全文获取类型
收费全文 | 25057篇 |
免费 | 2048篇 |
国内免费 | 5214篇 |
专业分类
安全科学 | 2840篇 |
废物处理 | 353篇 |
环保管理 | 3969篇 |
综合类 | 15828篇 |
基础理论 | 2788篇 |
环境理论 | 16篇 |
污染及防治 | 1668篇 |
评价与监测 | 1981篇 |
社会与环境 | 1807篇 |
灾害及防治 | 1069篇 |
出版年
2024年 | 95篇 |
2023年 | 434篇 |
2022年 | 748篇 |
2021年 | 926篇 |
2020年 | 938篇 |
2019年 | 793篇 |
2018年 | 698篇 |
2017年 | 880篇 |
2016年 | 995篇 |
2015年 | 1147篇 |
2014年 | 1240篇 |
2013年 | 1520篇 |
2012年 | 1735篇 |
2011年 | 1939篇 |
2010年 | 1436篇 |
2009年 | 1419篇 |
2008年 | 1169篇 |
2007年 | 1716篇 |
2006年 | 1725篇 |
2005年 | 1350篇 |
2004年 | 1155篇 |
2003年 | 1289篇 |
2002年 | 1072篇 |
2001年 | 932篇 |
2000年 | 846篇 |
1999年 | 737篇 |
1998年 | 573篇 |
1997年 | 472篇 |
1996年 | 397篇 |
1995年 | 344篇 |
1994年 | 339篇 |
1993年 | 268篇 |
1992年 | 215篇 |
1991年 | 168篇 |
1990年 | 119篇 |
1989年 | 63篇 |
1988年 | 56篇 |
1987年 | 50篇 |
1986年 | 36篇 |
1985年 | 38篇 |
1984年 | 20篇 |
1983年 | 19篇 |
1982年 | 29篇 |
1981年 | 28篇 |
1980年 | 21篇 |
1979年 | 21篇 |
1978年 | 20篇 |
1977年 | 18篇 |
1973年 | 16篇 |
1971年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 19 毫秒
1.
从欧盟空气质量监测政策和监测网络建设现状两个方面描述了欧盟空气质量监测发展现状。分析了我国空气污染现状和空气质量监测体系中存在的问题,并借鉴欧盟的经验,提出了加大政策支持和财政保障力度、逐步健全空气质量监测网络体系、加强空气质量监测技术研究、完善空气质量监测数据库、开展能力建设、提高公众参与度等加强我国空气质量监测体系建设的建议。 相似文献
2.
Waste accumulation is a grave concern and becoming a transboundary challenge for environment. During Covid-19 pandemic, diverse type of waste were collected due to different practices employed in order to fight back the transmission rate of the virus. Covid-19 was proved to be capricious catastrophe of this 20th century and even not completely eradicated from the world. The havoc created by this imperceptible quick witted, pleomorphic deadly virus can't be ignored. Though a number of vaccines have been developed by the scientists but there is a fear of getting this virus again in our life. Medical studies prove that immunity drinks will help to reduce its reoccurrences. Coconut water is widely used among all drinks available globally. Its massive consumption created an incalculable pile of green coconut shells around the different corners of the world. This practice generating enormous problem of space acquisition for the environment. Both the environment and public health will benefit from an evaluation of quantity of coconut waste that is being thrown and its potential to generate value added products. With this context, present article has been planned to study different aspects like, coconut waste generation, its biological properties and environmental hazards associated with its accumulation. Additionally, this review illustrates, green technologies for production of different value added products from coconut waste. 相似文献
3.
温彦平 《环境监测管理与技术》2015,27(1):22-26
选取太原汾河景区跨桥断面8个监测点,在2012年3月—2013年10月期间对河流8项水质参数进行监测,并结合派生的水体综合污染指数及主成分分析方法分析和评价景区水污染时空变化特征。结果表明,景区水质污染变化时空差异明显,上游污染相对较小,下游污染较重;春季溶解氧和p H值变化幅度最大,夏季除总氮和氨氮外,其他各污染物均有显著变化特征,秋季则以氨氮、总氮和总磷变化最为显著。主成分分析结果显示,虽然各监测点水体污染的关键影响因子不同,但总磷是太原市河流水体污染的共同解释因子。 相似文献
4.
5.
Amirhossein Moosavi Adel Nikfarjam 《International Journal of Sustainable Engineering》2019,12(3):174-188
In this paper, the inventory-routing problem is studied for a closed-loop supply chain. This closed-loop supply chain considers suppliers, manufacturers, whole-sellers, and disposal centers. To formulate this problem, a mixed integer linear programming model is proposed. This mathematical model minimizes the total costs of the supply chain, including the fixed and variable costs of vehicles, and holding inventory costs of final products and scraps. The proposed model considers the road roughness degree, multi-path setting and the heterogeneous fleet of vehicles, which increases its flexibility and the quality of solutions. Then, two symmetry-breaking constraints are proposed to reduce the complexity of the mathematical model. In order to evaluate the integrity of the proposed model, 20 instances of different sizes are randomly generated and solved. Finally, a comprehensive sensitivity analysis is conducted with respect to five key features of the problem, such as the impact of the symmetry-breaking constraints on the CPU time, multi-path setting, fixed cost of vehicles, heterogeneous fleet of vehicles, and lost sales. The results indicate that the consideration of multi-path setting and the heterogeneous fleet of vehicles improves the quality of solutions significantly. 相似文献
6.
Quantitative methods have been applied to the study of floristic structure and diversity in Samarskaya Luka. The results show that Samarskaya Luka is a floristically heterogeneous area in which six elementary floras can be distinguished. This area has been assessed as a floristically autonomous formation, and its floristic representativeness was estimated. 相似文献
7.
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
8.
9.
Abstract: Introduction of artificial light into wildlife habitat represents a rapidly expanding form of human encroachment, particularly in coastal systems. Light pollution alters the behavior of sea turtles during nesting; therefore, long-wavelength lights—low-pressure sodium vapor and bug lights—that minimize impacts on turtles are required for beach lighting in Florida (U.S.A.). We investigated the effects of these two kinds of lights on the foraging behavior of Santa Rosa beach mice ( Peromyscus polionotus leucocephalus ). We compared patch use and giving-up densities of mice for experimental food patches established along a gradient of artificial light in the field. Mice exploited fewer food patches near both types of artificial light than in areas with little light and harvested fewer seeds within patches near bug lights. Our results show that artificial light affects the behavior of terrestrial species in coastal areas and that light pollution deserves greater consideration in conservation planning. 相似文献
10.