全文获取类型
收费全文 | 10340篇 |
免费 | 8篇 |
国内免费 | 11篇 |
专业分类
安全科学 | 30篇 |
废物处理 | 801篇 |
环保管理 | 1270篇 |
综合类 | 1086篇 |
基础理论 | 3253篇 |
环境理论 | 1篇 |
污染及防治 | 1921篇 |
评价与监测 | 1077篇 |
社会与环境 | 918篇 |
灾害及防治 | 2篇 |
出版年
2023年 | 12篇 |
2022年 | 29篇 |
2021年 | 28篇 |
2020年 | 21篇 |
2019年 | 13篇 |
2018年 | 1489篇 |
2017年 | 1397篇 |
2016年 | 1232篇 |
2015年 | 150篇 |
2014年 | 58篇 |
2013年 | 85篇 |
2012年 | 496篇 |
2011年 | 1388篇 |
2010年 | 716篇 |
2009年 | 627篇 |
2008年 | 893篇 |
2007年 | 1247篇 |
2006年 | 21篇 |
2005年 | 25篇 |
2004年 | 52篇 |
2003年 | 76篇 |
2002年 | 111篇 |
2001年 | 23篇 |
2000年 | 19篇 |
1999年 | 7篇 |
1998年 | 12篇 |
1997年 | 5篇 |
1996年 | 8篇 |
1995年 | 7篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1984年 | 14篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1967年 | 3篇 |
1965年 | 2篇 |
1964年 | 4篇 |
1963年 | 2篇 |
1961年 | 4篇 |
1960年 | 4篇 |
1959年 | 6篇 |
1958年 | 10篇 |
1957年 | 4篇 |
1956年 | 6篇 |
1935年 | 2篇 |
1928年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
921.
Use of Descriptors of Ecosystem Functioning for Monitoring a National Park Network: A Remote Sensing Approach 总被引:1,自引:0,他引:1
Baseline assessments and monitoring of protected areas are essential for making management decisions, evaluating the effectiveness
of management practices, and tracking the effects of global changes. For these purposes, the analysis of functional attributes
of ecosystems (i.e., different aspects of the exchange of matter and energy) has advantages over the traditional use of structural
attributes, like a quicker response to disturbances and the fact that they are easily monitored through remote sensing. In
this study, we described the spatiotemporal patterns of different aspects of the ecosystem functioning of the Spanish national
parks and their response to environmental changes between 1982 and 2006. To do so, we used the NOAA/AVHRR-GIMMS dataset of
the Normalized Difference Vegetation Index (NDVI), a linear estimator of the fraction of photosynthetic active radiation intercepted
by vegetation, which is the main control of carbon gains. Nearly all parks have significantly changed during the last 25 years:
The radiation interception has increased, the contrast between the growing and nongrowing seasons has diminished, and the
dates of maximum and minimum interception have advanced. Some parks concentrated more changes than others and the degree of
change varied depending on their different environmental conditions, management, and conservation histories. Our approach
identified reference conditions and temporal changes for different aspects of ecosystem functioning, which can be used for
management purposes of protected areas in response to global changes. 相似文献
922.
We conducted field surveys and laboratory analyses to test the effects of soil characteristics in habitat mitigation sites and natural sites on the growth and condition of blue elderberry (Sambucus mexicana), which is the sole host plant for the federally threatened Valley elderberry longhorn beetle (Desmocerus californicus dimorphus). Thirty mitigation and 16 natural sites were selected throughout the range of the beetle. We found that although plant relative growth rates were comparable between mitigation sites and a natural site, mitigation sites contained substantially less soil nutrients than mitigation sites. Within mitigation sites, elderberry health and growth were positively correlated with the amount of total nitrogen in soils and less strongly with other soil nutrients and soil moisture. Analyses demonstrated reductions in the relative growth rate of elderberry as mitigation sites aged, and that soil nutrients and soil moisture became depleted over time. For mitigation sites, it took approximately seven years to develop basal stem diameters that have been linked to successful beetle colonization. Mitigation sites have smaller shrubs than natural sites and growth slows as mitigation sites age, thus delaying convergence of conditions between natural and mitigation sites. Analyses of soil particle size and whether sites were within the 100-year floodplain (as an indicator of riparian conditions) were inconclusive. We recommend investigating fertilizing and optimum planting densities for elderberry at restoration and mitigation sites, as well as increasing the duration of irrigation and monitoring. 相似文献
923.
