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1.
Based on energetic analysis, a novel approach for copper electrodeposition via cathodic reduction in microbial fuel cells (MFCs) was proposed for the removal of copper and recovery of copper solids as metal copper and/or Cu(2)O in a cathode with simultaneous electricity generation with organic matter. This was examined by using dual-chamber MFCs (chamber volume, 1L) with different concentrations of CuSO(4) solution (50.3 ± 5.8, 183.3 ± 0.4, 482.4 ± 9.6, 1007.9 ± 52.0 and 6412.5 ± 26.7 mg Cu(2+)/L) as catholyte at pH 4.7, and different resistors (0, 15, 390 and 1000 Ω) as external load. With glucose as a substrate and anaerobic sludge as an inoculum, the maximum power density generated was 339 mW/m(3) at an initial 6412.5 ± 26.7 mg Cu(2+)/L concentration. High Cu(2+) removal efficiency (>99%) and final Cu(2+) concentration below the USA EPA maximum contaminant level (MCL) for drinking water (1.3mg/L) was observed at an initial 196.2 ± 0.4 mg Cu(2+)/L concentration with an external resistor of 15 Ω, or without an external resistor. X-ray diffraction analysis confirmed that Cu(2+) was reduced to cuprous oxide (Cu(2)O) and metal copper (Cu) on the cathodes. Non-reduced brochantite precipitates were observed as major copper precipitates in the MFC with a high initial Cu(2+) concentration (0.1M) but not in the others. The sustainability of high Cu(2+) removal (>96%) by MFC was further examined by fed-batch mode for eight cycles.  相似文献   

2.
The environmental behavior and the potential toxicity of copper nanoparticles (nano-Cu) in water are major concerns for assessing their environmental safety. The present study was undertaken to characterize the properties of nano-Cu in E3 medium, such as size changes, solubility, zeta-potential and pH, and to test the toxicity of nano-Cu suspension to zebrafish embryos. Dynamic light scattering and solubility experiments showed that three components coexisted in the nano-Cu exposure system, including small nano-Cu aggregates still suspended in E3 medium, large nano-Cu aggregates deposited on the container bottom and dissolved copper species (Cu(dis)). Both the zeta-potential of nano-Cu particles in E3 medium and the pH of the nano-Cu suspension showed no change during a 24 hour period. It is found that nano-Cu retarded the hatching of zebrafish embryos and caused morphological malformation of the larvae, and high concentrations (>0.1 mg/L) of nano-Cu even killed the gastrula-stage zebrafish embryos. Cu2+ ions were used to study the toxicity caused by nano-Cu dissolution. The embryo toxicity of nano-Cu at 0.01 and 0.05 mg/L showed no significant difference from Cu2+ at the corresponding concentrations (0.006 and 0.03 mg/L), but 0.1 mg/L nano-Cu had a greater toxicity than 0.06 mg/L Cu2+.  相似文献   

3.
A pilot scale conventional activated sludge was operated for over 600 days to study its effectiveness at further remediating the effluent of an existing industrial site's thermophilic biological treatment stage. During the course of the study, the activated sludge was able to further biodegrade the contaminants in the incoming industrial wastewater in terms of both BOD and nitrogen reductions at varying hydraulic and solids retention times, despite elevated concentrations of soluble copper being present. A limiting hydraulic retention time (HRT) for BOD removal of 1.5 days was observed as well as the loss of nitrification occurred at a solids retention time (SRT) of approximately 6 days. Biokinetic coefficients were determined with the maximum rate of substrate utilization per unit mass of microorganisms, k, of 0.14 mgVSS/(mgsBOD-d) and the Monod half velocity constant, K(s), of 9.4 mgsBOD/L. Simultaneous nitrification and denitrification (SND) of the nitrogenous compounds found in this wastewater was observed throughout the majority of the experimentation while the bulk DO in the system was greater than 1 mg/L. The activated sludge was estimated to contain soluble copper on the order of 1 mg/L throughout the course of operation with no apparent detriment to nitrification. Additionally, the activated sludge was able to biologically remove the main solvents found in the influent wastewater. The removals of trace levels of N-nitrosodimethylamine (NDMA) were also observed.  相似文献   

