全文获取类型
收费全文 | 2671篇 |
免费 | 126篇 |
国内免费 | 107篇 |
专业分类
安全科学 | 776篇 |
废物处理 | 16篇 |
环保管理 | 526篇 |
综合类 | 694篇 |
基础理论 | 246篇 |
环境理论 | 2篇 |
污染及防治 | 118篇 |
评价与监测 | 140篇 |
社会与环境 | 133篇 |
灾害及防治 | 253篇 |
出版年
2024年 | 4篇 |
2023年 | 31篇 |
2022年 | 34篇 |
2021年 | 70篇 |
2020年 | 81篇 |
2019年 | 54篇 |
2018年 | 29篇 |
2017年 | 82篇 |
2016年 | 96篇 |
2015年 | 98篇 |
2014年 | 84篇 |
2013年 | 146篇 |
2012年 | 140篇 |
2011年 | 224篇 |
2010年 | 120篇 |
2009年 | 168篇 |
2008年 | 143篇 |
2007年 | 163篇 |
2006年 | 137篇 |
2005年 | 144篇 |
2004年 | 120篇 |
2003年 | 135篇 |
2002年 | 95篇 |
2001年 | 68篇 |
2000年 | 69篇 |
1999年 | 60篇 |
1998年 | 34篇 |
1997年 | 44篇 |
1996年 | 28篇 |
1995年 | 31篇 |
1994年 | 24篇 |
1993年 | 36篇 |
1992年 | 25篇 |
1991年 | 17篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 5篇 |
1987年 | 8篇 |
1986年 | 4篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 3篇 |
1981年 | 9篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有2904条查询结果,搜索用时 359 毫秒
681.
Regional vegetation pattem dynamics has a great im- pact on ecosystem and climate change.Remote sensing data and geographical information system (GIS) analysis were widely used in the detection of vegetation pattern dynamics.In this study,the Yellow River Delta was selected as the study area.By using 1986, 1993,1996,1999 and 2005 remote sensing data as basic informa- tion resource,with the support of GIS,a wetland vegetation spa- tial information dataset was built up.Through selecting the land- scape met... 相似文献
682.
Regional vegetation pattern dynamics has a great impact on ecosystem and climate change. Remote sensing data and geographical information system (GIS) analysis were widely used in the detection of vegetation pattern dynamics. In this study, the Yellow River Delta was selected as the study area. By using 1986, 1993, 1996, 1999 and 2005 remote sensing data as basic information resource, with the support of GIS, a wetland vegetation spatial information dataset was built up. Through selecting the landscape metrics such as class area (CA), class percent of landscape (PL), number of patch (NP), largest patch index (LPI) and mean patch size (MPS) etc., the dynamics of vcgetation pattern was analyzed. The result showed that the change of vegetation pattern is significant from 1986 to 2005. From 1986-1999, the area of the vegetation, the percent of vegetation, LPI and MPS decreased, the NP increased, the vegetation pattern tends to be fragmental. The decrease in vegetation area may well be explained by the fact of the nature environment evolution (Climate change and decrease in Yellow River runoff) and the increase in the population in the Yellow River Delta. However, from 1999 2005, the area of the vegetation, the percent of vegetation, LPI and MPS increased, while the NP decreased. This trend of restoration may be due to the implementation of water resources regulation for the Yellow River Delta since 1999. 相似文献
683.
Peter J. Taylor Glen R. Walker Geoff Hodgson Thomas J. Hatton Ray L. Correll 《Environmental management》1996,20(4):553-564
Irrigated agriculture has resulted in substantial changes in water flows to the lower reaches of the River Murray. These changes have led to large-scale occurrences of dieback inEucalyptus largiflorens (black box) woodlands as well as increased inputs of salt to the river. Management options to address problems of this scale call for the use of spatial data sets via geographic information systems (GIS). A GIS exists for one floodplain of the River Murray at Chowilla, and a simple model predicted six health classes ofEucalyptus largiflorens based on groundwater salinity, flooding frequency, and groundwater depth.To determine the usefulness of the model for vegetation management, the quality of both the model and the GIS data sets were tested. Success of the testing procedure was judged by the degree of spatial matching between the model's predictions of health and that assessed from aerial photographs and by field truthing. Analyses at 80 sites showed that tree health was significantly greater where groundwater salinity was less than 40 dS/m or flooding occurred more frequently than 1 in 10 years or depth to groundwater exceeded 4 m. Testing of the GIS data sets found that vegetation was misclassified at 15% of sites. Association was shown between GIS-predicted values and field-truthed values of groundwater salinity but not groundwater depth. The GIS model of health is a useful starting point for future vegetation management and can be further improved by increasing the quality of the data coverages and further refining of the model to optimize parameters and thresholds. 相似文献
684.
