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991.
用荧光光谱研究腐殖酸与金属离子Al^3+的配合作用 总被引:2,自引:1,他引:2
用同步荧光法对两种来源不同的腐殖酸与金属离子Al^3+的配合作用进行了研究,采用非线性回归分析,用荧光强度变化数据,拟合出金属配合物(1:1)的条件稳定常数K,在配合滴定进行的同时,探讨了溶液在500nm处的瑞利散射现象。 相似文献
992.
Heather N. Koopman 《Marine Biology》2007,151(1):277-291
To explore ecological, phylogenetic, and developmental factors affecting the structure of blubber in Odontocetes (toothed
whales), lipid composition of this specialized adipose tissue was determined in 260 specimens (30 species representing all
families except the river dolphins), most of which were collected between 1995 and 2005, from all over the world. In most
odontocetes, blubber contained primarily triacylglycerols; the blubber of beaked and sperm whales was dominated by wax esters
(WE), exhibiting ontogenetic patterns of deposition. WEs may represent an adaptation to deep diving for marine mammals that
do not rely on blubber for stored energy. Fatty acid (FA) composition was stratified through blubber depth, with higher concentrations
of dietary FA in the inner and endogenous FA in the outer layers of the blubber. Stratification can be considered a characteristic
feature of odontocetes, and is likely the result of differential metabolism through the blubber. Small body size appears to
constrain blubber lipid content to be high. Thermal habitat also represents an important selective pressure for blubber composition.
Species inhabiting colder waters exhibited both higher lipid content and increased FA stratification in blubber, compared
to species from warm/tropical habitats. The isolation of mobilization to inner blubber may permit metabolic enzymes to function
without limitation by lower temperatures. The variation in composition and distribution of blubber lipids in odontocetes suggests
that different species may have evolved slightly diverse arrays of secondary functions for this specialized tissue as adaptations
for specific ecological niches.
Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users. 相似文献
993.
农药杀虫双的代谢毒理学研究 总被引:5,自引:0,他引:5
杀虫双为我国首创的农用杀虫剂,属沙蚕毒互类农药,以同位素示踪法和现代化学分离技术相结合的手段,进行了杀虫双在动物体内吸收、分布、排泄、转化、动力学以及代谢产物的分离鉴定等一系列研究,杀虫双进入体现人首先转化成沙蚕毒素,胃是主要转化部位,进入体循环,在血液中主要存在于红细胞中,且吸收、分布、排泄迅速,不易蓄积,杀虫双与沙蚕毒素、巴丹、易卫杀的最终代谢产物轮相符,杀虫双中毒死者血液中分离鉴定出沙蚕毒素 相似文献
994.
995.
996.
Sorption of tylosin and sulfamethazine on solid humic acid 总被引:3,自引:0,他引:3
Tylosin(TYL) and sulfamethazine(SMT) are ionizable and polar antimicrobial compounds,which have seeped into the environment in substantial amounts via fertilizing land with manure or sewage. Sorption of TYL and SMT onto humic acid(HA) may affect their environmental fate. In this study, the sorption of TYL and SMT on HA at different conditions(pH, ionic strength) was investigated. All sorption isotherms fitted well to the Henry and Freundlich models and they were highly nonlinear with values of n between 0.5 and 0.8, which suggested that the HA had high heterogeneity. The sorption of TYL and SMT on HA decreased with increasing p H(2.0–7.5), implying that the primary sorption mechanism could be due to cation exchange interactions between TYL~+/SMT~+ species and the functional groups of HA.Increasing ionic strength resulted in a considerable reduction in the K_d values of TYL and SMT,hinting that interactions between H bonds and π–π EDA might be an important factor in the sorption of TYL and SMT on HA. Results of Fourier transform infrared(FT-IR) and ~13C-nuclear magnetic resonance(NMR) analysis further demonstrated that carboxyl groups and O-alkyl structures in the HA could interact with TYL and SMT via ionic interactions and H bonds,respectively. Overall, this work gives new insights into the mechanisms of sorption of TYL and SMT on HA and hence aids us in assessing the environmental risk of TYL and SMT under diverse conditions. 相似文献
997.
采用农药三唑醇生产过程中产生的含铝酸性废水为原料,合成了聚合硫酸铝(PAS)液体混凝剂,并用于厂区污水站好氧池出水的混凝处理。考察了碱化剂用量、聚合温度、聚合时间等合成条件及PAS加入量、混凝pH等混凝条件对混凝效果的影响,并比较了PAS与商售聚合氯化铝(PAC)的混凝效果。实验结果表明:在n(碱化剂)∶n(硫酸铝)为2.1∶1、聚合温度为80℃、聚合时间为60 min的条件下,所得PAS液体混凝剂产品的w(Al2O3)为7.8%~9.0%,盐基度为45%~60%,pH为3.5~4.0,产量为0.75 t/t(以废水计);在PAS加入量为2.0 m L/L、混凝pH为10.0时,COD和SS的去除率则分别达到14.6%和83.0%;该PAS可替代厂区常规使用的商售PAC,日节约废水处理成本5 922元。 相似文献
998.
Thermal treatments of five different types of non-ferrous metallurgical wastes, under a controlled atmosphere, were carried out at temperatures lower than 800°C for the separation of their toxic compounds and the concentration of valuable metals in the treatments residues. The best results were obtained by the treatments in air or hydrogen, or both successively. Simple treatments, using air or hydrogen, of three samples allowed the elimination of more than 95% of their toxic elements and almost doubled their valuable metals concentration. For the rest of the samples, a combined treatment was necessary for their efficient decontamination. In this case, the valuable metals content in the treatment's residue was increased to a reasonable value. Most of the solids issuing from these treatments can be recycled in current non-ferrous metallurgical processes. 相似文献
999.
The effects of exogenous salicylic acid on growth and H2O2-metabolizing enzymes in rice seedlings under lead stress 总被引:4,自引:0,他引:4
Salicylic acid (SA) was an essential component of the plant resistance to pathogens and also plays an important role in mediating plant response to some abiotic stress. The possible effects of SA on the growth and H2O2-metabolizing enzymes in rice seedlings under lead stress were studied. When rice seedlings grown in nutrient solution containing Pb^2+ (0, 0.05, 0.15, 0.25 mmol/L) for 18 d, the plant biomass as well as the chlorophyll content of leaves decreased with increasing Pb concentration. The pre-treatment with SA (treated with 0.1 mmol/L SA for 48 h before Pb stress) partially protected seedlings from Pb toxicity. The chlorophyll contents were significant higher in leaves of Pb-exposed with SA pre-treatment seedlings than in Pb-exposed plants at the same Pb intensity. SA pre-treated alone could significantly increase the length of shoot and root of seedlings but the vigour difference was not marked under long-term exposure to Pb toxicity. SA pre-treated influence the H2O2 level in leaves of seedlings by up-regulating the activity of superoxide dismutase (SOD), repressing the activity of catalase (CAT) and ascorbate peroxidase (APX) depending on the concentrations of Pb^2+ in the growth medium. The results supported the conclusion that SA played a positive role in rice seedlings against Pb toxicity. 相似文献
1000.