4.
In this work, batch activated sludge studies were investigated for the treatment of raw pet food wastewater characterized by oil and grease concentrations of 50,000-66,000 mg/L, COD and BOD concentrations of 100,000 and 80,000 mg/L, respectively, as well as effluent from an existing anaerobic digester treating the aforementioned wastewater. A pre-treatment process, dissolved air flotation (DAF) achieved 97-99% reduction in O&G to about 400-800 mg/L, which is still atypically high for AS. The batch studies were conducted using a 4-L bioreactor at room temperature (21 degrees C) under different conditions. The experimental results showed for the DAF pretreated effluent, 92% COD removal efficiency can be achieved by using conventional activated sludge system at a 5 days contact time and applied initial soluble COD to biomass ratio of 1.17 mg COD/mg VSS. Similarly for the digester effluent at average oil and grease concentrations of 13,500 mg/L, activated sludge affected 63.7-76.2% soluble COD removal at 5 days. The results also showed that all kinetic data best conformed to the zero order biodegradation model with a low biomass specific maximum substrate utilization rate of 0.168 mg COD/mg VSS day reflecting the slow biodegradability of the wastewater even after 99% removal of oil and grease.  相似文献   

5.
The present work evaluates pre-ozonation for removal of acute toxicity, color and COD as well as reduction of inert soluble COD fractions in two wastewater samples (S1 and S2) taken from a textile finishing industry, located in Istanbul (Turkey). The wastewater samples were oxidized at original pH of 8.6-8.8 under 18.5-24 mg/L of applied ozone doses. Acute toxicity was monitored using Daphnia magna. The results showed that pre-ozonation improved the biodegradability and reduced the acute toxicity. Acute toxicity in raw wastewaters was reduced by 80-90% using 129-200 mg/L transferred ozone (TrO(3)) concentrations. At this point, 86-96% of color, 33-39% of soluble COD and 57-64% of total COD were removed from wastewaters. Both color and COD parameters were found related to the acute toxicity of the wastewater. Pre-ozonation decreased the inert soluble COD fraction (S(I)) of raw wastewater while soluble product formation (S(P)) increased slightly (5-10 mg/L). However, residual COD (the sum of S(I) and S(P)) remained below discharge limit.  相似文献   

6.
Although selected heavy metals (HMs) stimulate biological reactions at low concentrations, all HMs are toxic to microorganisms (MOs) at moderate concentrations and can cause inhibitory effects on the biological processes. Therefore, MOs must be acclimated to HMs or other toxic substances present in wastewaters (WWs) before they are used in an activated sludge process (ASP). In this study, combined effect of Cu(2+) and Zn(2+) ions in a synthetic WW on the efficiency of a laboratory-scale ASP without recycle was investigated using acclimated MOs at different extents.A synthetic feed solution of 1222 mg L(-1) proteose-peptone (corresponding to 1300 mg COD L(-1)) served as a source of carbon. Cu(2+) and Zn(2+) ions at different concentrations (1.5, 4.5 and 9, 27 mg L(-1), respectively) were introduced in the feed to a continuously stirred activated sludge reactor at different hydraulic residence times (2-40 h) keeping pH, temperature and stock feed composition constant. The combined effects of copper and zinc ions were determined by mixing these metallic ions at the specified combinations of concentrations such as "1.5 mg L(-1) of Cu(2+)+9 mg L(-1) of Zn(2+)" and "4.5 mg L(-1) of Cu(2+)+27 mg L(-1) of Zn(2+)". It was observed that using seed MOs acclimatized to two times of the combined threshold concentration of these HMs for an unduly long period of time (1-4 months) caused adverse effects on the ASP performance. Besides, it was found that usual inhibition effects of these HMs were enhanced with increasing period of acclimation. Substantially lower substrate removal efficiencies were obtained with acclimatized MOs than those obtained with non-acclimatized MOs. At the higher initial substrate concentration of 2500 mg COD L(-1), substrate-inhibition occurred causing a decrease in the specific growth rate constant (k); however, HM inhibition was suppressed, resulting to about 20% increase in treatment efficiency of the ASP. It can be concluded that the time period necessary for acclimatization of seed MOs must be adjusted carefully with concentrations of HMs lower than their threshold concentrations to achieve an optimal operation of an aerobic biological process.  相似文献   

