全文获取类型
收费全文 | 18424篇 |
免费 | 1325篇 |
国内免费 | 3148篇 |
专业分类
安全科学 | 2746篇 |
废物处理 | 338篇 |
环保管理 | 3028篇 |
综合类 | 10551篇 |
基础理论 | 1691篇 |
环境理论 | 9篇 |
污染及防治 | 1512篇 |
评价与监测 | 868篇 |
社会与环境 | 1264篇 |
灾害及防治 | 890篇 |
出版年
2024年 | 87篇 |
2023年 | 373篇 |
2022年 | 599篇 |
2021年 | 716篇 |
2020年 | 748篇 |
2019年 | 568篇 |
2018年 | 497篇 |
2017年 | 687篇 |
2016年 | 786篇 |
2015年 | 784篇 |
2014年 | 841篇 |
2013年 | 1048篇 |
2012年 | 1252篇 |
2011年 | 1350篇 |
2010年 | 963篇 |
2009年 | 1049篇 |
2008年 | 780篇 |
2007年 | 1253篇 |
2006年 | 1230篇 |
2005年 | 1057篇 |
2004年 | 932篇 |
2003年 | 865篇 |
2002年 | 761篇 |
2001年 | 636篇 |
2000年 | 591篇 |
1999年 | 561篇 |
1998年 | 375篇 |
1997年 | 308篇 |
1996年 | 216篇 |
1995年 | 202篇 |
1994年 | 167篇 |
1993年 | 167篇 |
1992年 | 110篇 |
1991年 | 61篇 |
1990年 | 41篇 |
1989年 | 22篇 |
1988年 | 29篇 |
1987年 | 22篇 |
1986年 | 10篇 |
1985年 | 14篇 |
1984年 | 21篇 |
1983年 | 20篇 |
1982年 | 12篇 |
1981年 | 10篇 |
1980年 | 18篇 |
1979年 | 14篇 |
1974年 | 6篇 |
1973年 | 7篇 |
1972年 | 6篇 |
1971年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
891.
根据湖南地区节能建筑的发展现状和问题,比较国际建筑节能方面的一些先进经验,通过工程设计实例,探讨建筑产业可持续发展这一关键环节的重要性及其改进措施,并预测了节能建筑在我省的发展态势。 相似文献
892.
用密切值法评价沙湾荒漠区生态环境质量 总被引:3,自引:0,他引:3
利用多目标决策中的密切值法进行沙湾荒漠区生态环境综合评价。该方法简便、适用、且分辨率较高,对各监测点群的定量描述符合实际状况。 相似文献
893.
大叶冬青资源的开发利用与发展前景 总被引:1,自引:0,他引:1
大叶冬青是一种用途较广的珍贵药用植物资源,近年来市场对大叶冬青资源的需求日益增大。论述了大叶冬青的形态特征、生态习性、高产栽培技术、采收、加工以及其经济、生态和社会效益。 相似文献
894.
Olanike O. Aladenola Ayodele E. Ajayi Ayorinde A. Olufayo Babatunde Ajayi 《The Environmentalist》2008,28(2):123-127
The performance of a mixture of a forest bye product and cement for the production of storage structure for harvested rainwater
was assessed. Three mix ratios of Cement: Gmelina arborea sawdust 3.0:1.0 (specimen A), 2.5:1.0 (specimen B) and 2.0:1.0 (specimen C) were considered. Engineering properties and dimensional
stability of the different mix-ratios were monitored from prototypes cylindrical pots and test billet specimens. Possible
change in quality of stored rainwater, with time was monitored in all the three cases. Water quality parameters monitored
include pH, hardness, total suspended solids, alkalinity, acidity and total dissolved CO2. The tensile stress obtained were 110, 104, and 95 N/mm2, while the compressive strength were 5,000, 3,000, and 2,000 kN for specimens A, B and C respectively. Accelerated aging
test showed that sample A were more resistant to deformation, while specimen C were more susceptible to change in structure
over time. Similarly, the values of tensile and compressive strength after accelerated aging test increased in the order of
specimen A > B > C. Except in specimen C where significant differences in alkalinity and acidity were observed, there were
no significant differences in quality of the water stored in the pots after 2 months of storage. The results indicate the
suitability of the Gmelina arborea waste as an alternative in constructing water storage structures in rural communities. 相似文献
895.
