首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 203 毫秒
1.
蔓茎堇菜细胞悬浮培养的研究   总被引:5,自引:0,他引:5  
对蔓茎堇菜细胞悬浮培养的条件进行了选择,并测定悬浮培养的生长动态。结果表明:蔓茎堇菜细胞悬浮培养的最适接种量为2.0~3.5g(50mL);最适培养基为MS+2.0mg/L2,4-D+1.0mg/L ZT+300mg/L LH+200g/L蔗糖(或葡萄糖),pH5.8;细胞悬浮培养一个周期过程中细胞数目增长的动态基本上是一条S型曲线,对数生长期明显;细胞鲜重(mFW)和细胞干重(mDW)则与细胞  相似文献   

2.
负载型固体超强酸催化剂上的烷基化反应   总被引:3,自引:0,他引:3  
本文利用Pt/SO^2-4/ZrO2,Pt/WO3/ZrO2负载于大比表面Al2O3固体强酸催化剂,进行异丁烷和丁烯的烷基化反应。  相似文献   

3.
微乳法制备W/O型Fe3O4磁流体及其清除水面浮油模拟研究   总被引:6,自引:0,他引:6  
柴波  张文军  李德忠 《环境化学》2005,24(4):419-422
应用复合乳化剂和助表面活性剂制备出稳定的油包水(W/O)型微乳液,利用拟三元相图和体系电导随组成的变化,探明了一定条件下形成W/O型微乳液的最佳体系,进而利用W/O型微乳液作为“微反应器”合成Fe2O4磁流体,应用TEM对制备的磁流体进行了表征.初步模拟了用磁流体清除水面浮油的实验,获得令人满意的结果。  相似文献   

4.
Fe(Ⅲ)水解过程中无机阴离子的影响作用   总被引:18,自引:5,他引:18  
田宝珍  汤鸿霄 《环境化学》1993,12(5):365-372
本文通过PO^3- 4,F^-,SO^2- 4,Cl^-,NO^- 3和ClO^- 4存在时,0.1mol/1 FeCl3溶液的碱中和曲线的分析对比,说明了用曲线斜率区分滴定曲线为三个区域:(A)自发水解反应;(B)聚合反应;(C)沉淀反应,以及阴离子对中和曲线的影响及其规律,指出阴子子对Fe(Ⅲ)浓度中和反应影响为不同程度的竞争配位,参与聚合及电中和脱稳,使沉淀反应提前等。并与OH^-共同形成F  相似文献   

5.
除草剂2,4-D在土壤中吸附常数的测定   总被引:2,自引:0,他引:2  
曹罡  莫汉宏  安凤春 《环境化学》2001,20(4):362-366
介绍除草剂2,4-D在4种不同有机碳含量、不同pH值的土壤中吸附常数的测定.结果表明,4种土壤对2,4-D的吸附等温线均符合非线形的Freundlich吸附等温式,其有机碳吸附常数的平均值为239.6.2,4-D的吸附常数与土壤有机碳含量呈正相关,土壤的pH值对2,4-D的吸附也有一定的影响.  相似文献   

6.
土壤中结合态苯氧羧酸类除草剂的测定   总被引:9,自引:0,他引:9  
利用超临界CO2流体萃取的方法提取2甲4氯(MCPA),2,4-D和除草醚在三种土壤中的结合残留.结果表明,在培养200d的时间内,MCPA的结合残留量为1.0l-5.12mg·kg-1,占添加总量的2.0-10.1%;2,4-D的结合残留量为0.24-2.65mg·kg-1,占添加总量的0.5-5.3%;除草醚的结合残留量为6.53-19.30mg·kg-1,占添加总邑的12.9—38.2%.农药结合态与游离态含量的比值随时间的延长而增加.  相似文献   

7.
研究了Novozym435脂肪酶在烷基聚葡糖苷形成的W/O微乳液体系中,催化正丁醇与正己酸合成酯的反应动力学.反应初始速率V0与正丁醇(ROH)和正己酸(HA)摩尔浓度的比值(CROH^0/CHA^0)有关,在CROH^0/CHA^0=0.2-17范围内,随CROH^0/CHA^0比值减小,初始速率V0增大,尤其是当CROH^0/CHA^0〈3时,V0迅速增大.其原因可能是醇浓度较高时,醇与酶结合形成的死端复合物在较高浓度酸的作用下分解,重新析出游离态酶所致.脂肪酶加入量、水相介质组成和醇的种类等对反应速率有重要影响.  相似文献   

