全文获取类型
收费全文 | 947篇 |
免费 | 39篇 |
国内免费 | 331篇 |
专业分类
安全科学 | 51篇 |
废物处理 | 66篇 |
环保管理 | 98篇 |
综合类 | 484篇 |
基础理论 | 139篇 |
污染及防治 | 345篇 |
评价与监测 | 48篇 |
社会与环境 | 50篇 |
灾害及防治 | 36篇 |
出版年
2023年 | 18篇 |
2022年 | 45篇 |
2021年 | 37篇 |
2020年 | 30篇 |
2019年 | 33篇 |
2018年 | 44篇 |
2017年 | 44篇 |
2016年 | 47篇 |
2015年 | 40篇 |
2014年 | 57篇 |
2013年 | 96篇 |
2012年 | 66篇 |
2011年 | 86篇 |
2010年 | 67篇 |
2009年 | 57篇 |
2008年 | 56篇 |
2007年 | 61篇 |
2006年 | 47篇 |
2005年 | 45篇 |
2004年 | 29篇 |
2003年 | 32篇 |
2002年 | 31篇 |
2001年 | 21篇 |
2000年 | 37篇 |
1999年 | 24篇 |
1998年 | 27篇 |
1997年 | 26篇 |
1996年 | 24篇 |
1995年 | 13篇 |
1994年 | 15篇 |
1993年 | 6篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 15篇 |
1989年 | 4篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1986年 | 3篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有1317条查询结果,搜索用时 187 毫秒
971.
972.
Using sequence variation in the mitochondrial cytochrome oxidase I locus, we estimated the population structure and phylogeography
of the intertidal acorn barnacle, Chthamalus anisopoma, and its gastropod predator, Mexacanthina lugubris angelica. Both are endemic to the Gulf of California, being derived from taxa on the Pacific coast of the Baja peninsula, and both
exhibit phenotypic plasticity for traits affecting their coevolutionary interactions. Consistent with expectations based on
differences in dispersal, C. anisopoma populations generally lack geographic structure, while those of M. l. angelica are more strongly structured. However, the variable degree of differentiation in both species suggests that the extent of
reciprocal selection and local adaptation in the species will vary geographically, a result consistent with the concept of
a geographic mosaic of coevolution. The pattern of variation in C. anisopoma shows clear evidence of recent spatial expansion, possibly due to increased habitat availability following the last glacial
maximum. Phylogeographic analyses suggest that M. l. angelica diversified into three distinct clades after the colonization of the Gulf. Overall, our results illustrate how dispersal
potential, geological and climatic events, and recent population growth have impacted the pattern of sequence variation in
the two species. 相似文献
973.
采用Fenton试剂氧化—曝气生物滤池组合工艺对某制药厂常规生化处理后的废水进行深度处理.实验结果表明,Fenton试剂氧化的适宜操作条件为pH=5,ρ(H2O2)∶COD=1.5、n(H2O2)∶n(Fe2+)=2,反应时间为60min.经氧化处理后的废水再进入曝气生物滤池进行生化处理,最终出水COD小于80 mg/L,色度小于10倍,处理效果良好. 相似文献
974.
975.
976.
As the backland of the Qinghai-Tibet Plateau, the river source region is highly sensitive to changes in global climate. Air temperature estimation using remote sensing satellite provides a new way of conducting studies in the field of climate change study. A geographically weighted regression model was applied to estimate synchronic air temperature from 2001 to 2015 using Moderate-Resolution Imaging Spectroradiometry (MODIS) data. The results were R2?=?0.913 and RMSE?=?2.47 °C, which confirmed the feasibility of the estimation. The spatial distribution and variation characteristics of the average annual and seasonal air temperature were analyzed. The findings are as follows: (1) the distribution of average annual air temperature has significant terrain characteristics. The reduction in average annual air temperature along the elevation of the region is 0.19 °C/km, whereas the reduction in the average annual air temperature along the latitude is 0.04 °C/degree. (2) The average annual air temperature increase in the region is 0.37 °C/decade. The average air temperature increase could be arranged in the following decreasing order: Yangtze River Basin > Mekong River Basin > Nujiang River Basin > Yarlung Zangbo River Basin > Yellow River Basin. The fastest, namely, Yangtze River Basin, is 0.47 °C/decade. (3) The average air temperature rise in spring, summer, and winter generally increases with higher altitude. The average annual air temperature in different types of lands following a decreasing order is as follows: wetland > construction land > bare land glacier > shrub grassland > arable land > forest land > water body and that of the fastest one, wetland, is 0.13 °C/year. 相似文献
977.
