全文获取类型
收费全文 | 25924篇 |
免费 | 278篇 |
国内免费 | 242篇 |
专业分类
安全科学 | 762篇 |
废物处理 | 1107篇 |
环保管理 | 3497篇 |
综合类 | 3403篇 |
基础理论 | 6984篇 |
环境理论 | 6篇 |
污染及防治 | 7392篇 |
评价与监测 | 1715篇 |
社会与环境 | 1408篇 |
灾害及防治 | 170篇 |
出版年
2022年 | 211篇 |
2021年 | 215篇 |
2020年 | 152篇 |
2019年 | 195篇 |
2018年 | 367篇 |
2017年 | 353篇 |
2016年 | 588篇 |
2015年 | 453篇 |
2014年 | 692篇 |
2013年 | 2174篇 |
2012年 | 828篇 |
2011年 | 1118篇 |
2010年 | 888篇 |
2009年 | 1021篇 |
2008年 | 1200篇 |
2007年 | 1239篇 |
2006年 | 1095篇 |
2005年 | 920篇 |
2004年 | 908篇 |
2003年 | 921篇 |
2002年 | 864篇 |
2001年 | 1141篇 |
2000年 | 812篇 |
1999年 | 465篇 |
1998年 | 350篇 |
1997年 | 332篇 |
1996年 | 376篇 |
1995年 | 403篇 |
1994年 | 354篇 |
1993年 | 313篇 |
1992年 | 304篇 |
1991年 | 274篇 |
1990年 | 313篇 |
1989年 | 299篇 |
1988年 | 254篇 |
1987年 | 242篇 |
1986年 | 202篇 |
1985年 | 221篇 |
1984年 | 250篇 |
1983年 | 248篇 |
1982年 | 237篇 |
1981年 | 222篇 |
1980年 | 188篇 |
1979年 | 214篇 |
1978年 | 145篇 |
1977年 | 145篇 |
1976年 | 128篇 |
1975年 | 141篇 |
1973年 | 133篇 |
1972年 | 133篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
The dynamics and structure of the phytomass and production of an undisturbed mesotrophic dwarf shrub–sphagnum phytocenosis and one burned by fire have been compared. The net primary production (NPP) of both sites of phytocenoses in the postpyrogenic period is estimated by direct field determination of the productivity parameters, and C emission from the fire is assessed. The obtained data on emission (0.7 kg/m2) differ from the results obtained in the peatlands of western Canada (3.2 kg/m2). 相似文献
922.
Viacheslav I. Kharuk Mariya L. Dvinskaya Ilya A. Petrov Sergei T. Im Kenneth J. Ranson 《Regional Environmental Change》2016,16(8):2389-2397
Fire history within the northern larch forests of Central Siberia was studied (65 + °N). Fires within this area are predominantly caused by lightning strikes rather than human activity. Mean fire return intervals (FRIs) were found to be 112 ± 49 years (based on firescars) and 106 ± 36 years (based on firescars and tree natality dates). FRIs were increased with latitude increase and observed to be about 80 years at 64°N, about 200 years near the Arctic Circle and about 300 years nearby the northern range limit of larch stands (~71° + N). Northward FRIs increase correlated with incoming solar radiation (r = ?0.95). Post-Little Ice Age (LIA) warming (after 1850) caused approximately a doubling of fire events (in comparison with a similar period during LIA). The data obtained support a hypothesis of climate-induced fire frequency increase. 相似文献
923.
Robin Warner Mary Kaidonis Olivia Dun Kerrylee Rogers Yubing Shi Thang T. X. Nguyen Colin D. Woodroffe 《Sustainability Science》2016,11(4):661-677
Increasing value is attributed to mangroves due to their considerable capacity to sequester carbon, known as ‘blue carbon’. Assessments of opportunities and challenges associated with estimating the significance of carbon sequestered by mangroves need to consider a range of disciplinary perspectives, including the bio-physical science mangroves, social and economic issues of land use, local and international law, and the role of public and private finance. We undertook an interdisciplinary review based on available literature and fieldwork focused on parts of the Mekong River Delta (MRD). Preliminary estimates indicate mangrove biomass may be 70–150 t ha?1, but considerably larger storage of carbon occurs in sediments beneath mangroves. These natural stores of carbon are compromised when mangroves are removed to accommodate anthropogenic activities. Mangroves are an important resource in the MRD that supplies multiple goods and services, and conservation or re-establishment of mangroves provides many benefits. International law and within-country environmental frameworks offer increasing scope to recognize the role that mangrove forests play through carbon sequestration, in order that these might lead to funding opportunities, both in public and private sectors. Such schemes need to have positive rather than negative impacts on the livelihoods of the many people living within and adjacent to these wetlands. Nevertheless, many challenges remain and it will require further targeted and coordinated scientific research, development of economic and social incentives to protect and restore mangroves, supportive law and policy mechanisms at global and national levels, and establishment of long-term financing for such endeavours. 相似文献
924.