8.
均匀沉淀法制备纳米TiO2及其在环保方面的应用   总被引:46,自引:0,他引:46  
张汝冰  刘宏英 《环境化学》1999,18(6):579-583
本文以偏钛酸为原料,采用均匀沉淀法制备纳米TiO2,所制得的纳米微晶平均粒径约为8.5nm,并能在700℃保持锐钛矿型晶体结构,当它应用于染料溶液的光催化分解,与MT-150W光催化相比,具有较好的催化活性。同时,我们用Al2O3陶瓷膜回怍纳米TiO2循环再利用,这为纳米TiO2在环保方面的大规模应用创造了条件。  相似文献   

9.
罗孟飞  朱波 《环境化学》1996,15(3):193-198
本文考察了An-Mn,Ag-Co和Ag-Ce复合氧化物上CO,丙酮和吡啶的催化氧化性能,结果表明,双组分Ag-Mn/Al2O3和Ag-Co/Al2O3催化剂的氧化活性均高于单组分Ag/Al2O3.在Ag-Ce/Al2O3催化剂上,CO氧化反应的速率言程可用r=kPo2^mPCO来表示,随着催化剂中氧化铈含量的增加,对氧的反应级数明显下降。  相似文献   

10.
二氧化硫与环己烷的光化学反应   总被引:2,自引:0,他引:2  
杜尧国  郭海忱 《环境化学》1994,13(6):530-535
本文研究了SO2与环己烷在无氧及有氧体系中的光化学反应,观察到了白色烟雾有生成并凝聚,利用GC和GC/MS法确定了部分反应产物-环烯烃、醇、酮、二元酸酯、呋喃衍生物以及硫酸二甲酯等有机化合物,探讨了影响光化学反应的几种因素及反应机理。  相似文献   

11.
The Macrocystis pyrifera (L.) C. Ag. frond is here described in terms of chlorophyll a, fucoxanthin, chlorophyll c and photosynthetic rate. Pigment concentrations increased back from the apical meristem reaching a maximum after 2 to 3 m. Pigment concentrations were then generally constant throughout most of the length of the frond, finally decreasing again in the oldest parts of the frond with the exception of the sporophylls. Pigment ratios remained relatively constant throughout. Maximum net photosynthetic rates on a given frond showed a decrease with tissue age on both an area basis (1040 down to 463 nmol O2 cm-2 h-1) and on a chlorophyll a basis, which was shown as half-saturation constants (quantum irradiance) which dropped on an area basis from 85 mol m-2 sec-1 at 4.5 m above the holdfast to 26 mol m-2 sec-1 at 15.5 m. Young sporophytes transplanted from the sea floor to the surface (12 m) tended to decrease pigment content, while those transplanted to the bottom tended to increase all pigments, but especially fucoxanthin. Photosynthetic rates, however, changed little on a unit area basis. The results of these data are considered in the light of recent work on photosynthetic units, tissue age effects and general adaptations of the M. pyrifera frond to its light environment.  相似文献   

12.
乙草胺和丁草胺的水解及其动力学   总被引:20,自引:1,他引:19  
郑和辉  叶常明 《环境化学》2001,20(2):168-171
本文研究了乙草胺和丁草肢在恒温25℃,pH值为4,7,10蒸馏水和河水中的水解动力学.酰胺类除草剂的水解反应属于一级反应.结果显示乙草胺和丁草胺在蒸馏水和河水中的水解速度差不多,在pH 4水溶液中的水解速度较在pH7和10的速度快,H+有催化水解的作用.乙草胺在pH4,7,10的速率常数分别为5×l0-4d-1,3×10-4d-1,3×10-4d-1.半衰期分别为1386d,23l0d,2310d.丁草胺在pH4,7,10的速率常数分别为 l.1× 10-3d-1,6 × 10-4d-1,6 × 10-4d-1.半衰期分别为 630d,1155d,1155d.  相似文献   

