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971.
BENJAMIN S. HALPERN†§§ CHRISTOPHER R. PYKE HELEN E. FOX‡§ J. CHRIS HANEY MARTIN A. SCHLAEPFER†† PATRICIA ZARADIC‡‡ 《Conservation biology》2006,20(1):56-64
Abstract: Several international conservation organizations have recently produced global priority maps to guide conservation activities and spending in their own and other conservation organizations. Surprisingly, it is not possible to directly evaluate the relationship between priorities and spending within a given organization because none of the organizations with global priority models tracks how they spend their money relative to their priorities. We were able, however, to evaluate the spending patterns of five other large biodiversity conservation organizations without their own published global priority models and investigate the potential influence of priority models on this spending. On average, countries with priority areas received greater conservation investment; global prioritization systems, however, explained between only 2 and 32% of the US$1.5 billion spent in 2002, depending on whether the United States was removed from analyses and whether conservation spending was adjusted by the per capita gross domestic product within each country. We also found little overlap in the spending patterns of the five conservation organizations evaluated, suggesting that informal coordination or segregation of effort may be occurring. Our results also highlight a number of potential gaps and mismatches in how limited conservation funds are spent and provide the first audit of global conservation spending patterns. More explicit presentation of conservation priorities by organizations currently without priority models and better tracking of spending by those with published priorities are clearly needed to help make future conservation activities as efficient as possible. 相似文献
972.
This paper presents an empirical approach to select and prioritize sewerage projects within set budgetary limitations. The methodology includes a model which quantifies benefits of a sewerage project as an index or dimensionless number. The index considers need and urgency of sewerage and other project goals. Benefit is defined as the difference in anticipated impact between the current condition (without the project) and the expected condition with the project. Anticipated benefits primarily include reduction in environmental pollution, reduction of human diseases and morbidity, and other tangible and intangible improvement. This approach is a powerful decision tool for sewerage prioritization and an effective alternative to conventional cost-benefit analysis. Unlike conventional analysis, this approach makes no attempt to convert project benefits and other impacts into a monetary measure. This work recognizes that the decision to provide sewerage based solely on net benefits is not practical. Instead, benefit-cost ratios (B/C) are calculated utilizing cost-effectiveness approach. Using these ratios, 16 unserviced areas of Ensenada, Mexico are ranked. The prioritization rankings produced by this method must be further scrutinized and carefully reviewed for logic, accuracy of input data, and practicality of implementation. A similar framework may also be useful for prioritizing other public works projects. 相似文献
973.
Water resources and land use are closely linked with each other and with regional climate, assembling a very complex system. The understanding of the interconnecting relations involved in this system is an essential step for elaborating public policies that can effectively lead to the sustainable use of water resources. In this study, an integrated modelling framework was assembled in order to investigate potential impacts of agricultural expansion and climate changes on Irrigation Water Requirements (IWR) in the Taita Hills, Kenya. The framework comprised a land use change simulation model, a reference evapotranspiration model and synthetic precipitation datasets generated through a Monte Carlo simulation. In order to generate plausible climate change scenarios, outputs from General Climate Models were used as reference to perturbing the Monte Carlo simulations. The results indicate that throughout the next 20 years the low availability of arable lands in the hills will drive agricultural expansion to areas with higher IWR in the foothills. If current trends persist, agricultural areas will occupy roughly 60% of the study area by 2030. This expansion will increase by approximately 40% the annual water volume necessary for irrigation. Climate change may slightly decrease crops' IWR in April and November by 2030, while in May a small increase will likely be observed. The integrated assessment of these environmental changes allowed a clear identification of priority regions for land use allocation policies and water resources management. 相似文献
974.
Krause N 《Journal of environmental psychology》2011,31(1):62-69
The purpose of this study is to develop and test a latent variable model that explores the ways in which social structural factors influence the amount of social support that older adults provide to their social network members. Neighborhood conditions play a key role in this conceptual scheme. The findings provide support for the following conceptual linkages: (1) low parental education is associated with low respondent education; (2) older people with less education encounter more economic difficulty; (3) greater financial problems are associated with living in a rundown neighborhood; (4) older individuals who live in dilapidated neighborhoods are more hostile; and (5) older adults who are hostile are less likely to provide social support to their social network members. Research indicates that helping others is a key to successful aging. Ways must be found to help economically disadvantaged elders provide support to their social network members. 相似文献
975.
220 kV高压输电线电磁辐射水平及防护距离预测 总被引:1,自引:0,他引:1
周杨 《环境监测管理与技术》2007,19(3):46-48
依据<500 kV超高压送变电工程电磁辐射环境影响评价技术规范>(HJ/T 24-1998)中的预测模式对监测点周围地面1.5 m处工频电场进行了验证性监测,表明实际测定结果与理论计算结果基本吻合.通过对220 kV双回同相、双回逆相和单回线路下地面1.5 m、4.5 m、和7.5 m处工频电场变化趋势分析,预测了220 kV高压输电线产生的电磁辐射水平,以及不同房屋结构的防护距离.提出了220 kV高压输电线电磁辐射的防护措施. 相似文献
976.
