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961.
962.
尾矿库溃坝淹没范围的定量计算方法研究 总被引:1,自引:1,他引:0
为降低人造高势能饱和体-尾矿库在金属非金属矿山安全生产中的危险,提高尾矿库工程溃决的预报预测水平,以溃坝洪水与泥浆的动力学过程作为研究重点,以溃坝洪水运动为主线,综合运用水文学、水动力学等运动理论和有限差分数值计算方法,建立描述尾矿库溃决泥浆运动的数值模型,研究得到尾矿库溃坝淹没范围的定量评估方法。最后进行实际工程预测,计算表明该模型和计算方法可为尾矿库溃坝风险等级的划分提供依据。 相似文献
963.
964.
为了处理淀粉加工过程中产生的大量高浓度有机废水,采用可移动的新型生物处理器,即"厌氧-好氧一体式高浓度有机废水处理器"对淀粉废水进行处理.为了提高反应器的处理效率,将无机矿物变质岩作为好氧微生物生长的填料.对变质岩的表面结构进行了微生物挂膜前、挂膜后的SEM分析,并考察了不同反应室对COD的去除效果.结果表明,高浓度马铃薯淀粉废水在25-35℃.pH=5.0-8.0,水力停留时间为9 h时.经处理反应器的出水COD可降到120mg/L,COD总去除率达到95%以上,出水水质能达标排放. 相似文献
965.
966.
Restoration of waterbird diversity and abundance is a key objective of river system management in Australia. Therefore, understanding the effects of climatic and hydrological variables on waterbird population dynamics is fundamental for successful river restoration programs. We investigated the population dynamics of waterbirds (total abundance) and seven functional waterbird groups in the floodplains of lower Murrumbidgee River. We found a general declining abundance trend from 1983 to 2007, except for the deep water foragers. We modelled the relative contribution of the climatic and hydrological factors to waterbird population decrease using the generalized additive model (GAM) framework after identifying the negative binomial distribution. Most of the seven functional groups were positively related to both annual rainfall and water usage, defined as the total water volume intercepted by the river reach, and the models indicated that rainfall was slightly more important. Temperature also played a role in waterbird abundance: the maximum summer temperature negatively influenced the abundance of dabbling ducks, shoreline foragers and fish eaters, while the minimum winter temperature positively affected the abundance of dabbling ducks and shoreline foragers. Overall, our results support the practice of providing environmental water for sustaining waterbird populations. However, environmental water provision is likely to be most effective when timed to coincide with antecedent rainfall. 相似文献
967.
Human activities disturb the long-term phosphorus (P) cycle in nature, whereby the resulting intensive release of P contributes to the eutrophication of surface water. Hence, a detailed understanding of P flow as it relates to socioeconomic systems is essential for effective nutrient management. This study develops a substance-flow-analysis model for P metabolism for the socioeconomic ecosystem of Shucheng County in Anhui Province in central China as a case study. We estimate P flow using data from questionnaires, face-to-face interviews, published literature, and official statistical databases. Our results show that P flow in Shucheng's current socioeconomic system is linear and openly metabolic. The total P input into Shucheng in 2008 reached 12 748 Mg, mainly as P ores and crops. In all, 43.83% of the total P input was exported, and 30.44% was discharged into surface water. More-balanced nutrient management and options for improving nutrient use efficiency are discussed. The quantifiable, science-based methods used in this study may be applied to neighboring regions of central China for sustainable development and water management. 相似文献
968.
Kinmen is located in the southwest of Mainland China. Groundwater supplies 50% of the domestic water use on the island. Residents
of Kinmen drink groundwater over the long term because surface water resources are limited. Nitrate–N pollution is found and
distributed primarily in the western part of groundwater aquifer whereas saline groundwater is distributed to the northeastern
Kinmen. This work applied the DRASTIC model to construct the vulnerability map of Kinmen groundwater. MT3D was then used to
evaluate the contamination potential of nitrate–N. The health risk associated with the ingestion of nitrate–N contaminated
groundwater is also assessed. The results from DRASTIC model showed that the upland crop and grass land have high contamination
potential, whereas the forest, reservoir and housing land have low contamination potential. The calibrated MT3D model inversely
determined the high strength sources (0.09–2.74 kg/m2/year) of nitrate contaminant located in the west to the north west area and required 2–5 years travel time to reach the monitoring
wells. Simulated results of MT3D also showed that both the continuous and instantaneous contaminant sources of nitrate–N release
may cause serious to moderate nitrate contamination in the western Kinmen and jeopardize the domestic use of groundwater.
