全文获取类型
收费全文 | 1474篇 |
免费 | 141篇 |
国内免费 | 426篇 |
专业分类
安全科学 | 160篇 |
废物处理 | 47篇 |
环保管理 | 131篇 |
综合类 | 981篇 |
基础理论 | 227篇 |
污染及防治 | 283篇 |
评价与监测 | 91篇 |
社会与环境 | 63篇 |
灾害及防治 | 58篇 |
出版年
2024年 | 8篇 |
2023年 | 30篇 |
2022年 | 90篇 |
2021年 | 80篇 |
2020年 | 71篇 |
2019年 | 43篇 |
2018年 | 48篇 |
2017年 | 56篇 |
2016年 | 57篇 |
2015年 | 68篇 |
2014年 | 101篇 |
2013年 | 127篇 |
2012年 | 155篇 |
2011年 | 138篇 |
2010年 | 115篇 |
2009年 | 124篇 |
2008年 | 103篇 |
2007年 | 124篇 |
2006年 | 97篇 |
2005年 | 58篇 |
2004年 | 65篇 |
2003年 | 49篇 |
2002年 | 43篇 |
2001年 | 46篇 |
2000年 | 31篇 |
1999年 | 30篇 |
1998年 | 19篇 |
1997年 | 18篇 |
1996年 | 11篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1982年 | 1篇 |
1977年 | 2篇 |
1971年 | 1篇 |
排序方式: 共有2041条查询结果,搜索用时 15 毫秒
571.
Restoration of waterbird diversity and abundance is a key objective of river system management in Australia. Therefore, understanding the effects of climatic and hydrological variables on waterbird population dynamics is fundamental for successful river restoration programs. We investigated the population dynamics of waterbirds (total abundance) and seven functional waterbird groups in the floodplains of lower Murrumbidgee River. We found a general declining abundance trend from 1983 to 2007, except for the deep water foragers. We modelled the relative contribution of the climatic and hydrological factors to waterbird population decrease using the generalized additive model (GAM) framework after identifying the negative binomial distribution. Most of the seven functional groups were positively related to both annual rainfall and water usage, defined as the total water volume intercepted by the river reach, and the models indicated that rainfall was slightly more important. Temperature also played a role in waterbird abundance: the maximum summer temperature negatively influenced the abundance of dabbling ducks, shoreline foragers and fish eaters, while the minimum winter temperature positively affected the abundance of dabbling ducks and shoreline foragers. Overall, our results support the practice of providing environmental water for sustaining waterbird populations. However, environmental water provision is likely to be most effective when timed to coincide with antecedent rainfall. 相似文献
572.
Human activities disturb the long-term phosphorus (P) cycle in nature, whereby the resulting intensive release of P contributes to the eutrophication of surface water. Hence, a detailed understanding of P flow as it relates to socioeconomic systems is essential for effective nutrient management. This study develops a substance-flow-analysis model for P metabolism for the socioeconomic ecosystem of Shucheng County in Anhui Province in central China as a case study. We estimate P flow using data from questionnaires, face-to-face interviews, published literature, and official statistical databases. Our results show that P flow in Shucheng's current socioeconomic system is linear and openly metabolic. The total P input into Shucheng in 2008 reached 12 748 Mg, mainly as P ores and crops. In all, 43.83% of the total P input was exported, and 30.44% was discharged into surface water. More-balanced nutrient management and options for improving nutrient use efficiency are discussed. The quantifiable, science-based methods used in this study may be applied to neighboring regions of central China for sustainable development and water management. 相似文献
573.
Kinmen is located in the southwest of Mainland China. Groundwater supplies 50% of the domestic water use on the island. Residents
of Kinmen drink groundwater over the long term because surface water resources are limited. Nitrate–N pollution is found and
distributed primarily in the western part of groundwater aquifer whereas saline groundwater is distributed to the northeastern
Kinmen. This work applied the DRASTIC model to construct the vulnerability map of Kinmen groundwater. MT3D was then used to
evaluate the contamination potential of nitrate–N. The health risk associated with the ingestion of nitrate–N contaminated
groundwater is also assessed. The results from DRASTIC model showed that the upland crop and grass land have high contamination
potential, whereas the forest, reservoir and housing land have low contamination potential. The calibrated MT3D model inversely
determined the high strength sources (0.09–2.74 kg/m2/year) of nitrate contaminant located in the west to the north west area and required 2–5 years travel time to reach the monitoring
wells. Simulated results of MT3D also showed that both the continuous and instantaneous contaminant sources of nitrate–N release
may cause serious to moderate nitrate contamination in the western Kinmen and jeopardize the domestic use of groundwater.
