research has demonstrated the potential value of conservation development for conserving species, ecological functions, and other resource values on private lands, especially when traditional sources of conservation funding are not available. Nevertheless, the aggregate extent and effects of conservation development were previously unknown. To address this gap, we estimated the extent and trends of conservation development in the United States and characterized its key attributes to understand its aggregate contribution to land‐conservation and growth‐management objectives. We interviewed representatives from land trusts, planning agencies, and development companies, searched the Internet for conservation development projects and programs, and compiled existing databases of conservation development projects. We collected data on 3884 projects encompassing 1.38 million ha. About 43% of the projects targeted the conservation of specific plant or animal species or ecological communities of conservation concern; 84% targeted the protection of native ecosystems representative of the project area; and 42% provided buffers to existing protected areas. The percentage of protected land in conservation development projects ranged from <40% to >99%, and the effects of these projects on natural resources differed widely. We estimate that conservation development projects have protected roughly 4 million ha of land in the United States and account for about 25% of private‐land conservation activity nationwide.  相似文献   
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