Rosamund McDougall 《The Environmentalist》2008,28(2):155-157
Europe’s growing energy deficit and destabilising climate may lead the EU and its constituent member states to change its
attitude to population size and growth. 相似文献
896.
河北省钢铁工业主要大气污染物减排潜力分析 总被引:1,自引:0,他引:1
通过对河北省钢铁工业存在问题的分析,得出我省钢铁行业主要大气污染物为二氧化硫和粉尘.结合我省钢铁企业的实际情况,从工程技术、政策管理等方面提出相应治理措施,并对"十一五"期间我省钢铁行业二氧化硫和粉尘减排效益进行预测.预测结果显示:采用所建议的减排措施后,我省钢铁工业二氧化硫减排量对全省"十一五"减排计划的贡献率为81.4%;粉尘可减排60%. 相似文献
897.
898.
本文对湿式脱硫除尘一体化设备的结构和性能进行了较为全面的分析,指出了该设备存在的诸多弊病,提出了解决方案--脱硫、除尘分体组合式的思路. 相似文献
899.
In Ireland, dairy farmyard washwater commonly comprises farmyard run-off and dairy parlour washings. Land-spreading is the most widely used method for treating this wastewater. However, this method can be labour intensive and can cause, in some cases, the degradation of surface and ground waters, mainly due to nitrogen contamination. In this study, a horizontal flow biofilm reactor (HFBR) with step-feed was constructed and tested in the laboratory, to remove organic carbon and nitrogen from a agricultural strength synthetic washwater (SWW). The HFBR had an average top plan surface area (TPSA) of 0.1002 m(2) and consisted of a stack of 45 polystyrene horizontal sheets--15 sheets embedded with 25 mm deep frustums above 30 sheets with 10 mm deep frustums. The frustums acted as miniature reservoirs. The sheets were alternately offset to allow the wastewater to flow horizontally along each sheet and vertically from sheet to sheet down through the reactor. Biofilms developed on the sheets and treated the wastewater. During the 212-d study, the total hydraulic loading rate based on the TPSA of the sheets was 35 l m(-2) d(-1). SWW was pumped for 10 min each hour, in a step feed arrangement at a rate of 23.33 l m(-2) d(-1) on to the top sheet during Phases 1 and 2, and 11.67 l m(-2) d(-1) onto Sheet 16 during Phase 1 (days 1-92) and onto Sheet 30 during Phase 2 (days 93-212). The substrate loading rate during Phases 1 and 2 was 94.8 g total chemical oxygen demand (COD) m(-2) d(-1) and 10.5 g total nitrogen (TN) m(-2) d(-1), based on the TPSA. At steady state in Phase 2, the unit achieved excellent carbon removal of 99.7% 5-day biochemical oxygen demand (BOD(5)) and 96.7% total COD, equivalent to TPSA removal rates of 67.5 g BOD(5)m(-2)d(-1) and 91.7 g COD m(-2) d(-1). The nitrogen removal percentages were 98.3% total ammonium-nitrogen (NH(4)-N(t)) and 72.8% TN, which equated to TPSA removal rates of 4.8 g NH(4)-N(t) m(-2) d(-1) and 7.6g TN m(-2) d(-1). No sloughing of solids or clogging of media occurred during the study. The unit was simple to construct and operate, with little maintenance. 相似文献
900.
One of the primary challenges in resource and environmental planning is successful implementation of plans. Plan implementation is a complex process influenced by many factors. This study identifies 19 criteria affecting implementation success and tests the impact of these criteria through a case study of collaborative plan implementation in British Columbia, Canada. The significance of criteria and degree to which they are met is assessed by a survey of senior officials responsible for plan implementation. An implementation evaluation index (IEI) is constructed to assess the quality of plan implementation systems and best practices for effective implementation are identified. 相似文献