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 46 毫秒
1.
Large numbers of viable mesophyll protoplasts are isolated from soil-grown plants of Pinellia ternata Breit of Araceae by liquid-solid double layer media with different concentrations of mineral salts, hormones and sugar. The first division of protoplasts takes place in 4—7 days of culture, with a division frequency of 3—8%. Cell clusters of 80—100 cells form in 3 weeks. They are transferred into a liquid medium to culture for a month on a shaker to form calli of 1—2 mm diameter which are transferred onto a solid differentiation agar medium. The calli first proliferate and grow, and differentiate into green buds and small seedlings in 3—4 weeks. The plantlets of Pinellia ternata regenerated from protoplasts grow to a length of 6—10 em in another month. It was found that the shoot-forming process in the calli was to proceed in two ways: one was the organogenesis way, and the other was the embryoid way. Comparisons were made between the effects obtained from the 3 different methods, i.e. component c  相似文献   

2.
The transitions and morphology of a series of main-chain liquid crystalline polymer with X-shaped mesogens were studied by means of DSC,SALS and polarizing microscopy techniques. Aneven-odd effect was observed for samples with different size of the substituents on the mesogenends. The isotropization process was similar to that of main-chain polymers with rod-likemesogens. No crystallization was detected for specimens cooling down from their isotropic meltstate. However two of the samples may crystallize in cooling process directly from the liquidcrystalline state.  相似文献   

3.
This study is concerned with the removal of Staph aureus from water by polyurethaneionomers. All the samples are quaternary ammonium salts which possess a positive chargeon the surface. The ratio of the soft segment to diisocyanate and chain extender is 1:2:1and the ionization degree is 100%. The ionomers strongly capture microbial cells on theirsurfaces in a living state and the hydrophilicity of polymer matrix used in the studyenhanced the affinity of the polymer for bacterial cells. The adhesion of the microorganismto polymer was due mainly to electrostatic interaction between them. The calculation ofthe viable cell count showed that D value for Staph.aureus is not proportional to the nitro-gen concentration. The microorganism capture ability of pyridinium-containing polymer isgreater than that of piperazine based samples.  相似文献   

4.
From 15 strains of Agrobacterium tumefaciens 7 were selected as the best inductors oftumors on soybean and 94 tumor formation genotypes were screened from 1553 varieties andforms of Glycine soja, G. gracilis and G. max. The frequency of tumor formation was 6%.The bacteria-free calluses were obtained. The data of biochemical analysis verify that someof the above-mentioned calluses contained nopaline. This means that Ti-plasmid of Agrobac-terium tumefaciens can be used as a vector for the transfer of nopaline, a marker gene, intogenome of several species of soybean. In the soybean genome the transferred nopaline genewas integrated and expressed. The transformed gene can be stably integrated in the soybeangenome through vegetative propagation.  相似文献   

5.
The adsorption behaviors of 2-naphthalenesulfonic acid and aniline on a conventional macroporous resin Amberlite XAD4 and the other two newly-developed hypercrosslinked resins NDA101 and NDA100 were investigated in a single or binary batch system at 293 K and 313 K,respectively.All the adsorption isotherms of 2-naphthalenesulfonic acid and aniline on the test resins in both systems can fit well with the Langmuir equation,indicating that the adsorption is a favorable process.At the identical equilibrium concentration,the amount of aniline adsorbed on polymeric resins in the single system is higher than that in the binary system because of the competitive adsorption between 2-naphthalenesulfonic acid and aniline on the resin surface.However,the uptake amount of 2-naphthalenesulfonic acid in the binary system is markedly larger than that in the single system,which is presumably due to the cooperative effect arisen from the electrostatic interaction between 2-naphthalenesulfonic acid and aniline adsorbed on the resin surface.The simultaneous adsorption system was proven to be helpful for the selective adsorption toward 2-naphthalenesulfonic acid due to its larger selective index.  相似文献   

6.
The potential of using denitrifying and nitrifying concurrent biofilters for the removal of nitrogen oxides from synthetic gas streams was studied under the condition of high oxygen concentration. It was found that more than 85% of nitric oxide was removed from synthetic combustion gas-streams which contained 20% oxygen and 350 μL/L NO, with a residence time of 60 seconds. In the process, it was found that the existing of oxygen showed no evident negative effect on the efficiency of nitrogen removal.  相似文献   

