全文获取类型
收费全文 | 1262篇 |
免费 | 90篇 |
国内免费 | 151篇 |
专业分类
安全科学 | 180篇 |
废物处理 | 14篇 |
环保管理 | 278篇 |
综合类 | 406篇 |
基础理论 | 361篇 |
环境理论 | 1篇 |
污染及防治 | 86篇 |
评价与监测 | 29篇 |
社会与环境 | 121篇 |
灾害及防治 | 27篇 |
出版年
2024年 | 1篇 |
2023年 | 19篇 |
2022年 | 30篇 |
2021年 | 47篇 |
2020年 | 44篇 |
2019年 | 37篇 |
2018年 | 30篇 |
2017年 | 36篇 |
2016年 | 54篇 |
2015年 | 53篇 |
2014年 | 42篇 |
2013年 | 68篇 |
2012年 | 80篇 |
2011年 | 135篇 |
2010年 | 71篇 |
2009年 | 106篇 |
2008年 | 79篇 |
2007年 | 80篇 |
2006年 | 86篇 |
2005年 | 45篇 |
2004年 | 51篇 |
2003年 | 38篇 |
2002年 | 42篇 |
2001年 | 35篇 |
2000年 | 35篇 |
1999年 | 21篇 |
1998年 | 15篇 |
1997年 | 16篇 |
1996年 | 18篇 |
1995年 | 16篇 |
1994年 | 10篇 |
1993年 | 7篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 7篇 |
1989年 | 4篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
排序方式: 共有1503条查询结果,搜索用时 46 毫秒
111.
喀斯特石山地区社会经济与生态环境可持续发展系统研究:以桂西北为例 总被引:5,自引:0,他引:5
本建立了广西西北部喀斯特石山地区可持续发展的系统动力学模型。并用DYNAMO程序预测了未来20年桂西北地区的人口、工业、农业、第三产业,生态环境,土地资源,社会总产值,人均国民收人等的动态变化趋势,结果显示,该地区由于人口,工业资产增加使物质和能源消耗增长太快,而对污染治理的投入又太少,导致桂西北地区的生存环境质量下降,因此应当加大对污染治理的投入力度,改善区域环境质量,这是实现息烽县区域可持续发展的关键,根据区域特点探讨了桂西北喀斯特贫困山区的形成演化,提出了可持续发展的途径。 相似文献
112.
For about 50 years the desertion of areas by traditional activities has led to an important evolution of landscapes and environments
on the island of Ouessant. The study of this evolution has been undertaken at different spatial and temporal scales. On one
part of the island, a scientific investigation carried out at the scale of the parcel enabled the form of the landscape in
1850 to be compared with that of 1985. On the whole island, the evolution of spatial organization and land use was compared
between 1950 and 1985. For each of three main ecological environments, vegetational successions after the decrease of agriculture
have been studied along with their future potential changes. This work highlights some considerations about the present management
of the environment in relation to the major objectives of island environmental policies. 相似文献
113.
大气中SO2的液相氧化研究 总被引:2,自引:0,他引:2
大气中SO2液相氧化是形成酸雨的重要途径,降雨中含有各种无机离子和有机物质,它们可能催化或抑制液相氧化反应的进行。本文根据四川酸雨样品组成,进行了SO2在模拟雨水及实际雨水中的氧化实验,考查了V,Fe,Mn等离子对SO2氧化的催化作用,H2O2对SO2的氧化以及降水中有机物质甲醛对各反应的影响。实验结果为了解酸雨的成固,研究酸雨控制对策提供了科学依据。 相似文献
114.
Modeling the Suitability of Potential Wetland Mitigation Sites with a Geographic Information System 总被引:1,自引:0,他引:1
Wetland mitigation is frequently required to compensate for unavoidable impacts to wetlands. Site conditions and landscape context are critical factors influencing the functions that created wetlands perform. We developed a spatial model and used a geographic information system (GIS) to identify suitable locations for wetland mitigation sites. The model used six variables to characterize site conditions: hydrology, soils, historic condition, vegetation cover, adjacent vegetation, and land use. For each variable, a set of suitability scores was developed that indicated the wetland establishment potential for different variable states. Composite suitability scores for individual points on the landscape were determined from the weighted geometric mean of suitability scores for each variable at each point. These composite scores were grouped into five classes and mapped as a wetland mitigation suitability surface with a GIS. Sites with high suitability scores were further evaluated using information on the feasibility of site modification and project cost. This modeling approach could be adapted by planners for use in identifying the suitability of locations as wetland mitigation sites at any site or region. 相似文献
115.
