全文获取类型
收费全文 | 21608篇 |
免费 | 1484篇 |
国内免费 | 4639篇 |
专业分类
安全科学 | 1609篇 |
废物处理 | 394篇 |
环保管理 | 5274篇 |
综合类 | 12245篇 |
基础理论 | 2465篇 |
环境理论 | 5篇 |
污染及防治 | 1916篇 |
评价与监测 | 1538篇 |
社会与环境 | 1652篇 |
灾害及防治 | 633篇 |
出版年
2024年 | 89篇 |
2023年 | 399篇 |
2022年 | 618篇 |
2021年 | 634篇 |
2020年 | 696篇 |
2019年 | 595篇 |
2018年 | 551篇 |
2017年 | 802篇 |
2016年 | 977篇 |
2015年 | 1003篇 |
2014年 | 1006篇 |
2013年 | 1446篇 |
2012年 | 1523篇 |
2011年 | 1644篇 |
2010年 | 1200篇 |
2009年 | 1233篇 |
2008年 | 929篇 |
2007年 | 1506篇 |
2006年 | 1387篇 |
2005年 | 1124篇 |
2004年 | 967篇 |
2003年 | 988篇 |
2002年 | 842篇 |
2001年 | 687篇 |
2000年 | 682篇 |
1999年 | 575篇 |
1998年 | 421篇 |
1997年 | 397篇 |
1996年 | 361篇 |
1995年 | 331篇 |
1994年 | 281篇 |
1993年 | 255篇 |
1992年 | 199篇 |
1991年 | 152篇 |
1990年 | 114篇 |
1989年 | 95篇 |
1988年 | 98篇 |
1987年 | 73篇 |
1986年 | 50篇 |
1984年 | 55篇 |
1983年 | 64篇 |
1982年 | 61篇 |
1981年 | 77篇 |
1980年 | 84篇 |
1979年 | 75篇 |
1978年 | 54篇 |
1977年 | 48篇 |
1973年 | 45篇 |
1972年 | 40篇 |
1971年 | 60篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
91.
区域分工对区域经济发展具有重要作用。山东地处我国东部沿海,是全国人口大省、经济大省,在全国经济发展格局中占有举足轻重的地位。根据区域分工理论,对山东省在全国和区域内部分工进行了分析,揭示了山东省在全国的区际地位以及所辖17个市之间的区域分工与合作格局,为山东省强化区域分工和联系,提高区域竞争力提供决策依据。 相似文献
92.
Guoyi Zhou Ge Sun Xu Wang Chuanyan Zhou Steven G. McNulty James M. Vose Devendra M. Amatya 《Journal of the American Water Resources Association》2008,44(1):208-221
Abstract: It is critical that evapotranspiration (ET) be quantified accurately so that scientists can evaluate the effects of land management and global change on water availability, streamflow, nutrient and sediment loading, and ecosystem productivity in watersheds. The objective of this study was to derive a new semi‐empirical ET modeled using a dimension analysis method that could be used to estimate forest ET effectively at multiple temporal scales. The model developed describes ET as a function of water availability for evaporation and transpiration, potential ET demand, air humidity, and land surface characteristics. The model was tested with long‐term hydrometeorological data from five research sites with distinct forest hydrology in the United States and China. Averaged simulation error for daily ET was within 0.5 mm/day. The annual ET at each of the five study sites were within 7% of measured values. Results suggest that the model can accurately capture the temporal dynamics of ET in forest ecosystems at daily, monthly, and annual scales. The model is climate‐driven and is sensitive to topography and vegetation characteristics and thus has potential to be used to examine the compounding hydrologic responses to land cover and climate changes at multiple temporal scales. 相似文献
93.
Abstract: Apparent ground‐water ages as determined by the noble gas isotope 85Kr and the water isotope 3H are compared. Refined gas extraction methodology at the wellhead permits efficient collection of Kr for 85Kr isotope enrichment. 85Kr isochrones elucidate areas of much younger ground‐water ages than 3H. Declining 3H activities in the catchment prevent its correlation with the youngest measured 85Kr ages. Source water for most drinking water supplies in the Collyer River catchment is recharged within 40 years BP (2004). Mean‐age (τ) transport modeling suggests uncertainty of ground‐water ages is greatest in the central basin area. 相似文献
94.
我国水事纠纷解决机制探析 总被引:2,自引:0,他引:2
毛涛 《中国环境管理干部学院学报》2008,18(4):48-54
水事纠纷解决机制是一系列水事纠纷解决方式所组成的整体,该机制是民事主体或行政区域水资源权利受到侵害,以及遭受水污染侵权损害的重要救济途径。虽然我国相关法律对水事纠纷的解决方式已作出规定,但是这些法律规定较为分散、不系统,还没有形成一个有机的整体,造成运用该机制解决水事纠纷的效果较差。为了保障水事纠纷及时、有效地得以解决,完善我国的水事纠纷解决机制已迫在眉睫。 相似文献
95.
