全文获取类型
收费全文 | 3417篇 |
免费 | 49篇 |
国内免费 | 141篇 |
专业分类
安全科学 | 84篇 |
废物处理 | 168篇 |
环保管理 | 341篇 |
综合类 | 673篇 |
基础理论 | 1180篇 |
污染及防治 | 657篇 |
评价与监测 | 258篇 |
社会与环境 | 234篇 |
灾害及防治 | 12篇 |
出版年
2023年 | 17篇 |
2022年 | 51篇 |
2021年 | 51篇 |
2020年 | 36篇 |
2019年 | 18篇 |
2018年 | 150篇 |
2017年 | 145篇 |
2016年 | 214篇 |
2015年 | 78篇 |
2014年 | 50篇 |
2013年 | 71篇 |
2012年 | 452篇 |
2011年 | 241篇 |
2010年 | 72篇 |
2009年 | 63篇 |
2008年 | 83篇 |
2007年 | 89篇 |
2006年 | 89篇 |
2005年 | 406篇 |
2004年 | 547篇 |
2003年 | 431篇 |
2002年 | 57篇 |
2001年 | 52篇 |
2000年 | 24篇 |
1999年 | 32篇 |
1998年 | 6篇 |
1997年 | 14篇 |
1996年 | 6篇 |
1995年 | 12篇 |
1994年 | 4篇 |
1993年 | 4篇 |
1992年 | 4篇 |
1991年 | 7篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 3篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 1篇 |
1969年 | 1篇 |
1968年 | 1篇 |
1967年 | 1篇 |
1966年 | 2篇 |
1961年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有3607条查询结果,搜索用时 15 毫秒
1.
区域多样化发展在提高生产力、促进就业以及稳定经济等方面发挥着重要作用.一直以来演化经济地理学框架下区域多样化发展中外部资源的作用被忽略,而跨区域合作创新是区域获取外部知识的重要途径之一.研究使用2000~2017年长三角地区41个城市的发明专利数据,对区域经济一体化特征显著的长三角地区多样化水平与合作创新进行测度,并实证检验区域内部与跨区域的合作创新在区域多样化进程中所发挥的作用.结果表明:(1)长三角地区各城市的相关与不相关多样化水平总体呈现逐渐上升并趋于稳定的趋势;(2)合作创新作为知识流动的重要载体,合作参与者大多位于长三角内,合作创新所产生的知识溢出往往发生在具有技术关联性的产业间,从而有助于促进长三角地区发展相关多样化,但对不相关多样化没有表现出显著影响;(3)合作创新中参与团队数量与区域相关与不相关多样性没有显著关系;(4)合作创新中跨区域合作比例越高,越能够促进区域相关与不相关多样化的发展.因此,在推动区域产业多样化的过程中应注重强化区域间的合作,借助外部力量引导区域产业发展. 相似文献
2.
A.?R.?M.?Towfiqul?IslamEmail author Shuanghe?Shen Muhammed?Atikul?Haque Md.?Bodrud-Doza K.?W.?Maw Md.?Ahosan?Habib 《Environment, Development and Sustainability》2018,20(5):1935-1959
Sustainable groundwater quality is a key global concern and has become a major issue of disquiets in most parts of the world including Bangladesh. Hence, the assessment of groundwater quality is an important study to ensure its sustainability for various uses. In this study, a combination of multivariate statistics, geographical information system (GIS) and geochemical approaches was employed to evaluate the groundwater quality and its sustainability in Joypurhat district of Bangladesh. The results showed that the groundwater samples are mainly Ca–Mg–HCO3 type. Principal component analysis (PCA) results revealed that geogenic sources (rock weathering and cation exchange) followed by anthropogenic activities (domestic sewage and agro-chemicals) were the major factors governing the groundwater quality of the study area. Furthermore, the results of PCA are validated using the cluster analysis and correlation matrix analysis. Based on the groundwater quality index (GWQI), it is found that all the groundwater samples belong to excellent to good water quality domains for human consumption, although iron, fluoride and iodide contaminated to the groundwater, which do not pose any significant health hazard according to World Health Organization’s and Bangladesh’s guideline values. The results of irrigation water quality index including sodium adsorption ratio (SAR), permeability index and sodium percentage (Na %) suggested that most of the groundwater samples are good quality water for agricultural uses. The spatial distribution of the measured values of GWQI, SAR, Fe (iron), EC (electrical conductivity) and TH (total hardness) were spatially mapped using the GIS tool in the study area. 相似文献
3.