7.
Chitosan coated perlite beads were prepared by drop-wise addition of slurry, made of chitosan dissolved in oxalic acid and perlite, to an alkaline bath (0.7 M NaOH). The beads that contained 32% chitosan enhanced the accessibility of OH and amine groups present in chitosan for adsorption of copper ions. The experiments using Cu(II) ions were carried out in the concentration range of 50-4100 mg/L (0.78-64.1 mmol/L). Adsorption capacity for Cu(II) was pH dependent and a maximum uptake of 104 mg/g of beads (325 mg/g of chitosan) was obtained at pH 4.5 when its equilibrium concentration in the solution was 812.5 mg/L at 298 K. The XPS and TEM data suggested that copper was mainly adsorbed as Cu(II) and was attached to amine groups. The adsorption data could be fitted to one-site Langmuir adsorption model. Anions in the solution had minimal effect on Cu(II) adsorption by chitosan coated perlite beads. EDTA was used effectively for the regeneration of the bed. The diffusion coefficient of Cu(II) onto chitosan coated beads was calculated from the breakthrough curve and was found to be 2.02 x 10(-8) cm(2)/s.  相似文献   

8.
Carbonate hydroxylapatite (CHAP) synthesized by using eggshell waste as raw material has been investigated as metal adsorption for Cd(II) and Cu(II) from aqueous solutions. The effect of various parameters on adsorption process such as contact time, solution pH, amount of CHAP and initial concentration of metal ions was studied at room temperature to optimize the conditions for maximum adsorption. The results showed that the removal efficiency of Cd(II) and Cu(II) by CHAP could reach 94 and 93.17%, respectively, when the initial Cd(II) concentration 80 mg/L and Cu(II) 60 mg/L and the liquid/solid ratio was 2.5 g/L. The equilibrium sorption data for single metal systems at room temperature could be described by the Langmuir and Freundlich isotherm models. The highest value of Langmuir maximum uptake, (b), was found for cadmium (111.1mg/g) and copper (142.86 mg/g). Similar Freundlich empirical constants, K, were obtained for cadmium (2.224) and copper (7.925). Ion exchange and surface adsorption might be involved in the adsorption process of cadmium and copper. Desorption experiments showed that CaCl2, NaCl, acetic acid and ultrasonic were not efficient enough to desorb substantial amount of metal ions from the CHAP. The results obtained show that CHAP has a high affinity to cadmium and copper.  相似文献   

9.
Supported Cu(II) polymer catalysts were used for the catalytic oxidation of phenol at 30 degrees C and atmospheric pressure using air and H(2)O(2) as oxidants. Heterogenisation of homogeneous Cu(II) catalysts was achieved by adsorption of Cu(II) salts onto polymeric matrices (poly(4-vinylpyridine), Chitosan). The catalytic active sites were represented by Cu(II) ions and showed to conserve their oxidative activity in heterogeneous catalysis as well as in homogeneous systems. The catalytic deactivation was evaluated by quantifying released Cu(II) ions in solution during oxidation, from where Cu-PVP(25) showed the best leaching levels no more than 5 mg L(-1). Results also indicated that Cu-PVP(25) had a catalytic activity (56% of phenol conversion when initial Cu(II) catalytic content was 200 mg L(Reaction)(-1)) comparable to that of commercial catalysts (59% of phenol conversion). Finally, the balance between activity and copper leaching was better represented by Cu-PVP(25) due to the heterogeneous catalytic activity had 86% performance in the heterogeneous phase, and the rest on the homogeneous phase, while Cu-PVP(2) had 59% and CuO/gamma-Al(2)O(3) 68%.  相似文献   

