全文获取类型
收费全文 | 6320篇 |
免费 | 317篇 |
国内免费 | 641篇 |
专业分类
安全科学 | 109篇 |
废物处理 | 19篇 |
环保管理 | 1443篇 |
综合类 | 2666篇 |
基础理论 | 1083篇 |
环境理论 | 53篇 |
污染及防治 | 240篇 |
评价与监测 | 290篇 |
社会与环境 | 1162篇 |
灾害及防治 | 213篇 |
出版年
2024年 | 41篇 |
2023年 | 121篇 |
2022年 | 179篇 |
2021年 | 201篇 |
2020年 | 196篇 |
2019年 | 242篇 |
2018年 | 245篇 |
2017年 | 333篇 |
2016年 | 351篇 |
2015年 | 305篇 |
2014年 | 218篇 |
2013年 | 469篇 |
2012年 | 381篇 |
2011年 | 452篇 |
2010年 | 339篇 |
2009年 | 307篇 |
2008年 | 297篇 |
2007年 | 401篇 |
2006年 | 336篇 |
2005年 | 247篇 |
2004年 | 230篇 |
2003年 | 219篇 |
2002年 | 170篇 |
2001年 | 135篇 |
2000年 | 156篇 |
1999年 | 155篇 |
1998年 | 87篇 |
1997年 | 72篇 |
1996年 | 71篇 |
1995年 | 38篇 |
1994年 | 40篇 |
1993年 | 59篇 |
1992年 | 30篇 |
1991年 | 29篇 |
1990年 | 28篇 |
1989年 | 10篇 |
1988年 | 11篇 |
1987年 | 5篇 |
1986年 | 4篇 |
1985年 | 9篇 |
1984年 | 2篇 |
1983年 | 8篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 11篇 |
1979年 | 3篇 |
1978年 | 3篇 |
1977年 | 7篇 |
1975年 | 9篇 |
1971年 | 3篇 |
排序方式: 共有7278条查询结果,搜索用时 15 毫秒
101.
CLIMATE CHANGE AND NATURAL HAZARDS IN NORTHERN CANADA: INTEGRATING INDIGENOUS PERSPECTIVES WITH GOVERNMENT POLICY 总被引:1,自引:0,他引:1
John?NewtonEmail author C.?D.?James?Paci Aynslie?Ogden 《Mitigation and Adaptation Strategies for Global Change》2005,10(3):541-571
A study of the relationship between natural hazards and climate change in the international context provides the background
for a discussion of the expected changes. In the context of this global discussion, this paper reviews the current perspectives
of those natural hazards that are likely to be influenced by climate change, using northern Canada as a regional case study.
The northern implications of the United Nations Framework Convention on Climate Change are examined, including the status
of climate change action by the northern territorial governments, the evolving role of indigenous people, and the responsibility
for climate change impacts. The difficulties surrounding natural hazards research in remote locations, and the approaches
of indigenous people to natural hazards are then presented. The paper concludes with a suggested policy approach for climate
change and natural hazards in northern Canada, underscoring the need for more comprehensive adaptive strategies to complement
the current tendency to focus on the mitigation of greenhouse gases produced in this region. 相似文献
102.
秦皇岛近海养殖区域夜光藻种群动态与环境温度的关系 总被引:3,自引:0,他引:3
王素凤 《中国环境管理干部学院学报》2003,13(3):52-54
本文通过对秦皇岛近海养殖区夜光藻的调查,分析研究了夜光藻种群的动态与温度变化的关系。结论:夜光藻在秦皇岛近海养殖区内出现在3月份,并在7月份出现密度高峰,9—10月份偶有出现,11—2月份则未出现。夜光藻最高密度出现的温度为25—26℃,夜光藻在秦皇岛近海的出现及7月份的密度高峰与水温的变化密切相关。 相似文献
103.
V. Krishna Prasad K.V.S. Badarinath H. Tsuruta S. Sudo S. Yonemura John Cardina Benjamin Stinner Richard Moore Deborah Stinner Casey Hoy 《The Environmentalist》2003,23(2):175-187
Forests and soils are a major sink of carbon, and land use changes can affect the magnitude of above ground and below ground carbon stores and the net flux of carbon between the land and the atmosphere. Studies on methods for examining the future consequences of changes in patterns of land use change and carbon flux gains importance, as they provide different options for CO2 mitigation strategies. In this study, a simulation approach combining Markov chain processes and carbon pools for forests and soils has been implemented to study the carbon flows over a period of time. Markov chains have been computed by converting the land use change and forestry data of India from 1997 to 1999 into a matrix of conditional probabilities reflecting the changes from one class at time t to another class time t+1. Results from Markov modeling suggested Indian forests as a potential sink for 0.94 Gt carbon, with an increase in dense forest area of about 75.93 Mha and decrease of about 3.4 Mha and 5.0 Mha in open and scrub forests, if similar land use changes that occurred during 1997–1999 would continue. The limiting probabilities suggested 34.27 percent as dense forest, 6.90 as open forest, 0.4 percent mangrove forest, 0.1 percent scrub and 58 percent as non-forest area. Although Indian forests are found to be a potential carbon sink, analysis of results from transition probabilities for different years till 2050 suggests that, the forests will continue to be a source of about 20.59 MtC to the atmosphere. The implications of these results in the context of increasing anthropogenic pressure on open and scrub forests and their contribution to carbon source from land use change and forestry sector are discussed. Some of the mitigation aspects to reduce greenhouse gas emissions from land use change and forestry sector in India are also reviewed in the study. 相似文献
104.
Keith E. Schilling Robert D. Libra 《Journal of the American Water Resources Association》2003,39(4):851-860
ABSTRACT: Historical trends in annual discharge characteristics were evaluated for 11 gauging stations located throughout Iowa. Discharge records from nine eight‐digit hydrologic unit code (HUC‐8) watersheds were examined for the period 1940 to 2000, whereas data for two larger river systems (Cedar and Des Moines Rivers) were examined for a longer period of record (1903 to 2000). In nearly all watersheds evaluated, annual base flow, annual minimum flow, and the annual base flow percentage significantly increased over time. Some rivers also exhibited increasing trends in total annual discharge, whereas only the Maquoketa River had significantly decreased annual maximum flows. Regression of stream discharge versus precipitation indicated that more precipitation is being routed into streams as base flow than as storm flow in the second half of the 20th Century. Reasons for the observed stream flow trends are hypothesized to include improved conservation practices, greater artificial drainage, increasing row crop production, and channel incision. Each of these reasons is consistent with the observed trends, and all are likely responsible to some degree in most watersheds. 相似文献
105.
106.
Foreword Inglobalview ,droughtdisasterisregardedasthemostserioustypeofnaturaldisasterintheworld ,whichhascausedthewidestrangeofeffectsandthebiggesteconomiclosses .Se veredroughtsmainlyoccurinAfrica ,India ,China ,formerSovietUnion ,NorthAmerica ,andAustralia,accountingforalmosthalfofcountriesintheworld .Droughtdisasteroccursfre quentlyinChina ,withwiderangeofinfluence ,whichisthemostseriousmeteorologicaldisas ter ,causingeconomiclossesinagriculture .Fromthe 50’stothe 80’sinthe 2 0thcent… 相似文献
107.
湛江市位于祖国大陆的最南端,地形以平原、台地为主,土地资源利用受台风、干早等自然因素的影响。作者对湛江市土地资源可持续利用的限制因子进行了分析,提出了滋江市土地资源可持续利用的对策和措施。 相似文献
108.
林地产权政策是决定资源配置效率的基础条件。对临安示范林地区研究基点河桥乡的林地产权政策、林地流转的基本情况及农户对林地产权的意愿进行了介绍,找出了现行政策存在的问题,并提出了一套科学合理的适合当地水平的林地产权政策方案。 相似文献
109.
110.