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871.
872.
新疆塔里木河流域生态脆弱带的环境质量综合评价 总被引:32,自引:0,他引:32
塔里木河流域是我国生态环境脆弱地区之一,流域内的不同区域,由于物质及能量匹配上不够协调,宏观上表现出不同的脆弱性特征.依据生态环境质量评价的有关原则,结合塔河流域生态环境的实际情况,筛选出20个指标,建立生态环境综合评价的指标体系.通过构建生态脆弱性指数,综合地反映了塔河流域生态环境质量的优劣程度.结果表明,阿克苏河流域属于生态环境改善区,叶尔羌河流域及塔河上游属于生态环境基本平衡区,和田河流域及塔河中游属于生态环境失调区,而塔河下游属于生态环境严重受损区,评价结果符合实际情况,对指导流域生态环境建设具有重要意义. 相似文献
873.
青霉菌GX2对蒽醌染料的吸附作用 总被引:28,自引:1,他引:27
GX2生长菌体对 4种蒽醌染料均表现出优良的吸附性能 ,但由于染料分子的结构不同 ,吸附速率和吸附率也表现出一定的差异 .染料对菌体的生长具有一定的抑制作用 ,但即使在很高的染料浓度下 ,GX2生长菌体仍表现出很强的吸附性能 .对 250mg/L活性艳蓝KN-R的吸附率高达 100% ,对 400mg/LKN R的吸附率也可达91.4% .在 0~2%范围内 ,随着盐度 (NaCl)的增加 ,菌体干重增加 ;颗粒状菌团的直径却随之减小 ,比表面积增大 ,对GX2生长菌体的染料吸附表现出较为明显的促进作用 .碳源浓度通过影响菌体的生长而影响染料吸附 ,当培养基中的葡萄糖浓度大于 2.5g/L时 ,即可使浓度为 120mg/L的活性艳蓝KN R溶液完全脱色 .生长菌体具有比静止活体和死体更好的吸附性能 . 相似文献
874.
膨润土对土壤腐殖质特性的影响 总被引:1,自引:0,他引:1
砂质土壤腐殖质含量低,影响了土壤肥力.文章通过田间条件下砂滤管试验,利用膨润土的吸附和粘结功能,研究了膨润土不同用量对土壤腐殖质特性的影响.结果表明:膨润土在促进松结态腐殖质分解、加速紧结态腐殖质合成方面发挥了重要作用,有利于增加土壤系统的内稳性.施用膨润土促进了紧结态和稳结态腐殖质中HA的积累,提高了HA/FA比.胡敏酸红外吸收光谱表明,膨润土能使其脂肪族物质增多、芳化度降低.膨润土具有提高土壤腐殖质含量,改善土壤腐殖质特性,从而提高了土壤肥力. 相似文献
875.
876.
Jihoon Park Moon Seong Kang Inhong Song 《Journal of the American Water Resources Association》2015,51(3):859-876
The objective of this article was to assess flood vulnerability based on the representative concentration pathways (RCP) scenarios at city and county levels. A quantile mapping method was adopted to correct bias that is inherent in climate change scenarios. A series of proxy variables related to climate exposure, sensitivity, and adaptive capacity were chosen to assess flood vulnerability. Proxy variables were standardized using the Z‐score method. Principal component analysis was carried out to calculate the weighting of proxy variables. The study area was the Korean peninsula. The spatial resolution was on a city and county basis and the temporal resolution was 1990s, 2025s, 2055s, and 2085s (divided into 1976‐2005, 2011‐2040, 2041‐2070, and 2071‐2100). In the spatial comparison, we found that the areas with high‐level flood vulnerability increased over time in the central region, including metropolitan areas, and near the southern coast. In the temporal comparison, we found that the RCP4.5 scenario showed a tendency to increase steadily and the RCP8.5 scenario showed a tendency to decrease in the 2055s slightly and increase again in the 2085s. The study findings may provide useful data for the determination of priority for countermeasure development, though robustness of these findings with additional future projections should be established. 相似文献
877.
Effects of regional vs. ecological factors on plant species richness: an intercontinental analysis 总被引:3,自引:0,他引:3
Conclusions from past studies on the roles that historical and regional factors and contemporary and ecological factors have played in regulating large-scale patterns of species richness have been controversial. Conflicting past results were likely affected by differences in the range of environments analyzed and the scales of observation. Eastern North America and eastern Asia are ideal regions for examining the relative effects of historical and regional factors and contemporary and ecological factors on large-scale patterns of plant species richness because these two regions are closely matched in terms of climate and because their floras originated from the same paleoflora but have experienced different histories of development since the late Paleogene when climate cooling caused their separation. We report on a comprehensive data set of 471 floras ranging from 10 km2 to 4.7 x 10(6) km2 and spanning a wide range of climate and latitude (from 21 degrees to 55 degrees N) to examine whether the contribution of region relative to climate persists from small to large floras and increases from cooler to warmer climates. We found that eastern Asia is richer than eastern North America when sample area, maximum elevation, and climate are accounted for, that this difference diminishes toward higher latitudes, and that elevation plays a much stronger role in eastern Asia than in eastern North America. Our analysis reconciles contemporary/ecological and historical/regional explanations for species richness variation and helps explain why different conclusions have been reached by different authors working in the same geographical areas: the strength of the region effect itself varies with location and range of climatic conditions of the observations. 相似文献
878.
Mobilization of heavy metals from contaminated paddy soil by EDDS,EDTA, and elemental sulfur 总被引:1,自引:0,他引:1
Wang G Koopmans GF Song J Temminghoff EJ Luo Y Zhao Q Japenga J 《Environmental geochemistry and health》2007,29(3):221-235
For enhanced phytoextraction, mobilization of heavy metals (HMs) from the soil solid phase to soil pore water is an important
process. A pot incubation experiment mimicking field conditions was conducted to investigate the performance of three soil
additives in mobilizing HMs from contaminated paddy soil (Gleyi-Stagnic Anthrosol): the [S, S]-isomer of ethylenediamine disuccinate
(EDDS) with application rates of 2.3, 4.3, and 11.8 mmol kg−1 of soil, ethylenediamine tetraacetate (EDTA; 1.4, 3.8, and 7.5 mmol kg−1), and elemental sulfur (100, 200, and 400 mmol kg−1). Temporal changes in soil pore water HM and dissolved organic carbon concentrations and pH were monitored for a period of
119 days. EDDS was the most effective additive in mobilizing soil Cu. However, EDDS was only effective during the first 24
to 52 days, and was readily biodegraded with a half-life of 4.1 to 8.7 days. The effectiveness of EDDS decreased at the highest
application rate, most probably as a result of depletion of the readily desorbable Cu pool in soil. EDTA increased the concentrations
of Cu, Pb, Zn, and Cd in the soil pore water, and remained effective during the whole incubation period due to its persistence.
The highest rate of sulfur application led to a decrease in pH to around 4. This increased the pore water HM concentrations,
especially those of Zn and Cd. Concentrations of HMs in the soil pore water can be regulated to a large extent by choosing
the proper application rate of EDDS, EDTA, or sulfur. Hence, a preliminary work such as our pot experiment in combination
with further plant experiments (not included in this study) will provide a good tool to evaluate the applicability of different
soil additives for enhanced phytoextraction of a specific soil. 相似文献
879.
880.