全文获取类型
收费全文 | 15523篇 |
免费 | 158篇 |
国内免费 | 125篇 |
专业分类
安全科学 | 356篇 |
废物处理 | 666篇 |
环保管理 | 1797篇 |
综合类 | 2543篇 |
基础理论 | 4308篇 |
环境理论 | 4篇 |
污染及防治 | 4021篇 |
评价与监测 | 1056篇 |
社会与环境 | 963篇 |
灾害及防治 | 92篇 |
出版年
2022年 | 121篇 |
2021年 | 103篇 |
2020年 | 100篇 |
2019年 | 106篇 |
2018年 | 196篇 |
2017年 | 233篇 |
2016年 | 326篇 |
2015年 | 267篇 |
2014年 | 452篇 |
2013年 | 1203篇 |
2012年 | 493篇 |
2011年 | 691篇 |
2010年 | 613篇 |
2009年 | 581篇 |
2008年 | 672篇 |
2007年 | 715篇 |
2006年 | 589篇 |
2005年 | 514篇 |
2004年 | 521篇 |
2003年 | 508篇 |
2002年 | 489篇 |
2001年 | 647篇 |
2000年 | 472篇 |
1999年 | 248篇 |
1998年 | 170篇 |
1997年 | 204篇 |
1996年 | 201篇 |
1995年 | 236篇 |
1994年 | 234篇 |
1993年 | 180篇 |
1992年 | 195篇 |
1991年 | 183篇 |
1990年 | 203篇 |
1989年 | 187篇 |
1988年 | 151篇 |
1987年 | 162篇 |
1986年 | 153篇 |
1985年 | 156篇 |
1984年 | 148篇 |
1983年 | 140篇 |
1982年 | 125篇 |
1981年 | 120篇 |
1980年 | 115篇 |
1979年 | 124篇 |
1978年 | 100篇 |
1977年 | 113篇 |
1975年 | 87篇 |
1974年 | 87篇 |
1973年 | 96篇 |
1972年 | 86篇 |
排序方式: 共有10000条查询结果,搜索用时 140 毫秒
91.
92.
Globally, greenhouse gas budgets are dominated by natural sources, and aquatic ecosystems are a prominent source of methane (CH4) to the atmosphere. Beaver (Castor canadensis and Castor fiber) populations have experienced human-driven change, and CH4 emissions associated with their habitat remain uncertain. This study reports the effect of near extinction and recovery of beavers globally on aquatic CH4 emissions and habitat. Resurgence of native beaver populations and their introduction in other regions accounts for emission of 0.18–0.80 Tg CH4 year−1 (year 2000). This flux is approximately 200 times larger than emissions from the same systems (ponds and flowing waters that became ponds) circa 1900. Beaver population recovery was estimated to have led to the creation of 9500–42 000 km2 of ponded water, and increased riparian interface length of >200 000 km. Continued range expansion and population growth in South America and Europe could further increase CH4 emissions.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-014-0575-y) contains supplementary material, which is available to authorized users. 相似文献93.
Anna Maria J?nsson Olle Anderbrant Jennie Holmér Jacob Johansson Guy Schurgers Glenn P. Svensson Henrik G. Smith 《Ambio》2015,44(3):249-255
In recent years, climate impact assessments of relevance to the agricultural and forestry sectors have received considerable attention. Current ecosystem models commonly capture the effect of a warmer climate on biomass production, but they rarely sufficiently capture potential losses caused by pests, pathogens and extreme weather events. In addition, alternative management regimes may not be integrated in the models. A way to improve the quality of climate impact assessments is to increase the science–stakeholder collaboration, and in a two-way dialog link empirical experience and impact modelling with policy and strategies for sustainable management. In this paper we give a brief overview of different ecosystem modelling methods, discuss how to include ecological and management aspects, and highlight the importance of science–stakeholder communication. By this, we hope to stimulate a discussion among the science–stakeholder communities on how to quantify the potential for climate change adaptation by improving the realism in the models. 相似文献
94.
Jay M. Iwasaki Barbara I. P. Barratt Janice M. Lord Alison R. Mercer Katharine J. M. Dickinson 《Ambio》2015,44(7):694-704
The Varroa mite (Varroa destructor) is implicated as a major disease factor in honey bee (Apis mellifera) populations worldwide. Honey bees are extensively relied upon for pollination services, and in countries such as New Zealand and Australia where honey bees have been introduced specifically for commercial pollinator services, the economic effects of any decline in honey bee numbers are predicted to be profound. V. destructor established in New Zealand in 2000 but as yet, Australia remains Varroa-free. Here we analyze the history of V. destructor invasion and spread in New Zealand and discuss the likely long-term impacts. When the mite was discovered in New Zealand, it was considered too well established for eradication to be feasible. Despite control efforts, V. destructor has since spread throughout the country. Today, assessing the impacts of the arrival of V. destructor in this country is compromised by a paucity of data on pollinator communities as they existed prior to invasion. Australia’s Varroa-free status provides a rare and likely brief window of opportunity for the global bee research community to gain understanding of honey bee-native pollinator community dynamics prior to Varroa invasion. 相似文献
95.
Wei Gao Dennis P. Swaney Bongghi Hong Robert W. Howarth Yong Liu Huaicheng Guo 《Ambio》2015,44(7):635-646
The environmental degradation of lakes in China has become increasingly serious over the last 30 years and eutrophication resulting from enhanced nutrient inputs is considered a top threat. In this study, a quasi-mass balance method, net anthropogenic N inputs (NANI), was introduced to assess the human influence on N input into three typical Chinese lake basins. The resultant NANI exceeded 10 000 kg N km−2 year−1 for all three basins, and mineral fertilizers were generally the largest sources. However, rapid urbanization and shrinking agricultural production capability may significantly increase N inputs from food and feed imports. Higher percentages of NANI were observed to be exported at urban river outlets, suggesting the acceleration of NANI transfer to rivers by urbanization. Over the last decade, the N inputs have declined in the basins dominated by the fertilizer use but have increased in the basins dominated by the food and feed import. In the foreseeable future, urban areas may arise as new hotspots for nitrogen in China while fertilizer use may decline in importance in areas of high population density.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-015-0638-8) contains supplementary material, which is available to authorized users. 相似文献96.
97.
98.
99.
100.