10.
The present study deals with pre-treatment of wastewater sludge by ultrasonic waves at frequency of 20 kHz using fully automated lab-scale ultrasonication equipment. Different wastewater sludge solids concentrations, ultrasonication intensities, and exposure times of pre-treatment were investigated for the optimization of ultrasonication treatment process. The parameters of pre-treatment process were optimized by using response surface methodology. A 2(3) central composite design was performed for optimization. The screening experiment step comprised steepest ascent methodology to determine optimal domain. The effect of ultrasonication treatment was assessed in terms of increase in soluble solids and the biodegradability of the wastewater sludge. In addition, rheological parameter of wastewater sludge, namely, viscosity was also measured to ascertain the suitability of wastewater sludge for conventional treatment processes as well as submerged fermentation, a major step for the production of value-added products from sludge. It was observed that the ultrasonication intensity and pre-treatment exposure time significantly affected the efficiency of the ultrasonication process followed by the solids concentration. The optimal conditions of ultrasonic pre-treatment were 0.75 W/cm(2) ultrasonication intensity, 60 min, and 23 g/L total solids concentration. The increases in soluble chemical oxygen demand and biodegradability, by aerobic sludge digestion process, in terms of total solids consumption increased by 45.5% and 56%, respectively. The flowability of ultrasonicated sludge in terms of viscosity showed exponential behaviour at different total solids concentrations, and pseudoplastic and thixotropic behaviour similar to raw sludge. Nevertheless, the magnitude of viscosity values of ultrasonicated sludge was always lower than the raw sludge.  相似文献   

11.
Effect of humic substances on Cu(II) solubility in kaolin-sand soil   总被引:4,自引:0,他引:4  
The type and amount of organic matter present in industrially contaminated soils will influence the risk they pose. Previous studies have shown the importance of humic and fulvic acids (FAs) (important components of soil organic matter) in increasing the solubility of toxic metals but were not carried out using toxic metal levels and the pH range typical of industrially contaminated soils. This study investigated the influence of three humic substances (HSs: humates, fulvates and humins) on the solubility of copper(II) ions in kaolinitic soil spiked with Cu at levels representative of industrially contaminated soil. Humates, fulvates and humin were extracted from Irish moss peat, and controlled pH batch leaching tests were conducted on an artificial kaolin-sand soil that was spiked with each. Further leaching tests were conducted on soil spiked with each HS and copper nitrate. Dissolved organic contents were determined by titration and total and free aqueous copper concentrations in the leachate were measured using AAS and ion selective electrode (ISE) potentiometry respectively (dissolved complexed copper levels were determined by difference). It was found that humates and fulvates are partially sorbed by the soil, probably by chemisorption on positively charged gibbsite (Al-hydroxide) sites in the kaolinite. The addition of 340 mg/kg Cu(II) ions did not significantly affect the amount of humate or fulvate sorbed. Dissolved humates and fulvates form soluble complexes with copper over the pH range 3-11. However, in the presence of kaolinite, soluble copper humates and fulvates are unable to compete with the kaolinite for Cu ions at pH 6-7. Above pH 8, humate and fulvate complexes are the only forms of dissolved Cu. Humin is largely insoluble and has little effect on Cu mobility between pH 2 and 12. The implication of this study is that measurement of total soil organic content and water leaching tests should be a standard part of contaminated site investigation.  相似文献   

12.
A batch upflow fixed-bed sulphate-reducing bioreactor has been set up and monitored for the treatment of synthetic solutions containing divalent iron (100mg/L and 200mg/L), zinc (100mg/L and 200mg/L), copper (100mg/L and 200mg/L), nickel (100mg/L and 200mg/L) and sulphate (1700 mg/L and 2130 mg/L) at initial pH 3-3.5, using ethanol as the sole electron donor. The reactor has been operated at the theoretical stoichiometric ethanol/sulphate ratio. Complete oxidation of ethanol has been achieved through complete oxidation of the intermediately, microbially produced acetate. This is mainly attributed to the presence of Desulfobacter postgatei species which dominated the sulphate-reducing community in the reactor. The reduction of sulphate was limited to about 85%. Quantitative precipitation of the soluble metal ions has been achieved. XRD and SEM-EDS analyses performed on samples of the produced sludge showed poorly crystalline phases of marcasite, covellite and wurtzite as well as several mixed metal sulphides.  相似文献   

13.
采用交流阻抗法和极化曲线法,研究了两种环境友好型水处理药剂聚冬天氨酸和钨酸钠的单一配方以及复配对3%NaCl溶液中铜的缓蚀效果.研究表明:聚冬天氨酸和钨酸钠各自的单一配方对于铜均具有一定的缓蚀效果,其中聚冬天氨酸在浓度为40 mg/L时效果最佳,钨酸钠在浓度为350 mg/L时效果最佳.当二者复配使用时,在缓蚀剂总浓度为40 mg/L时,聚冬天氨酸与钨酸钠配比为1:5时效果最佳,具有协同效应;在缓蚀剂总浓度为350 mg/L时,聚冬天氨酸与钨酸钠配比为7:1,5:1,3:1,1:5,1:7时具有明显的缓蚀效果,且具有协同效应,其中以配比7:1为最佳.  相似文献   

