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391.
S. D. Worley H. D. Burkett J. F. Price 《Journal of the American Water Resources Association》1984,20(3):369-371
A new organic N-chloramine disinfectant (3-chloro-4, 4-dimethyl-2-oxazolidinone, agent I) has been compared with calcium hypochlorite as to its tendency to react with organic matter in water to produce toxic trihalomethanes. Agent I reacts much less readily with organic demand than does calcium hypochlorite. This study shows that agent I should be safe to use as a disinfectant for water containing appreciable organic load in either sunlight or darkness. On the other hand, calcium hypochlorite may not be a satisfactory disinfectant from the toxicity standpoint for water which contains organic load which must be stored for extended time periods in either sunlight or darkness. 相似文献
392.
改性淀粉的合成及其对重金属离子的捕集效果 总被引:3,自引:0,他引:3
以玉米淀粉为原料,经过交联、间接醚化、胺化以及cs:亲核加成反应,得到二硫代氨基甲酸基(DTC)改性淀粉(DTCS),并对其合成条件进行优化;考察了交联度、醚化温度、氯含量及胺化剂对DTCS捕集重金属离子效果的影响。优化后的DTCS合成条件:交联淀粉(CS)沉降积为30—34mL,醚化温度为80℃,氯质量分数为7.82%,胺化剂为二乙烯四胺。实验结果表明,DTCS对Cu^2+,Pb^2+,Zn^2+,Cd^2+,Ni^2+均有较好的去除效果,其对Cu^2+,Pb^2+,Zn^2+,Cd^2+,Ni^2+的饱和吸附量分别为0.85,0.83,0.65,0.74,0.47mmol/g。 相似文献
393.
In this study, a constrained minimization method, the flexible tolerance method, was used to solve the optimization problems for determining hydrologic parameters in the root zone: water uptake rate, spatial root distribution, infiltration rate, and evaporation. Synthetic soil moisture data were first generated using the Richards' equation and its associated initial and boundary conditions, and these data were then used for the inverse analyses. The results of inverse simulation indicate the following. If the soil moisture data contain no noise, the rate of estimated water uptake and spatial root distribution parameters are equal to the true values without using constraints. If there is noise in the observed data, constraints must be used to improve the quality of the estimate results. In the estimation of rainfall infiltration and surface evaporation, interpolation methods should be used to reduce the number of unknowns. A fewer number of variables can improve the quality of inversely estimated parameters. Simultaneous estimation of spatial root distribution and water uptake rate or estimation of evaporation and water uptake rate is possible. The method was used to estimate the water uptake rate, spatial root distribution, infiltration rate, and evaporation using long‐term soil moisture data collected from Nebraska's Sand Hills. 相似文献
394.
不同底物条件下金属离子螯合剂对厌氧消化的影响 总被引:1,自引:0,他引:1
借助气相色谱分析,研究了金属离子螯合剂在不同有机酸存在时对厌氧消化的影响.结果表明,螯合剂A的添加可以有
效提高不同有机酸的甲烷产量和产甲烷速率,促进有机酸向甲烷的转化. 当螯合剂A的添加量为10μmoI/L时,丁酸、丙酸和乙酸的甲烷产量分别增加了19.8%、133.0%和45.2%.产甲烷的延滞期也明显缩短,最高产甲烷速率提高了4倍多.丁酸厌氧氧消化的4~8d间,丁酸降解率达56%,同时,气相色谱未检测到乙酸的累积,说明丁酸转化为乙酸后,乙酸很快被产甲烷菌利用.螯合剂A对有机酸产甲烷的促进作用可从酶学上得到支持,以乙酸为例,添加10μmoI/L螯合剂A时,污泥(vss)中辅酶F420含量由空白实验的1.20μmoI/g提高到1.52μmoI/g. 相似文献
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398.
When substance substitution is implemented to reduce the target risk of production processes, countervailing risks may occur. The goal of this study is to analyze the risk trade-off relationships between organic solvents and aqueous agents in the case study of metal cleaning processes. Global environmental impacts and local risks were evaluated for the eight scenarios by life cycle and risk assessments, respectively. The results show that the contribution of the processes using chlorinated solvents to photochemical ozone creation, human toxicity, ozone depletion, and ecotoxicity was larger than processes using aqueous detergents, while the contribution of aqueous processes to eutrophication was larger than chlorinated processes. Neighbors’ health risk around a cleaning site using chlorinated solvents was sufficiently small in all scenarios, whereas ecological risk due to surfactants which are contained in aqueous detergents and emitted to the local aquatic environment should be reduced. Cleansing agents and process facilities should be selected on the basis of the comprehensive analysis of risk trade-off relationships for feasible and cleaner production. 相似文献
399.