全文获取类型
收费全文 | 1201篇 |
免费 | 104篇 |
国内免费 | 195篇 |
专业分类
安全科学 | 34篇 |
废物处理 | 30篇 |
环保管理 | 296篇 |
综合类 | 625篇 |
基础理论 | 129篇 |
污染及防治 | 28篇 |
评价与监测 | 145篇 |
社会与环境 | 108篇 |
灾害及防治 | 105篇 |
出版年
2024年 | 5篇 |
2023年 | 28篇 |
2022年 | 33篇 |
2021年 | 31篇 |
2020年 | 35篇 |
2019年 | 48篇 |
2018年 | 43篇 |
2017年 | 41篇 |
2016年 | 62篇 |
2015年 | 55篇 |
2014年 | 47篇 |
2013年 | 78篇 |
2012年 | 77篇 |
2011年 | 96篇 |
2010年 | 66篇 |
2009年 | 69篇 |
2008年 | 60篇 |
2007年 | 67篇 |
2006年 | 74篇 |
2005年 | 70篇 |
2004年 | 44篇 |
2003年 | 58篇 |
2002年 | 54篇 |
2001年 | 37篇 |
2000年 | 35篇 |
1999年 | 29篇 |
1998年 | 12篇 |
1997年 | 11篇 |
1996年 | 9篇 |
1995年 | 8篇 |
1994年 | 10篇 |
1993年 | 13篇 |
1992年 | 6篇 |
1991年 | 5篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1985年 | 6篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 5篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1974年 | 4篇 |
1971年 | 4篇 |
排序方式: 共有1500条查询结果,搜索用时 31 毫秒
81.
82.
Ruiqiang Yang An Li Chuanyong Jing Pu Wang Guibin Jiang 《Environmental pollution (Barking, Essex : 1987)》2010,158(6):2310-2316
High mountains may play significant roles in the global transport of persistent organic pollutants (POPs). This work aims to investigate the levels, patterns and distribution of semi-volatile organoclorine pollutants and to improve the understanding of the long-range atmospheric transport and fate of contaminants on the Tibetan Plateau. A total of 60 fish samples were collected from eight lakes located between 2813 and 4718 m above sea level across the Plateau. Concentrations of polychlorinated biphenyls (PCBs), organochlorine pesticides (OCPs) including dichlorodiphenyltrichloroethane and its metabolites (DDTs), hexachlorocyclohexanes (HCHs) and hexachlorobenzene (HCB) were measured in fish muscle. The results showed that concentrations of DDT, HCH and HCB were comparable to or lower than those found in remote mountains of Europe, Canada and US, while PCB concentrations in fish were, on average, about 4-150 times lower on Tibet than at other mountain areas. The transport and fate of contaminants in the Plateau are significantly influenced by the unique climatological and meteorological conditions, particularly by the summer Indian monsoon and winter westerly jet stream. 相似文献
83.
Monica Lipscomb Smith Weiqi Zhou Mary Cadenasso Morgan Grove Lawrence E. Band 《Journal of the American Water Resources Association》2010,46(2):429-442
Smith, Monica Lipscomb, Weiqi Zhou, Mary Cadenasso, Morgan Grove, and Lawrence E. Band, 2010. Evaluation of the National Land Cover Database for Hydrologic Applications in Urban and Suburban Baltimore, Maryland. Journal of the American Water Resources Association (JAWRA) 46(2):429-442. DOI: 10.1111/j.1752-1688.2009.00412.x Abstract: We compared the National Land Cover Database (NLCD) 2001 land cover, impervious, and canopy data products to land cover data derived from 0.6-m resolution three-band digital imagery and ancillary data. We conducted this comparison at the 1 km2, 9 km2, and gauged watershed scales within the Baltimore Ecosystem Study to determine the usefulness and limitations of the NLCD in heterogeneous urban to exurban environments for the determination of land-cover information for hydrological applications. Although the NLCD canopy and impervious data are significantly correlated with the high-resolution land-cover dataset, both layers exhibit bias at <10 and >70% cover. The ratio of total impervious area and connected impervious area differs along the range of percent imperviousness – at low percent imperviousness, the NLCD is a better predictor of pavement alone, whereas at higher percent imperviousness, buildings and pavement together more resemble NLCD impervious estimates. The land-cover composition and range for each NLCD urban land category (developed open space, low-intensity, medium-intensity, and high-intensity developed) is more variable in areas of low-intensity development. Fine-vegetation land-cover/lawn area is incorporated in a large number of land use categories with no ability to extract this land cover from the NLCD. These findings reveal that the NLCD may yield important biases in urban, suburban, and exurban hydrologic analyses where land cover is characterized by fine-scale spatial heterogeneity. 相似文献
84.