14.
In this paper, a laboratory-scale process which combined electrolysis (EL) and electrodialysis (ED) was developed to treat copper-containing wastewater. The feasibility of such process for copper recovery as well as water reuse was determined. Effects of three operating parameters, voltage, initial Cu(2+) concentration and water flux on the recovery of copper and water were investigated and optimized. The results showed that about 82% of copper could be recovered from high concentration wastewater (HCW, >400mg/L) by EL, at the optimal conditions of voltage 2.5 V/cm and water flux 4 L/h; while 50% of diluted water could be recycled from low concentration wastewater (LCW, <200mg/L) by ED, at the optimal conditions of voltage 40 V and water flux 4 L/h. However, because of the limitation of energy consumption (EC), LCW for EL and HCW for ED could not be treated effectively, and the effluent water of EL and concentrated water of ED should be further treated before discharged. Therefore, the combination process of EL and ED was developed to realize the recovery of copper and water simultaneously from both HCW and LCW. The results of the EL-ED process showed that almost 99.5% of copper and 100% of water could be recovered, with the energy consumption of EL ≈ 3 kW h/kg and ED ≈ 2 kW h/m(3). According to SEM and EDX analysis, the purity of recovered copper was as high as 97.9%.  相似文献   

15.
Distribution of heavy metals in Lakes Doirani and Kerkini, Northern Greece   总被引:2,自引:0,他引:2  
The distribution of heavy metals in two lakes of high ecological significance, Doirani and Kerkini, located in Northern Greece was studied. Eight metals (Cd, Cr, Cu, Fe, Mn, Ni, Pb and Zn) were determined in water, total suspended solids, fine and coarse sediments. Moreover, the modified BCR fractionation scheme was employed in sediments and suspended solids to determine soluble, oxidisable, reducible and residual fractions of metals. The Lake Doirani presents higher metal concentrations in aqueous phase than Lake Kerkini; Cd, Cu, Ni, Pb and Zn are above the chronic freshwater quality criteria for aquatic life. In both lakes, Fe and Mn are the most abundant elements in total suspended solids whereas Cd the less abundant. The Lake Kerkini exhibits higher concentrations of all the examined metals in sediments comparing to the Lake Doirani, however the concentrations are lower than the sediment quality guidelines. Cd in sediments is mainly in soluble fraction, Pb and Cu exhibit significant oxidisable fractions whereas, Cr and Fe associated mainly with residual fraction.  相似文献   

16.
Chemically enhanced primary treatment (CEPT) is a technology that uses coagulants for enhanced pollutants removal at the primary stage of the wastewater treatment. This paper presents the detailed characteristics of tannery wastewater. It also explains effectiveness of CEPT in removing pollutants from tannery wastewater using various metal salts. The results of this study demonstrated that the tannery effluent had high concentrations of organic matter, solids, sulfates, sulfides and chromium. Alum, ferric chloride and ferric sulfate were tested as coagulants using jar test apparatus. Alum was found to be the suitable coagulant for tannery wastewater in a dose range of 200-240 mg/L as Al(2)(SO(4))(3). With alum, percentage removal efficiency for turbidity, total suspended solids (TSS), chemical oxygen demand (COD) and chromium was found to be 98.7-99.8, 94.3-97.1, 53.3-60.9, and 98.9-99.7%, respectively. National effluent quality standards for total suspended solids and chromium were met after CEPT. However, COD content was high, emphasizing the need of secondary treatment for the tannery effluent.  相似文献   

17.
Batch adsorption experiments were carried out for the removal of copper from its aqueous solution using Ulva fasciata sp. a marine green algae as adsorbent. The adsorption of Cu(II) by Ulva fasciata sp. was investigated as a function of pH, contact time, initial Cu(II) and adsorbent concentrations and adsorbent size. About 0.1 g of Ulva fasciata sp. was found to be enough to remove 95% of 20 mg/L copper from 30 mL aqueous solution in 20 min. The optimum pH value was found to be 5. The dynamic data fitted to the pseudo-second order kinetic model. The Langmuir and Freundlich adsorption models were applied to describe the equilibrium isotherms and the isotherm constants were determined. The experimental adsorption data were fitted to the Langmuir adsorption model. The maximum adsorption capacity was 26.88 mg/g. The applicability of Lagergren kinetic model was also investigated.  相似文献   

