全文获取类型
收费全文 | 15005篇 |
免费 | 5146篇 |
国内免费 | 27488篇 |
专业分类
安全科学 | 2022篇 |
废物处理 | 337篇 |
环保管理 | 1351篇 |
综合类 | 32402篇 |
基础理论 | 3064篇 |
环境理论 | 1篇 |
污染及防治 | 5643篇 |
评价与监测 | 1665篇 |
社会与环境 | 554篇 |
灾害及防治 | 600篇 |
出版年
2024年 | 87篇 |
2023年 | 266篇 |
2022年 | 544篇 |
2021年 | 555篇 |
2020年 | 1164篇 |
2019年 | 2125篇 |
2018年 | 2228篇 |
2017年 | 2317篇 |
2016年 | 2018篇 |
2015年 | 2529篇 |
2014年 | 3120篇 |
2013年 | 3364篇 |
2012年 | 3426篇 |
2011年 | 2877篇 |
2010年 | 2655篇 |
2009年 | 2575篇 |
2008年 | 2157篇 |
2007年 | 2227篇 |
2006年 | 1688篇 |
2005年 | 1289篇 |
2004年 | 1102篇 |
2003年 | 806篇 |
2002年 | 674篇 |
2001年 | 688篇 |
2000年 | 790篇 |
1999年 | 626篇 |
1998年 | 466篇 |
1997年 | 425篇 |
1996年 | 461篇 |
1995年 | 417篇 |
1994年 | 262篇 |
1993年 | 199篇 |
1992年 | 277篇 |
1991年 | 265篇 |
1990年 | 228篇 |
1989年 | 199篇 |
1988年 | 143篇 |
1987年 | 72篇 |
1986年 | 74篇 |
1985年 | 53篇 |
1984年 | 59篇 |
1983年 | 40篇 |
1982年 | 45篇 |
1981年 | 34篇 |
1979年 | 3篇 |
1978年 | 4篇 |
1972年 | 5篇 |
1971年 | 5篇 |
1961年 | 2篇 |
1932年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
建立了模拟单一潜在震源区地震孕育和发生的等效物理模型,给出了通过调整各次地震之间断层位移速率来拟合已有地震序列的方法。通过考虑模型参数的不确定性,提出了在未来一定年限内潜在震源区发生震级在不同震级段的概率预报方法。通过两种等效物理模型的对比,本文认为就工程地震危险性评定而言,可用简单的滑块-弹簧模型代替滑块-弹粘塑性模型 相似文献
6.
喷射溶气回流浮选工艺处理含油废水 总被引:8,自引:0,他引:8
采用喷射溶气回流浮选工艺处理含油废水,替代原来的全加压溶气浮选工艺,提高了浮选过程的处理效果,增强了系统的抗负荷冲击能力,浮选出水油含量由原来的〈40mg/L降至〈20mg/L,COD由原来的〈150mg/L降至〈110mg/L。 相似文献
7.
8.
M. R. Theobald U. Dragosits C. J. Place J. U. Smith M. Sozanska L. Brown D. Scholefield A. Del Prado J. Webb P. G. Whitehead A. Angus I. D. Hodge D. Fowler M. A. Sutton 《Water, Air, & Soil Pollution: Focus》2004,4(6):135-142
The distribution and impacts of different nitrogen pollutants are inextricably linked. To understand the problem fully, the interactions between the different pollutants need to be taken into account. This is particularly important when it comes to abatement techniques, since measures to reduce emissions of one nitrogen pollutant can often lead to an increase in another. This project represents a step towards greater understanding of these issues by linking together new and existing nitrogen flux models into a larger framework. The modelling framework has been constructed and some of the nitrogen flows between fields, farms and the atmosphere have been modelled for a UK study area for typical farm management scenarios. 相似文献
9.
Davey L. Jones John F. Farrar Kevin K. Newsham 《Water, Air, & Soil Pollution: Focus》2004,4(6):169-175
Amino acids constitute one of the largest inputs of organic nitrogen (N) to most polar soils and have been hypothesized to be important in regulating vegetational succession and productivity in Arctic ecosystems. Our understanding of amino acid cycling in these soils, however, is poor. The aim of this study was to investigate the size and rate of turnover of the amino acid pool in a range of Arctic and Antarctic soils. Our results indicate that in polar soils with either high or low ornithogenic inputs the amino acid pool is small in comparison to the inorganic N pool (NO–3 and NH+4). The free amino acid pool constituted only a small proportion of the total dissolved organic nitrogen (DON) pool in these soils. Here we show that these low concentrations may be due to rapid use by the soil microbial community in both Arctic and Antarctic soils. The turnover of the amino acid pool in soil was extremely rapid, with a half-life ranging from 2 to 24 h, indicating that this N pool can be turned over many hundred times each summer when polar soils are frequently unfrozen. The implications of amino acids in N cycling and plant and microbial nutrition are discussed. 相似文献
10.
Ed Gidman Royston Goodacre Bridget Emmett Lucy J. Sheppard Ian D. Leith Dylan Gwynn-Jones 《Water, Air, & Soil Pollution: Focus》2004,4(6):251-258
The potential for metabolic fingerprinting via Fourier-transform infrared (FT-IR) spectroscopy to provide a novel approach for the detection of plant biochemical responses to N deposition is examined. An example of spectral analysis using shoot samples taken from an open top chamber (OTC) experiment simulating wet ammonium deposition is given. Sample preparation involved oven drying and homogenisation via mill grinding. Slurries of a consistent dilution were then prepared prior to FT-IR analysis. Spectra from control, 8 and 16 kg N ha–1 yr–1 treatments were then subjected to cross-validated discriminant function analysis. Ordination diagrams showed clear separation between the three N treatments examined. The potential for using Calluna vulgaris (L.) Hull as a bioindicator of N deposition is further evident from these results. The results also clearly demonstrate the power of FT-IR in discriminating between subtle phenotypic alterations in overall plant biochemistry as affected by ammonium pollution. 相似文献