全文获取类型
收费全文 | 6056篇 |
免费 | 558篇 |
国内免费 | 2938篇 |
专业分类
安全科学 | 173篇 |
废物处理 | 161篇 |
环保管理 | 506篇 |
综合类 | 4996篇 |
基础理论 | 2261篇 |
污染及防治 | 666篇 |
评价与监测 | 341篇 |
社会与环境 | 297篇 |
灾害及防治 | 151篇 |
出版年
2024年 | 49篇 |
2023年 | 185篇 |
2022年 | 284篇 |
2021年 | 303篇 |
2020年 | 264篇 |
2019年 | 273篇 |
2018年 | 279篇 |
2017年 | 287篇 |
2016年 | 380篇 |
2015年 | 386篇 |
2014年 | 447篇 |
2013年 | 698篇 |
2012年 | 546篇 |
2011年 | 543篇 |
2010年 | 436篇 |
2009年 | 414篇 |
2008年 | 368篇 |
2007年 | 453篇 |
2006年 | 439篇 |
2005年 | 345篇 |
2004年 | 293篇 |
2003年 | 278篇 |
2002年 | 239篇 |
2001年 | 217篇 |
2000年 | 200篇 |
1999年 | 137篇 |
1998年 | 99篇 |
1997年 | 110篇 |
1996年 | 101篇 |
1995年 | 108篇 |
1994年 | 75篇 |
1993年 | 65篇 |
1992年 | 44篇 |
1991年 | 52篇 |
1990年 | 42篇 |
1989年 | 29篇 |
1988年 | 15篇 |
1987年 | 16篇 |
1986年 | 9篇 |
1985年 | 2篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 5篇 |
1978年 | 4篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 2篇 |
排序方式: 共有9552条查询结果,搜索用时 171 毫秒
191.
水入渗条件下边坡破坏离心模型试验研究 总被引:3,自引:0,他引:3
水的人渗能对土体强度产生较大的影响,它是造成边坡破坏的一个主要因素.不同含水量土质边坡的离心模型试验表明:边坡的破坏类型与其含水量大小有关,且主要存在两种破坏类型:一种是含水量较小时形成的拉裂缝破坏,另一种是含水量较大时形成的整体滑塌破坏;同时,含水量与边坡的最大稳定高度呈非线性关系.进一步的损伤力学分析表明,随着土体含水量的增加,损伤变量增大,并存在一个突变点;通过同离心模型试验结果比较,发现该突变点对应的含水量可作为两种破坏类型的判据. 相似文献
192.
介绍头屯河流域气候、植被、水土资源状况,分析了流域水土流失的现状,提出了水土流失治理对策,总结了水土流失治理措施并提出一些建议。 相似文献
193.
辽河三角洲土壤中石油类含量光谱分析初探 总被引:2,自引:0,他引:2
石油类物质对土壤的污染在油田区域内是一个普遍存在的问题。全面了解土壤中石油类物质含量是评价土壤石油污染的前提条件。对土壤石油污染评价的传统方法是在野外实地进行大量土壤采样,然后在试验室内分析石油类物质的含量。文中提出了利用少量野外土壤石油类物质样品,并结合野外光谱测量的方法对土壤中石油类物质进行分析的新方法。该方法应用于辽河三角洲,具有快速、省钱、省时、省力的特点,能对土壤中石油类物质含量进行宏观分析。满足了油田开发对土壤及环境污染评价的需要,并能为制定油田开发管理保护对策提供辅助信息。 相似文献
194.
Craig A. Evans Kevin S. McLeary George P. Partridge Richard S. Huebner 《Journal of the American Water Resources Association》2004,40(2):409-417
ABSTRACT: Computer programs that model the fate and transport of organic contaminants through porous media typically use Fick's first law to calculate vapor phase diffusion. Fick's first law, however, is limited to the case of a single, dilute species diffusing into a stagnant, high concentration, bulk vapor phase. When dealing with more than one diffusing species and at higher concentrations, the multicomponent coupling effects on vapor phase diffusion and advection of the various constituents become significant. VLEACH, a one‐dimensional finite difference model developed for the U.S. Environmental Protection Agency (USEPA), is typical of the models using Fick's first law to model vapor‐phase diffusion. The VLEACH model was modified to accommodate up to 10 components and to calculate the binary diffusion coefficients for each of the components based on molecular weight, molecular volume, temperature and pressure, and to address the coupling effects on multiple component vapor phase diffusion and its impact on ground water. The resulting model was renamed MC‐CHEMSOIL. At low vapor phase concentrations, MC‐CHEMSOIL predicts identical ground water impacts (dissolved phase loading) to those from VLEACH 2.2a. At higher vapor phase concentrations, however, the relative difference between the models exceeded 20 percent. 相似文献
195.