An Ecological Integrity Index for Littoral Wetlands in Agricultural Catchments of Semiarid Mediterranean Regions 总被引:1,自引:0,他引:1
The main goal of the present study was to develop an ecological integrity index for littoral wetland management and conservation in semiarid Mediterranean areas that have been highly impacted by agriculture, including the selection of pressure and state indicators at landscape and wetlands scales that reflect the status, condition, and trends of wetlands ecosystems. We used a causality framework based on the relationship between pressure of anthropogenic activities and the ecological state of wetlands and their catchments, integrating environmental, biologic, economic, and social issues. From the application of 51 indicators in 7 littoral wetlands in the southeastern Iberian Peninsula, we selected 12 indicators (5 at catchment scale and 7 at wetland scale) to constitute the ecological integrity index proposed. The potential nitrogen export per area at catchment scale and the potential relative nitrogen export from the area surrounding the wetlands were the best pressure single predictors of state indicators with a causal relationship with environmental meaning. Wetlands in catchments with more agriculture had less ecological integrity than those in less impacted areas. A wide riparian zone in some wetlands acts as a buffer area, diminishing the effects of intensive agriculture. The index of ecological integrity developed here has a number of essential characteristics that make it a useful tool for ecosystem managers and decision-makers. The index can be used to (1) assess and control ecological integrity, (2) diagnose probable causes of ecological impairment, (3) establish criteria for protecting and restoring wetland ecosystems, and (4) integrate catchment management.
Published online 相似文献
116.
Martín-Duque JF Pedraza J Sanz MA Bodoque JM Godfrey AE Díez A Carrasco RM 《Environmental management》2003,32(4):488-498
Landform-based physiographic maps, also called land systems inventories, have been widely and successfully used in undeveloped/rural areas in several locations, such as Australia, the western United States, Canada, and the British ex-colonies. This paper presents a case study of their application in a developed semi-urban/suburban area (Segovia, Spain) for land use planning purposes. The paper focuses in the information transfer process, showing how land use decision-makers, such as governments, planners, town managers, etc., can use the information developed from these maps to assist them. The paper also addresses several issues important to the development and use of this information, such as the goals of modern physiography, the types of landform-based mapping products, the problem of data management in developed areas, and the distinctions among data, interpretations, and decisions. 相似文献
117.
Qiu Z 《Environmental management》2003,32(3):299-311
Conservation buffers have the potential to reduce agricultural nonpoint source pollution and improve terrestrial wildlife habitat, landscape biodiversity, flood control, recreation, and aesthetics. Conservation buffers, streamside areas and riparian wetlands are being used or have been proposed to control agricultural nonpoint source pollution. This paper proposes an innovative strategy for placing conservation buffers based on the variable source area (VSA) hydrology. VSAs are small, variable but predictable portion of a watershed that regularly contributes to runoff generation. The VSA-based strategy involves the following three steps: first, identifying VSAs in landscapes based on natural characteristics such as hydrology, land use/cover, topography and soils; second, targeting areas within VSAs for conservation buffers; third, refining the size and location of conservation buffers based on other factors such as weather, environmental objectives, available funding and other best management practices. Building conservation buffers in VSAs allows agricultural runoff to more uniformly enter buffers and stay there longer, which increases the buffers capacity to remove sediments and nutrients. A field-scale example is presented to demonstrate the effectiveness and cost-effectiveness of the within-VSA conservation buffer scenario relative to a typical edge-of-field buffer scenario. The results enhance the understanding of hydrological processes and interactions between agricultural lands and conservation buffers in agricultural landscapes, and provide practical guidance for land resource managers and conservationists who use conservation buffers to improve water quality and amenity values of agricultural landscape. 相似文献
118.