7.
Gas phase selective catalytic oxidation of toluene to benzaldehyde was studied on V2O5-Ag2O/η-Al2O3 catalyst prepared by impregnation. The catalyst was characterized by XRD, XPS, TEM,and FT-IR. The catalytic results showed that toluene conversion and selectivity for benzaldehyde on catalyst sample No.4 (V/(V Ag)=0.68) was higher than other catalysts with different V/Ag ratios. This was attributed to the higher surface area, larger pore volume and pore diameter of the catalyst sample No.4 than the other catalysts. The XRD patterns recorded from the catalyst before and after the oxidation reaction revealed that the new phases were developed, and this suggested that silver had entered the vanadium lattice. XPS results showed that the vanadium on the surface of No.4 and No.5 sample was more than that in the bulk, thus forming a vanadium rich layer on the surface. It was noted that when the catalyst was doped by potassium promoter, the toluene conversion and selectivity for benzalde hydewere higher than those on the undoped catalyst. This was attributed to the disordered structure of V2O5 lattice of the K-doped catalyst and a better interfacial contact between the particles.  相似文献   

8.
6H-SiC bulk crystals have been prepared by sublimation method in an indu-ctively heated growth reactor. The effect of nitrogen doping on absorption for 6H-SiC was investigated. The absorption measurement based on optical method is a non-destructive and non-contact method. The band-gap narrowing with higher doping concentration was observed. For n-type doping below band-gap absorption band at 623 nm for 6H-SiC was observed. The peak intensity of the absorption band increased with increasing charge carrier concentration obtained from Hall measurements. It is also found that the nitrogen doping level decreased in the radial direction and it was the highest at the beginning of growth.  相似文献   

9.
Incubating plasma membranes prepared from pig liver with varying concentrations of insulin (50—1000 μU/ml) resulted in the release of at least two insulin chemical mediators. One of them was fraction 1 of insulin mediator (M. W. 3700—4000 daltons) which had a significant lipogenesis-stimulatlug activity. The other was fraction 2 of insulin mediator (M. W. about 1000 daltons) which exhibited a lipogenesis-inhibitory activity.The ratio of yield between the two mediators produced from the membranes was not only dependent on the concentration but also on the potency of insulin and its analogs added. The result showed that there was more production of fraction 2 than fraction 1 with the inducer at low concentration (100 μU/ml), while the production of fraction 1 from the plasma membranes incubated with high concentration of insulin (300 μU/ml) was higher than fraction 2. On the other hand, insulin and its analogs which have different biological activities and receptor bindtng activities have been used t  相似文献   

10.
Embryogenic calli were induced from the mature seeds of the hexaploid semi-winter wheat. The embryogenic cell line was established, and then the friable calli suitable for suspension were induced by adjusting the content of reduced N and changing the 2,4DAA concentration. Protoplasts were isolated from the suspension cells and cultured(?)in KM8P and some other media. A great number of microcolonies were obtained. By altering media, the microcolonies were promoted to grow further and form compact or nodule-like calli. Intact plants were regenerated through organogenesis and embryogenesis on differentiation media.  相似文献   

11.
Nuclei from the normal mouse liver were partially digested with micrococcal nuclease, followed by DNA extraction, agarose gel clectrophoresis and dot blot hybridization with ~(32)P-labeled cDNA probes of CPS_1 and ACT complex, It was clearly shown that the CPS_1 genes were distributed on the monomer, dimer. and trimer of nucleosomes, while the genes coding for ACT complex were distributed on the condensed oligonucleosomes. An opposite manner of distribution of CPS_1 and ACT complex genes was, however, noted in the case of ascites hepatoma cells, in which the specific activity of ACT was 13 times higher than that in the normal liver, while that of CPS_1 was remarkably reduced. Similar patterns of change in mRNA level of CPS_1 and ACT complex were observed in the normal mouse liver and ascites hepatoma cells, indicating a close relationship between chromatin structure and gene expression of these enzymes.  相似文献   

12.
A dibromo substituted BOPHY derivative(2) was prepared and found to exhibit photo-sensitization capability. Rapid oxidation of 80% DPBF at the first 6 min was observed suggesting that 2 is a superior photo-sensitizer than methylene blue. The HOMO–LUMO band gap for the lowest energy absorption bands of the BOPHY 1 is smaller than that of PS 2, which is in good agreement with the red shift in the absorption observed between 1 and 2.  相似文献   

