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171.
Altun L Baskent EZ Gunlu A Kadiogullari AI 《Environmental monitoring and assessment》2008,137(1-3):149-161
The productivity of forest sites has been indirectly determined with solo wood production objective in forest management.
Forest site productivity should, however, be determined directly in order to implement ecosystem based multipurpose forest
management philosophy. This article tackles the problem in distinguishing and mapping forest sites using both direct method
and indirect method in Genya Mountain located in central of Artvin State Forest Enterprise. About 112 sample plots were designed
and distributed over the area. In each sample plot, soil samples were collected and the classical timber inventory measurements
were taken. According to direct method, Soil Moisture Regime (SMR) method is preferred due to a water deficiency in the study
area. Water holding capacity was used as an essential criterion for the classification of the forest site. Forest site classifications
were assigned regarding the physiographic factors such as landform, aspect, and slope. Five different forest sites classes;
dry, moderate fresh, fresh, humid and hygric were determined. According to direct method, the guiding curve was used to generate
anamorphic site index (SI) equations and three site index classes; good (SI=I–II), medium (SI=III) and low (SI=IV–V) were
determined. Some important differences between the methods were realized. The forest sites determined with site index estimation
method indicate that site index I and II is 505.99 ha, III 1095.79 ha and IV and V 992.95 ha, whereas forest sites determined
with direct method related to dry site of 937.58 ha, moderate fresh site of 931.90 ha, fresh site of 1,797.71 ha, humid site
of 80.48 ha and hygric site of 356.55 ha. The forest site maps of both methods were created using GIS functions. The forest
sites of open and degraded areas should be determined according to direct method. 相似文献
172.
Recognition and understanding of landscape dynamics as a historical legacy of disturbances are necessary for sustainable management
of forest ecosystems. This study analyzed spatial and temporal changes in land use and land cover patterns in a typical mountain
watershed in the Gumushane district along the Northeastern part of Turkey. The area is investigated by comparing LANDSAT images
from 1987 to 2000 and evaluated the temporal changes of spatial structure of forest conditions through spatial analysis of
forest cover type maps from 1971 and 1987 using GIS and FRAGSTATS™.
The results show a general decreasing trend in area of natural land cover types including broadleaf and conifer forests as
well as coppice between 1971 and 1987 (0.54%, respectively). In contrast, between 1987 and 2000 this natural land cover types
show increasing trend (1.6%). In parallel with forest dynamics, the area of managed land including lowland and upland agricultural
areas, rangelands and grasslands increased during the first period and decreased during second period. In terms of spatial
configuration, Gümüşhane forests aren’t generally fragmented by intensive forest utilization in the latter periods. This is
partially due to out-migration of rural population in Gümüşhane. Nevertheless, land use pattern significantly changed over
time depending on a few factors such as unregulated management actions, social pressure and demographic movements. The study
revealed that demographic movements have a major effect on landscape dynamics. 相似文献
173.
Field Validation of a Conservation Network on the Eastern Shore of Maryland,USA, Using Breeding Birds as Bio-Indicators 总被引:1,自引:0,他引:1
Maryland’s Green Infrastructure (GI) is a network of large, intact natural areas (hubs), interconnected by linear swaths of
riparian or upland vegetation (corridors). The GI serves significant ecological functions and provides the bulk of the state’s
natural support system. This study examined whether the GI as mapped does, in fact, identify Maryland’s most ecologically
valuable forested lands, using forest interior dwelling birds (hereafter called “forest birds”) as bio-indicators. We conducted
bird point counts within forest both inside and outside of hubs on Maryland’s Eastern Shore. We also collected a wide variety
of habitat data. We found that both the condition of a forest and its surrounding landscape influenced the bird communities.
On average, forest bird richness was significantly higher within hubs; furthermore, almost all sites with at least five forest
bird species present were in hubs. Forest bird richness and abundance were highest in undisturbed, mature broadleaf forest
with wetlands and streams nearby. We detected a significant relationship between forest bird richness and the ecological score
of a finer-scale landscape assessment, focused on “cells” of about 0.1 ha in size. This field study also validated the Rapid
Field Assessment (RFA) protocol developed in 2001 to assess, on the ground, the relative condition of individual sites or
properties within the GI. Forest bird richness and abundance were positively correlated with the RFA community scores. Our
results underscore the importance of maintaining regional biological diversity by retaining large blocks of forest, especially
mature forest containing streams and wetlands. 相似文献
174.
Conservation-based development programs have sought to create economic opportunities for people negatively impacted by biological diversity protection. The USDA Forest Service, for example, developed policies and programs to create contracting opportunities for local communities to restore public lands to replace jobs lost from reduced timber harvest. This article examines 12 years of Forest Service land management contracting in western Oregon, Washington, and northern California to evaluate if contractors located in communities near national forests have been awarded more land management contracts and contract value over time. We find that land management contracting spending has declined dramatically and, once we control for intervening factors, we find that local contractors have received a smaller proportion of land management contracts over time. 相似文献
175.
