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991.
A Forest Planning Language and Simulator (FORPLAN) has been developed to facilitate the use of simulation for integrating fire into the land management planning process.FORPLAN incorporates unique characteristics of previous systems, links numerous models and data bases, allows selection of variable resolution levels, and permits discrete time simulation of disturbances on plants, fuels, and animals. No previous computer experience is required of the user, sinceFORPLAN recognizes simple English words and phrases. 相似文献
992.
D. L. Anderson P. C. Rosendahl 《Journal of the American Water Resources Association》1998,34(2):235-249
ABSTRACT: South Florida and the Everglades have been under intensive development since 1850 by Federal and State governments who encouraged and financed extensive drainage and hydraulic changes, primarily for agricultural settlement. Agricultural development of the sugar industry in the northern Everglades adjacent to Lake Okeechobee rapidly progressed only after the 1900s. Political and resource management conflicts have arisen because policies which once favored development are now being reversed by policies and regulation efforts to restore and conserve natural ecosystems. Currently, the environmental and ecological impacts of agricultural land use adjacent to natural wtlands of the Everglades are being assessed. The objectives of this paper are: (1) to outline the historical development of south Florida and the sugar industry, (2) to relate this history to political and management policy changes occurring as it pertains to ecosystem restoration and the multiuser competition for water/land resources, and (3) to propose how integrated resource management might be utilized for a sustainable Everglades and south Florida. This paper outlines the historical paradox of urban settlement, land development, and agricultural production, with efforts in the recent decade to acquire, manage, and preserve land and water resources for natural areas conservation. Only though the use of integrated resource management will the defined resource conflicts be mediated. 相似文献
993.
Alicia L. Carriquiry F. Jay Breidt P. G. Lakshminarayan 《Environmental management》1998,22(4):505-515
/ Evaluating the environmental and economic impacts of agricultural policies is not a simple task. A systematic approach to evaluation would include the effect of policy-dependent factors (such as tillage practices, crop rotations, and chemical use) as well as the effect of policy-independent covariates (such as weather, topography, and soil attributes) on response variables (such as amount of soil eroded or chemical leached into the groundwater). For comparison purposes, the effects of these input combinations on the response variable would have to be assessed under competing policy scenarios. Because the number of input combinations is high in most problems, and because policies to be evaluated are often not in use at the time of the study, practitioners have resorted to simulation experiments to generate data. However, generating data from simulation models is often costly and time consuming; thus, the number of input combinations in a study may be limiting even in simulation experiments. In this paper, we discuss the problem of designing computer simulation experiments that require generating data for just a fraction of the possible input combinations. We propose an approach that is based on subsampling the 1992 National Resources Inventory (NRI) points. We illustrate the procedure by assessing soil erosion in a situation where there are "observed" data [reported by the Natural Resources Conservation Service (NRCS)] for comparison. Estimates for soil erosion obtained using the procedure we propose are in good agreement with NRCS reported values.KEY WORDS: Metamodel; National Resources Inventory; Nonpoint source pollution 相似文献
994.
/ Roxborough State Park in Colorado's Front Range was established in 1975 following a history of cattle and sheep ranching by private ownership. Survey work conducted from 1979 to 1995 resulted in the documentation of 93 species of butterflies. A variety of factors are responsible for the composition of the butterfly community: (1) overgrazing and its effect on the presence or absence of specific butterfly host plants; (2) habitat differences resulting from topographical and geological features; and (3) ecological and historical biogeography. This study provides data on community sampling adequacy, along with estimates of effort needed to monitor trends in abundance by using a community self-similarity curve and power analysis. An annual monitoring plan is proposed to assess trends in community composition. The plan includes collection of presence/absence and abundance data for select butterflies based on natural history information.KEY WORDS: Butterfly communities; Grazing; Inventory; Monitoring; Natural history 相似文献
995.
N. H. Ravindranath I. K. Murthy R. K. Chaturvedi K. Andrasko J. A. Sathaye 《Mitigation and Adaptation Strategies for Global Change》2007,12(6):1027-1050
Carbon forestry mitigation potential estimates at the global-level are limited by the absence or simplicity of national-level
estimates, and similarly national-level estimates are limited by absence of regional-level estimates. The present study aims
to estimate the mitigation potential for a large diverse country such as India, based on the GTAP global land classification
system of agro-ecological zones (AEZs), as well the Indian AEZ system. The study also estimates the implications of carbon
price incentive (US$50 and $100) on mitigation potential in the short-, medium- and long-term, since afforestation and reforestation
(A & R) is constrained by lack of investment and financial incentives. The mitigation potential for short and long rotation
plantations and natural regeneration was estimated using the GCOMAP global forest model for two land area scenarios. One scenario
included only wastelands (29 Mha), and the second enhanced area scenario, included wastelands plus long fallow and marginal
croplands (54 Mha). Under the $100 carbon price case, significant additional area (3.6 Mha under the wasteland scenario and
6.4 Mha under the enhanced area scenario) and carbon mitigation is gained in the short-term (2025) compared to the baseline
when using the GTAP land classification system. The area brought under A & R increases by 85–100% for the $100 carbon price
compared to $50 carbon price in the short-term, indicating the effectiveness of higher carbon price incentives, especially
in the short-term.
A comparison of estimates of mitigation potential using GTAP and Indian AEZ land classification systems showed that in the
short-term, 35% additional C-stock gain is achieved in the $100 carbon price case in the enhanced area scenario of the Indian
AEZ system. This difference highlights the role of the land classification system adopted in estimation of aggregate mitigation
potential estimates, particularly in the short-term. Uncertainty involved in the estimates of national-level mitigation potential
needs to be reduced, by generating reliable estimates of carbon stock gain and losses, and cost and benefit data, for land
use sector mitigation options at a scale disaggregated enough to be relevant for national mitigation planning. 相似文献
996.
蒋端生 《湖南环境生物职业技术学院学报》1995,(1)
本文介绍了南岳的自然条件以及森林土壤的基本特点如酸碱度、土壤含水量、比重、浸水容重、质地、有机质、有效氮、速效磷、速效钾等情况。作者首次应用定量方法即回归分析研究了土壤紧实度与土壤层次、结构及其有机质含量的关系,还讨论了土壤侵蚀和人畜践踏对土壤紧实度的影响。 相似文献
997.
生命周期评价--清单分析方法探讨 总被引:6,自引:0,他引:6
清单分析是生命周期评价方法中极重要的环节,是对整个生命周期阶段的资源和能源的使用及环境排放的定量分析过程,详细阐述了清单流程编制和清单数据获得的分析及收集方法,并示例说明。 相似文献
998.
999.
1000.
There is an increasing interest in the quality of soil, especially for small geographical areas. We present a method to estimate the percent of the area in a county or hydrological basin that is eroded. There are sample data (for several counties in eastern Iowa) from the National Resources Inventory and population data on land use, land capability class, rainfall and slope length and steepness. Using the Gibbs sampler we perform Bayesian predictive inference to obtain estimates for the non-sampled units. These estimates, together with the sample data, provide an estimate of the proportion of the total area that is eroded. We assess the quality of fit of our model using two cross-validation exercises and graphical methods. 相似文献