全文获取类型
收费全文 | 3350篇 |
免费 | 152篇 |
国内免费 | 1179篇 |
专业分类
安全科学 | 194篇 |
废物处理 | 214篇 |
环保管理 | 226篇 |
综合类 | 1863篇 |
基础理论 | 589篇 |
污染及防治 | 1172篇 |
评价与监测 | 125篇 |
社会与环境 | 164篇 |
灾害及防治 | 134篇 |
出版年
2024年 | 2篇 |
2023年 | 38篇 |
2022年 | 138篇 |
2021年 | 117篇 |
2020年 | 116篇 |
2019年 | 78篇 |
2018年 | 97篇 |
2017年 | 149篇 |
2016年 | 136篇 |
2015年 | 218篇 |
2014年 | 231篇 |
2013年 | 312篇 |
2012年 | 280篇 |
2011年 | 282篇 |
2010年 | 208篇 |
2009年 | 227篇 |
2008年 | 235篇 |
2007年 | 214篇 |
2006年 | 169篇 |
2005年 | 117篇 |
2004年 | 107篇 |
2003年 | 120篇 |
2002年 | 110篇 |
2001年 | 101篇 |
2000年 | 111篇 |
1999年 | 116篇 |
1998年 | 115篇 |
1997年 | 110篇 |
1996年 | 113篇 |
1995年 | 75篇 |
1994年 | 66篇 |
1993年 | 56篇 |
1992年 | 42篇 |
1991年 | 20篇 |
1990年 | 15篇 |
1989年 | 12篇 |
1988年 | 9篇 |
1987年 | 7篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1983年 | 3篇 |
1982年 | 2篇 |
排序方式: 共有4681条查询结果,搜索用时 515 毫秒
381.
382.
Zhang Y Chen Z Zhu B Luo X Guan Y Guo S Nie Y 《Environmental monitoring and assessment》2008,147(1-3):327-337
The objective of this study is to develop techniques for assessing and analysing land desertification in Yulin of Northwest China, as a typical monitoring region through the use of remotely sensed data and geographic information systems (GIS). The methodology included the use of Landsat TM data from 1987, 1996 and 2006, supplemented by aerial photos in 1960, topographic maps, field work and use of other existing data. From this, land cover, the Normalised Difference Vegetation Index (NDVI), farmland, woodland and grassland maps at 1:100,000 were prepared for land desertification monitoring in the area. In the study, all data was entered into a GIS using ILWIS software to perform land desertification monitoring. The results indicate that land desertification in the area has been developing rapidly during the past 40 years. Although land desertification has to some extent been controlled in the area by planting grasses and trees, the issue of land desertification is still serious. The study also demonstrates an example of why the integration of remote sensing with GIS is critical for the monitoring of environmental changes in arid and semi-arid regions, e.g. in land desertification monitoring in the Yulin pilot area. However, land desertification monitoring using remote sensing and GIS still needs to be continued and also refined for the purpose of long-term monitoring and the management of fragile ecosystems in the area. 相似文献
383.
384.
385.
386.
Xiaoqing?DongEmail author Chaolin?Li Binbin?Ding Xiaofeng?He Jia?Zhu Peibing?Shao 《Environmental Modeling and Assessment》2016,21(4):517-529
Frequent monitoring and relatively high fines are usually necessary to bring about improvements in environmental quality, but more challenging for many countries with limited human, material, and financial resources is to put them into practice. This paper developed a three-group model of a state-dependent enforcement in a repeated game to improve the policy implementation under limited inspection capacities. A certain number of firms are grouped (group 1, group 2, group 3) for different supervision intensity (e.g., the order of inspection probability corresponding to each group is p 1?<?p 2?<?p 3) based on their environmental performance. The optimal policy parameters, such as inspection probability of each group and the probability that a firm found in compliance is moved to a better reputation group, were obtained as the basis for regulator’s policy making. Numerical simulations indicated that the three-group inspection regime can significantly increase compliance rate as compared with static enforcement with the same monitoring probability. Among the number of firms in each group under steady state conditions, group 2 had the most, group 1 was the second, and group 3 had the smallest. Analysis and prediction of a three-group reputation example provided a good experiment for the model. The results give a practical reference for the policy makers with inspection capacity constraints to achieve higher compliance rate. 相似文献
387.
388.
389.
Spatial and temporal distribution of polycyclic aromatic hydrocarbons (PAHs) in sediments of the Nansi Lake, China 总被引:2,自引:0,他引:2
Hong-Li Li Hong Gao Chen Zhu Guo-Gang Li Fan Yang Zheng-Yu Gong Jun Lian 《Environmental monitoring and assessment》2009,154(1-4):469-478
Polycyclic aromatic hydrocarbons (PAHs) were measured in surface sediments and dated core sediments from the Nansi Lake of China to investigate the spatial and temporal distribution characteristics. The concentrations of 16 kinds priority PAH compounds were determined by GC-MS method. And 210Pb isotope dating method was used to determine the chronological age of the sediment as well as the deposition rate. The results indicated that the total PAHs concentration ranges in surface and core sediment samples were 160 ~32,600 and 137 ~ 693 ng/g (dry wt.), respectively. The sediment rate and the average mass sedimentation were calculated to be 0.330 cm·year???1 and 0.237 g·cm???2·yr???1 and the sediment time of the collected core sample ranged from 1899 to 2000. The peak of PAH concentrations came at recent years. The source analysis showed PAHs mainly came from the contamination of low temperature pyrogenic processes, such as coal combustion. The PAHs concentrations were lower than ERL and LEL values for most collected samples. However, in several surface sediment samples especially in estuary sites, the PAHs concentrations were not only higher than ERL and LEL values, but also higher than ERM values. 相似文献
390.
Effects of fomesafen on soil enzyme activity,microbial population,and bacterial community composition 总被引:2,自引:0,他引:2
Qingming Zhang Lusheng Zhu Jun Wang Hui Xie Jinhua Wang Fenghua Wang Fengxia Sun 《Environmental monitoring and assessment》2014,186(5):2801-2812
Fomesafen is a diphenyl ether herbicide that has an important role in the removal of broadleaf weeds in bean and fruit tree fields. However, very little information is known about the effects of this herbicide on soil microbial community structure and activities. In the present study, laboratory experiments were conducted to examine the effects of different concentrations of fomesafen (0, 10, 100, and 500 μg/kg) on microbial community structure and activities during an exposure period of 60 days, using soil enzyme assays, plate counting, and denaturing gradient gel electrophoresis (DGGE). The results of enzymatic activity experiments showed that fomesafen had different stimulating effects on the activities of acid phosphatase, alkaline phosphatase, and dehydrogenase, with dehydrogenase being most sensitive to fomesafen. On the tenth day, urease activity was inhibited significantly after treatment of different concentrations of fomesafen; this inhibiting effect then gradually disappeared and returned to the control level after 30 days. Plate counting experiments indicated that the number of bacteria and actinomycetes increased in fomesafen-spiked soil relative to the control after 30 days of incubation, while fungal number decreased significantly after only 10 days. The DGGE results revealed that the bacterial community varied in response to the addition of fomesafen, and the intensity of these six bands was greater on day 10. Sequencing and phylogenetic analyses indicated that the six excised DGGE bands were closely related to Emticicia, Bacillus, and uncultured bacteria. After 10 days, the bacterial community exhibited no obvious change compared with the control. Throughout the experiment, we concluded that 0–500 μg/kg of fomesafen could not produce significant toxic effects on soil microbial community structure and activities. 相似文献