This paper explains briefly the conceptual framework of an ecosystem-based multiple-use forest management planning focusing on biodiversity conservation and participation. Some results from a case study were documented to realize the implementation of the concept. A strong liaison between the related institutions and major stakeholders and the effective use of Geographic Information System (GIS) and Remote Sensing (RS) are necessary. Effective participation is evident only with the involvement of enthusiastic and skillful stakeholders. A case study of ??neada, Turkey, supported the idea that participation as communication has better possibilities to promote multiple-use forest management than participation as information gathering. Primary challenges relate to the effectiveness of conservation program, availability of coherent biodiversity data, capacity building; awareness, training, and common understanding of biodiversity and protected area concept; coordination among the related institutions and stakeholders; and willingness and enthusiasm of authorities to accept and implement the concept. 相似文献
176.
177.
Nitrogen (N) pollution is a growing concern in forests of the greater Sierra Nevada, which lie downwind of the highly populated
and agricultural Central Valley. Nitrogen content of Letharia vulpina tissue was analyzed from 38 sites using total Kjeldahl analysis to provide a preliminary assessment of N deposition patterns.
Collections were co-located with plots where epiphytic macrolichen communities are used for estimating ammonia (NH3) deposition. Tissue N ranged from 0.6% to 2.11% with the highest values occurring in the southwestern Sierra Nevada (range:
1.38 to 2.11). Tissue N at 17 plots was elevated, as defined by a threshold concentration of 1.03%. Stepwise regression was
used to determine the best predictors of tissue N from among a variety of environmental variables. The best model consisted
only of longitude (r
2 = 0.64), which was reflected in the geographic distribution of tissue values: the southwestern Sierra Nevada, the high Sierras
near the Tahoe Basin, and the Modoc Plateau, are three apparent N hotspots arranged along the tilted north–south axis of the
study area. Withholding longitude and latitude, the best regression model suggested that NH3 estimates and annual number of wetdays interactively affect N accumulation (r
2 = 0.61; % N ∼ NH3 + wetdays + (NH3 × wetdays)). We did not expect perfect correspondence between tissue values and NH3 estimates since other N pollutants also accumulate in the lichen thallus. Additionally, other factors potentially affecting
N content, such as growth rate and leaching, were not given full account. 相似文献
178.
A serious forest decline of Betula ermanii Cham. has been observed at Mt. Mae-Shirane, Oku-Nikko, Japan, where high ozone (O3) concentration and severe water deficiency have been measured. In order to consider the possibility whether O3 and/or water stresses could have been the causes of the forest decline of B. ermanii, plant growth experiments were conducted in environment-controlled growth cabinets. Two-year-old seedlings of B. ermanii were exposed to either charcoal-filtered air (O3 concentration <5 ppb) or 50 ppb O3 (daily average, ranging between 20–100 ppb) for 123 days at 20.0/12.5 ± 1.0°C (day/night) and 70/80 ± 7% relative humidity
(day/night). Simultaneously, seedlings were treated with three watering regime: 1.0 < pF < 1.8 (no water stress), 1.8 < pF < 2.5
(mild water stress) or 2.5 < pF < 3.0 (severe water stress). O3 exposure significantly reduced the dry weights of leaf, root and the whole plant, while water stress significantly reduced
the dry weights of each organ and the whole plant. Significant reductions of net photosynthesis, transpiration and stomatal
conductance were also observed under O3 and/or water deficiency treatments, while contents of RuBP carboxylase/oxygenase (Rubisco), chlorophyll
a+b
and some essential nutrient elements (N, P, K, Mg and Ca) were not markedly changed. It was suggested that the decrease in
net photosynthetic rate induced mainly by stomatal closure was the major cause of the growth reduction under O3 and/or water stresses. No significant interactions between O3 and water stresses were observed in terms of the depression of dry matter production, which suggested that simultaneous stress
treatments of O3 exposure and water deficiency could affect the tree growth of B. ermanii additively. 相似文献
179.
We developed a simple conceptual model that tracks nitrogen and carbon jointly through an N fertilized forest ecosystem. The
stimulation of growth increases the litterfall and imports substrate for soil microorganisms. Microbial biomass forms according
to the supply of C and N. The formation of microbial biomass is accompanied by respiratory C losses. The quantity of CO2 efflux depends on the C use efficiency of microbes. When excess N is available, the microbial activity is accelerated and
the demand for substrate is high. Litterfall supplies an insufficient amount of C to the soil. In such a case, labile soil
C is mineralized and the net effect of N fertilization is a loss of soil C. A strong N fertilization effect on the aboveground
biomass can offset the soil C loss. In the case of a low N dosage or high N losses due to leaching or emission of nitrogen
oxides, the soil C loss is small. The conceptual model was applied to a case study. The field data, collected over a time
span of several decades, could not support sound conclusions on the temporal trend of soil C because the spatial and temporal
variability of the chemical data was high. The conceptual model allowed to give an evaluation of the fertilization effect
on soil C based on reproducible principles. 相似文献
180.
Understanding the historical dynamics, composition, and environmental disturbances of forest landscapes provides a context
for monitoring changes, describing trends, and establishing reference conditions. This study analyses the temporal changes
in forest ecosystem structure in Artvin Forest Planning Unit (AFPU), Turkey, during 1972–2002 period based on digitized forest
stand type maps using geographic information system (GIS) and interpretation of satellite data. The results showed that there
was a net decrease of 450 ha in total forested areas between 1972 and 2002. Forest ecosystem structure changed over time depending
on a few factors such as demographic movements, insect outbreaks, dam and road construction, unregulated management actions,
and social pressure. In conclusion, temporal changes and the factors affecting these changes should be determined for sustainable
management of natural resources. 相似文献