共查询到19条相似文献，搜索用时 406 毫秒
1.
Enhancing the dispersion and dissolution of substrate particles in substrate water suspension is a feasible way to improve steroid bioconversion. The aim of the present study is to investigate the effects of applying surfactant to microbial conversion system on the dispersion, solubilization and in turn bioconversion of steroid substrate. The model system is hydroxylation of substrate 19α- 17α-epoxy- 4-pregnene- 3.2It-dine by microbial enzymes from Rhizopus nigricanl. The results show that the presence of substrate leads to an increase in critical micelle concentration （ CMC） of surfactant PSE compared with the normal CMC of PSE in aqueous solution. The grinding time during substrate suspension preparation affects the substrate aqueous solubility differently with the varied surfactant concentrations while barely making any difference in substrate solubility in the absence of surfactant. The properly prolonged grinding time can make up for the loss in substrate solubility arising from the reduction in surfactant concentration. The surfactant complexes composed of surfactants PSE and MGE at appropriate ratios are screened out with orthodoxy experiment method. the interaction between PSE and MGE exerts the most prominent effects on substrate bioconversion, and the surfactant complexes show more beneficial effects on steroid bioconversion than the surfactant PSE used alone. 相似文献
2.
As a large number of foreign films have flooded into the Chinese film market, subtitling translation plays an important role in helping the audience understand and learn about some information and cultures from different countries. This paper mainly uses Peter Newmark’s"equivalent effect"as a theoretical foundation to analyze the features of two kitties’(Garfield and Prince) source language (English) and target language (Chinese) in the film Garfield Ⅱ based on their living surroundings and social status. 相似文献
3.
WANG Jian-hua LV Zheng-jian XU Shi-rong 《重庆大学学报(英文版)》2005,4(4):223-228
A new series of Schiff base ligands were synthesized by the condensation of 2-amino-5-mercaptan-l,3,4-thiadiazole and salicylaldehyde or 2,4-dihydroxybenzaldehyde and their derivatives with choroacetic acid, and further reaction with corresponding metal acetate to form metal complexes. The compositions and structures of the ligands and their complexes were characterized by elemental analysis, molar conductivities, electronic absorption spectra and infra-red spectra. Their inhibition rates to free radical, such as O2, were also tested. The results show that all of the obtained complexes display significant activities, among which the copper（Ⅱ） complexes have the best inhibitive effects. 相似文献
4.
Objective： A series of 2-benzylideneaminonaphthothiazoles were designed and synthesized incorporating the lipophilic naphthalene ring to render them more capable of penetrating various biomembranes. Methods： Schiff bases were synthesized by the reaction of naphtha[1,2-d]thiazol-2-amine with various substituted aromatic aldehydes. 2-（2＇-Hydroxy）ben- zylideneaminonaphthothiazole was converted to its Co（Ⅱ）, Ni（Ⅱ） and Cu（Ⅱ） metal complexes upon treatment with metal salts in ethanol. All the compounds were evaluated for their antibacterial activities by paper disc diffusion method with Gram positive Staphylococcus aureus and Staphylococcus epidermidis and Gram negative Escherichia coli and Pseudomonas aeruginosa bacteria. The minimum inhibitory concentrations of all the Schiff bases and metal complexes were determined by agar streak dilution method. Results： All the compounds moderately inhibited the growth of Cram positive and Gram negative bacteria. In the present study among all Schiff bases 2-（2＇-hydroxy）benzylideneaminonaphthothiazole showed maximum inhibitory activity and among metal complexes Cu（Ⅱ） metal complex was found to be most potent. Conclusion： The results obtained validate the hypothesis that Schiff bases having substitution with halogens, hydroxyl group and nitro group at phenyl ring are required for the antibacterial activity while methoxy group at different positions in the aromatic ring has minimal role in the inhibitory activity. The results also indicated that the metal complexes are better antibacterial agents as compared to the Schiff bases. 相似文献
5.