Windblown dust is known to impede visibility, deteriorate air quality and modify the radiation budget. Arid and semiarid areas with unpaved and unvegetated land cover are particularly prone to windblown dust, which is often attributed to high particulate matter (PM) pollution in such areas. Yet, windblown dust is poorly represented in existing regulatory air quality models. In a study by the authors on modeling episodic high PM events along the US/Mexico border using the state-of-the-art CMAQ/MM5/SMOKE air quality modeling system [Choi, Y.-J., Hyde, P., Fernando, H.J.S., 2006. Modeling of episodic particulate matter events using a 3D air quality model with fine grid: applications to a pair of cities in the US/Mexico border. Atmospheric Environment 40, 5181–5201], some of the observed PM10 NAAQS exceedances were inferred as due to windblown dust, but the modeling system was incapable of dealing with time-dependent episodic dust entrainment during high wind periods. In this paper, a time-dependent entrainment parameterization for windblown dust is implemented in the CMAQ/MM5/SMOKE modeling system with the hope of improving PM predictions. An approach for realizing windblown dust emission flux for each grid cell over the study domain on an hourly basis, which accounts for the influence of factors such as soil moisture content, atmospheric stability and wind speed, is presented in detail. Comparison of model predictions with observational data taken at a pair of US/Mexico border towns shows a clear improvement of model performance upon implementation of the dust emission flux parameterization. 相似文献
96.
This investigation conducted a full-scale survey the drinking water distribution system in Kaohsiung city, Taiwan. The aim
was to investigate whether the distribution system was capable of maintaining high water quality from the water treatment
facilities through to the end user. The results showed that the distribution system can maintain high water quality, except
for suitable chlorine residuals. The authors plotted chlorine residual contour maps to identify areas with low chlorine residuals,
helping them prioritize sections that must be flushed or renewal. The contour maps also provide sufficient and clear information
for locating booster chlorination stations. Contour maps enable water facilities to identify how water quality decays in the
distribution systems and the locations of such decay. Water quality decay can be caused by properties of pipeline materials,
hydraulic conditions, and/or biofilm thickness. However, understanding the exact reasons is unnecessary because the contour
maps provide sufficient information for trouble-shooting the distribution systems. 相似文献
97.
Bolca M Turkyilmaz B Kurucu Y Altinbas U Esetlili MT Gulgun B 《Environmental monitoring and assessment》2007,131(1-3):409-419
Because of their intense vegetation and the fact that they include areas of coastline, deltas situated in the vicinity of big cities are areas of greet attraction for people who wish to get away from in a crowded city. However, deltas, with their fertile soil and unique flora and fauna, need to be protected. In order for the use of such areas to be planned in a sustainable way by local authorities, there is a need for detailed data about these regions. In this study, the changes in land use of the Balçova Delta, which is to the immediate west of Turkey’s third largest city Izmir, from 1957 up to the present day, were investigated. In the study, using aerial photographs taken in 1957, 1976 and 1995 and an IKONOS satellite image from the year 2005, the natural and cultural characteristics of the region and changes in the coastline were determined spatially. Through this study, which aimed to reveal the characteristics of the areas of land already lost as well as the types of land use in the Balçova delta and to determine geographically the remaining areas in need of protection, local authorities were provided with the required data support. Balçova consists of flat and fertile wetland with mainly citrus-fruit orchards and flower-producing green houses. The marsh and lagoon system situated in the coastal areas of the delta provides a habitat for wild life, in particular birds. In the Balçova Delta, which provides feeding and resting for migratory birds, freshwater sources are of vital importance for fauna and flora. The settlement area, which in 1957 was 182 ha, increased 11-fold up to the year 2005 when it reached 2,141 ha. On the other hand, great losses were determined in farming land, olive groves, forest and in the marsh and lagoon system. This unsystematic and rapid urbanization occurring in the study region is not only causing the loss of important agricultural land and wetland, but also lasting water and soil pollution. 相似文献
98.
99.
底泥中重金属毒性的室内孔隙水分析技术 总被引:1,自引:0,他引:1
根据孔隙水中重金属的浓度可以判定底泥中重金属的毒性但获得真正的底泥孔隙水十分困难。本文提供了一套简便易行的室内原状孔隙水取样技术,将碳化硅砂芯埋入底泥,添加表层水并静置90d,通过渗滤获得孔隙水,测定孔隙水中重的浓度,所得结果与微生态系统暴露试验中生物指示的重金属的毒性大小相吻合,与生物积累重金属的浓度显著正相关。 相似文献
100.
通过亚铵法制浆蒸煮黑液直接作农肥施于水稻田的研究,给出了不同施肥方式连续数天田间水和渗滤水中黑液污染物变化情况,定量描述了黑液作肥料直接施于水稻田对水环境的影响。 相似文献