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排序方式: 共有494条查询结果,搜索用时 31 毫秒
1.
通过中试考察了改性蜂窝陶瓷催化臭氧氧化(催化氧化)—活性炭过滤的净水效果,并与臭氧—活性炭工艺进行比较。试验条件下蜂窝陶瓷催化剂在静态和动态条件下均不会促进气体向水中的传质;静态条件下催化氧化对水中有机物的去除效率比臭氧单独氧化高;动态试验中,催化氧化对UV254的去除率高于臭氧氧化,但对TOC的去除没有优势,与臭氧氧化相比催化氧化有利于后续活性炭对有机物的去除。GC/MS测定表明,催化氧化及其后续活性炭出水中半挥发性有机物种类分别比臭氧单独氧化少9%和32%。经Ames试验发现,两种氧化及其后续活性炭处理后水的致突变活性均有微小增加。 相似文献
2.
Yi‐Hung Chen Ching‐Yuan Chang Wei‐Ling Su Chun‐Yu Chiu Yue‐Hwa Yu Pen‐Chi Chiang Chiung‐Fen Chang Je‐Lueng Shie Chyow‐San Chiou Sally IM Chiang 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(1):68-75
This study investigates the ozonation of CI Reactive Black 5 (RB5) by using the rotating packed bed (RPB) and completely stirred tank reactor (CSTR) as ozone contactors. The RPB, which provides high gravitational force by adjusting the rotational speed, was employed as a novel ozone contactor. The same ozone dosage was separately introduced into either the RPB or the CSTR for the investigation, while the experimental solution was continuously circulated within the apparatus consisting of the RPB and CSTR. The decolorization and mineralization efficiencies of RB5 in the course of ozonation are compared for these two methods. Moreover, the dissolved and off‐gas ozone concentrations were simultaneously monitored for the further analysis. As a result, the ozone mass transfer rate per unit volume of the RPB was significantly higher because of its higher mass transfer coefficient and gas–liquid concentration driving force. Furthermore, ozonation kinetics was found to be independent of the gravitational magnitude of an ozone gas–liquid contactor. Therefore, the results suggest employing RPBs as ozone‐contacting devices with the advantage of volume reduction. The experimental results, which can be used for further modeling of the ozonation process in the RPB, also show the requirement of correct design for the RPB. Consequently, the present study is useful for the understanding of practical application of RPBs. Copyright © 2004 Society of Chemical Industry 相似文献
3.
臭氧氧化-光催化降解水中的五氯酚 总被引:5,自引:1,他引:4
利用臭氧氧化-光催化技术降解水中的有机污染物五氯酚(PCP)。对比了紫外光照射、臭氧氧化、光催化、臭氧氧化-光催化4种方法降解PCP的情况。考察了臭氧氧化-光催化体系中臭氧流量、臭氧产量、PCP初始质量浓度、pH和CO23-等因素对PCP降解率的影响。实验结果表明,臭氧氧化-光催化法比单独使用紫外光照射、臭氧氧化、光催化法更能有效的去除PCP;增加臭氧流量和臭氧产量有利于提高PCP的降解率;降低PCP的初始浓度,PCP的降解率显著提高;pH对PCP的降解效果影响不明显;CO23-的存在显著降低了PCP的降解率。在臭氧氧化-光催化体系中,除臭氧直接氧化降解PCP外,臭氧与TiO2协同作用产生的.OH对PCP的降解也起到了重要作用。 相似文献
4.
ABSTRACT: This study determined the efficacy and safety of ozonation in degrading aflatoxin in corn. Ozonation (10 to 12 wt%) reduced aflatoxin levels by 92% and no reversion to the parent compound was observed. Ozonation had minimal effect on fatty acids of uncontaminated corn, but had significant effect on fatty acids of contaminated corn. Crude extracts showed no mutagenic potential in the Ames assay using TA98 and TA100. Clean-up using hexane increased their mutagenic potentials. Clean-up using Mycosep columns increased the mutagenic potentials 18 to 617%. Hexane extracts from ozone-treated contaminated corn had lower inhibitory effect. This suggested that a fat-soluble mutagen is being formed or natural inhibitors of mutagenicity are being destroyed. 相似文献
5.