基于复杂系统建模的水管理政策研究进展 总被引:3,自引:0,他引:3
基于Agent的建模方法(ABSS)通过自下而上的方式,考察系统中主体的不同状态和行为特征、主体与环境的作用、主体之间的作用,来表征系统的宏观特征,是进行复杂社会环境系统分析和政策研究的重要手段,在水资源、水环境管理系统中得到了有效的应用。本文在大量文献调研的基础上,讨论了ABSS建模方法的基本原理、主要特征、系统构成、分类方法和开发工具等特征,总结了其供水系统发展、水资源分配和流域水资源管理、农业土地和水资源利用、居民用水行为、农业污染控制及人类活动的水环境影响等方面的应用,分析了其在研究内容、研究方法、研究结果等方面的发展趋势,讨论了利用该方法研究我国水资源管理和水污染控制政策的必要性和重要性。 相似文献
4.
技术变化是应对气候变化问题的关键。对技术变化的模拟和分析能够识别技术变化的作用.在评估减排成本以及确定减排目标时起到重要作用。但是早期的气候政策模型通常将技术变化视为非经济的外生变量,因而无法对技术变化的起因和效果做深入分析。近年来的气候政策模型则开始逐渐利用内生方法模拟技术变化。在介绍内生技术变化的概念及与传统的外生技术变化的区别的基础上,重点介绍和评述研发投入和技术学习这两种主要的内生技术变化模拟方法的原理、特点以及如何在不同的气候政策模型中得到应用。但是现有建模方法无法表征技术变化过程中的动态性、不确定性等特征,因而传统的建模方法需要扩展到一个更为综合的框架并需要更坚实的实证研究基础上。基于该框架介绍内生技术变化模拟方法的未来可能拓展。 相似文献
5.
6.
Ohne Zusammenfassung
Original erschienen in UWSF – Z Umweltchem ?kotox 20(2):133–144 (2008) DOI:
Herausgeber: Martin Pehnt und Eckard Helmers 相似文献
7.
Helena M?kinen Kalevi Nieminen Susanna M?ki Sirkku Siiskonen 《International journal of occupational safety and ergonomics》2008,14(1):19-28
High temperature alkaline chemical liquids have caused injuries and hazardous situations in Finnish pulp manufacturing mills. There are no requirements and/or test method standards concerning protection against high temperature alkaline chemical splashes. This paper describes the test method development process to test and identify materials appropriate for hot liquid chemical hazard protection. In the first phase, the liquid was spilled through a stainless steel funnel and the protection performance was evaluated using a polyvinyl chloride (PVC) film under the test material. After several tentative improvements, a graphite crucible was used for heating and spilling the chemical, and a copper-coated K-type thermometer with 4 independent measuring areas was designed to measure the temperature under the material samples. The thermometer was designed to respond quickly so that peak temperatures could be measured. The main problem was to keep the spilled amount of chemical constant, which unfortunately resulted in significant variability in data. 相似文献
8.
9.
Pyrite ash is created as waste from the roasting of pyrite ores during the production of sulphuric acid. These processes generate great amounts of pyrite ash waste that is generally land filled. This creates serious environmental pollution due to the release of acids and toxic substances. Pyrite ash waste can be utilized in the iron production industry as a blast furnace feed to process this waste and prevent environmental pollution. The essential parameters affecting the pelletization process of pyrite ash were studied using bentonite as a binder. Experiments were then carried out using bentonite and a mixture of bentonite with calcium hydroxide and calcium chloride in order to make the bentonite more effective. The metallurgical properties of pyrite ash, bentonite, calcium hydroxide, calcium chloride, a mixture of these and sintered pellets were studied using X-ray analysis. The crushing strength tests were carried out to investigate the strength of pyrite ash waste pellets. The results of these analyses showed that pyrite ash can be agglomerated to pellets and used in the iron production industry as a blast furnace feed. The crushing strength of the pellets containing calcium hydroxide and calcium chloride in addition to bentonite was better than the strength of pellets prepared using only bentonite binder. 相似文献
10.
Le Nguyen Truc Thinh Nguyen An Ha Nguyen Thi Vinh Tien Nguyen Dinh Lam Nguyen Duc Hong Nguyen Van Tuan Nguyen Tat Hanh Ta Van Khanh Nguyen Ngoc Thanh Nguyen Ngoc Hens Luc 《Environment, Development and Sustainability》2022,24(10):12427-12445
Environment, Development and Sustainability - The recent growth of agriculture, industry and urban areas in Vietnam requires a large amount of water consumption as a production factor. This paper... 相似文献