Jahn Kallis Leo Bodensteiner Anthony Gabriel 《Journal of the American Water Resources Association》2010,46(4):744-756
Kallis, Jahn, Leo Bodensteiner, and Anthony Gabriel, 2010. Hydrological Controls and Freshening in Meromictic Soap Lake, Washington, 1939-2002. Journal of the American Water Resources Association (JAWRA) 46(4): 744-756. DOI: 10.1111/j.1752-1688.2010.00446.x Abstract: The chemically stratified layer of naturally formed meromictic lakes exhibits unusual and often extreme physical and chemical conditions that have resulted in the evolution of uniquely adapted species. The Columbia Basin Irrigation Project appears to have had a marked effect on the hydrology of Soap Lake, a meromictic lake in the Grand Coulee of central Washington. The relation of hydrology to salinity was assessed by analyzing water budgets before and after the introduction of the irrigation project. Before irrigation, water gains were balanced by losses; after irrigation began groundwater gains approximately doubled. To manage lake levels and reduce groundwater influx, wells were installed to intercept groundwater. Although the hydrological cycle has been restored to pre-irrigation conditions, the meromictic character of the lake continues to change. Interception wells remove 10 to 16 Mm3 of groundwater annually, but influx continues based on change in the monimolimnion. From 1958 to 2003 the chemocline descended 1.1 m and the volume of the monimolimnion from 698,000 m3 to 114,000 m3. Annual loss of volume is occurring at a rate of 1.9% since 1958. Although groundwater interception wells are maintaining the volume of the entire lake, the recession of the chemocline indicates that conditions that have maintained meromixis at Soap Lake are currently not in equilibrium. 相似文献
85.
Polybrominated diphenyl ethers (PBDEs) and mercury in fish from lakes of the Tibetan Plateau 总被引:2,自引:0,他引:2
High mountains may act as cold traps for globally transported persistent organic pollutants (POPs) and mercury (Hg). In the present study, 60 fish samples were collected from eight alpine lakes across the Tibetan Plateau. Concentrations of polybrominated diphenyl ethers (PBDEs), total mercury (HgT) and methyl mercury (MeHg) were quantified in the fish muscle tissues to improve the understanding of pollution status and factors regulating the transport and fate of these contaminants on the Plateau. The results showed that lake-averaged ∑14PBDEs concentration was between 0.09 ng g−1 dw and 4.32 ng g−1 dw, which was lower than those reported for European mountains. The total mercury concentration in individual fish ranged from 243 to 2384 ng g−1 dw, and that of MeHg from 131 to 1610 ng g−1 dw, which is much higher than those reported in other mountain fish. The spatial variation of PBDEs and mercury in the Plateau is largely controlled by the specific meteorological patterns. 相似文献
86.