PDM（product data management)is one kind of techniques based on software and database,which integrates information and process related to products.But it is not enough to perform the complication of PDM in enterprises.Then the mechanism to harmonize all kinds of information and process in needed.The paper introduces a novel approach to implement the intelligent monitor of PDM based on MAS(multi-0agent system).It carries out the management of information and process by MC( monitor Center).The paper first puts forward the architecture of the whole system,then defines the structure of MC and its interoperation mode. 相似文献
6.
Selenocosmia huwena and Selenocosmia hainana are two tarantula species found in southern China.Their venoms contain abundant peptide toxins.Two new neurotoxic peptides,huwentoxin-Ⅲ(HWTX-Ⅲ) and hainantoxin-VI(HNTX-VI),were obtained from the venom using ion-exchange chromatography and reverse-phase high performance liquid chromatography(RP-HPLC).The mechanism of action of HWTX-Ⅲ and HNTX-VI on insect neuronal voltage-gated sodium channels(VGSCs) was studied via whole-cell patch clamp techniques.In a fashion similar to δ-atracotoxins,HNTX-VI can induce a slowdown of current inactivation of the VGSC and reduction in the peak of Na+ current in cockroach dorsal unpaired median(DUM) neurons.Meanwhile,10 μmol/L HNTX-IV caused a positive shift of steady-state inactivation of sodium channel.HWTX-ⅡI inhibited VGSCs on DUM neurons(concentration of toxin at half-maximal inhibition(IC50)≈1.106 μmol/L) in a way much similar to tetrodotoxin(TTX).HWTX-Ⅲ had no effect on the kinetics of activation and inactivation.The shift in the steady-state inactivation curve was distinct from other depressant spider toxins.The diverse effect and the mechanism of action of the two insect toxins illustrate the diverse biological activities of spider toxins and provide a fresh theoretical foundation to design and develop novel insecticides. 相似文献
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8.
Density function M06 method has been used to optimize the geometries of camptothecin-cytosine at 6-31+G* basis.Finally, thirteen stabilized complexes have been obtained.Theories of atoms in molecules (AIM) and natural bond orbital (NBO) have been utilized to investigate the hydrogen bonds involved in all the complexes.The interaction energies of all the complexes are corrected by basis set superposition error (BSSE).By the analysis of complexes interaction energy, charge density, second-order interaction energies E(2), it is indicated that the complex 6 is the most stable structure. 相似文献
9.
It is difficult to directly dope europium complexes in gel because the excessive water or high acidic condition may lead to their decomposition. We prepared a novel homogeneous TiO2 gel containing Eu-phen complexes by using an in-situ synthesis method. The formation of Eu-phen complexes in sol-gel derived TiO2 was confirmed by luminescence excitation spectra. The effects of temperature and aging time on in-situ synthesis are discussed. The luminescence spectra of gel containing europium complexes were also compared with the pure Eu-phen complexes. 相似文献
10.
The influence of external low frequency (0-100 Hz) vibration on the tip-sample interaction in SPM is the main concern of this paper. A concept, vibration rejection ratio (VRR) proposed by Thompson et al, was investigated theoretically and experimentally. A concise theoretical background was introduced, a vibration stimulating and measuring system for SPM was built up, and an experimental research of the influence on SPM VRR was carried out with different SPM probes, samples, tip pre-loads and open/close loops of tip-sample interaction. It was proved both in theory and experiment that SPM VRR had correlations with the spring constant, the air damping constant, the effective mass of the cantilever, the contact spring constant and the contact damping constant between tip and sample. SPM's vibration rejecting ability can be improved by longer cantilever probe, softer sample surface, greater tip pre-load, and close-loop control for tip-sample interaction. More attention should be paid to a proper combination of the above parameters. 相似文献
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12.
刘丹萍 《郧阳师范高等专科学校学报》2007,27(3):62-63
以Pt（Ⅱ）离子配位化合物为例，研究了该配合物进行取代反应的一般机理，讨论了影响形成平面正方形配合物取代反应的主要因素． 相似文献
13.
