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排序方式: 共有133条查询结果,搜索用时 15 毫秒
1.
R. V. Iyer K. Sooryanarayana T. N. Guru Row K. Vijayan 《Journal of Materials Science》2003,38(1):133-139
Using X-ray diffraction data, the behaviour of Kevlar 49 fibres at low temperatures, up to –100°C, has been analysed. During cooling, the basal plane of the monoclinic unit cell shrinks whereas the c- (unique, chain axis) length is not significantly affected. In contrast, in the return heating cycle to ambient temperature, the basal plane expands and contraction occurs along the chain direction. The unit cell registers a reduction in volume in both the cooling and heating cycles. