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341.
锌铜复合氧化物光催化降解甲基对硫磷 总被引:3,自引:0,他引:3
采用共沉淀法制了锌铅复合氧化物光催化剂,并通过其光催化降解甲基对硫磷农药。结果发现,锌铜复合氧化物能有效地利用空气中的氧,使甲基对硫磷快速光降解,其中ZnO是一个较好的氧化物半导体。 相似文献
342.
污水零排放可以最大限度地减少工业废水对环境的污染,减少水资源的浪费。企业通过环境论证和风险分析,不断完善工业废水的排水控制和污染物治理措施,制定科学实用的应急预案,实现废水零排放,从而使水资源充分得到利用,环境安全更可靠。 相似文献
343.
白腐真菌对染料的脱色与降解 总被引:4,自引:0,他引:4
利用白腐真菌对染料脱色和降解的过程机理及影响因素进行了较为系统的介绍,结果认为,白腐真菌对染料的脱色及降解作用可能主要是由于其在次生代谢阶段产生的木质素过氧化酶LIPs和锰过氧化酶MnPs所致。在培养基中加入黎芦醇等能够显著提高LIPs的产生;富氮培养基会抑制LIPs的生成;缓冲液的选择对维持适宜的pH值和菌丝的形态有一定作用,从而影响其脱色效果;富氧环境是一切白腐真菌对染料进行脱色和降解的必要条件;适度的搅拌混合有利于反应时的物质之间传递;一般地,在培养时间达到3d以后白腐真菌才能达到较高的脱色与降解活性。染料分子大小和结构及其基团的位置对脱色及降解效果有明显影响。使用特殊填料来提高处理系统中的生物量以克服真菌生长速度相对较慢,提高处理能力是该技术今后的研究重点。 相似文献
344.
在超临界水中聚苯乙烯泡沫的降解 总被引:31,自引:0,他引:31
本文研究了聚苯乙烯泡沫在超临界水中的降解反应。考查了反应时间、温度和添加剂对降解反应的影响.实验结果显示,超临界水能将聚苯乙烯泡沫降解为油状产物。在反应的前30分钟内,分子量降低了约98%;提高温度对反应时间短的或无添加剂的配方有明显的促降解作用;添加剂用量在5%左右时,能得到更大的效率成本比。 相似文献
345.
半导体光催化降解分散染料溶液的研究 总被引:26,自引:0,他引:26
以TiO2半导体为光催化剂对溶液中的分散染料的降解进行了研究,在通空气的条件下,光照50分钟可使50mg/L的染料溶液完全色,COD.r作文经可达70%以上。研究中探讨了通空气、溶液的PH值,光距TiO2重复使用等因素对光催化降解的影响。 相似文献
346.
阐述了在土地处理制革废水过程中污染物的去除机理。其主要方式是物理、化学和生物的去除,并给出在一定土壤状况下去除机理的综合模型。 相似文献
347.
348.
AbstractChlorinated volatile organic compounds are common constituents observed at many contaminated groundwater sites. Common industry practice has been to measure these constituents in groundwater on a weight concentration basis (e.g. µg/l, mg/l). This paper highlights the use of molar-based concentrations, especially in the case of parent-daughter degradation sequences commonly observed with the chloroethene, chloroethane, and chloromethane families of compounds. Converting to molar-based concentrations provides the practitioner greater insight into groundwater plume behavior including better evaluation of degradation processes, remedial progress, possible commingling, and/or sourcing. For example, this paper provides a tank analogy to evaluate whether the commonly misinterpreted observation of “DCE-stall” may be occurring at a site. Multiple examples of the benefits of using molar-based concentration data are also summarized in a project case study presented herein. As demonstrated in this paper, molarity does provide better clarity and can be a powerful evaluation tool in the groundwater practitioner’s toolbox. 相似文献
349.
Summary. HPLC analysis of secondary metabolites represents an efficient tool for the studying of plant chemical diversity under different
aspects: chemotaxonomy, metabolomics, adaptative responses to ecological factors, etc. Statistical analyses of HPLC databases,
e.g. correlation analysis between HPLC peaks, can reliably provide information on the similarity/dissimilarity degrees between
the chemical compounds. The similarities, corresponding to positive correlations, can be interpreted in terms of analogies
between chemical structures, synchronic metabolisms or co-evolution of two compounds under certain environment conditions,
etc. . In terms of metabolism, positive correlations can translate precursor-product relationships between compounds; negative
correlations can be indicative of competitive processes between two compounds for a common precursor(s), enzyme(s) or substrate(s).
Furthermore, the correlation analysis under a metabolic aspect can help to understand the biochemical origins of an observed
polymorphism in a plant species. With the aim of showing this, we present a new approach based on a simplex mixture design,
Scheffé matrix, which provides a correlation network making it possible to graphically visualise and to numerically model
the metabolic trends between HPLC peaks. The principle of the approach consisted in mixing individual HPLC profiles representative
of different phenotypes, then from a complete mixture set, a series of average profiles were calculated to provide a new database
with a small variability. Several iterations of the mixture design provided a smoothed final database from which the relationships
between the secondary metabolites were graphically and numerically analysed. These relationships were scale-dependent, namely
either deterministic or systematic: the first consisted of a monotonic global trend covering the whole variation field of
each metabolites’ pair; the second consisted of repetitive monotonic variations which gradually attenuated or intensified
along a global trend. This new metabolomic approach was illustrated from 404 individual plants of Astragalus caprinus (Leguminoseae), belonging to four chemical phenotypes (chemotypes) on the basis of flavonoids analysed in their leaves. After
smoothing, the relationships between flavonoids were numerically fitted using linear or polynomial models; therefore the co-response
coefficients were easily interpreted in terms of metabolic affinities or competitions between flavonoids which would be responsible
of the observed chemical polymorphism (the four chemotypes). The statistical validation of the approach was carried out by
comparing Pearson correlations to Spearman correlations calculated from the smoothed and the crude HPLC database, respectively.
Moreover, the signs of the smoothed relationships were finely supported by analogies and differences between the chemical
structures of flavonoids, leading to fluent interpretation in relation to the pathway architecture. 相似文献
350.
V. A. Sakkas A. Dimou K. Pitarakis G. Mantis T. Albanis 《Environmental Chemistry Letters》2005,3(2):57-61
The photocatalytic degradation of diazinon was studied over TiO2 catalysts. The kinetics obtained demonstrated that powder titania (t1/2 = 9.7 min) was more efficient compared to pure titania thin film catalysts (t1/2 = 29.4 min). Mineralization of organic carbon to CO2 after 360 min of irradiation was found to be 75% while heteroatoms (P, S, N) were mineralized into phosphate, sulfate and
nitrate ions, respectively. A microtox test was performed to evaluate the toxicity of solutions treated by catalysts. Illumination
of diazinon in the presence of TiO2 gave rise to several intermediates that have been identified by means of solid phase extraction and gas chromatography-mass
spectrometry, while a simple degradation pathway is proposed. 相似文献