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151.
152.
The power sector in Thailand is the largest contributor to CO2 emissions. There is high potential to mitigate CO2 emission via alternative power generating plants. Alternative plants considered in this study include nuclear plants, integrated gasification combined cycle plants, biomass-based plants and supercritical thermal power plants. The biomass-based plants considered here are fueled with four types of biomass; paddy husk, municipal solid waste (MSW), fuel wood and corncob. The methodology for the optimal expansion plan of the power generating system over the planning horizon is based on the least-cost approach. The results from the least-cost planning analyses show that the nuclear alternative has the highest potential to mitigate not only CO2 but also other airborne emissions. Moreover, the nuclear option is the most effective abatement strategy for CO2 reduction due to its negative incremental cost of CO2 reduction. 相似文献
153.
Sulc J Stojdl J Richter M Popelka J Svoboda K Smetana J Vacek J Skoblja S Buryan P 《Waste management (New York, N.Y.)》2012,32(4):692-700
A pilot scale gasification unit with novel co-current, updraft arrangement in the first stage and counter-current downdraft in the second stage was developed and exploited for studying effects of two stage gasification in comparison with one stage gasification of biomass (wood pellets) on fuel gas composition and attainable gas purity. Significant producer gas parameters (gas composition, heating value, content of tar compounds, content of inorganic gas impurities) were compared for the two stage and the one stage method of the gasification arrangement with only the upward moving bed (co-current updraft). The main novel features of the gasifier conception include grate-less reactor, upward moving bed of biomass particles (e.g. pellets) by means of a screw elevator with changeable rotational speed and gradual expanding diameter of the cylindrical reactor in the part above the upper end of the screw. The gasifier concept and arrangement are considered convenient for thermal power range 100-350 kWth. The second stage of the gasifier served mainly for tar compounds destruction/reforming by increased temperature (around 950 °C) and for gasification reaction of the fuel gas with char. The second stage used additional combustion of the fuel gas by preheated secondary air for attaining higher temperature and faster gasification of the remaining char from the first stage. The measurements of gas composition and tar compound contents confirmed superiority of the two stage gasification system, drastic decrease of aromatic compounds with two and higher number of benzene rings by 1-2 orders. On the other hand the two stage gasification (with overall ER = 0.71) led to substantial reduction of gas heating value (LHV = 3.15 MJ/Nm3), elevation of gas volume and increase of nitrogen content in fuel gas. The increased temperature (>950 °C) at the entrance to the char bed caused also substantial decrease of ammonia content in fuel gas. The char with higher content of ash leaving the second stage presented only few mass% of the inlet biomass stream. 相似文献
154.
Extending livestock grazing to the steep slopes has led to unstable grazing systems in the East African Highlands, and new
solutions and approaches are needed to ameliorate the current situation. This work was aimed at studying the effect of livestock
grazing on plant attributes and hydrological properties. The study was conducted from 1996 to 2000 at the International Livestock
Research Institute at Debre Ziet Research Station. Two sites were selected: one at 0–4% slope, and the other at 4–8% slope.
The treatments were: (1) no grazing (control); (2) light grazing, 0.6 animal unit months per hectare (aum/ha); (3) moderate
grazing, 1.8 aum/ha; (4) heavy grazing, 3.0 aum/ha; (5) very heavy grazing, 4.2 aum/ha; (6) initially plowed and continuously
very heavily grazed, 4.2 aum/ha. The result showed that species richness, infiltration rate, bare ground, and soil loss significantly
varied with grazing pressure. Species richness was higher in grazed plots compared to nongrazed plots. Biomass yield improved
on heavily grazed plots as cow dung accumulated over years. Cynodon dactylon plant species persisted with livestock grazing pressure in both sites. Infiltration rate improved and soil erosion declined
in all treatments after the first year. 相似文献
155.
Understanding the problems of grazing land in vertisol areas and seeking long-lasting solutions is the central point where
mixed crop livestock is the second stay for the majority of the population. In order to understand this, the current study
was conducted at two sites, one with 0–4% slope and the other with 4–8% slope at Ginchi watershed, 80 km west of Addis Ababa,
Ethiopia. The specific objectives of the study were to quantify changes in plant species richness, biomass, plant cover, and
soil physical and hydrological properties. The grazing regimes were: moderate grazing (regulated), heavy grazing (free grazing),
and no grazing (closed to any grazing), which was considered the control treatment. The results showed that the biomass yield
in nongrazed plots was higher than in the grazed plots. However, the biomass yield in grazed plots improved over the years.
Species richness and percentage of dominant species attributes were better in medium grazed plots than the other treatments.
Soil compaction was higher in very heavily grazed plots than in nongrazed and medium-grazed plots. In contrast to that, the
soil water content and infiltration rate were better in nongrazed plots than in grazed plots. Soil loss in grazed plots decreased
with the increase of biomass yields and as the soil was more compacted by livestock trampling during the wet season. Finally
since the medium stocking rate is better in species richness and plant attributes, and lies between nongrazed and heavily
grazed plots in the rest of the measured parameters, it could be the appropriate stocking rate to practice by the smallholder
farmer. 相似文献
156.
