全文获取类型
收费全文 | 1518篇 |
免费 | 167篇 |
国内免费 | 340篇 |
专业分类
安全科学 | 88篇 |
废物处理 | 50篇 |
环保管理 | 328篇 |
综合类 | 890篇 |
基础理论 | 319篇 |
环境理论 | 4篇 |
污染及防治 | 108篇 |
评价与监测 | 31篇 |
社会与环境 | 190篇 |
灾害及防治 | 17篇 |
出版年
2024年 | 13篇 |
2023年 | 46篇 |
2022年 | 73篇 |
2021年 | 90篇 |
2020年 | 94篇 |
2019年 | 79篇 |
2018年 | 69篇 |
2017年 | 77篇 |
2016年 | 99篇 |
2015年 | 82篇 |
2014年 | 78篇 |
2013年 | 139篇 |
2012年 | 132篇 |
2011年 | 102篇 |
2010年 | 84篇 |
2009年 | 85篇 |
2008年 | 66篇 |
2007年 | 106篇 |
2006年 | 87篇 |
2005年 | 64篇 |
2004年 | 60篇 |
2003年 | 57篇 |
2002年 | 41篇 |
2001年 | 46篇 |
2000年 | 39篇 |
1999年 | 19篇 |
1998年 | 18篇 |
1997年 | 18篇 |
1996年 | 17篇 |
1995年 | 9篇 |
1994年 | 13篇 |
1993年 | 7篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1984年 | 2篇 |
1982年 | 1篇 |
1976年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有2025条查询结果,搜索用时 22 毫秒
131.
中国生态农业与绿色食品 总被引:8,自引:0,他引:8
本文从农业环境问题和食品安全性出发,阐述了中国生态农业的兴起及特点,绿色食品生产的要求,生态农业与绿色食品的关系。介绍了几种可用于开发绿色食品的优化生态模式。 相似文献
132.
133.
R. M. Patel S. O. Prasher P. K. God R. Bassi 《Journal of the American Water Resources Association》2002,38(1):91-100
ABSTRACT: This study explores the applicability of Artificial Neural Networks (ANNs) for predicting salt build‐up in the crop root zone. ANN models were developed with salinity data from field lysimeters subirrigated with brackish water. Different ANN architectures were explored by varying the number of processing elements (PEs) (from 1 to 30) for replicate data from a 0.4 m water table, 0.8 m water table, and both 0.4 and 0.8 m water table lysimeters. Different ANN models were developed by using individual replicate treatment values as well as the mean value for each treatment. For replicate data, the models with twenty, seven, and six PEs were found to be the best for the water tables at 0.4 m, 0.8 m and both water tables combined, respectively. The correlation coefficients between observed salinity and ANN predicted salinity of the test data with these models were 0.89, 0.91, and 0.89, respectively. The performance of the ANNs developed using mean salinity values of the replicates was found to be similar to those with replicate data. Not only was there agreement between observed and ANN predicted salinity values, the results clearly indicated the potential use of ANN models for predicting salt build‐up in soil profile at a specific site. 相似文献
134.
135.
136.
输变电项目环评存在问题分析及对策建议 总被引:2,自引:0,他引:2
列举了国家环保总局环境工程评估中心在输变电项目环境影响技术评估中遇到的一些技术和管理上亟待解决的问题,在对其分析的基础上,提出相应的对策建议. 相似文献
137.
利用小波的时频局部化的特征,将信息的加密过程由传统的时域中进行改为在时域和频域中进行,达到信息加密和增强信息安全性的目的。采用两种方法实现信息的加密与解密的过程,一种是将明文保存为图像文件格式,对图像文件进行小波的分解与重构,实现信息的加密与解密;另一种是将明文数值化为一个系数矩阵,对数值矩阵进行小波的分解与重构,实现信息的加密与解密。通过小波分解过程进行加密,小波的重构过程进行解密,改变了传统的在空域中通过一系列的移位、迭代和置换的方式进行的加密过程,因此也不能通过传统的解密方式进行解密,增强了信息的安全性。由于小波的多样性,不同的小波变换得到的结果也会不同,增加了解密的难度,保证了数据的安全。 相似文献
138.
Aslı Aksoy 《International Journal of Green Energy》2019,16(1):34-48
All economic sectors are associated with energy use; therefore, government organizations aim to supply sustainable energy for human needs and economic growth. In particular, increased environmental concerns of the public in Turkey have impacted policymaking for renewable energy (RE) management in Turkey. The primary objective for RE sources of the Turkish Ministry of Energy is to ensure that 30% of the share of electricity production is from RE resources in 2023. In this paper, the integrated multi-objective, multi-period linear programming model is presented to determine effective allocation of RE supply for seven different geographical regions in Turkey for the period of 2017 to 2024. The integrated model consists of two different stages. The first stage involves qualitative evaluations of RE sources for seven geographical regions. Analytical Hierarchy Process (AHP) is applied to determine criteria priorities and overall ratings of geographical regions across determined criteria for RE sources are computed. The second stage of the integrated model consists of a multi-objective, multi-period linear programming model. The proposed multi-objective linear programming model is coded in MPL (Mathematical Programming Language) and solved using the GUROBI 5.1.0 solver. The output of the integrated model presents the total supply amount of RE sources for geographical regions in planning period. The ε-constraints method is applied to compute the total supply amount of RE from geographical regions for the period of 2017 to 2024. In this study, a systematic decision-making model is generated to allocate renewable energy sources to the geographical regions. The presented model integrates qualitative evaluations and quantitative parameters of different geographical regions to determine the optimal supply amount of RE. The obtained results are consistent with the potential quantities of RE alternatives in geographical regions, regional specifications, and social requirements. 相似文献
139.
"两山"理论,即"绿水青山就是金山银山",是习近平新时代中国特色社会主义思想的重要内容。浙江是"两山"理论的发源地,思考探寻基于浙江情境的"两山"转化路径,意义重大且十分迫切。本研究从顶层设计、高质量发展、营商环境、协同治理、技术创新等方面,总结浙江"两山"转化的实践经验及其实践特征,探讨其"两山"转化路径,以期为在全国范围内推广"两山"转化与践行提供参考。 相似文献
140.
Trends in plant cover synanthropization along a plain-foothills-mountains gradient have been revealed in the reserve. Characteristics of plant communities in anthropogenically disturbed habitats, centers of concentration of anthropophytes and apophytes, and pathways of their migration are described. 相似文献