全文获取类型
收费全文 | 3769篇 |
免费 | 336篇 |
国内免费 | 513篇 |
专业分类
安全科学 | 152篇 |
废物处理 | 28篇 |
环保管理 | 1224篇 |
综合类 | 1258篇 |
基础理论 | 1339篇 |
环境理论 | 2篇 |
污染及防治 | 165篇 |
评价与监测 | 117篇 |
社会与环境 | 239篇 |
灾害及防治 | 94篇 |
出版年
2023年 | 56篇 |
2022年 | 103篇 |
2021年 | 114篇 |
2020年 | 136篇 |
2019年 | 109篇 |
2018年 | 111篇 |
2017年 | 160篇 |
2016年 | 168篇 |
2015年 | 185篇 |
2014年 | 162篇 |
2013年 | 250篇 |
2012年 | 190篇 |
2011年 | 278篇 |
2010年 | 194篇 |
2009年 | 219篇 |
2008年 | 213篇 |
2007年 | 251篇 |
2006年 | 196篇 |
2005年 | 185篇 |
2004年 | 143篇 |
2003年 | 134篇 |
2002年 | 91篇 |
2001年 | 85篇 |
2000年 | 88篇 |
1999年 | 94篇 |
1998年 | 63篇 |
1997年 | 56篇 |
1996年 | 68篇 |
1995年 | 56篇 |
1994年 | 40篇 |
1993年 | 30篇 |
1992年 | 34篇 |
1991年 | 24篇 |
1990年 | 18篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 25篇 |
1986年 | 26篇 |
1985年 | 24篇 |
1984年 | 25篇 |
1983年 | 13篇 |
1982年 | 13篇 |
1980年 | 15篇 |
1979年 | 17篇 |
1978年 | 20篇 |
1977年 | 14篇 |
1975年 | 10篇 |
1973年 | 17篇 |
1972年 | 15篇 |
1971年 | 16篇 |
排序方式: 共有4618条查询结果,搜索用时 203 毫秒
161.
为探究地表水体与沉积物中酚类化合物的污染分布特征和生态风险,选择天津市3个水源地与6条主要河流,采集了26个地表水样与6个沉积物样品,利用固相萃取与超声萃取、高效液相色谱-串联质谱法(HPLC-MS/MS)测定了水样及沉积物中1-萘酚(1-naphthol)、壬基酚(nonylphenol, NP)、双酚A(bisphenol A, BPA)、2-苯基苯酚(biphenyl-2-ol)、3,4-二氯酚(3,4-dichlorophenol)、四溴双酚A(tetrabromobisphenol A, TBBPA)和对叔丁基苯酚(p-tert-butylphenol, PTBP)等7种高关注酚类化合物的浓度水平,并应用物种敏感性分布(species sensitivity distribution, SSD)法和熵值法(ecological risk quotient, RQ)评估7种酚类化合物水环境和沉积物的生态风险。结果表明,地表水样中7种酚类化合物均全部检出;其中壬基酚的检出浓度最高,其次为四溴双酚A、对叔丁基苯酚、1-萘酚、2-苯基苯酚、3,4-二氯酚和双酚A。沉积物中酚类化合物的污染分布规律与水样相似,除双酚A外的目标物全部检出。其中,壬基酚浓度比其他物质浓度高2个数量级。风险评估结果显示,壬基酚对水环境与沉积物存在不可接受的风险;而四溴双酚A、对叔丁基苯酚、1-萘酚、2-苯基苯酚、3,4-二氯酚和双酚A则对环境具有较低风险或者存在一定的风险。 相似文献
162.
环境生态风险评估(ERA)流程已经被纳入全球环境政策中,既用于规范新化学物质的授权和营销(前瞻性环境生态风险评估),也用于评估潜在的污染场地(回顾性环境生态风险评估)。将土壤生态毒理学应用于风险评估,能阐明有毒物质对土壤生态系统中生命有机体的危害程度与范围。笔者主要介绍了应用评估因子法和物种敏感度分布法对基于效应数据进行的外推与估算,并综述了欧美等主要国家和地区的土壤生态风险评估框架、相关法律法规及其实施情况等,为中国开展土壤污染物生态毒理效应和风险评估等相关研究提供参考。 相似文献
163.
