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121.
Baselines for land-use change in the tropics: application to avoided deforestation projects 总被引:2,自引:0,他引:2
Sandra Brown Myrna Hall Ken Andrasko Fernando Ruiz Walter Marzoli Gabriela Guerrero Omar Masera Aaron Dushku Ben DeJong Joseph Cornell 《Mitigation and Adaptation Strategies for Global Change》2007,12(6):1001-1026
Although forest conservation activities, particularly in the tropics, offer significant potential for mitigating carbon (C)
emissions, these types of activities have faced obstacles in the policy arena caused by the difficulty in determining key
elements of the project cycle, particularly the baseline. A baseline for forest conservation has two main components: the
projected land-use change and the corresponding carbon stocks in applicable pools in vegetation and soil, with land-use change
being the most difficult to address analytically. In this paper we focus on developing and comparing three models, ranging
from relatively simple extrapolations of past trends in land use based on simple drivers such as population growth to more
complex extrapolations of past trends using spatially explicit models of land-use change driven by biophysical and socioeconomic
factors. The three models used for making baseline projections of tropical deforestation at the regional scale are: the Forest
Area Change (FAC) model, the Land Use and Carbon Sequestration (LUCS) model, and the Geographical Modeling (GEOMOD) model.
The models were used to project deforestation in six tropical regions that featured different ecological and socioeconomic
conditions, population dynamics, and uses of the land: (1) northern Belize; (2) Santa Cruz State, Bolivia; (3) Paraná State,
Brazil; (4) Campeche, Mexico; (5) Chiapas, Mexico; and (6) Michoacán, Mexico.
A comparison of all model outputs across all six regions shows that each model produced quite different deforestation baselines.
In general, the simplest FAC model, applied at the national administrative-unit scale, projected the highest amount of forest
loss (four out of six regions) and the LUCS model the least amount of loss (four out of five regions). Based on simulations
of GEOMOD, we found that readily observable physical and biological factors as well as distance to areas of past disturbance
were each about twice as important as either sociological/demographic or economic/infrastructure factors (less observable)
in explaining empirical land-use patterns.
We propose from the lessons learned, a methodology comprised of three main steps and six tasks can be used to begin developing
credible baselines. We also propose that the baselines be projected over a 10-year period because, although projections beyond
10 years are feasible, they are likely to be unrealistic for policy purposes. In the first step, an historic land-use change
and deforestation estimate is made by determining the analytic domain (size of the region relative to the size of proposed
project), obtaining historic data, analyzing candidate baseline drivers, and identifying three to four major drivers. In the
second step, a baseline of where deforestation is likely to occur–a potential land-use change (PLUC) map—is produced using
a spatial model such as GEOMOD that uses the key drivers from step one. Then rates of deforestation are projected over a 10-year
baseline period based on one of the three models. Using the PLUC maps, projected rates of deforestation, and carbon stock
estimates, baseline projections are developed that can be used for project GHG accounting and crediting purposes: The final
step proposes that, at agreed interval (e.g., about 10 years), the baseline assumptions about baseline drivers be re-assessed.
This step reviews the viability of the 10-year baseline in light of changes in one or more key baseline drivers (e.g., new
roads, new communities, new protected area, etc.). The potential land-use change map and estimates of rates of deforestation
could be re-done at the agreed interval, allowing the deforestation rates and changes in spatial drivers to be incorporated
into a defense of the existing baseline, or the derivation of a new baseline projection. 相似文献
122.
Stable hydrogen isotopes of two chlorinated solvents, trichloroethylene (TCE) and 1,1,1-trichloroethane (TCA), provided by five different manufacturers, were determined and compared to their carbon and chlorine isotopic signatures. The isotope ratio for delta2H of different TCEs ranged between +466.9 per thousand and +681.9 per thousand, for delta13C between -31.57 per thousand and -27.37 per thousand, and for delta37Cl between -3.19 per thousand and +3.90 per thousand. In the case of the TCAs, the isotope ratio for delta2H ranged between -23.1 per thousand and +15.1 per thousand, for delta13C between -27.39 per thousand and -25.84 per thousand, and for delta37Cl between -3.54 per thousand and +1.39 per thousand. As well, a column experiment was carried out to dechlorinate tetrachloroethylene (PCE) to TCE using iron. The dechlorination products have completely different hydrogen isotope ratios than the manufactured TCEs. Compared to the positive values of delta2H in manufactured TCEs (between +466.9 per thousand and +681.9 per thousand), the dechlorinated products had a very depleted delta2H (less than -300 per thousand). This finding has strong implications for distinguishing dechlorination products (PCE to TCE) from manufactured TCE. In addition, the results of this study show the potential of combining 2H/1H analyses with 13C/12C and 37Cl/35Cl for isotopic fingerprinting applications in organic contaminant hydrogeology. 相似文献
123.
后京都议定书时代的二氧化碳排放格局与中国面临的发展挑战 总被引:1,自引:0,他引:1
阐述了近期世界主要国家的温室气体排放状况,以及2012年<京都议定书>第一承诺期到期后,全球二氧化碳可能的排放格局.分析了气候变化对中国发展带来的挑战.指出气候变化是人类共同面临的挑战,世界各国都在采取各种措施努力减少额外的二氧化碳排放量;作为发展中的温室气体排放大国,中国面临巨大的减排压力,为此,中国必须尽快做出调整,向低碳经济转型. 相似文献
124.