Pollution-induced illnesses are caused by toxicants that result from human activity and are often entirely preventable. However, where industrial priorities have undermined responsible governance, exposed populations must reduce their exposure by resorting to voluntary protective measures and demanding emissions abatement. This paper presents a coupled human–environment system model that represents the effects of water pollution on the health and livelihood of a fishing community. The model is motivated by an incident from 1949 to 1968 in Minamata, Japan, where methylmercury effluent from a local factory poisoned fish populations and humans who ate them. We model the critical role of risk perception in driving both social learning and the protective feedbacks against pollution exposure. These feedbacks are undermined in the presence of social misperceptions such as stigmatization of the injured. Through numerical simulation and scenario analysis, we compare our model results with historical datasets from Minamata, and find that the conditions for an ongoing pollution epidemic are highly unlikely without social misperception. We also find trade-offs between human health outcomes, the viability of the polluting industry and the survival of the fishery. We conclude that an understanding of human–environment interactions and misperception effects is highly relevant to the resolution of contemporary pollution problems, and merits further study. 相似文献
925.
926.
S. Alvandi W. Li M. Schönemann C. Herrmann 《International Journal of Sustainable Engineering》2016,9(6):354-362
Value stream mapping (VSM) is a well-accepted tool within lean manufacturing concept which is often used for analysing and designing the flow of materials and information required to manufacture a product. However, the analysis is static and single product oriented, which fails to cope with either the variation of production plan or a multi-product environment. In addition, the environmental impact of a manufacturing system is highly associated with the dynamic consumption of energy and resources. Despite the recent integration of VSM with simulation or environmental studies (in the domain of energy efficiency), still neglected is the dynamic assessment of all the resources involved in a multi-product production environment. This paper presents a methodology for modelling multi-product manufacturing systems with dynamic material, energy and information flows with the aim to generate economic and environmental value stream maps (E2VSM). The proposed methodology is validated with an industrial case. 相似文献
927.
The concept of climate compatible development (CCD) is increasingly employed by donors and policy makers seeking ‘triple-wins’ for development, adaptation and mitigation. While CCD rhetoric is becoming more widespread, analyses drawing on empirical cases that present triple-wins are sorely lacking. We address this knowledge gap. Drawing on examples in rural sub-Saharan Africa, we provide the first glimpse into how projects that demonstrate triple-win potential are framed and presented within the scientific literature. We identify that development projects are still commonly evaluated in terms of adaptation or mitigation benefits. Few are framed according to their benefits across all three dimensions. Consequently, where triple-wins are occurring, they are likely to be under-reported. This has important implications, which underestimates the co-benefits that projects can deliver. A more robust academic evidence base for the delivery of triple-wins is necessary to encourage continued donor investment in activities offering the potential to deliver CCD. 相似文献
928.
929.
Two industrial sites were investigated based on years of available hydrogeologic information and monitoring data for soil and groundwater. Collected data were forensically evaluated using age-dating and fingerprinting methods. The previous business uses of the project sites were as a gas station, laundry/dry-cleaning service, and car wash with petroleum underground storage tanks (USTs). As a result, these sites were exposed to a number of toxic contaminants at relatively high concentrations. Source control was necessary for successful remediation and the ultimate removal of the remaining compounds from these industrial sites. Although contaminated soil around the source was excavated during the remedial action and the high concentrations of contaminants were reduced, typical groundwater contaminants such as petroleum hydrocarbons as gasoline (TPH-G), benzene, toluene, ethylbenzene, xylenes (BTEX), and oxygenates including methyl tert-butyl ether (MTBE), diisopropyl ether (DIPE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME), and tert-butyl alcohol (TBA) were persistently found at the studied sites around the source points. The plume and concentration of contaminants had changed their shapes and strength for all monitoring periods. Thus, additional source control seems to be a requirement for the complete removal of source contamination, which must be ascertained with groundwater and soil monitoring on a regular time base. For the study sites, monitored natural attenuation was relatively feasible for the long-term plan; however, it did not offer a perfect remediation solution for an ultimate goal because of residual toxic compounds that might have affected the surrounding residential areas at higher concentrations than their health limits. Therefore, as a remediation strategy, the combination of clean-up technology and natural attenuation with monitoring activities are more highly recommended than either clean-up or natural attenuation used separately. 相似文献
930.
以膨润土为辅助添加剂固化/稳定化污泥的试验研究 总被引:15,自引:1,他引:14
针对传统以水泥固化污泥,带来的水泥用量大与固化体的浸出液pH过高等问题,提出了以膨润土为添加剂辅助水泥固化/稳定化污泥的思路.通过开展无侧限抗压强度试验、毒性浸出试验,测量掺入膨润土后污泥固化体的强度、重金属浸出率、浸出液COD及pH值,研究该固化/稳定化方法的效果.结果表明,膨润土的掺入极大地提高了固化体的抗压强度,将掺入量为0.4(相对污泥的质量比)的水泥一半用膨润土替代时,固化体的强度提高了6左右.体积安定性也能够满足要求.随膨润土掺入量增加,固化体中锌、铅的浸出率与浸出液的pH值呈现不断减小的趋势,锌与铅的浸出率分别由6.9%下降至0.25%,9.6%下降至5%,pH值由12.3下降至12.1.在强碱条件下及烘干或风干条件下,铜会随着有机物的分解而析出,从而增加铜的浸出率,而膨润土的加入能弥补水泥造成的强碱环境及风干或烘干过程对固化污泥中铜的稳定产生的不利影响. 相似文献