18.
Biological reduction of sulfate to sulfide using sulfate reducing bacteria (SRB) was investigated. A respirometer was used to study the sulfide toxicity in the systems fed glucose, the results showed that sulfide would start to inhibit methanogens when the dissolved sulfide and total sulfide concentrations were 276.4 and 304.6 mg/L, respectively. When chemostats were used to study the Monod kinetic coefficients, Y, kd, Ks, and k were 0.36 mg VSS (volatile suspended solids) using SRB/mg SO4-S, 0.05/day, 147.30 mg SO4-S/L, and 6.50 mg SO4-S/mg VSS using SRB-d, respectively. Using pure cultural techniques, SRB were found to be 29.45% of the VSS in the chemostats. Sulfate removal using an upflow anaerobic filter packed with immobilized cells was also investigated. Under sulfate loading rates of 0.2 and 0.4 g SO4-S/L day, and a hydraulic retention time (HRT) of 2 days, a sulfate removal efficiency greater than 93% could be achieved. When the filter was operated under COD (chemical oxygen demand)/S from 10/1 to 5/1 and HRTs of 2, 1 and 0.5 days, sulfate removal efficiency was between 98.1 and 70.9%. It is believed that protection by the immobilized cell structure caused the microbial cells in the filter to tolerate higher dissolved sulfide (447.8 mg/L) and total sulfide (940.3 mg/L) levels, allowing a much higher biomass concentration (13.2-13.5 g VSS/L) to be reached.  相似文献   

19.
吉宁  王瑞  曹森  马立志 《包装工程》2021,42(9):56-63
目的研究1-MCP结合臭氧处理对水晶葡萄低温贮藏期间品质的影响,以期为延长水晶葡萄采后保鲜期提供依据。方法用浓度为1μL/L的1-MCP先熏蒸2 h,随后使用4个不同浓度的臭氧对其处理2 h,处理完后贮藏于温度为(1±0.3)℃、相对湿度为(90±5)%的保鲜库内。结果经1-MCP结合浓度为4 mg/L的臭氧处理贮藏到60 d时,腐烂率(20.43%)、褐变率(40.44%)、脱粒率(33.43%)均低于其余各处理组,可溶性固形物(13.36%)、可滴定酸(0.48%)含量均高于其余各组,维生素C(82.71 mg/kg)、多酚(398.62 mg/kg)含量也高于其余各组。结论使用1-MCP熏蒸后,再使用4 mg/L的臭氧进行处理,更有利于维持水晶葡萄贮藏期间的品质。  相似文献   

20.
Clinoptilolite, a natural zeolite, was used for the synthesis of a high surface area clinoptilolite-iron oxide system, in order to be used for the removal of Cu2+ ions from drinking water samples. The solid system was obtained by adding natural clinoptilolite in an iron nitrate solution under strongly basic conditions. The Clin-Fe system has specific surface area equal to 151 m2 g(-1) and is fully iron exchanged (Fe/Al=1.23). Batch adsorption experiments were carried out to determine the effectiveness of the Clin and the Clin-Fe system in removal of copper from drinking water. Adsorption experiments were conducted by mixing 1.00 g of each of the substrates with certain volume of water samples contaminated with 10 different Cu concentrations (from 3.15x10(-5) to 315x10(-2) M or from 2.00 to 2000 ppm Cu). For our experimental conditions, the maximum adsorbed Cu amount on Clin was 13.6 mg g(-1) whereas on the Clin-Fe system was 37.5 mg g(-1). The main factors that contribute to different adsorption capacities of the two solids are due to new surface species and negative charge of the Clin-Fe system. In addition, the release of counterbalanced ions (i.e. Ca2+, Mg2+, Na+ and K+) was examined, as well as the dissolution of framework Si and Al. It was found that for the most of the samples the Clin-Fe system releases lower concentrations of Ca, Mg and Na and higher concentrations of K than Clin, while the dissolution of Si/Al was limited. Changes in the composition of water samples, as well as in their pH and conductivities values were reported and explained.  相似文献   

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