13.
In order to create a functionalized biodegradable polymer for vascular tissue engineering application,poly(DL- lactide-co-RS-β-malic acid)(PDLLMAc)was synthesized.PDLLMAc was obtained after hydrogenolysis of poly(DL- lactide-co-RS-β-benzyl malolactonate)(PDLLMA),which was from the ring-opening polymerization of DL-lactide(DLLA) and RS-β-benzyl malolactonate(MA)using stannous octoate as catalyst.The copolymers were characterized by ~1H-NMR, FTIR,GPC and DSC.The tensile strength and water uptake of the copolymers were measured.In copolymerization,the proportion of MA in the derived copolymers was lower than that in the feeding dose,a consequence of its lower reactivity. The molecular weight of the copolymers decreased with increasing MA content.The protective benzyl groups were completely removed in hydrogenolysis.The glass transition temperature(T_g)of the protected copolymers decreased with increasing MA content.The mechanical strength test showed that the tensile strength of PDLLMA decreased while elongation increased with MA content increasing,and the tensile strength increased and elongation decreased with increasing malic acid content in PDLLMAc for the formation of hydrogen bonding.The water uptake showed that more hydrophilic malic acid adsorbed more water in PDLLMAc.In order to test the reactivity of functional pendant groups,bioactive RGD peptide was immobilized on the functionalized polymer film surface and smooth muscle cells(SMCs)were cultured on it. The results showed that the functionalized copolymer was biocompatible and could be potentially applied in vascular tissue engineering.  相似文献   

14.
The catalytic performance of bimetallic Ru-Co catalysts prepared from a series of H3Ru3Co(CO)12. RuCo2(CO)11 and HRuCo3(CO)12 in CO hydrogenation was investigated, and it was found that the Ru-Co bimetallic carbonyl cluster-derived catalysts showed a high activity for products, particularly higher oxygenates, compared with the catalysts prepared from impregnation or co-impregnation of monometallic clusters such as [HRu3(CO)11] and Co4(CO)12. The selectivity for oxygenates in CO hydrogenation highly increased with the molar ratio of Co/Ru in the Ru-Co bimetallic cluster to CO/H2 in feed gas. Raising reaction temperature led to an intensive increase of CO conversion and a considerable decrease of selectivity for oxygenates. In situ FT-IR studies revealed that the band at 1584 cm-1 on Ru-Co bimetallic cluster-derived catalysts at 453 K under syngas (CO/H2 = 0. 5) has a good linear relationship to rates of oxygenate formation, which is likely associated with an intermediate to produce oxygenates in CO hydro  相似文献   

15.
This work presented the synthesis of Ni-based metal-organic framework material with a paddle-wheel structure Ni_3(BTC)_2(Ni-BTC) and its application in thiophene(TP) adsorption from gasoline distillate by batch method. Adsorption isotherms of TP, cyclohexene, and toluene in cyclohexane onto Ni-BTC were conducted at 298–308 K to interpret the different effect of cyclohexene and toluene on TP adsorption.The results showed that, compared with cyclohexene, toluene addition in model gasoline led to a more evident decline in sulfur capacity of Ni-BTC, which is opposite to isostructural HKUST-1. The adsorption isotherms of TP, cyclohexene and toluene fit Langmuir model, S-type model and Temkin model well, respectively, indicating that the adsorption mechanisms of TP and the two competitors are different from one another. The adsorption capacities on Ni-BTC followed the order of cyclohexene toluene TP at the same equilibrium concentrations, implying the order of the adsorption affinities, which is in good agreement with the different extent of influence by the two competitors. The enthalpy of TP adsorption on Ni-BTC was estimated to be-80.01 kJ/mol, almost twice that on HKUST-1. The poor reusability of Ni-BTC in batch experiment, which is owing to its sensitivity to the air, can be prevented from regenerating used Ni-BTC in fixed-bed reactor by N_2 flow. The difference between Ni-BTC and HKUST-1 in maximum adsorption capacity(q_0), H of TP adsorption, and stability demonstrates that the central metal in isostructural MOFs plays a key role in adjusting the desulfurization performance, which may open up a potential avenue for the development of MOF-based adsorbents with superior desulfurization performance.  相似文献   

