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71.
72.
利用Pro/E三维模型与二维图形双向关联功能可以快速生成工程图,但由于在视图表达上有些方面不符合我国制图标准而影响其有效使用.本文针对Pro/E制作工程剖视图时所存在的与制图国标不相符合的问题,提出了解决这些问题的方法和技巧. 相似文献
73.
A statistical-thermodynamic model for binary nonstoichiometric A5B3 with D81-structure has been established on the basis of the grand canonical ensemble. In the model the average chemical potentials according to the composition and a new extra equation as a boundary condition are proposed for more accuracy and free experimental data calculations. The model can be used in any A5B3 type compounds with D81 structure. The establishment method of the statistical-thermodynamic model can be extended to other complicated structures. We apply the statistical-thermodynamic model to α-Nb5Si3 and the parameters used in the model are obtained from the first-principles' calculations. From these parameters the expression for the point defect concentrations as a function of compositions and temperatures is obtained by numeral calculations. The constitutional defects and thermal defects in α-Nb5Si3 are discussed. 相似文献
74.
75.
铁氮共掺杂纳米TiO2的水热法制备及其在可见光下抗菌性能的研究 总被引:2,自引:0,他引:2
以硫酸氧钛为前驱体,硝酸铁和盐酸胍作为掺杂的铁源和氮源,采用水热法制备了铁氮共掺杂纳米TiO2粉体。利用XRD、BET对样品进行表征,研究了掺杂后TiO2粉体的晶型、粒径、比表面积等性能。结果表明,所制备的共掺杂TiO2粉体呈黄色,均为锐钛矿相TiO2,经谢尔公式计算其粒径约为10nm,比表面积分布为(135~150)m^2/g。采用紫外.可见光漫反射光谱对样品进行表征,结果表明经过铁氮共掺杂改性后的TiO2具有很强的紫外线的吸收能力,并实现了良好的可见光响应。采用菌落计数法进行了样品抗菌性能的研究,在可见光照射下样品对大肠杆菌表现出良好的杀灭性能。 相似文献
76.
Many isotopic techniques can be applied to determine the relative immediate and residual effectiveness of P fertilizers. Using isotopes as tracers, the percentage of utilization by plants of the P derived from a fertilizer can be determined. However this is only possible during the three or four months after the application. Therefore, the P fertilizers may be classified only according to their relative immediate effectiveness. To also evaluate residual effect, which can be observed when more P is applied than is removed with harvest, isotopes of phosphorus can be used. This residual effect is determined by comparing pool sizes of bioavailable soil P in soils with and without P fertilizer aged in soil. The bioavailable soil P pool may be analyzed according to three isotopic experimental procedures which give access to either the A value, or the E value or the L value. The aims, the similarities and the differences between these three procedures, are examined. Some of the theoretical and practical constraints of each method are described in this paper; they must be followed in order to obtain reliable information for agronomic purposes. A method involves measuring the rate of isotopic exchange of phosphate ions in soil-solution systems maintained in steady-state. It is now possible to predict the effectiveness of P fertilizers, whatever their chemical form when this method is applied on soil samples where P fertilizers were applied.This paper was originally submitted as part of the special issue on Evaluation of the Agronomic Effectiveness of Phosphate Fertilizers through the use of Nuclear Related Techniques edited by F. Zapata 相似文献
77.
人Leptin基因的克隆及其在大肠杆菌中的表达 总被引:1,自引:0,他引:1
目的克隆Leptin基因,构建其重组表达菌株,并对表达产物进行免疫学鉴定。方法利用RT-PCR方法从脂肪细胞RNA中扩增出人瘦素前体(pre-Leptin)的cDNA片段和去信号肽序列的Leptin成熟基因片段,并插入pET32a中,转化大肠杆菌BL21(DE3),获得表达重组人瘦素(rh-Leptin)的菌株。结果DNA序列分析显示获得的pre-Leptin和成熟基因片段的序列与预计序列一致,菌株诱导后经SDS-PAGE检测,rh-Leptin表达量达菌体总蛋白的40%以上。Western blot分析显示重组Lep-tin具有免疫学活性。结论已获得高效表达Leptin的重组菌株。 相似文献
78.
[摘 要]目的 克隆并表达大肠杆菌肉碱脱水酶基因。方法 用聚合酶链反应(PCR)从大肠杆菌K12s中扩增大肠杆菌肉碱脱水酶基因caiB,测定其DNA序列,将caiB基因重组到T7启动子控制下的表达载体pET-28a(+)中,构建表达质粒pETCaiB,转化大肠杆菌BL21(DE3),用1mmol/L异两基硫代-β-D半乳糖苷(IPTG)诱导表达。结果 克隆得到的肉碱脱水酶编码基因 caiB长度为 1221bp,与文献报道值相比,DNA序列有26个不同,氨基酸序列只有一个不同,即302位的丙氨酸变为苏氨酸。重组菌经IPTG诱导,可高效表达,SDS-PAGE分析表达蛋白相对分子质量约43000,表达产物含量占菌体总蛋白45%以上。结论 得到了高效表达肉碱脱水酶的重组菌,为制备L-肉碱创造了条件。 相似文献
79.
S. A. Katovich P. D. Swedenborg M. Giblin E. W. Underhill 《Journal of chemical ecology》1989,15(2):581-590
The sex pheromone ofCydia toreuta (Grote), the eastern pine seedworm, was investigated using electroantennogram (AG) measurements, gas chromatography (combined GC-FID-EAD) measurements, and field tests. (E,Z)-8,10-dodecadienyl acetate (E,Z8,10-12:Ac) and (E,E)-8,10-dodecadienyl actetate (E,E8,10-12: Ac) produced both the highest EAG and EAD responses. Only a single antennal stimulatory peak was observed when female abdominal tip extracts were analyzed by GC-FID-EAD, which corresponded exactly with that of authenticE,Z8,10-12: Ac. Field tests confirmedE,Z8,10-12: Ac as the major pheromone component. TheE,Z isomer by itself caught equivalent numbers of male moths as did caged females. The addition of theE,E isomer to theE,Z form increased trap catch, although not significantly (P = 0.05). The addition of (Z,Z)-8,10-dodecadienyl acetate to theE,Z isomer significantly (P=0.05) reduced trap catch, while the addition of (Z,E)-8,10-dodecadienyl acetate to theE,Z form also decreased trap catch, but not significantly (P=0.05). 相似文献
80.
P. N. Mayamol C. Balachandran T. Samuel A. Sundaresan C. Arumughan 《Journal of the American Oil Chemists' Society》2007,84(6):587-596
Crude palm oil (CPO) is the richest natural source of carotenes that are destroyed in the conventional processing. There is
a growing demand for nutritional products containing bioactive constituents externally fortified or preserved through modified
process. A commercially viable process for the production of red palm olein (RPOn) rich in carotenes, tocols and sterols has
been developed at pilot scale. The process developed involved neutralization of CPO followed by crystallization at controlled
rate of cooling and deodorization of the resultant neutralized and winterized palm olein (WPOn) under controlled conditions
of temperature and high vacuum. Analytical data related to micronutrients at each process step was monitored. The RPOn thus
produced had not more than 0.25% of free fatty acids (FFA) and it retained more than 80% of the carotenes, about 85% of tocols
and 65% of sterols originally present in the CPO. The physico-chemical characteristics of RPOn revealed that it is nutritionally
of superior quality compared to that of the commercial refined bleached deodorized (RBD) palm olein currently available in
the market. The carotenes, tocols and sterols profile of RPOn by HPLC showed that they were retained in their natural forms. 相似文献