金属(Ni、Co、Zn)--Salen配合物的合成及性质研究 总被引：16，自引：0，他引：16
本论述了水杨醛与乙二胺，丙二胺，邻苯二胺，对苯二胺合成西佛碱及西佛碱与Co(Ⅱ），Ni(Ⅱ),Zn(Ⅱ)合成Salen金属配合物，这些化合物均被1HNMR，IR和元素分析证实，并讨论它们的电导，紫外，可见光光谱性质。 相似文献
14.
报道了L-半胱氨酸尾式卟啉铜(II)及四苯基卟啉铜(II)配合物作为超氧化物歧化酶(SOD)和过氧化氢酶(CAT)模拟物催化歧化O22-和催化分解过氧化氢及有毒氧自由基的活性.结果表明:这两种铜卟啉配合物具有较好的仿酶活性. 相似文献
15.
谭君 《重庆第二师范学院学报》2006,19(6):11-12,15
槲皮素对金属离子具有强烈的螯合作用。本文研究表明在pH4．6的HAc—NaAc缓冲液中，槲皮素能与Cu（Ⅱ）形成稳定的配合物，在紫外光谱中其吸收带Ⅰ比单独槲皮素红移了59nm。采用等摩尔连续变化法测得槲皮索-Cu（Ⅱ）配合物的配位比为2：1，采用平衡移动法测得配合物的稳定常数为2．0410^8。并初步探讨了槲皮素与Cu（Ⅱ）配位的部位是30H～4C=0。 相似文献
16.
AZAM Faizul SINGH Satendra KHOKHRA Sukhbir Lal PRAKASH Om 《Journal of Zhejiang University. Science. B》2007,8(6)
Objective: A series of 2-benzylideneaminonaphthothiazoles were designed and synthesized incorporating the lipo- philic naphthalene ring to render them more capable of penetrating various biomembranes. Methods: Schiff bases were synthe- sized by the reaction of naphtha[1,2-d]thiazol-2-amine with various substituted aromatic aldehydes. 2-(2'-Hydroxy)ben- zylideneaminonaphthothiazole was converted to its Co(II), Ni(II) and Cu(II) metal complexes upon treatment with metal salts in ethanol. All the compounds were evaluated for their antibacterial activities by paper disc diffusion method with Gram positive Staphylococcus aureus and Staphylococcus epidermidis and Gram negative Escherichia coli and Pseudomonas aeruginosa bac- teria. The minimum inhibitory concentrations of all the Schiff bases and metal complexes were determined by agar streak dilution method. Results: All the compounds moderately inhibited the growth of Gram positive and Gram negative bacteria. In the present study among all Schiff bases 2-(2'-hydroxy)benzylideneaminonaphthothiazole showed maximum inhibitory activity and among metal complexes Cu(II) metal complex was found to be most potent. Conclusion: The results obtained validate the hypothesis that Schiff bases having substitution with halogens, hydroxyl group and nitro group at phenyl ring are required for the antibacterial activity while methoxy group at different positions in the aromatic ring has minimal role in the inhibitory activity. The results also indicated that the metal complexes are better antibacterial agents as compared to the Schiff bases. 相似文献
17.
超导材料的合成机理研究极富挑战性，已引起人们的极大兴趣，铜氧桥联配合物在超导方面的研究很有价值。首先用计算机模拟出合理的分子模型，经筛选，确定邻苯二酚，对苯二酚的铜氧桥联配合物，设计出合理的路线，合成并利用元素分析，红外光谱等表征了该配合物。 相似文献
18.
用自制的5-氯水杨醛与甘氨酸缩合,制备了一种氨基酸schiff碱配体,再将其与Cu(Ⅱ)、Zn(Ⅱ)作用,合成出了两种新型的Schiff配合物.采用元素分析、红外光谱、紫外光谱、差热热重分析、摩尔电导率等方法对化合物进行了表征,推测出化合物的组成与结构. 相似文献