13.
采用HPLC—UV及GC—MS技术鉴定了灭幼脲(Ⅲ)在水相中的表观光解产物,通过分析表观光解反应与暗反应产物的相对含量,确认对氯苯基异氰酸酯和邻氯苯甲酰胺是灭幼脲(Ⅲ)在永相中光解的主要产物。另外,依据反应产物的组成和相对含量,对灭幼脲(Ⅲ)在水相中的光解反应速率常数作了估算。  相似文献   

14.
The roles of copepod sensory systems in the recognition of food were investigated using the Bugwatcher, a video-computer system designed to track and describe quantitatively the swimming patterns of aquatic organisms. The swimming behavior of the copepodPseudocalanus minutus in the presence of phytoplankton is characterized by a decrease in average swimming speed and an increase in pause behaviors compared to its swimming behavior in filtered seawater. Copepods exposed to chemosensory stimulation alone (filtered phytoplankton exudate) exhibited an increase in average swimming speed and an increase in the number of burst swimming behaviors. When exposed to a novel, non-food chemosensory stimulus (morpholine), no change in swimming behavior was observed unless the copepods had been conditioned to this odor in the presence of phytoplankton. Copepods exposed to mechanosensory stimulation alone (plastic spheres) exhibited a decrease in swimming speed and an increase in pause behaviors. When exposed to both forms of stimulation simultaneously (phytoplankton exudate and plastic spheres), a further decrease in swimming speed and increase in pause behaviors occurs, yielding a swimming pattern similar to that found in the presence of phytoplankton. This analysis of swimming pattern indicates that both chemoreception and mechanoreception contribute to the recognition of food inP. minutus.Contribution No. 406 of the US EPA Environmental Research Laboratory; Narragansett, Rhode Island 02882, USA  相似文献   

15.
有机化合物水解的研究方法   总被引:39,自引:1,他引:39  
杨克武  莫汉宏 《环境化学》1994,13(3):206-209
有机化合物在水中的化学降解是其在环境中消失的重要途径之一,本文介绍有机化合物在水中的化学降解的研究方法,并给出研究实例。  相似文献   

16.
A method for the determination of volatile fatty acids (VFA) in coastal marine sediments is presented. Acidified porewater was vacuum distilled to extract the VFA and the distillate was analysed by gas chromatography (Porapak QS column and flame ionization detection). The limit of detection was 2 M in the samples, but was increased tenfold by lyophilization. In the upper 10 cm of the sediments 2–70 nmol acetate cm-3 sediment was found. Uniformly labelled 14C-acetate (0.02 nmol, 10-3 ci) was injected at 1- to 2-cm intervals through silicone-stoppered holes in the tubing of undisturbed sediment cores. Turnover rate constants were determined from semilogrithmic plots of the 14C-acetate radioactivity versus the incubation time. The 14C-acetate was shown to be distributed in at least three sediment pools: a porewater pool, an adsorbed pool which was displaced by excess acetate, and an adsorbed pool which was not displaced by excess acetate. The rate constants ranged from 1.5–13 h-1 in the investigated sediments. The turnover rates of acetate were calculated from the turnover rate constants and the acetate concentrations in the porewater. The rate of acetate turnover calculated from the NH 4 * turnover and the N:C ratio of the sediment organic matter was only 16% of the measured rate of acetate turnover. The apparent overstimation of the acetate turnover was most likely due to an overestimation of the degradable acetate pool. A gel filtration of 14C-acetate-containing porewater showed that the fractions which contained the tracer had only 25% of the total acetate. This implied that a large fraction of the acetate in the porewater was unavailable to the microbes. This was also indicated by the fact that the measured acetate pool in porewater incubated with 14C-acetate did not decrease, when the added 14C-acetate was oxidized.  相似文献   

