全文获取类型
收费全文 | 1898篇 |
免费 | 51篇 |
国内免费 | 20篇 |
专业分类
安全科学 | 129篇 |
废物处理 | 82篇 |
环保管理 | 445篇 |
综合类 | 209篇 |
基础理论 | 490篇 |
环境理论 | 2篇 |
污染及防治 | 384篇 |
评价与监测 | 124篇 |
社会与环境 | 72篇 |
灾害及防治 | 32篇 |
出版年
2023年 | 14篇 |
2022年 | 23篇 |
2021年 | 22篇 |
2020年 | 26篇 |
2019年 | 24篇 |
2018年 | 47篇 |
2017年 | 61篇 |
2016年 | 67篇 |
2015年 | 64篇 |
2014年 | 60篇 |
2013年 | 131篇 |
2012年 | 86篇 |
2011年 | 155篇 |
2010年 | 100篇 |
2009年 | 88篇 |
2008年 | 114篇 |
2007年 | 125篇 |
2006年 | 120篇 |
2005年 | 72篇 |
2004年 | 71篇 |
2003年 | 71篇 |
2002年 | 59篇 |
2001年 | 40篇 |
2000年 | 28篇 |
1999年 | 30篇 |
1998年 | 28篇 |
1997年 | 15篇 |
1996年 | 25篇 |
1995年 | 16篇 |
1994年 | 20篇 |
1993年 | 17篇 |
1992年 | 17篇 |
1991年 | 9篇 |
1990年 | 11篇 |
1989年 | 5篇 |
1988年 | 10篇 |
1987年 | 15篇 |
1986年 | 9篇 |
1985年 | 5篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1969年 | 3篇 |
1937年 | 2篇 |
1936年 | 2篇 |
1935年 | 3篇 |
1926年 | 2篇 |
排序方式: 共有1969条查询结果,搜索用时 203 毫秒
121.
122.
123.
124.
125.
Mark C. Roberts 《Resources Policy》1988,14(4)
This paper explores the general reasons for the sudden decline in the growth of world metal demand which began after 1974 and continues to impact the metal industries. For all of the eight metals studied, except aluminium, the dominant cause of this atrophy in demand is the stagnation in total world economic growth, which has caused reduced demand for all goods and services. In addition, consumer preferences have shifted away from metal-intensive goods, further reducing the need for metals. However, materials substitutions and manufacturing technologies have continued to evolve towards lower use of metal in each product at much the same rate after 1974 as before. Therefore, these aspects do not explain the sudden shortfall after 1974 except in the case of aluminium which experienced a dramatic change during the energy crisis years. 相似文献
126.
127.
The impact of variations in pore-water velocity on the nonequilibrium sorption and transport of organic chemicals was investigated. Miscible displacement experiments were performed with four organic chemicals (dichlorobenzene, naphthalene, tetrachloroethene and p-xylene) and three aquifer materials having low organic-carbon contents (0.02–0.1%). The results of the experiments were analyzed by using a one-dimensional advective-dispersive transport model, wherein sorption is considered instantaneous for a fraction of the sorbent and rate-limited for the remainder. An inverse relationship between the reverse sorption rate constant and the equilibrium sorption constant was evident for each of two velocities. However, there was an order-of-magnitude difference between the rate constants obtained at the two velocities. This suggests the existence of a time-scale effect, which must be accounted for when modeling the transport of organic solutes. 相似文献
128.
241Am, 137Cs, Sr and Pb uptake by tobacco as influenced by application of Fe chelators to soil 总被引:1,自引:0,他引:1
To determine the potential for phytoextraction of 241Am and other contaminants from soil, accumulation of 241Am, 137Cs, Sr, Fe, Al, Pb, and Mg by tobacco was determined for soil applications of two concentrations of ethylenediaminetetraacetic acid (EDTA), citric acid, and ascorbic acid. In tobacco receiving EDTA at 3.1 mmol/kg of soil, 241Am content of plants averaged 15 Bq/kg (ranging up to 26 Bq/kg) while Fe concentrations became constant at 4.5 mmol/kg. Soil treatment with 18.8 mmol/kg EDTA resulted in average 241Am concentrations of 29 Bq/kg (19 times higher than controls). Uptake of Pb was similar to 241Am. In these samples, Fe increased to a maximum of almost 18 mmol/kg and 241Am content increased linearly with both Fe and Al. Plants receiving ascorbic and citric acids took up smaller quantities of 241Am, Pb, and Fe, even though these reagents were able to elute about as much Fe from the soil as EDTA. Synchrotron microbeam X-ray fluorescence (SXRF) was used to determine radial distributions of elements in roots and stems with and without EDTA treatment. SXRF maps indicate differences in behavior between Fe and Pb that are consistent with the bulk plant observations and provide insight into changes in metal content of the roots in the presence of EDTA. 相似文献
129.
130.
Joseph L. Horowitz Mark D. Shulman 《Journal of the American Water Resources Association》1967,3(2):19-31
A comparative evaluation is made of the frequency of air mass and frontal types during a 4-year representative portion of the drought as opposed to an equivalent non-drought period. Selection of the non-drought period is based on the Palmer Drought Index. Results indicate a statistically significant increase in the occurrence of continental polar air during the drought. Other conclusions concerning conditions during the drought, not statistically significant but worth further study, are: lower frequency of maritime tropical air in the summer months, more occurrences of cold and occluded fronts, and fewer occurrences of stationary fronts. 相似文献