García del Barrio JM Ortega M Vázquez De la Cueva A Elena-Rosselló R 《Environmental monitoring and assessment》2006,119(1-3):137-159
This paper mainly aims to study the linear element influence on the estimation of vascular plant species diversity in five Mediterranean landscapes modeled as land cover patch mosaics. These landscapes have several core habitats and a different set of linear elements -habitat edges or ecotones, roads or railways, rivers, streams and hedgerows on farm land- whose plant composition were examined. Secondly, it aims to check plant diversity estimation in Mediterranean landscapes using parametric and non-parametric procedures, with two indices: Species richness and Shannon index.Land cover types and landscape linear elements were identified from aerial photographs. Their spatial information was processed using GIS techniques. Field plots were selected using a stratified sampling design according to relieve and tree density of each habitat type. A 50×20 m2 multi-scale sampling plot was designed for the core habitats and across the main landscape linear elements. Richness and diversity of plant species were estimated by comparing the observed field data to ICE (Incidence-based Coverage Estimator) and ACE (Abundance-based Coverage Estimator) non-parametric estimators.The species density, percentage of unique species, and alpha diversity per plot were significantly higher (p < 0.05) in linear elements than in core habitats. ICE estimate of number of species was 32% higher than of ACE estimate, which did not differ significantly from the observed values. Accumulated species richness in core habitats together with linear elements, were significantly higher than those recorded only in the core habitats in all the landscapes. Conversely, Shannon diversity index did not show significant differences. 相似文献
164.
Hyperspectral Characteristics of Canopy Components and Structure for Phenological Assessment of an Invasive Weed 总被引:1,自引:0,他引:1
Ge S Everitt J Carruthers R Gong P Anderson G 《Environmental monitoring and assessment》2006,120(1-3):109-126
Spectral reflectance values of four canopy components (stems, buds, opening flowers, and postflowers of yellow starthistle (Centaurea solstitialis)) were measured to describe their spectral characteristics. We then physically combined these canopy components to simulate the flowering stage indicated by accumulated flower ratios (AFR) 10%, 40%, 70%, and 90%, respectively. Spectral dissimilarity and spectral angles were calculated to quantitatively identify spectral differences among canopy components and characteristic patterns of these flowering stages. This study demonstrated the ability of hyperspectral data to characterize canopy components, and identify different flowering stages. Stems had a typical spectral profile of green vegetation, which produced a spectral dissimilarity with three reproduction organs (buds, opening flowers, and postflowers). Quantitative differences between simulated flower stages depended on spectral regions and phenological stages examined. Using full-range canopy spectra, the initial flowering stage could be separated from the early peak, peak, and late flowering stages by three spectral regions, i.e. the blue absorption (around 480 nm) and red absorption (around 650 nm) regions and NIR plateau from 730 nm to 950 nm. For airborne CASI data, only the red absorption region and NIR plateau could be used to identify the flowering stages in the field. This study also revealed that the peak flowering stage was more easily recognized than any of the other three stages. 相似文献
165.