924.
We conducted case studies of three successful examples of collaborative, community-based natural resource conservation and development. Our purpose was to: (1) identify the functions served by interactions within the social networks of involved stakeholders; (2) describe key structural properties of these social networks; and (3) determine how these structural properties varied when the networks were serving different functions. The case studies relied on semi-structured, in-depth interviews of 8 to 11 key stakeholders at each site who had played a significant role in the collaborative projects. Interview questions focused on the roles played by key stakeholders and the functions of interactions between them. Interactions allowed the exchange of ideas, provided access to funding, and enabled some stakeholders to influence others. The exchange of ideas involved the largest number of stakeholders, the highest percentage of local stakeholders, and the highest density of interactions. Our findings demonstrated the value of tailoring strategies for involving stakeholders to meet different needs during a collaborative, community-based natural resource management project. Widespread involvement of local stakeholders may be most appropriate when ideas for a project are being developed. During efforts to exert influence to secure project approvals or funding, however, involving specific individuals with political connections or influence on possible sources of funds may be critical. Our findings are consistent with past work that has postulated that social networks may require specific characteristics to meet different needs in community-based environmental management. 相似文献
925.
Inter-seasonal studies on the trace metal load of surface water, sediment and Tympanotonus fuscatus var. radula of Iko River were conducted between 2003 and 2004. The impact of anthropogenic activities especially industrial effluent,
petroleum related wastes, gas flare and episodic oil spills on the ecosystem are remarkable. Trace metals analyzed included
cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), lead (Pb), manganese (Mn), nickel (Ni), vanadium (V) and zinc (Zn). Sediment
particle size analysis revealed that they were characteristically psammitic and were predominantly of medium to fine grained
sand (>73%), less of silt (<15%) and clay (<10%). These results correlated with low levels of trace elements such as Pb (0.03 ± 0.02 mg kg−1), Cr (0.22 ± 0.12 mg kg−1), Cd (0.05 ± 0.03 mg kg−1), Cu (0.04 ± 0.02 mg kg−1) and Mn (0.23 ± 0.22 mg kg−1) in the sediment samples. This observation is consistent with the scarcity of clayey materials known to be good scavengers
for metallic and organic contaminants. Sediments indicated enhanced concentration of Fe, Ni and V, while other metal levels
were relatively low. The concentrations of all the metals except Pb in surface water were within the permissible levels, suggesting
that the petroleum contaminants had minimal effect on the state of pollution by trace metals in Iko River. Notably, the pollutant
concentrations in the sediments were markedly higher than the corresponding concentrations in surface water and T. fuscatus tissues, and decreased with distance from point sources of pollution. 相似文献
926.
Wastewater management in small and medium-sized enterprises representing the chemical and food industries was investigated.
The results showed that wastewater discharged from an ink-production factory was highly contaminated with organic pollutants.
Anaerobic biological treatment followed by chemical coagulation using ferric chloride aided with lime proved to be very effective
and produced an effluent that complied with national regulatory standard for wastewater discharge into public sewage network.
Also, management of wastewater from a confectionery factory representing the food sector was carried out. Aerobic biological
treatment using plastic-packed trickling filter proved to be an effective treatment method. However, application of in-plant
control measures alleviated the requirement for the construction of a wastewater treatment plant. The applied pollution prevention
and cleaner production measures involved good housekeeping, recovery of spent chocolate, modification of floor cleaning and
installation of suction devices for the removal of sugar and starch powders. All improvement measures were documented by cost/benefit
analysis. 相似文献
927.