Only a few empirical studies on forest aesthetics have adopted a water-based perspective for observers and have investigated
the perceived visual quality of forested shorelines. In forested environments with many lakes, such as the boreal forest in
the Canadian Shield, individuals have greater exposure to forests from water-based rather than in-stand vantage points. This
study employed the psychophysical research direction to explore the relationships between scenic beauty and biophysical characteristics
of the forested shorelines in the boreal forests. Two model forms were tested. One model related the variation of shoreline
forest aesthetic evaluations of near-vista views (140 m offshore) to a set of forest mensuration data. Tree size, tree mortality,
conifer shrubs, tree density, amount of hardwood, and slope explained 60.2% of the variance in scenic beauty between the study
sites. A second model was calibrated to test the relationship between an already existing ecosystem vegetation classification
system and the aesthetic evaluations of the same forested shorelines. When the ecosystem classification was simplified to
eight groups, the model explained 48.5% of variance. These models suggest that the psychophysical approach to studying aesthetics
can be applied successfully to near-vista evaluations of scenic beauty. The finding that a forest ecosystem classification
system is highly related to scenic beauty suggests that, at least in the boreal forest, managers can reasonably estimate the
scenic beauty of forested shoreline environments from an ecosystem classification, with little need for intensive data on
these sites. 相似文献
119.
Traditional Land-Use Systems and Patterns of Forest Fragmentation in the Highlands of Chiapas, Mexico 总被引:1,自引:0,他引:1
Ochoa-Gaona S 《Environmental management》2001,27(4):571-586
The influence of slash-and-burn agriculture and tree extraction on the spatial and temporal pattern of forest fragmentation
in two municipalities in the highlands of Chiapas, Mexico was analyzed. The data series were derived from two subsets of satellite
images taken in 1974 and 1996. The analysis was based on area, edge, shape, core area, and neighbor indices. During the 22
years, the dense forest decreased by 8.9%/yr in Huistán and by 8.6%/yr in Chanal, while open/disturbed forest, secondary vegetation,
and developed area increased in both municipalities. The total number of fragments increased by 1.4%/yr and 2.3%/yr in Huistán
and Chanal, respectively. Dense forest showed the highest increase in the number of fragments (6%/yr in Huistán and 12%/yr
in Chanal), while edge length, core area, and number of dense forest core areas decreased. The larger fragments of dense forest
present in 1974 were divided into smaller fragments in 1996; at the same time, they experienced a process of degradation toward
open/disturbed forest and secondary vegetation. Two different fragmentation patterns could be distinguished based on agricultural
or forestry activities. Forest fragmentation did not occur as a continuous process; the pattern and degree of fragmentation
were functions of land tenure, environmental conditions, and productive activities. The prevalence of rather poor soil conditions,
small-holdings, growing human population densities, increasing poverty, and the absence of alternative economic options will
maintain a high rate of deforestation and forest fragmentation in the studied region. 相似文献
120.
The literature guides environmental planning and, specifically, how to use ecological rehabilitation projects to achieve long-term
planning goals and landscape-scale environmental sustainability. There is, however, a perceived gap between principles in
the literature and the use of them by practitioners involved in smaller-scale ecological rehabilitation projects. Using interviews
with practitioners involved in 11 projects within the Regional Municipality of Waterloo, Ontario, Canada, we tested whether
practitioners used five principles for effective planning and implementation of ecological rehabilitation that we derived
from the literature. These five principles were: establishing political and ecological context, using ecologically appropriate
objectives and practices, using comparative multidisciplinary and cross-scale approaches, using adaptive planning and implementation,
and establishing good communication within and external to projects. Few projects followed all five principles, and practitioners
indicated that they used three more project-specific principles: obtaining political/social support, promoting projects and
changing attitudes about projects, and securing sufficient and persistent funding to maintain a project's life. While the
literature emphasizes that ecological rehabilitation is only effective if projects are coordinated on a watershed basis, most
practitioners focused solely on the goals of their specific project. The gap between literature and practice may arise because
most practitioners are new to the field of ecological rehabilitation and still are focused on the methods involved. Time pressures
force practitioners to obviate the literature and get projects started quickly, lest support evaporate. Complicating these
difficulties is decreased support from federal and provincial governments for large-scale environmental planning. It is unclear
whether ecological rehabilitation projects in Waterloo Region (at least) will ever become effective at promoting landscape-scale
ecological goals or remain smaller-scale stop-gaps. 相似文献