水库岸坡变形体灾害的信息评价和预测 总被引:2,自引:0,他引:2
较真实地评价水库岸坡的稳定性是工程界普遍关注的问题,本文将工程地质逻辑定性分析和信息法定量分析方法结合起来,对丹江口水库库岸岸坡变形体灾害的信息进行评价和预测,分析结果可供工程设计人员参考。 相似文献
685.
地质灾害管理信息系统 总被引:7,自引:1,他引:6
在地质灾害普查、勘查、防治、社会经济状况、统计信息等资料的基础上,设计出为决策提供服务的地质灾害管理信息系统,以便对地质灾害进行科学管理 相似文献
686.
首先叙述信息、灾害信息及其相互关系,提出关于灾害信息的个人观点.在此基础上,按照作者长期灾害信息的研究实践,用大量事例阐明灾害信息的采集、及成果积累的有关技术问题,最后归纳出几点认识。 相似文献
687.
Angel Hsu Amy Weinfurter Jeffrey Tong Yihao Xie 《Journal of Environmental Policy & Planning》2020,22(1):138-153
ABSTRACTInformation communication technologies (ICTs) generate new forums for transparency via governance-by-disclosure initiatives designed to improve environmental management and policy. Data generated by these programs are a means to empower citizens, narrowing the accountability gap between governments and people and enhancing public service. There is little empirical evidence, however, that supports the theory that citizen-generated data can be used to improve the accountability of local government officials. Citizen-led transparency efforts are emerging in China, as the country undergoes an information revolution that has brought ICTs to near ubiquity. We evaluate the transformative potential of a new ICT initiative, the ‘Black and Smelly Waters’ program, which China’s government launched to help enforce local government water remediation efforts. Many examples of citizen-generated transparency are grassroots initiatives, yet the Black and Smelly Waters program is distinct in its top-down structure. An empirical evaluation of preliminary data illuminates Black and Smelly Waters’s early successes and challenges as a means to generate transparency and accountability. We discuss these findings and propose a broad application of this new type of disclosure to reshape environmental management in China. 相似文献
688.
Icko Iben 《Journal of the American Water Resources Association》1969,5(2):51-58
The ages-old and ever-growing need for communication and information retrieval among scientists has found expression in the development of indexes, abstracts, reviews and combinations or variations of such. A short review of such efforts is followed by a discussion of efforts along these lines in the new field of water resources science and technology. Such undertakings as the Information Retrieval System of the American Society of Civil Engineers and of the U.S. Water Resources Research Office are compared with that of the American Water Resources Association. 相似文献
689.
Paul F. Hudak Hugo A. Loaiciga F Andrew Schoolmaster 《Journal of the American Water Resources Association》1993,29(3):383-390
ABSTRACT: Effective monitoring configurations for contaminant detection in groundwater can be designed by analyzing the spatial relationships between candidate sampling sites and aquifer zones susceptible to contamination. Examples of such zones are the domain underlying the contaminant source, zones of probable contaminant migration, and areas occupied by water supply wells. Geographic information systems (GIS) are well-suited to performing key groundwater monitoring network design tasks, such as calculating values for distance variables which quantify the proximity of candidate sites to zones of high pollution susceptibility, and utilizing these variables to quantify relative monitoring value throughout a model domain. Through a case study application, this paper outlines the utility of GIS for detection-based groundwater quality monitoring network design. The results suggest that GIS capabilities for analyzing spatially referenced data can enhance the field-applicability of established methodologies for groundwater monitoring network design. 相似文献
690.
Kurt J. Robinson Robert M. Ragan 《Journal of the American Water Resources Association》1993,29(6):1003-1008
ABSTRACT: The reauthorization of the Clean Water Act reemphasizes the need for regional scale monitoring and management of nonpoint pollution loads. The magnitude of the task will require that local governments and their consultants integrate information systems and modeling if they are to manage the massive data sets and conduct the array of simulations that will be needed to support the decision making processes. Interfacing geographic information systems (GIS) and nonpoint pollution modeling is a logical approach. The objective of the present study was to use the 37,000-acre area defined by the Kensington Quadrangle sheet in Montgomery County, Maryland, to show that GIS-supported nonpoint pollution modeling is practical and economically attractive. The purpose of the GIS is to estimate the spatial distribution of nonpoint nitrogen, phosphorous, zinc, lead, BOD, and sediment using a model developed by the Northern Virginia Planning District Commission. The system allows the user to change land uses in subareas to simulate the consequences of additional development or alternate management strategies. The tests show that in-house development of this type of special purpose GIS is a practical alternative to vendor supplied systems and that the required databases can be developed quite reasonably. 相似文献