Lars T. Waser Meinrad Kuechler Markus Schwarz Eva Ivits Silvia Stofer Christoph Scheidegger 《Environmental Modeling and Assessment》2007,12(4):315-328
The present study focuses on developing models to predict lichen species richness in a UNESCO Biosphere Reserve of the Swiss
Pre-Alps following a gradient of land-use intensity combining remote sensing data and regression models. The predictive power
of the models and the obtained r ranging from 0.5 for lichens on soil to 0.8 for lichens on trees can be regarded as satisfactory to good, respectively. The
study revealed that a combination of airborne and spaceborne remote sensing data produced a variety of ecological meaningful
variables. 相似文献
977.
Many different models can be built to explain the distributions of species. Often there is no single model that is clearly better than the alternatives, and this leads to uncertainty over which environmental factors are limiting species’ distributions. We investigated the support for different environmental factors by determining the drop in model performance when selected predictors were excluded from the model building process. We used a paired t-test over 37 plant species so that an environmental factor was only deemed significant if it consistently improved the results for multiple species. Geology and winter minimum temperatures were found to be the environmental factors with the most support, with a significant drop in model performance when either of these factors was excluded. However, there was less support for summer maximum temperature, as other environmental factors could combine to produce similar model performance. Our method of evaluating environmental factors using multiple species will not be capable of detecting predictors that are only important for one or two species, but it is difficult to distinguish these from spurious correlations. The strength of the method is that it increases inference for factors that consistently affect the distributions of many species. We discourage the assessment of models against predefined benchmarks, such as an area under the curve (AUC) of more than 0.7, as many alternative models for the same species produce similar results. Therefore, the benchmarks do not provide any indication of how the performance of the selected model compares to alternative models, and they provide weak inference to accept any selected model. 相似文献
978.
Many different spatio-temporal individual-based models (IBM) for forests have been developed for studying the development of trees in space and time. Such models typically depend on various numerical parameters that represent the ecological processes of growth (G), inter-plant competition (C) and birth-and-death (B&D; also called regeneration and mortality). Until now little work has been done to systematically trace the influence of these processes and their model parameters on the spatial structure of forest ecosystems.This paper attempts to fill this gap by addressing an important aspect of forest structure, spatial variability, characterised by the mark variogram as a summary characteristic. The model used was inspired by components of various well-established IBMs including a shot-noise competition field. Time series data from monospecies forests in three different countries of the northern hemisphere provided ecological reference scenarios. Though a case study, the paper's methodology is rather general and can be applied to any model and forest ecosystem.Methods of sensitivity analysis revealed that only a small number of model parameters is crucial for forming spatial variability. Particularly important is the range of competition between trees; with increasing range the variability increases. Growth processes have considerable importance particularly with short observation periods and in young forests, whereas mortality processes become more influential in the long-term. Naturally, these statements depend upon the initial structure and on the length of the observation period. 相似文献
979.
BRUCE E. KENDALL RICHARD A. FULLER DAVID A. MILTON HUGH P. POSSINGHAM 《Conservation biology》2011,25(4):758-766
Abstract: Estimating the abundance of migratory species is difficult because sources of variability differ substantially among species and populations. Recently developed state‐space models address this variability issue by directly modeling both environmental and measurement error, although their efficacy in detecting declines is relatively untested for empirical data. We applied state‐space modeling, generalized least squares (with autoregression error structure), and standard linear regression to data on abundance of wetland birds (shorebirds and terns) at Moreton Bay in southeast Queensland, Australia. There are internationally significant numbers of 8 species of waterbirds in the bay, and it is a major terminus of the large East Asian‐Australasian Flyway. In our analyses, we considered 22 migrant and 8 resident species. State‐space models identified abundances of 7 species of migrants as significantly declining and abundance of one species as significantly increasing. Declines in migrant abundance over 15 years were 43–79%. Generalized least squares with an autoregressive error structure showed abundance changes in 11 species, and standard linear regression showed abundance changes in 15 species. The higher power of the regression models meant they detected more declines, but they also were associated with a higher rate of false detections. If the declines in Moreton Bay are consistent with trends from other sites across the flyway as a whole, then a large number of species are in significant decline. 相似文献
980.
模拟多种阴离子共存的水体环境,采用氨基改性处理后的橘子皮作为吸附剂,研究其在不同离子共存条件下对高氯酸盐的竞争吸附.分析在不同pH条件下,竞争性阴离子对高氯酸盐吸附的影响;探讨单、双组分体系下的热力学、动力学吸附机理;采用红外光谱分析(FTIR)表征不同竞争吸附条件下吸附剂材料的结构特征.结果表明,不同pH范围内,3种阴离子与Cl O-4发生竞争吸附,其影响顺序不同:pH3时,其影响顺序为SO2-4NO-3PO3-4;3pH10时,其影响顺序为SO2-4PO3-4NO-3;pH10时,3种阴离子对Cl O-4吸附的影响趋于相同.单组分吸附下,改性橘子皮对Cl O-4、NO-3、SO2-4、PO3-4的最大吸附量分别为217.72、134.97、89.9、65.79 mg·g-1;竞争条件下,共存阴离子对Cl O-4吸附的影响顺序为PO3-4SO2-4NO-3,并且改性橘子皮对Cl O-4的吸附符合Freundlich等温线模型及准二级动力学模型,表明化学吸附为吸附的主要速率控制步骤.红外光谱分析结果证明了NO-3、SO2-4、PO3-4均在改性橘子皮吸附Cl O-4的过程中发生了竞争吸附. 相似文献