Large amounts of water containing-ammonium nitrogen(NH4+-N)have attracted increasing attention.Catalytic ozonation technology,involving the generation of hydroxyl radical(OH)with strong oxidation ability,was originally utilized to degrade organic-containing wastewater.In this paper,Ce/MnOx composite metal oxide catalysts prepared with different preparation conditions were used to degrade wastewater containing inorganic pollutant(NH4+-N).The as-prepared catalyst features were characterized using X-ray diffraction(XRD),Brunauer-Emmett-Teller method(BET),scanning electron microscopy(SEM),energy dispersive X-ray spectroscopy(EDS),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and H2-temperature programmed reduction(H2-TPR)techniques.The results show that the catalyst,prepared by conditions with precipitant Na2CO3 and Ce/Mn molar ratio 1:2 calcined at 400℃for 3 h in pH 11.0,displays the optimal performance,with the removal rate of NH4+-N and selectivity to gaseous nitrogen,88.14 wt%and 53.67 wt%,respectively.The effects of several operating factors including solution pH,initial NH4+-N concentrations and scavengers were evaluated.In addition,XRD patterns of catalyst with the best performance and the comparative study on decontamination of NH4+-N by various processes(O3,catalyst and catalyst/O3)show that the primary metal oxides are CeO2 and MnO2 in Ce/MnOx composite metal oxide catalysts,which have a synergistic effect on the catalytic ozonation of NH4+-N,and the new phase MnO2 plays a great role.After 5 consecutive use cycles,the degradation efficiency is declined slightly,and can still achieve better than 70 wt%over 1 h reaction.Additionally,the application of catalytic ozonation for actual wastewater on the removal rate of NH4+-N was investigated.Possible mechanism and degradation pathway of NH4+-N were also proposed.In a word,the application of CeO2-MnO2 composite metal oxide catalysts in catalytic ozonation can be regarded as an effective,feasible and promising method for the treatment of NH4+-N. 相似文献
6.
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8.
In this work, magnesia from natural brucite mineral has been used firstly for catalytic degradation of nitrobenzene and aniline
in presence of ozone. Compared with single ozonation, the catalytic ozonation accelerated markedly the degradation of nitrobenzene
and aniline. The influences of hydroxyl radical scavengers, pH values, and reaction temperatures on degradation were investigated.
It was found that the essential of catalysis was the homogeneous catalysis of hydroxyl ions in water, which accelerated the
generation of hydroxyl radicals. As a catalyst, magnesia from natural brucite has supplied an economical and feasible choice
for catalytic ozonation of nitrobenzene and aniline in industrial wastewater. 相似文献
9.
P.M. lvarez F.J. Beltrn J.P. Pocostales F.J. Masa 《Applied catalysis. B, Environmental》2007,72(3-4):322-330
A series of Co/Al2O3 catalysts were prepared by the incipient wetness impregnation method using γ-Al2O3 support and (CH3COO)2Co·4H2O solutions, followed by calcination at 500–800 °C. Characterization of catalysts was accomplished by several techniques such as thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), physisorption of nitrogen, mercury and helium-based pycnometries, Fourier transform-infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and pH of zero charge (PZC). Impregnation of support produced a moderate decrease of its surface area and pore volume and also led to minor changes of its PZC. Depending on preparation conditions (i.e., calcination atmosphere and temperature and metal loading), one or more of the following Co-containing compounds were identified: CoO, Co3O4 and CoAl2O4. The support and prepared Co/Al2O3 catalysts were tested to catalyze the ozonation of aqueous pyruvic acid at pH 2.5. Pyruvic acid was shown refractory towards single ozonation but the use of γ-Al2O3 and Co/Al2O3 catalysts resulted in 56–96% pyruvic acid conversion and 41–78% decrease in DOC after 2 h of ozonation of phosphate-buffered solutions. In the absence of the buffer, conversion rate was enhanced likely as a result of pH increase during the course of the process thus giving rise to the indirect way of ozonation through hydroxyl radicals. Acetic acid was found as the main by-product of pyruvic acid ozonation. Depending on the catalyst used, yield of acetic acid varied from 32 to 49%, values noticeably lower that that obtained from the control non-catalytic ozonation experiment (73%). Differences in catalytic activity amongst the various Co/Al2O3 catalysts investigated were attributed to the different Co active phases deposited on the γ-Al2O3 surface. The following sequence of increasing activity can be inferred from experimental results: CoO, CoAl2O4 and Co3O4. All the Co/Al2O3 catalysts prepared showed good stability as the percentage of cobalt leached out was rather low. 相似文献
10.
M Mahbubul Hassan Christopher J Hawkyard 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2002,77(7):834-841
Combined oxidation with ozone and Fenton's reagent (‘Fentozone’ process) for decolourisation of aqueous dyes was studied and compared with traditional Fenton's reagent. Although the ‘Fentozone’ process was found to be effective at a wide range of pH values, the maximum colour removal was achieved at pH 4. The effect of pre‐ozonation on colour removal efficiency of aqueous dyestuffs in the subsequent treatment with Fenton's reagent was investigated. The reaction kinetics using water‐soluble acid and reactive dyes were also studied. Our experimental results show that pre‐ozonation can considerably accelerate decomposition of dyestuffs in the subsequent treatment with Fenton's reagent. Different concentrations of ferrous sulfate were used to investigate their influences on the removal of colour. The rate of reaction increased with increasing doses of ferrous sulfate. © 2002 Society of Chemical Industry 相似文献