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781.
Igor V. Bartish Wim A. Ozinga Mark I. Bartish G.W. Wieger Wamelink Stephan M. Hennekens Benjamin Yguel Andreas Prinzing 《Conservation biology》2020,34(6):1536-1548
Present biodiversity comprises the evolutionary heritage of Earth's epochs. Lineages from particular epochs are often found in particular habitats, but whether current habitat decline threatens the heritage from particular epochs is unknown. We hypothesized that within a given region, humans threaten specifically habitats that harbor lineages from a particular geological epoch. We expect so because humans threaten environments that dominated and lineages that diversified during these epochs. We devised a new approach to quantify, per habitat type, diversification of lineages from different epochs. For Netherlands, one of the floristically and ecologically best-studied regions, we quantified the decline of habitat types and species in the past century. We defined habitat types based on vegetation classification and used existing ranking of decline of vegetation classes and species. Currently, most declining habitat types and the group of red-listed species are characterized by increased diversification of lineages dating back to Paleogene, specifically to Paleocene-Eocene and Oligocene. Among vulnerable habitat types with large representation of lineages from these epochs were sublittoral and eulittoral zones of temperate seas and 2 types of nutrient-poor, open habitats. These losses of evolutionary heritage would go unnoticed with classical measures of evolutionary diversity. Loss of heritage from Paleocene-Eocene became unrelated to decline once low competition, shade tolerance, and low proportion of non-Apiaceae were accounted for, suggesting that these variables explain the loss of heritage from Paleocene-Eocene. Losses of heritage from Oligocene were partly explained by decline of habitat types occupied by weak competitors and shade-tolerant species. Our results suggest a so-far unappreciated human threat to evolutionary heritage: habitat decline threatens descendants from particular epochs. If the trends persist into the future uncontrolled, there may be no habitats within the region for many descendants of evolutionary ancient epochs, such as Paleogene. 相似文献
782.
Ecological Effectiveness of Agri-Environment Schemes in Different Agricultural Landscapes in The Netherlands 总被引:12,自引:0,他引:12
DAVID KLEIJN‡ FRANK BERENDSE RUBEN SMIT NIELS GILISSEN JOHN SMIT BASTIAAN BRAK ROLF GROENEVELD† 《Conservation biology》2004,18(3):775-786
Abstract: Agri-environment schemes are an instrument used by western European countries to counteract the negative effects of contemporary agriculture on biodiversity, but not much is known about their effectiveness. We investigated the ecological effects of Dutch agri-environment schemes aimed at promoting botanical diversity or meadow birds, and we tested whether the effectiveness of the schemes depends on landscape type or structure. In three different types of landscape, we surveyed plants, birds, bees, and hover flies on 78 paired fields that either had agri-environment schemes or were managed conventionally, and we collected data on a range of different environmental variables. Neither plant species richness nor abundance of meadow birds was higher on fields with agri-environment schemes. Landscape type had a significant effect on both species groups, but the effects of the schemes were independent of landscape type. Neither the diversity of plants nor the abundance of birds was related to any of the environmental variables. Agri-environment schemes designed to promote plant species richness or bird abundance did have positive side-effects because they enhanced the species richness of bees and hover flies, irrespective of the type of landscape. Furthermore, landscape type, groundwater level (hover flies), and area of wooded edges (bees) significantly affected both species groups. The failure of the schemes to promote the target species may be related to the high intensity of land use in The Netherlands. Simple conservation measures taken by farmers may not be sufficient to counteract the impact of factors that are often controlled at the landscape level (e.g., hydrology). Similar studies in other countries are needed to place the results of our study into a European context. 相似文献
783.
784.
Abstract: We studied the potential for native birds to control insect pests on farms. We assessed habitat factors correlated with diversity, distribution, and insect-foraging activity of native birds on farms in north-central Florida and then characterized common bird species that consumed insect biomass in crops as "functional insectivores" (birds most likely to contribute to pest control). Analyses of point-count survey data and foraging observations collected over 2 years on paired organic and conventional farm sites indicated that (1) farms supported most (82–96%) land birds known to breed in the region; (2) bird species richness and abundance varied significantly with matrix habitat and field border type (but not with year or farm management type); (3) the highest bird abundances were associated with mixed crop plantings, field borders, and adjacent matrix composed of forest and hedge; and (4) abundances of 10 species identified as functional insectivores were primarily influenced by crop type (mixed crops attracted significantly more insect foragers into fields than monocrops). We documented birds eating pest insects in crops and did not observe substantive crop damage by birds during growing-season observations. We advocate use of the term functional insectivore to emphasize the potential positive role of avian insectivory on farms during the growing season. 相似文献
785.