Due to rapid industrialization and urbanization during last two decades, contamination of soils by heavy metals is on an increase globally. Lands under peri-urban agriculture are the worst affected. In NCT, Delhi about 14.4% of land area is chemically degraded. In order to take care of this problem, recently the Supreme Court of India ordered to shift various non-confirming (about 39,000 units) industries to regions outside NCT, Delhi. However in spite of this, there have been several reports and parliamentary debates on the phyto-toxicity and extensive accumulation of heavy metals in the region. Literature review revealed that the basis of these debates is a few studies on some point locations in/around Delhi. It was further observed that information on the distribution and extent of heavy metal pollution problem in the region was completely missing. The present study was thus basically aimed at assessing the spatial distribution/extent and type of heavy metal pollution in the study area, for enabling future designing of appropriate site-specific management measures by the decision makers.For this, detailed spatial information on bio-available heavy metal concentrations in the soils and surface/sub-surface waters of NCT (Delhi) was generated through actual soil/water surveys, standard laboratory methods and GIS techniques. The study showed that concentration of all micronutrients (viz. Zn: 0.05–0.18 ppm; Cu: in traces; Fe: 0–0.5 ppm; and Mn: 0–1.2 ppm) and most heavy metals (viz. Ni: 0–0.7 ppm; Pb: 0–0.15 ppm and Cd: in traces) in the surface/sub-surface irrigation waters were well within permissible limits. However Cr concentrations in irrigation waters of Alipur and Shahdara blocks were far above their maximum permissible limit of 1 ppm. It was further observed that Ni and Cr concentrations in the drinking waters of almost entire test area were far above maximum permissible levels of 0.02 and 0.01 ppm, respectively. Bio-available concentrations of several heavy metals (viz. Pb: 0.1–2 ppm; Cd: traces; Ni: 0.05–2 ppm and Cr: 0–0.4 ppm) in the study area soils were also observed to be well within the maximum permissible limits. However there were point Cu contaminations (5–10 ppm) in the sewage-sludge amended soils of vegetable growing areas near south Shahdara block. This was attributed to increased Cu availability due to oxidized acidic conditions generated by over-irrigation of agricultural lands. Available Mn concentrations in Kanjhawala, western Najafgarh and Alipur soils were also observed to be above maximum permissible limit of 10 ppm. This was observed to be mainly due to the geology (i.e. presence of Mn rich sedimentary rocks) and prevalence of reduced acidic conditions, due to paddy cultivation, in these areas. It was further observed that there is acute zinc (Zn) deficiency (< 0.6 ppm) in paddy growing soils of north Kanjhawala, Alipur and some parts of Najafgarh and Shahdara blocks due to extensive leaching of available Zn fractions to lower soil horizons. Similar available Zn deficiencies in high pH (8.5) soils of areas around Bamnoli village in E-Najafgarh block were also observed. 相似文献
166.
都昌县多宝砂山物种多样性研究及保护初探 总被引:2,自引:0,他引:2
对鄱阳湖都昌县多宝砂山地区土地风沙化过程中物种多样性的变化特征进行了分析,依据植物种在各类型风沙化土地的出现频率与不同风沙化阶段各生活型植物种的组成,探讨了风沙化过程中植物种的绝灭与定居特点.物种多样性指数分析表明:风沙化过程是物种多样性衰减的过程,风沙化首先导致特有种的绝灭,其次为稀有种.从植物的生活型来看,多年生草本与乔木类植物受风沙化影响最大,而灌木类植物可存活于风沙化过程的各个阶段,在风沙化过程中植物种的绝灭速率大于定居速率.最后,针对造成多宝砂山生物多样性衰减的原因,提出了治理对策,即在控制人类行为干扰的同时,要加强对固定沙丘的管理与保护. 相似文献
167.
长江口沙洲表层沉积物磷的赋存形态及生物有效性 总被引:34,自引:4,他引:30
利用磷的连续分级提取方法,研究了长江口沙洲沉积物中磷的赋存形态分布特征,并探讨了沉积物中磷的生物有效性.结果表明,沙洲沉积物中总磷的含量为437.6~1103.7μg·g-1,其中79.5%以无机磷的形式存在,而无机磷中以碎屑态磷灰石磷为主;有机磷约占总磷的20.5%.磷的生物有效性分析结果显示,潜在的生物有效性磷主要包括弱吸附态磷、铁结合态磷和有机磷等3种赋存形态,而长江口沙洲沉积物中潜在的生物有效性磷含量较少,约为60.5~510.9μg·g-1,平均仅占沉积物总磷的28.86%. 相似文献
168.