Shun'ichi Honda Naoyuki Miyata Keisuke Iwahori 《Journal of Material Cycles and Waste Management》2002,4(1):46-50
In our previous work, the primary sludge from wastewater treatment plants was shown to contain a considerable amount of cellulose
(about 20%, based on suspended solids) owing to the discharge of toilet paper. For the purpose of using the cellulose as a
biomass resource, this study examined a simple method for its recovery. When fibrous cellulose was suspended in 0.3% sulfuric
acid and autoclaved at 130°C for 60 min, 85%–88% of the initial solids remained without dissolving. Under these conditions,
an activated sludge sample not containing cellulose was strongly hydrolyzed and only 7% of the initial solids remained. The
prescribed amounts of cellulose added to the activated sludge sample were quantitatively recovered by the autoclaving treatment.
In the treatment of primary sludge containing >20% cellulose, residual solids with relatively high levels of cellulose (>69%)
could be obtained. The results indicate that the method proposed here could recover cellulose practically from waste sewage
sludge for biomass utilization.
Received: July 17, 2000 / Accepted: July 4, 2001 相似文献
157.
Fred J. Brenner Elaine K. Brenner Patricia E. Brenner Richard P. Steiner 《Environmental management》1994,18(2):307-315
Current surface mine regulations as ascribed under the Surface Mining Control and Reclamation Act of 1977 require that mine
lands be returned to the approximate original contours (AOC) with an area coverage of at least 70% and to biological productivity
equal to or greater than that which existed prior to mining. Six different procedures were evaluated on nine mine sites in
northwestern Pennsylvania as to their suitability to estimate aboveground biomass on mines reclaimed as hayland and pastures.
Biomass estimates determined by different procedures were compared to those obtained by random clip plots and with landowner
estimates of the annual yield from each site. Biomass estimates determined from a disk meter and landowner interviews varied
approximately ±10% from those obtained from random clip plots compared to a variation of ±8%–37% for the other procedures.
The number of samples required to obtain reliable estimates within ±10% of the mean at 95% confidence intervals varied among
the different sampling procedures according to the variance in biomass on the site. Although all procedures may be used either
singly or in combination to estimate above ground biomass on reclaimed mine lands, the combination of the disk meter, profile
board, and vegetation height is recommended because of their ease of measurement compared to the other procedures. 相似文献
158.
Disturbance of flora from utility construction tends to generate new plant growth. This growth changes productivity, diversity, and stability. Although the enhancement of vegetation may balance out the biomass destroyed by the original disturbance, it often adversely affects the quality of the vegetation. Percentage composition of the dominant long-lived perennials combined with quantitative measures are used to assess longterm effects of utility corridor construction. Differential effects of enhancement of vegetation are found along road edges, enhancement under wires of powerlines, and over trenches dug for pipelines. Areas under powerline pylons seem to receive the greatest damage and also show the most variable recovery of vegetation. Significant recovery rates are noticeable where the time span between year of construction has allowed for considerable regrowth of the older corridor. Recovery rates depend on soil type, landform, and other physical features of the disturbed sites. Drastic disturbance in one area or transect site may impede vegetation recovery, whereas slight disturbance might enhance vegetation in another, tending to offset the effect of the drastic disturbance. Disturbed areas and control areas may appear to have similar vegetation covers, biomasses, and densities, but these similarities often vanish when one examines qualitative aspects, such as proportion of long-lived species and presence of characteristic dominants. 相似文献
159.
Xiaoli Shan Jun Xu Yixue Li Feng Han Xiaohui Du Jingying Mao Yunbo Chen Youjiang He Fan Meng Xuezhi Dai 《环境科学学报(英文版)》2016,28(2):129-137
By aggregating MODIS(moderate-resolution imaging spectroradiometer) AOD(aerosol optical depth) and OMI(ozone monitoring instrument) UVAI(ultra violet aerosol index)datasets over 2010–2014, it was found that peak aerosol loading in seasonal variation occurred annually in spring over the Gulf of Tonkin(17–23°N, 105–110°E). The vertical structure of the aerosol extinction coefficient retrieved from the spaceborne lidar CALIOP(cloud-aerosol lidar with orthogonal polarization) showed that the springtime peak AOD could be attributed to an abrupt increase in aerosol loading between altitudes of 2 and 5 km.In contrast, aerosol loading in the low atmosphere(below 1 km) was only half of that in winter. Wind fields in the low and high atmosphere exhibited opposite transportation patterns in spring over the Gulf of Tonkin, implying different sources for each level. By comparing the emission inventory of anthropogenic sources with biomass burning, and analyzing the seasonal variation of the vertical structure of aerosols over the Northern Indo-China Peninsula(NIC), it was concluded that biomass burning emissions contributed to high aerosol loading in spring. The relatively high topography and the high surface temperature in spring made planetary boundary layer height greater than 3 km over NIC. In addition, small-scale cumulus convection frequently occurred, facilitating pollutant rising to over 3 km, which was a height favoring long-range transport. Thus, pollutants emitted from biomass burning over NIC in spring were raised to the high atmosphere, then experienced long-range transport, leading to the increase in aerosol loading at high altitudes over the Gulf of Tonkin during spring. 相似文献
160.
沸石一蛭石曝气生物滤池低温低浓度条件下生物膜特性研究 总被引:1,自引:0,他引:1
研究了低温(4~8℃)沸石一蛭石曝气生物滤池处理污水厂尾水稳态运行时生物膜形态、生物量和微生物活性变化特征,分析了反应器内生物量和微生物活性的空间变化规律。结果表明,曝气生物滤池的生物膜形态、生物量及微生物活性有沿水流方向渐变的特点,生物量及微生物活性沿水流方向呈现递减的趋势.且生物量、微生物活性呈正相关。 相似文献