Surface ozone and some meteorological parameters were continuously measured from June 2003 to May 2004 at urban Jinan, China. The levels and variations of surface ozone were studied and the influences of meteorological parameters on ozone were analyzed. Annual and diurnal ozone variation patterns in Jinan both show a typical pattern for polluted urban areas. Daytime ozone concentrations in summer were the highest in the four seasons. However, during nighttime from 2100 to 0600 hours ozone concentrations in spring was higher than that in summer. Daily averaged ozone showed negative correlation with pressure and relative humidity and positive correlation with temperature, total solar radiation, sunshine duration and wind speed during the study period. Further studies show that, solar radiation is a primary influence factor for the daytime variations of ozone concentrations at this site; transport of pollutants by wind could enhance the pollution at this site; precipitation has a significant influence on decreasing surface ozone. A multi-day ozone episode from 16 to 21 June 2003 was observed at this site. Surface meteorological data analysis and backward trajectory computation show that the episode is associated with the influence of typhoon Soudelor, attributing to both local photochemical processes and transport of air pollutants from southeastern coastal region, especially Yangtze River Delta region. 相似文献
978.
Effects of land cover changes induced by large physical disturbances on hydrological responses in Central Taiwan 总被引:1,自引:0,他引:1
Nien Ming Hong Hone-Jay Chu Yu-Pin Lin Dung-Po Deng 《Environmental monitoring and assessment》2010,166(1-4):503-520
This study analyzes the significant impacts of typhoons and earthquakes on land cover change and hydrological response. The occurrence of landslides following typhoons and earthquakes is a major indicator of natural disturbance. The hydrological response of the Chenyulan watershed to land use change was assessed from 1996 to 2005. Land use changes revealed by seven remote images corresponded to typhoons and a catastrophic earthquake in central Taiwan. Hydrological response is discussed as the change in quantities and statistical distributions of hydrological components. The land cover change results indicate that the proportion of landslide relative to total area increased to 6.1% after the Chi-Chi earthquake, representing the largest increase during the study period. The study watershed is dominated by forest land cover. Comparisons of hydrological components reveal that the disturbance significantly affects base flow and direct runoff. The hydrological modeling results demonstrate that the change in forest area correlates with the variation of base flow and direct runoff. Base flow and direct runoff are sensitive to land use in discussions of distinction. The proposed approach quantifies the effect of typhoons and earthquakes on land cover changes. 相似文献
979.
猪场废弃物强制通风静态仓堆肥系统的试验研究 总被引:1,自引:0,他引:1
通过组织5个猪场废弃物堆肥试验,度量温度、表观性状、体积、重量损失、全氮、全磷、大肠杆菌值、蛔虫卵杀灭率和发芽指数等指标,检验了开发的强制通风静态仓堆肥系统的性能.结果表明,除起始含水率为80%试验堆体因起始含水率过高导致发生厌氧反应外,其余4个堆体均实现堆肥无害化、减量化、稳定化和资源化的处理目标;堆肥温度维持50℃以上5~7 d,或55℃以上3 d是大肠杆菌值达到国家粪便无害化卫生标准的必要条件;堆肥过程能有效脱除堆料的生物毒性,后腐熟阶段是必需阶段;氮、磷、钾等主要营养元素在堆肥前后呈现"浓缩效应".因此,堆肥化能提高猪场废弃物肥效和利用价值. 相似文献
980.