125.
126.
This paper examines the energy and carbon balance of two residential house alternatives; a typical wood frame home using more conventional materials (brick cladding, vinyl windows, asphalt shingles, and fibreglass insulation) and a similar wood frame house that also maximizes wood use throughout (cedar shingles and siding, wood windows, and cellulose insulation) in place of the more typical materials used – a wood-intensive house. Carbon emission and fossil fuel consumption balances were established for the two homes based on the cumulative total of three subsystems: (1) forest harvesting and regeneration; (2) cradle-to-gate product manufacturing, construction, and replacement effects over a 100-year service life; and (3) end-of-life effects – landfilling with methane capture and combustion or recovery of biomass for energy production.The net carbon balance of the wood-intensive house showed a complete offset of the manufacturing emissions by the credit given to the system for forest re-growth. Including landfill methane emissions, the wood-intensive life cycle yielded 20 tons of CO2e emissions compared to 72 tons for the typical house. The wood-intensive home's life cycle also consumed only 45% of the fossil fuels used in the typical house.Diverting wood materials from the landfill at the end of life improved the life cycle balances of both the typical and wood-intensive houses. The carbon balance of the wood-intensive house was 5.2 tons of CO2e permanently removed from the atmosphere (a net carbon sink) as compared to 63.4 of total CO2e emissions for the typical house. Substitution of wood fuel for natural gas and coal in electricity production led to a net energy balance of the wood-intensive house that was nearly neutral, 87.1 GJ energy use, 88% lower than the scenario in which the materials were landfilled.Allocating biomass generation and carbon sequestration in the forest on an economic basis as opposed to a mass basis significantly improves the life cycle balances of both houses. Employing an economic allocation method to the forest leads to 3–5 times greater carbon sequestration and fossil fuel substitution attributable to the house, which is doubled in forestry regimes that remove stumps and slash as fuel. Thus, wood use has the potential to create a significantly negative carbon footprint for a house up to the point of occupancy and even offset a portion of heating and cooling energy use and carbon emissions; the wood-intensive house is energy and carbon neutral for 34–68 years in Ottawa and has the potential to be a net carbon sink and energy producer in a more temperate climate like San Francisco. 相似文献
127.
Carbon source is a critical constraint on nutrient removal in domestic wastewater treatment. However, the functions of particulate organic matter (POM) and some organics with high molecular weight (HMW) are overlooked in the conventional process, as they cannot be directly assimilated into cells during microbial metabolism. This further aggravates the problem of carbon source shortage and thus affects the effluent quality. Therefore, to better characterize organic matter (OM) based MW distribution, microfiltration/ultrafiltration/nanofiltration (MF/UF/NF) membranes were used in parallel to fractionate OM, which obtained seven fractions. Hydrolysis acidification (HA) was adopted to manipulate the MW distribution of dissolved organic matter (DOM) and further explore the correlation between molecular size and biodegradability. Results showed that HA pretreatment of wastewater not only promoted transformation from POM to DOM, but also boosted biodegradability. After 8 hr of HA, the concentration of dissolved organic carbon (DOC) increased by 65%, from the initial value of 20.25 to 33.48 mg/L, and the biodegradability index (BOD5 (biochemical oxygen demand)/SCOD (soluble chemical oxygen demand)) increased from 0.52 to 0.74. Using MW distribution analysis and composition optimization, a new understanding on the characteristics of organics in wastewater was obtained, which is of importance to solving low C/N wastewater treatment in engineering practice. 相似文献
128.
全球气候变化是当今全球关注的焦点和研究热点,碳排放核算对温室气体减排和控制具有重要意义。对当前碳排放核算方法进行了概述,介绍了各核算方法的基本原理和方法,并分析了各核算方法的特点,将为碳排放核算及其方法的选取提供参考依据。 相似文献
129.
采用联合式催化剂新技术,在低温下进行了一氧化碳和氢化同消除的试验,通过实验考察取得了良好的效果。 相似文献
130.
论我国用汞总量的削减 总被引:9,自引:2,他引:7
分析比较了我国的用汞数量、世界汞的产量及用量的统计数据,从汞本身的污染危害性,我国用汞和污染现状及发展趋势,以及应对全球限汞、禁汞趋势等方面论述了我国用汞总量亟待削减和削减的可行性。并以体温计行业为例,提出了我国削减用汞总量的具体建议:控制生产规模,慎批新建涉汞加工利用的生产项目,并逐渐淘汰生产规模过小的企业;充分运用法律和行政管理手段,逐渐提升对涉汞企业的要求,将最低环保门槛与择优审批相结合;严格限制某些含汞产品的销售和使用;大力推广替代产品和技术;组织对废弃产品中的汞进行集中回收和处置;修订和制订相关涉汞标准;制订我国涉汞行业的用汞削减规划和相应的产业调整计划,逐步限汞,最终禁汞。 相似文献