全文获取类型
收费全文 | 300篇 |
免费 | 59篇 |
国内免费 | 75篇 |
专业分类
安全科学 | 113篇 |
废物处理 | 5篇 |
环保管理 | 42篇 |
综合类 | 169篇 |
基础理论 | 22篇 |
污染及防治 | 24篇 |
评价与监测 | 36篇 |
社会与环境 | 3篇 |
灾害及防治 | 20篇 |
出版年
2024年 | 3篇 |
2023年 | 18篇 |
2022年 | 23篇 |
2021年 | 12篇 |
2020年 | 17篇 |
2019年 | 17篇 |
2018年 | 17篇 |
2017年 | 18篇 |
2016年 | 16篇 |
2015年 | 18篇 |
2014年 | 23篇 |
2013年 | 23篇 |
2012年 | 29篇 |
2011年 | 24篇 |
2010年 | 23篇 |
2009年 | 21篇 |
2008年 | 12篇 |
2007年 | 17篇 |
2006年 | 20篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 14篇 |
2002年 | 11篇 |
2001年 | 9篇 |
2000年 | 1篇 |
1999年 | 3篇 |
1998年 | 4篇 |
1997年 | 4篇 |
1996年 | 5篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1986年 | 1篇 |
1972年 | 1篇 |
排序方式: 共有434条查询结果,搜索用时 234 毫秒
1.
A submersible sonde equipped with a specific conductivity probe, linked with a global positioning satellite receiver was developed, deployed on a small boat, and used to map spatial and temporal variations in specific conductivity in a large reservoir. 7,695 sample points were recorded during 8 sampling trips. Specific conductivity ranged from 442,uS/cm to 3,378,uS/cm over the nine-month study. The data showed five statistically different zones in the reservoir: 2 different riverine zones, 2 different riverine transition zones, and a lacustrine zone (the main lake zone). These data were imported to a geographic information system where they were spatially interpolated to generate 8 maps showing specific conductivity levels across the entire surface of the lake. The highly dynamic nature of water quality, due to the widely differing nature of the rivers that flow into the reservoir and the effect of large inflows of fresh water during winter storms is easily captured and visualized using this approach. 相似文献
2.
3.
4.
5.
6.
结合我国家庭中水的利用现状,设计了一套具有广泛应用性的家庭中水利用装置系统,并实现了相应的自动化控制方案。同时,详细介绍了系统的设计思路与实现的主要功能,并对装置系统的有关问题进行了深入的探讨。 相似文献
7.
8.
9.
Abedalrazq F. Khalil Mac McKee Mariush Kemblowski Tirusew Asefa 《Journal of the American Water Resources Association》2005,41(1):195-208
ABSTRACT: Water scarcity in the Sevier River Basin in south‐central Utah has led water managers to seek advanced techniques for identifying optimal forecasting and management measures. To more efficiently use the limited quantity of water in the basin, better methods for control and forecasting are imperative. Basin scale management requires advanced forecasts of the availability of water. Information about long term water availability is important for decision making in terms of how much land to plant and what crops to grow; advanced daily predictions of streamflows and hydraulic characteristics of irrigation canals are of importance for managing water delivery and reservoir releases; and hourly forecasts of flows in tributary streams to account for diurnal fluctuations are vital to more precisely meet the day‐to‐day expectations of downstream farmers. A priori streamflow information and exogenous climate data have been used to predict future streamflows and required reservoir releases at different timescales. Data on snow water equivalent, sea surface temperatures, temperature, total solar radiation, and precipitation are fused by applying artificial neural networks to enhance long term and real time basin scale water management information. This approach has not previously been used in water resources management at the basin‐scale and could be valuable to water users in semi‐arid areas to more efficiently utilize and manage scarce water resources. 相似文献
10.
针对当前无线通信中的终端天线应用进行研究,提出了一种新型的宽带微带天线结构,并采用了高频电磁场仿真软件进行了仿真验证和实际样品测试。结果表明,该天线可在0.816GHz~1.099GHz频段和1.657GHz~2.260GHz频段内达到要求的驻波比,可以实现GSM850/900/1800/1900频段以及WCDMA2100频段的要求。同时该天线结构整体辐射性能好,具有全向辐射性,适合移动终端使用。 相似文献