B. Y. Aminuddin M. H. Ghulam W. Y. Wan Abdullah M. Zulkefli R. B. Salama 《Water, Air, & Soil Pollution: Focus》2005,5(1-2):89-101
Cameron Highlands is a mountainous region with steep slopes. Gradients exceeding 20∘ are common. The climate is favourable to the cultivation of tea, sub-tropical vegetables and flowers (under rain-shelter).
Crop production is sustained by high fertiliser and manure applications. However, agriculture in this environment is characterised
by high levels of soil erosion and environmental pollution. A study on the sustainability of these agro-ecosystems was conducted.
Results indicated that soil loss was in the range of 24–42 ton/ha/yr under vegetables and 1.3 ton under rain-shelter. Sediment
load in the vegetable sub-catchment reached 3.5 g/L, 50 times higher than that associated with flowers under rain-shelter
and tea. The sediments contained high nutrient loads of up to 470 kg N/ha/yr. The N, P and K lost in runoff from cabbage farms
was 154 kg/season/ha, whereas in chrysanthemum farms it was 5 kg. In cabbage farms, the N, P, and K lost through leaching
was 193 kg/season/ha. The NO3–N concentration in the runoff from the cabbage farms reached 25 ppm but less than 10 ppm in runoff from rain-shelters. Inorganic
pollution in the rivers was within the acceptable limit of 10 ppm. The sustainability of the agro-ecosystems is in the order
of tea { > } rain–shelter ≫ vegetables. 相似文献
196.
197.
198.
M. Stefanidou E. Anastasiou K. Georgiadis Filikas 《Waste management (New York, N.Y.)》2014,34(12):2595-2602
The increasing awareness of the society about safe guarding heritage buildings and at the same time protecting the environment promotes strategies of combining principles of restoration with environmentally friendly materials and techniques. Along these lines, an experimental program was carried out in order to investigate the possibility of producing repair, lime-based mortars used in historic buildings incorporating secondary materials. The alternative material tested was recycled fine aggregates originating from mixed construction and demolition waste. Extensive tests on the raw materials have been performed and mortar mixtures were produced using different binding systems with natural, standard and recycled sand in order to compare their mechanical, physical and microstructure properties. The study reveals the improved behavior of lime mortars, even at early ages, due to the reaction of lime with the Al and Si constituents of the fine recycled sand. The role of the recycled sand was more beneficial in lime mortars rather than the lime–pozzolan or lime–pozzolan–cement mortars as a decrease in their performance was recorded in the latter cases due to the mortars’ structure. 相似文献
199.
ABSTRACTThe present study was carried out to investigate the effect of three organic matters (stalk powder, microbial fertilizer, and manure) on Leymus chinensis germination, growth, and urease activity and available nitrogen (N) in coastal saline soil. The study was conducted in a completely randomized design with eight treatments: J0V0Y0, J1V0Y0, J0V1Y0, J0V0Y1, J1V1Y0, J1V0Y1, J0V1Y1, J1V1Y1. The notations were based on the quantities of each agent added to 1 kg of coastal saline soil: J0 – no straw powder, J1 – 0.2 kg straw powder, Y0 – no manure, Y1 – 0.3 kg manure, V0 – no microbial fertilizer, V1 – 0.2 L microbial fertilizer, each in quantic repeat. L. chinensis was sown as 50 seeds per pot. Results indicated that addition of organic agents exerted a significantly enhanced germination, increase in fresh weight and elevated soil urease activity. Soil available N levels were significantly positively correlated with soil urease activity and fresh weight, but not with germination rate. It is noteworthy that the halophyte L. chinensis showed improved characteristics when grown in coastal saline soil with addition of organic amendments. 相似文献
200.
改良剂对广西环江强酸铅锌污染土壤的修复作用 总被引:3,自引:3,他引:0
广西环江沿岸农田土壤具有强酸、多重金属污染等特点,失去了农业生产能力,为此,本研究试用了土壤淋溶实验探究不同类型改良剂(生石灰、钙镁磷肥、有机肥、聚丙烯酰胺)组合对广西环江沿岸污染土壤的修复效果,土壤重金属迁移规律及对农田适耕性的影响.结果表明,对照组T1土壤酸化严重,降低清洁接触土壤层p H值,而处理方式T2、T3、T4、T5均能显著提高污染土壤p H值(P0.05),对供试土壤p H变化大小分别为2.7~3.2、1.6~2.7,均能达到南方农业生产土壤p H值范围.较对照组T1,在污染土壤0~20 cm处,处理方式T2、T3、T4、T5能有效地活化Pb,钝化Zn的作用;在清洁土壤20~60cm处,各个处理方式对DTPA-Pb、DTPA-Zn的作用不存在显著差异(P0.05).较对照组T1,处理方式T4、T5能为植物提供良好的种植营养物质,以期能为今后结合生物修复等措施提供技术支撑. 相似文献