Tarsitano E 《Environmental management》2006,38(5):799-809
In urban ecosystems, the ecological system has become completely unbalanced; this, in turn, has led to an increase in well-known
problems such as air pollution, ground pollution, and water pollution. This imbalance has also led to the growth and spread
of pathogens harmful to man, animals, and plants. Urban sustainability indicators, both global and local, also “indicate”
the percentage of population, but these refer only to the human population, not the animal population. Cities need good waste,
water, and air management, effective traffic planning, and good zoning of businesses, crafts, and services; over and above
these activities, cities also need for planning to take into account the existence of pets (dogs, cats, and etc.) and nonpet
animals (insects, birds, mice, etc.). Cities tend to be designed around humans and “on a human scale,” without taking into
account the fact that a huge animal population is living side by side with people. That explains why overcrowding tends to
go hand in hand with urbanization; all these populations, including humans, need to adapt to new spaces and often need to
drastically change their behavior. This is a fact that must be included when drafting sustainable city plans. The supposed
strategy is that of “integrated-participatory” control of the interactions between the environment and animals in the cities.
Strategy will focus on the development of integrated approaches and tools for environment and animal management in the context
of urban settings. This will require such specific methods as ecological balance sheets and ecoplans for the planning, management,
and control of the interrelation among environment, animal, and public health. The objective is to develop a better understanding
of urban biodiversity and of urban ecosystem functioning, in order to understand and minimize the negative impacts of human
activities on them. The research will focus on assessing and forecasting changes in urban biodiversity, structure, function,
and dynamics of urban ecosystems, with relationships among society, economy, biodiversity, and habitats. 相似文献
169.
Collaboration has taken root in national forest planning, providing expanded opportunities for stakeholder participation in decision-making, but are these processes considered meaningful by key stakeholders? Do the processes result in increased participation by key stakeholders? We present results of a study of stakeholder perspectives of a collaborative planning process on the Grand Mesa, Uncompahgre, and Gunnison National Forests in Western Colorado, U.S.A. The stakeholders were stratified by participation levels in order to explore a possible relationship between participation and perceptions of the collaborative process. We used a Q-methodology approach to compare and contrast perspectives across participant levels in the North Fork Valley Landscape Working Group process. The results demonstrate four distinct perspectives on the collaborative process: 1) The collaborative process is valued by the Forest Service and will directly influence planning decisions; 2) The Forest Service, the collaborative process, and other stakeholders are not to be trusted; 3) The collaborative process is most effective when emphasizing place-specific dialogue that primarily involves stakeholders educating the Forest Service about issues; and 4) Forest planning involves issues requiring the application of scientific knowledge and expertise rather than collaboration. These perspectives were not strongly associated with participation levels, with time constraint being the primary mediating factor affecting participation. There are several possible actions policymakers and planners can take to enhance participation and overcome high rates of nonparticipation. 相似文献
170.
Improvements on Flood Alleviation in Germany: Lessons Learned from the Elbe Flood in August 2002 总被引:1,自引:0,他引:1
The increase in damage due to natural disasters is directly related to the number of people who live and work in hazardous
areas and continuously accumulate assets. Therefore, land use planning authorities have to manage effectively the establishment
and development of settlements in flood-prone areas in order to avoid the further increase of vulnerable assets. Germany faced
major destruction during the flood in August 2002 in the Elbe and Danube catchments, and many changes have been suggested
in the existing German water and planning regulations. This article presents some findings of a “Lessons Learned” study that
was carried out in the aftermath of the flood and discusses the following topics: 1) the establishment of comprehensive hazard
maps and flood protection concepts, 2) the harmonization of regulations of flood protection at the federal level, 3) the communication
of the flood hazard and awareness strategies, and 4) how damage potential can be minimized through measures of area precaution
such as resettlement and risk-adapted land use. Although attempts towards a coordinated and harmonized creation of flood hazard
maps and concepts have been made, there is still no uniform strategy at all planning levels and for all states (Lae
nder) of the Federal Republic of Germany. The development and communication of possible mitigation strategies for “unthinkable
extreme events” beyond the common safety level of a 100-year flood are needed. In order to establish a sustainable and integrated
flood risk management, interdisciplinary and catchment-based approaches are needed. 相似文献