Reduced Diversity and Complexity in the Leaf-Litter Ant Assemblage of Colombian Coffee Plantations 总被引:3,自引:0,他引:3
Abstract: Coffee agroecosystems have recently undergone a dramatic intensification in Colombia, a megadiverse country, especially in terms of the nature of shade cover. We tested for changes in the composition, ecological associations, and diversity of ants (Hymenoptera: Formicidae) along a gradient of intensification of coffee production in the Colombian Andes. We surveyed 16 farms in two regions, classified into four management types: (1) forest (no agriculture), (2) organic polygeneric shaded coffee, (3) monogeneric shaded coffee, and (4) sun coffee (unshaded). Forty sampling units (20 1-m2 plots on the ground and 20 coffee bushes) were established at each farm between 2001 and 2002. We sampled with a mini-winkler litter extraction technique and through visual searching. Organic polygeneric shaded-coffee plantations contained significantly higher ant species richness, and their ant assemblages resembled the forest patches more than any other management type. The number of statistically significant associations among ant species dropped with production intensification, as did the number of ant species involved in such associations. The network of ant associations in shaded systems transformed into an extremely simplified network in sun coffee, with a few dominant ants extending almost entirely throughout the crop. Intensification of coffee agriculture not only caused loss of litter ant species (especially forest species) but also a reduction in the complexity of the ant assemblage in the leaf litter of this agroecosystem. 相似文献
786.
Abstract: The 2010 biodiversity target adopted globally and in Europe is an important political commitment for improved biodiversity conservation and management. Whether or not it is achieved will be judged by a set of biodiversity indicators now under development. We reviewed the development of these indicators in Europe and globally, paying particular attention to the need to make the indicators relevant to the purpose; to distinguish between measures of pressure, state, and response; to design and validate the indicators in context; to ensure effective communication with relevant audiences; to turn lists of measures into simple or composite indicators; and to maximize the cost-effectiveness of the indicator process. We conclude that urgent steps are needed to complete the indicator set, reduce and refine the agreed measures, ensure that work is started soon so that reliable reporting occurs in 2010, and start soon on planning for subsequent assessments. 相似文献
787.
L. G. Firbank M. G. Telfer B. C. Eversham H. R. Arnold 《Journal of environmental management》1994,42(4)
The set-aside scheme of the E.C. is a way of dealing with the socio-economic problem of food surpluses, but it also presents opportunities for environmental benefits. To help target set-aside policies, three groups of species (scarce plants, butterflies and grasshoppers) were analysed by present and past distribution and by habitat. In those biotopes which could be restored using set-aside land, chalk grassland has shown the greatest decline of scarce plants, and the two insect groups have declined the most in heathland, water-fringe vegetation and woodland edges. However, declines were also observed for other biotopes. These and other data suggest that conservation efforts on a set-aside land should not be concentrated on a particular kind of habitat, but should address a diversity of habitats in a diversity of locations. This conclusions has been used to help defined the 1993 set-aside schemes for the U.K. 相似文献
788.
农田承灾力综合评价与分区:以河南省为例 总被引:2,自引:0,他引:2
我国地域辽阔,耕地面积大,农田承灾能力各地差异明显。本文从建立农业承灾力的评价模型入手,选择参评因子,划分评分标准,计算综合指数,确定地域等级。作者以河南省为例,通过调查与分析,分别对全省各县(市)进行系统计算,最后进行分区综合评价。 相似文献
789.
Using the example of Southern Ural forests, it is shown that the Braun-Blanquet method is promising for estimating the efficiency
of the system of specially protected natural areas (SPNAs) and drawing up guidelines for its further development. In particular,
evidence is provided that forests of the unions Aconito-Piceion and Lathyro-Quercion are protected quite insufficiently. Proposals concerning organization of new SPNAs are formulated. 相似文献
790.
Jonathan Ready Kristin Kaschner Paul D. Eastwood Josephine Rius Sven Kullander 《Ecological modelling》2010,221(3):467-478
We present and evaluate AquaMaps, a presence-only species distribution modelling system that allows the incorporation of expert knowledge about habitat usage and was designed for maximum output of standardized species range maps at the global scale. In the marine environment there is a significant challenge to the production of range maps due to large biases in the amount and location of occurrence data for most species. AquaMaps is compared with traditional presence-only species distribution modelling methods to determine the quality of outputs under equivalently automated conditions. The effect of the inclusion of expert knowledge to AquaMaps is also investigated. Model outputs were tested internally, through data partitioning, and externally against independent survey data to determine the ability of models to predict presence versus absence. Models were also tested externally by assessing correlation with independent survey estimates of relative species abundance. AquaMaps outputs compare well to the existing methods tested, and inclusion of expert knowledge results in a general improvement in model outputs. The transparency, speed and adaptability of the AquaMaps system, as well as the existing online framework which allows expert review to compensate for sampling biases and thus improve model predictions are proposed as additional benefits for public and research use alike. 相似文献