Recycling and conservation efforts for water are the need of the day because of the lack of new water sources and the ever-increasing
demand for drinking water. Seedlings of Acacia nilotica L. were irrigated with: canal water (T1, control); municipal effluent (T2); textile effluent (T3); steel effluent (T4); textile + municipal effluent in 1:1 ratio (T5); steel + municipal effluent in 1:2 ratio (T6); steel + textile in 1:2 ratio (T8) and steel + municipal + textile in 1:2:2 ratio (T7) with views to observe effluents effect on the seedlings and its adaptability and to recommend safe disposal of these effluents.
Seedlings in T6, T7 and T8 showed 50% lesser height and collar diameter than those in control. Seedlings in T2 attained greatest height, collar diameter, numbers of branches and produced 140 g dry biomass seedling−1. Highest concentration of manganese (Mn), iron (Fe), copper (Cu) and zinc (Zn) and lowest concentration of nitrogen (N),
phosphorus (P), potassium (K), calcium (Ca) and magnesium (Mg) in the seedlings of T4, T6, T7 and T8 resulted in nutritional imbalance, mineral toxicity and reduction in photosynthetic (Pn) and transpiration (E) rates and caused seedling mortality. Seedlings of T3 had highest sodium concentration and low concentration of Ca, Mg and micronutrients resulting in nutritional imbalance, augmented
chlorosis and reduced gas exchange and biomass by half as compared to control. Increased growth, Pn and E and biomass in seedlings of T5 over T3 and survival period in T6, T7 and T8 seedlings suggested a beneficial effect of effluents mixing. Unscientific disposal should be avoided and toxic concentration
of metal ions␣may be reduced for long-term application and harmless disposal of effluents in afforestation and urban development. 相似文献
928.
Itziar de Aranzabal María F. Schmitz Francisco D. Pineda 《Environmental management》2009,44(5):938-951
Tourism and landscape are interdependent concepts. Nature- and culture-based tourism are now quite well developed activities
and can constitute an excellent way of exploiting the natural resources of certain areas, and should therefore be considered
as key objectives in landscape planning and management in a growing number of countries. All of this calls for careful evaluation
of the effects of tourism on the territory. This article focuses on an integrated spatial method for landscape analysis aimed
at quantifying the relationship between preferences of visitors and landscape features. The spatial expression of the model
relating types of leisure and recreational preferences to the potential capacity of the landscape to meet them involves a
set of maps showing degrees of potential visitor satisfaction. The method constitutes a useful tool for the design of tourism
planning and management strategies, with landscape conservation as a reference. 相似文献
929.
A Comparative Approach for Ranking Contaminated Sites Based on the Risk Assessment Paradigm Using Fuzzy PROMETHEE 总被引:2,自引:0,他引:2
A ranking system for contaminated sites based on comparative risk methodology using fuzzy Preference Ranking Organization
METHod for Enrichment Evaluation (PROMETHEE) was developed in this article. It combines the concepts of fuzzy sets to represent
uncertain site information with the PROMETHEE, a subgroup of Multi-Criteria Decision Making (MCDM) methods. Criteria are identified
based on a combination of the attributes (toxicity, exposure, and receptors) associated with the potential human health and
ecological risks posed by contaminated sites, chemical properties, site geology and hydrogeology and contaminant transport
phenomena. Original site data are directly used avoiding the subjective assignment of scores to site attributes. When the
input data are numeric and crisp the PROMETHEE method can be used. The Fuzzy PROMETHEE method is preferred when substantial
uncertainties and subjectivities exist in site information. The PROMETHEE and fuzzy PROMETHEE methods are both used in this
research to compare the sites. The case study shows that this methodology provides reasonable results. 相似文献
930.