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自20世纪初期,德国化学家EmilFischer首先合成了甘氨酸二肽片段,并第一次提出“peptide”(多肽)这一名词,多肽化学的研究已经历了100多年的发展.1953年,Vigneand小组首次完成了生物活性肽催产素的合成,并因此于1955年获得了诺贝尔化学奖.1963年,Merrifield提出了多肽固相合成法,并发明了第一台多肽自动合成仪,大大简化了多肽合成的流程、提高了合成的效率,从而促使多肽化学实现了飞跃式发展,Merrifield也因此获得了1984年诺贝尔化学奖.1965年,我国科学家完成了牛结晶胰岛素的合成, 相似文献
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本文简述了塑科将成为未来世纪的主要工业材料,介绍了80年代至本世纪末,世界主要国家塑料工业的主要品种,产量,生产能力;分析了90年代世界塑料市场供需状况,并重点探讨了中国塑料市场供需矛盾,预测了2000年需求总量,提出了今后发展应注意的关键问题。最后,重点探讨了世界塑料工业几个主要品种,今后发展趋势及一些关键技术的开发热点。 相似文献
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基础化学实验室的建设与管理 总被引:2,自引:0,他引:2
化学实验室是全面完成化学教学任务的重要基地。 我院2002年建立了设备比较先进的化学实验室,给学生创造了良好的实验条件,并进行了科学化的管理,规定了各种规章制度和有关职责,较好地完成了化学教学任务。在实践中。采取:固定优秀代课教师兼管,勤工助学学生帮忙的管理办法,既减轻教师的劳动强度,又培养了学生的技能,且协调了各种关系,有利于化学教学质量的提高。 相似文献
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Both the organization and function of protein nanostructures in membranes are related to the substructural properties of the lipid portion of the membrane. Potential differences that are established across the membrane and generate electric fields in these very thin portions are shown to modulate the organizational and functional properties of the protein modules. Many protein modules also have nonisotropic distributions of charged sites, including configurations in which there are regions containing predominantly positive fixed charges, juxtaposed with adjacent regions containing predominantly negative fixed charges. In these double fixed charge regions, very large electric fields can manifest in the ionic depletion layer at the junction of the two fixed charge regions.Consideration is also given to the manner in which the intense electric fields that are established in protein modules, such as proton ATPases, can modulate the chemical reactions that are associated with proton transport and dehydration reactions. 相似文献
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Monte Carlo simulations are employed to investigate the bias in linear regression parameters for cases in which both variables are subject to normally distributed errors. Both homoscedastic and heteroscedastic errors are treated. The results show that, in general, the arithmetic mean, geometric mean, and angle mean (tangent of the mean of the arctangents) of the slopes are biased and non-normally distributed. The arithmetic and geometric means of the intercepts are generally biased and non-normally distributed as well. However, for all the cases considered, the medians of the slopes and of the intercepts are found to be unbiased. In view of the non-normal distributions of the slopes and intercepts, a nonparametric method is used to determine confidence intervals for the slopes and intercepts. 相似文献
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Pier Luigi Luisi 《Angewandte Chemie (International ed. in English)》1985,24(6):439-450
Reverse micelles are spheroidal aggregates formed by certain surfactants in apolar media. In contrast to normal micelles in water, the polar head groups of the surfactant molecules are directed towards the interior of the aggregate and form a polar core which can solubilize water (the “water pool”); the lipophilic chains are exposed to the solvent. The water of the water pool exhibits properties that (depending on the mole ratio of water to surfactant) differ from those of bulk water. Surprisingly, these reverse micelles are able to solubilize in hydrocarbon solvents hydrophilic molecules, e.g., enzymes and even plasmids, that are much larger than the original water-pool diameter. These biopolymer-containing reverse micelles can be viewed as novel microreactors, whose physical properties can be controlled through the water content. Remarkable is the ability of enzyme-containing micelles to react with water-insoluble, hydrocarbon-soluble substrates, as in the example of lipoxygenase with linoleic acid. 相似文献
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G. Derfel 《Liquid crystals》1988,3(10):1411-1424
The field effects in nematic liquid crystal layers are reanalysed using catastrophe theory. The layer with pretilted director orientation and obliquely applied magnetic field, the hybrid aligned nematic cell and twisted nematic structures are considered. The stable solutions are identified and transitions between them are specified. The results are in essential agreement with previous work. Some details concerning the behaviour near the threshold are revealed. 相似文献
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Nur Nasyifa Mohd Maidin Muhamad Ramdzan Buyong Ruslinda A. Rahim Mohd Ambri Mohamed 《Electrophoresis》2021,42(20):2033-2059
Dielectrophoresis (DEP) is a technique to manipulate trajectories of polarisable particles in nonuniform electric fields by utilizing unique dielectric properties. The manipulation of a cell using DEP has been demonstrated in various modes, thereby indicating potential applications in the biomedical field. In this review, recent DEP applications in the biomedical field are discussed. This review is intended to highlight research work that shows significant approach related to DEP application in biomedical field reported between 2016 and 2020. First, single-shell model and multiple-shell model of cells are introduced. Current device structures and recently introduced electrode patterns for DEP applications are discussed. Second, the biomedical uses of DEP in liquid biopsies, stem cell-based therapies, and diagnosis of infectious diseases due to bacteria and viruses are presented. Finally, the challenges in DEP research are discussed, and the reported solutions are explained. DEP's potential research directions are mentioned. 相似文献
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Kuvichkin VV 《Bioelectrochemistry (Amsterdam, Netherlands)》2002,58(1):3-12
The data on lipid-nucleic interactions and their role in vitro and in vivo are presented. The results of study of DNA-lipid complexes in absence and in presence of divalent metal cations (triple complexes) are discussed. The triple complexes represent the generation of cellular structures such as pore complexes of eucaryotes and "Bayer's junctions" of procaryotes. The participation of triple complexes in the formation of structure of bacterial and eucaryotic nucleoid and nuclear matrix is analysed. A model of formation of triple complexes and cellular structures and their role in DNA-lipid interactions are discussed. 相似文献
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Y. Takashima 《Journal of Radioanalytical and Nuclear Chemistry》1993,171(1):83-93
Although there are 430 govemment and private universities in Japan, only a limited number of them have departments associated with nuclear science education. Moreover, mainly because of financial pressures, this association is often limited to government universities. Nuclear engineering departments are incorporated with only seven of the larger universities, and there are three institutes with nuclear reactors. In these facilities, education in reactor physics, radiation measurements, electromagnetic and material sciences, are conducted. In terms of radiation safety and radiological health physics, tem radioisotope centers and seven radiochemistry laboratories in universities play an important role. Virtually all of the financial support for nuclear education comes from the Japanese Govemment via the Ministry of Education, Science, and Culture. These are supplemented via private and corporate grants to various university faculty members. In addition to these universities, and private/corporate research institutes, The Japan Atomic Energy Research Institute teaches a short lecture course in nuclear science on a regular basis. 相似文献
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G. Derfel 《Liquid crystals》2013,40(10):1411-1424
Abstract The field effects in nematic liquid crystal layers are reanalysed using catastrophe theory. The layer with pretilted director orientation and obliquely applied magnetic field, the hybrid aligned nematic cell and twisted nematic structures are considered. The stable solutions are identified and transitions between them are specified. The results are in essential agreement with previous work. Some details concerning the behaviour near the threshold are revealed. 相似文献