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91.
聚天冬氨酸的合成与表征 总被引:4,自引:0,他引:4
介绍了以L -天冬氨酸为原料 ,热缩合成聚天冬氨酸酐 ,水解得到聚天冬氨酸的合成工艺。采用凝胶色谱法测定了聚天冬氨酸的分子量 ,并用核磁共振对其进行了表征。 相似文献
92.
Bates Paul A.; McGregor Malcolm J.; Islam Suhail A.; Sattentau Quentin J.; Sternberg Michael J.E. 《Protein engineering, design & selection : PEDS》1989,3(1):13-21
A predicted three-dimensional structure of the two N-terminalextracellular domains of human CD4 antigen, a cell surface glycoprotein,is reported. This region of CD4, particularly the first domain,has been identified as containing the binding region for theenvelope gp120 protein of the human immuno-deficiency virus.The model was predicted based on the sequence homology of eachdomain with the variable light chain of immunoglobulins. Theframework ß-sheet regions were taken from the crystalcoordinates of REI. For one region in the first domain of CD4there was an ambiguity in the alignment with REI and two alternatemodels are presented. Loops connecting the framework were modeledfrom fragments selected from a database of main chain coordinatesfrom all known protein structures. Residues identified as involvedin binding gp120 have been located in several other studieswithin the first domain of CD4. Epitopes from eight monoclonalantibodies have been mapped onto residues in both domains. Competitionof these antibodies with each other and with gp120 can be interpretedfrom the structural model. 相似文献
93.
目的研制预防人乳头瘤病毒(HPV)感染的重组修饰的Ankara痘病毒(MVA)活载体疫苗。方法将HPV16L1基因插入MVA病毒转移载体psc11M2的P7·5启动子的下游,构建转移质粒psc11M2-L1,与MVA共转染鸡胚成纤维细胞(CEF),进行同源重组。通过9轮蓝斑筛选,以PCR和Westernblot鉴定重组病毒。结果获得的含目的片段的重组MVA病毒,表达产物与鼠抗人HPV16L1抗体发生阳性反应,目的蛋白相对分子质量约为55000。结论已成功地构建了可正确表达HPV16L1基因的重组MVA病毒株。 相似文献
94.
Poly(L‐lactide)‐poly(ethylene glycol) multiblock copolymers with predetermined block lengths were synthesized by polycondensation of PLA diols and PEG diacids. The reaction was carried out under mild conditions, using dicyclohexylcarbodiimide as the coupling agent and dimethylaminopyridine as the catalyst. The resulting copolymers were characterized by various analytical techniques, such as GPC, viscometry, 1H‐NMR, FTIR, DSC, X‐ray diffractometry, and contact angle measurement. The results indicated that these copolymers presented outstanding properties pertinent to biomedical use, including better miscibility between the two components, low crystallinity, and hydrophilicity. Moreover, the properties of the copolymers can be modulated by adjusting the block length of the two components or the reaction conditions. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 84: 1729–1736, 2002; DOI 10.1002/app.10580 相似文献
95.
96.
Application of a rice field experimental error distribution function to nitrogen-phosphorus-potassium fertilizer response model analysis 总被引:2,自引:0,他引:2
A distribution function of rice yield deviations from the mean was developed from field experiments with 555 plots at 16 sites in Zhejiang province, China, for three years. The deviation distribution in interval of 50kg/ha appeared as a symmetrical distribution with a high peak (Mean=0.279 [kg/ha], SD=240.686 [kg/ha]). Normality test using Kolmogrove-Smirnov test between the observed cumulative distribution and the normal cumulative distribution function indicates that the observed deviation distribution is not normal. An empirical exponential cumulative distribution function was developed. The distribution function was used to remove outliers during the development of a rice yield fertilizer response model, based on data from a non-replicated NPK field experiment. 相似文献
97.
98.
This paper describes the design and application of the Atmospheric Evaluation and Research Integrated model for Spain (AERIS). Currently, AERIS can provide concentration profiles of NO2, O3, SO2, NH3, PM, as a response to emission variations of relevant sectors in Spain. Results are calculated using transfer matrices based on an air quality modelling system (AQMS) composed by the WRF (meteorology), SMOKE (emissions) and CMAQ (atmospheric-chemical processes) models. The AERIS outputs were statistically tested against the conventional AQMS and observations, revealing a good agreement in both cases. At the moment, integrated assessment in AERIS focuses only on the link between emissions and concentrations. The quantification of deposition, impacts (health, ecosystems) and costs will be introduced in the future. In conclusion, the main asset of AERIS is its accuracy in predicting air quality outcomes for different scenarios through a simple yet robust modelling framework, avoiding complex programming and long computing times. 相似文献
99.
17O MAS NMR spectra for17O enriched solid heteropoly acid H3PMo12O40 are reported. The oxygen exchange between solid H3PMo12
17O40 and H2
16O vapor at 200–250°C is shown to be accompanied by fast mixing of terminal Mo=O and bridging Mo-O-Mo oxygens in the Keggin unit. The oxygen exchange in H3PMo12
17O40 is much faster than in H3PW12
17O40 in solution as well as in the gas phase. 相似文献
100.
以H3PW6Mo6O40为催化剂,对以环己酮与乙二醇为原料合成环己酮乙二醇缩酮的反应条件进行了研究,较系统地研究了酮醇物质的量比、催化剂用量、反应时间对收率的影响。实验结果表明,在n(环己酮):n(乙二醇)=1.0:1.5,催化剂用量占反应物料总质量的0.8%,反应时间0.75h,带水剂环己烷8mL的条件下,环己酮乙二醇缩酮的收率为84.9%。 相似文献