The chronic health hazard quotient (HQ) associated with the potential non-carcinogenic risk of drinking nitrate–N contaminated groundwater showed that the assessed
95th percentile of HQ is 2.74, indicating that exposure to waterborne nitrate poses a potential non-cancer risk to the residents of the island.
Corrective measures, including protecting groundwater recharge zones and reducing the number of agricultural and non-agricultural
nitrogen sources that enters the aquifer, should be implemented especially in the western part of Kinmen to assure a sustainable
use of groundwater resources. 相似文献
574.
中国生物入侵的现状与趋势 总被引:4,自引:0,他引:4
采用文献调研、实地考察与专家咨询相结合的方式,对中国境内森林、湿地、草原、荒漠、内陆水域和海洋等生态系统的外来入侵物种进行调查,共查明488种外来入侵物种并收集其详细信息,包括名称、分类地位、分布、起源、首次发现或引入的地点和时间、入侵途径、危害、营养和环境条件等.在这488种外来入侵物种中,植物265种,动物171种,菌物26种,病毒12种,原核生物11种,原生生物3种.对有较明确入侵时间记载的392种外来入侵物种入侵年代的分析结果表明,1850年以前,仅出现31种外来人侵物种,自1850年起,新的外来入侵物种种数总体呈逐步上升趋势,特别是1950年后的60a间,新出现209种.外来入侵物种首次发现的地点集中在沿海地区及云南和新疆等边疆地区,但首次发现地点有逐步北移的趋势.有意引进与无意引进的外来入侵物种种数所占比例十分接近,近年来无意引进成为首要途径.美洲、欧洲和亚洲其他地区是中国外来入侵物种的主要来源地.外来入侵物种的分布呈现由沿海向内陆逐步减少的趋势. 相似文献
575.
576.
577.
578.
在对区域经济差异识别方法归类总结的基础上,以青海省为案例,选取标准差、锡尔系数和聚类法对1999—2010年7个市和43个县的GDP、人口数据、人均GDP进行整理分析,研究了西部大开发以来青海省区域经济差异动态变化及1999年、2009年青海区域经济差异格局变化,并给出了建议,旨在为今后协调区域经济发展提供一定基础。结果表明,西部大开发以来,青海区域经济的绝对差异迅速扩大,呈直线型的增长趋势,相对差异总体呈现逐年扩大趋势,说明青海省经济发展差距拉大,发展不平衡性越来越明显,资源、交通条件和科技条件等都会扩大区域间的经济发展差异。 相似文献
579.
Blake Poland Chris Buse Paul Antze Randolph Haluza-DeLay Chris Ling Lenore Newman 《Local Environment》2013,18(3):180-200
ABSTRACTOriginating in the UK in 2006, the Transition movement is oriented to local grassroots citizen-led efforts that prepare for and support a societal energy transition to a low-carbon future in response to climate change, peak oil, ecological degradation, and economic instability. Overlapping significantly with relocalization, degrowth/slow growth, local food, and related movements, and based on permaculture principles and a distributed network model, it embraces the opportunity to turn crisis into an opportunity to build more resilient, convivial, and vibrant local communities, declaring that “if it’s not fun, it’s not sustainable”. The Transition approach has spread rapidly around the world, including initiatives in over 100 communities and cities in Canada. This paper reports on the methods and results of a Canadian community-based research study aimed at understanding how and where the movement has taken root across the country, what Transition practice looks like, challenges and opportunities encountered, and lessons learned that could be applied within the movement and by others interested in the role of citizen-led initiatives for sustainability transition. Utilising a practice theory lens, drawing on an extensive web-scan of the movement’s online presence, a survey and interviews with initiative (co)founders, an e-survey of Transition members/participants, regional “structured story-dialogue” workshops, and key informant interviews, and informed by input from a Movement Advisory Group, we describe the research process and explore what success and impact mean to those most active in the movement. 相似文献
580.