自20世纪80年代以来,桂林漓江由于上游森林遭受破坏出现水生态环境快速恶化的趋势。地表热场的时空变化直接影响森林蒸散及水文效应。因此,对漓江上游1989~2006年5景TM/ETM+卫星图像,利用归一化植被指数反演植被覆盖度,利用单窗算法反演地表温度,提出归一化温度使不同时相地表热场具有可比性,分析植被覆盖度时空变化对地表热场的影响。结果表明,在空间上,地表温度随植被覆盖度的增加而降低,在植被覆盖度很高或很低时,这种影响相对变弱;在时间上,漓江上游1989~2000年植被中、高度覆盖面积从96.1%逐年下降到65.9%,导致归一化地表温度数值较高的像元比例相应增加;2000~2006年植被中、高度覆盖面积逐渐恢复上升到90.8%,但仍略低于1989年,使得归一化地表温度数值较高的像元比例相应减少。植被覆盖可以有效地降低漓江上游地表温度 相似文献
87.
88.
利用卫星遥感监测,分析三峡工程建设前后库区城镇发展类型、时空过程,揭示库区城镇变化的驱动力,探索了城镇扩展与人口城镇化关系,研究城镇环境变化特征。三峡库区城镇规模发展不均衡,库尾城市规模庞大,库中、东部区县级城市规模较小,而乡镇的比例占城镇面积24%;在过去15 a中,建城区规模扩大172%,高于全国省会城市发展水平72%;三峡库区城镇规模扩大的同时,东西城镇规模差距逐步缩小,三峡工程建设起着重要的推动作用;城镇发展以侵占了优质耕地资源为代价,耕地占城镇变化83%;城镇用地变化与人口城市化发展不平衡,城镇空间发展快于人口城镇化过程,城镇对农村人口的吸引力不及全国省会城市平均水平,在2007年城市化率低于全国水平13%,差距进一步扩大;城市空间结构发展模式受地形和土地资源的限制,城市分维数和坡度分别增加12%和104°,城市向潜山区扩展或搬迁的同时,城市空间的完整性下降 相似文献
89.
绿化树木是园林景观的主体部分,同样也是园林建设中的目标植物.然而,绿化植物容易受到低温寒冻害的影响,进而影响园林布局美观.基于此,该文提出郑州园林绿化树木低温寒冻害空间分布特征研究方法,统计郑州园林绿化树木类型,对各样本按照乔木层与灌木层进行分类整理,将频度、显著度、密度等作为计算树木多样性的指标,分析比较结果,根据获... 相似文献
90.
Beverly Z.L. Oh Ana M.M. Sequeira Mark G. Meekan Jonathan L.W. Ruppert Jessica J. Meeuwig 《Conservation biology》2017,31(3):635-645
Fishing and habitat degradation have increased the extinction risk of sharks, and conservation strategies recognize that survival of juveniles is critical for the effective management of shark populations. Despite the rapid expansion of marine protected areas (MPAs) globally, the paucity of shark‐monitoring data on large scales (100s–1000s km) means that the effectiveness of MPAs in halting shark declines remains unclear. Using data collected by baited remote underwater video systems (BRUVS) in northwestern Australia, we developed generalized linear models to elucidate the ecological drivers of habitat suitability for juvenile sharks. We assessed occurrence patterns at the order and species levels. We included all juvenile sharks sampled and the 3 most abundant species sampled separately (grey reef [Carcharhinus amblyrhynchos], sandbar [Carcharhinus plumbeus], and whitetip reef sharks [Triaenodon obesus]). We predicted the occurrence of juvenile sharks across 490,515 km2 of coastal waters and quantified the representation of highly suitable habitats within MPAs. Our species‐level models had higher accuracy (? ≥ 0.69) and deviance explained (≥48%) than our order‐level model (? = 0.36 and deviance explained of 10%). Maps of predicted occurrence revealed different species‐specific patterns of highly suitable habitat. These differences likely reflect different physiological or resource requirements between individual species and validate concerns over the utility of conservation targets based on aggregate species groups as opposed to a species‐focused approach. Highly suitable habitats were poorly represented in MPAs with the most restrictions on extractive activities. This spatial mismatch possibly indicates a lack of explicit conservation targets and information on species distribution during the planning process. Non‐extractive BRUVS provided a useful platform for building the suitability models across large scales to assist conservation planning across multiple maritime jurisdictions, and our approach provides a simple for method for testing the effectiveness of MPAs. 相似文献