17.
E. Paasche 《Marine Biology》1973,19(2):117-126
The small marine plankton diatom Thalassiosira pseudonana Hasle and Heimdal (Guillard's clone 3H) was grown in chemostats with silicate as the limiting nutrient. The calculated maximum growth rates were comparable to those previously reported for this species. The silica content of the diatom shells varied with the growth rate. As the growth rate approached zero, there were still measurable quantities of residual reactive silicate in the medium. In one of the two chemostats used, silicate assimilation by the cells was inefficient due to some unknown internal or external factor. In the other chemostat, statistically calculated half-saturation constants of growth were in the range of 0.5 to 0.8 g—at Si/l, depending on which kind of correction was made for residual silicate. Half-saturation constants of steady-state mean silicate uptake per cell and hour, calculated in a similar fashion, were in the range of 1.4 to 2.6 g—at Si/l. These results indicate that the silicate concentrations causing a reduced silicate uptake by this species in nature do not necessarily result in a correspondingly reduced growth rate. Growth in coastal waters is likely to become seriously limited by a shortage of silicate only when most of the silicate originally present has been removed in the course of a diatom bloom.  相似文献   

18.
Mytilus edulis L. were exposed to abrupt (3015 and 1530) and fluctuating (sinusoidal 12 h cycles of 301530) changes in salinity, and the changes in the total osmoconcentration of the haemolymph were recorded. The response of nitrogen metabolism to the altered extracellular osmotic concentrations was investigated in terms of the concentrations of the total NPS (ninhydrin-positive substances) pool and the individual amino acids of the tissues, the concentration of the amino acids of the haemolymph, and the rates of excretion of ammonia and amino acids by whole individuals. The haemolymph became isosmotic with the seawater with abrupt changes in salinity, but with fluctuating salinity was slightly hyperosmotic as the salinity decreased and then slightly hypo-osmotic as the salinity increased. This resulted in a reduction in the extent of the extracellular osmotic change compared to the change in fluctuating salinity to which it was exposed. Total NPS of the tissues decreased with an abrupt decrease in salinity and increased with an abrupt increase in salinity, but a seasonal dependence of the response was indicated. The short-term response of tissue NPS to fluctuating salinity was equivocal, but with long-term exposure the concentration declined. Ammonia and amino acid excretion increased with both an abrupt decrease in salinity and fluctuating salinity and decreased with an abrupt increase in salinity. Haemolymph amino acids increased with an abrupt decrease in salinity. The increased rates of nitrogen excretion accounted for the reductions in the NPS concentrations of the tissues except in the early stages of fluctuating salinity. Taurine, aspartate, threonine, serine, glycine and arginine declined with an abrupt decrease in salinity while alanine and glutamate increased slightly. With an abrupt increase in salinity, alanine and ammonia accumulated in the tissues and then declined while the other amino acids increased slowly over a longer time-course. Similar individual amino acid responses were seen with long-term exposure to fluctuating salinity, except for taurine which did not decrease in concentration. On the basis of the changes in tissue amino acids and ammonia, it is suggested that the alanine dehydrogenase reaction is the primary nitrogen-fixing reaction in marine bivalves such as M. edulis.  相似文献   

19.
Microemulsion polymerization is widely used as a cleaner alternative way to prepare intrinsically conductive polymers. We studied isothermal phase diagrams for microemulsions of the electropolymerizable heterocyclic aromatic oil 3,4-ethylenedioxythiophene (EDOT), aqueous LiClO4 solution and alkyl polyethoxylate. Our specific goal was to assess the effect of LiClO4 salt on the phase behaviour. The phase behaviour was characterized by stepwise titration and microscopic analyses. Here we found that the increase of the concentration of LiClO4 salt shifts the microemulsion region to lower surfactant content.  相似文献   

20.
为明确环氟菌胺的水解动力学规律,采用室内模拟试验方法,探究了温度、p H值、表面活性剂和不同种类水体对环氟菌胺水解的影响。结果表明:随着温度的升高,环氟菌胺的水解速率加快;环氟菌胺在碱性条件下降解最快;十二烷基磺酸钠(sodium dodecyl sulfonate,SDS)抑制环氟菌胺的水解;腐植酸的浓度低于1 mg·L-1时促进环氟菌胺的水解,浓度高于1 mg·L-1时抑制环氟菌胺的水解;环氟菌胺在不同水体中的水解速率顺序为:海水>江水>河水,环氟菌胺在自然条件下的降解速率显著高于室内模拟条件。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号