16.
46 green plantlets were obtained by inoculating the anthers of F_1 hybrids of complicated combination ((Lovrin 18×5238-036) F_1×Hongliang No. 4) from wheat to the medium N_6 in 1977. Induced percentage of green plantlets was 11.50%. After chromosome doubling treatment, 28 plantlets set seeds. Diversity in morphological characters, growing periods and resistance to diseases were observed in H_2 generation, from which plantline for Jinghua No. 1 was selected for the first time this year. Variety comparative and regional adaptive experiments were performed in subsequent H_3, H_4,H, and H_6 generations.The area of planting Jinghua No. 1 amounted to 7000 ha in 1984. The evaluation of Jinghua No. 1 was passed by Beijing Variety Evaluation Committee.Jinghua No. 1 is a high yield and high quality new wheat variety. It resists strongly leaf, stem and stripe rust and powdery mildew and possesses good adaptation.The development of Jinghua No. 1 took only 7 generations, among which 3 years were spent for hybridiz  相似文献   

17.
FGS,isolated from the water solution of enzymolyzed laminaria japonica,is a mixture of acid theroglycans.Four fractions F1,F2,F3,and F4 were obtained from FGS by ion exchange chromatography.After further purified by gel filtration chromatography on a sepharose 2B and 6B column,we obtained F9,F10,F11,and F12.They showed single band when identified by electrophoresis.The molecular weight of F9,F10,F11,and F12 was estimated to be 216,120.138and 140kD respectively.They contained a -glucosidic bond by IR and 1H-NMR analysis.The typical absorption peaks of these polysaccharides were showed in UV and IR spectra.These polysaccharides contained rha,fuc,man,gal,and uronate when identified by paper chromatography (p.c) and gas chromatorgraphy(GC).The molar ratio of these sugars was also assayed.  相似文献   

18.
A series of “hairy-rod” polyimides, BBPA(n), with multiple alkyl side chains was prepared from 3,3′,4,4′-biphenyltetracarboxylic dianhydride (BPDA) and 4,4′-biphenyldiamine substituted in the 2,2′-positions with benzoate, which was substituted in the 3,4,5-positions with ether side chains of varying lengths. The number of the methylene units, n, in these alkyl side chains were in even numbers ranging from 8 to 18. Combining techniques of one-dimensional (1D) and 2D wide angle x-ray diffraction, 1D small angle X-ray scattering, differential scanning calorimetry experiments, it was found that this series of “hairy-rod” polyimides possess a micro-phase separation between the backbones and side chains. This led to the formation of ordered structures in two different length scales, of which both are hexagonal packing: one is attributed to the alkyl side chains on the sub-nanometer scale, and another is for the whole polymer chains on the nanometer scale. The development of the hexagonal structure on the sub-nanometer scale was critically dependent upon the lengths of the alkylside chains. Three relaxation processes were captured by dynamic mechanical analysis, i.e., segmental motion of the backbones, α the melting of the side chain crystals, β1, which exits only for the materials with longer side chains(n=18,16); and the subglass relaxation of side chains, β2- The peak relaxation temperature of the α process decreased with increasing the length of side chains, while the one of the β2 process increased. The activation energy of the α relaxation was relatively independent on the length of side chain, whereas, β2 process showed the increasing of activation energy with increasing the length of side chains.  相似文献   

19.
Populus tomentosa is one special species of poplar growing in North China. Mesophyllprotoplasts were isolated from the axenic shoots and cultured in the modified KM8p liquidmedium. Protoplast-derived cells started to divide after 7 days of culture. The frequencyof cell division reached about 20% in 10 days. The yellowish green calli grew compact andnodular after the hormone concentration of medium was adjusted. Shoot formation occurredwhen the protoplast--derived calli were transferred onto MS medium containing zeatin andIAA or NAA. The shoots rooted readily on 1/2 MS hormone--free medium.  相似文献   

20.
The Thermal Field-Flow Fractionation (TFFF) method was used to determine the elution volumeof a series of star branched polystyrene having different number of arms but the same arm molecularweigh and polystyrene standards with narrow distribution whose molecular weight ranged from5.0×10~4 to 8.6×10~5. Results were obtained by measuring at two temperature difference (△T=30℃and △T=50℃in THF. The same star branched samples were measured by means of GPC method.Comparison of Vr-Mrelationships obtained from TFFF and GPC showed that the displacement of V_r-M curves for star and linear polystyrene is larger than that in GPC. This difference is caused by theentirely different mechanism of separation for these two methods. As the controlling factor is hy-drodynamic volume of the polymer chain in solution for GPC, it is the diffusion coefficient of polymermolecules for TFFF. The experimental results indicate that the influence of variance of chain struc-ture on diffusion coefficient is stronger than that on the hydrodynamic volume and that TFFF tech-nique may be used as a method for characterizing branching of polymer molecules. For this pur-pose a proper theoretical model and more accurate experiments are needed.  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