The chronic health hazard quotient (HQ) associated with the potential non-carcinogenic risk of drinking nitrate–N contaminated groundwater showed that the assessed
95th percentile of HQ is 2.74, indicating that exposure to waterborne nitrate poses a potential non-cancer risk to the residents of the island.
Corrective measures, including protecting groundwater recharge zones and reducing the number of agricultural and non-agricultural
nitrogen sources that enters the aquifer, should be implemented especially in the western part of Kinmen to assure a sustainable
use of groundwater resources. 相似文献
969.
Rapid degradation of carbon tetrachloride by commercial micro-scale zinc powder assisted by citric acid 总被引:1,自引:0,他引:1
Xianchao Gao Feng Yang Yeqing Lan J.-D. Mao Xinyan Duan 《Environmental Chemistry Letters》2011,9(3):431-438
We developed an effective method for degradation of carbon tetrachloride (CT) in contaminated water. Zinc metal as a reducing
agent for CT in aqueous solutions has been previously studied in some detail, but the rapid corrosion of zinc surface usually
reduces its efficiency in removing CT. We assumed that citric acid could enhance the degradation of CT by zinc powder due
to the elimination of a passivation layer of Zn(II) (hydr)oxides on the surface of zinc powder through chelating of organic
ligands with Zn(II) produced from the reaction and keeping the exposure of active sites to targets. Here the influence of
citric acid on the decomposing of CT by commercial micro-scale zinc powder was investigated in a pH range of 3.5–7.5 at 25°C
in batch experiments. Reaction mixtures were analysed by gas chromatography/headspace analysis, and Cl− concentration was determined by turbidimetry. The results demonstrate that the degradation of CT by zinc metal alone is very
weak, but the addition of citric acid can assist zinc powder to decompose CT more completely and rapidly at all pHs. Degradation
of CT took place mainly in the first 10 min of reaction, coupled with 75–95% of CT removal. Maximum dechlorination percentage
(82.4%) of CT was obtained at pH 5.5. In that case, chloroform and dichloromethane, as main intermediates, were found at low
levels during the whole reaction, suggesting that CT may be sequentially and multiply degraded so quickly that methane is
yielded before the intermediates can be desorbed and released to aqueous solution. When compared with the current methods
of nano-scale zinc and bimetallic systems, the application of commercial micro-scale zinc particles assisted by organic ligands
is of environmental significance since it allows decontamination of aqueous chlorinated organic compounds at low cost and
with high efficiency. 相似文献
970.
采用选择性分离方法对药用植物红豆杉Taxus chinensis嫩枝和叶进行内生菌分离,得到一株放线菌En-1,经鉴定为链霉菌Streptomyces sp.;并对该菌进行液体培养条件优化、次生代谢物初筛及其抗菌活性的研究。通过添加宿主植物浸出物至En-1液体培养中以考察宿主对后者生长的影响,结果表明红豆杉叶浸出物能促进En-1的体外生长;而且En-1次生代谢物对5株供试菌中的黑曲霉具有抑制活性。通过En-1菌培养基优化并联合波谱法检测其发酵产物,显示8#配方(淀粉25 g.L-1,KNO3 1 g.L-1,K2HPO4.3H2O 0.5 g.L-1,NaCl 0.5 g.L-1,FeSO4.7H2O 0.01 g.L-1,MgSO4.7H2O 0.5 g.L-1)培养液中,En-1所产的次生代谢物最具结构多样性;同时8#配方也有利于该菌产生抗菌活性产物。本研究提示红豆杉内生放线菌可作为寻求药物先导化合物的资源菌。 相似文献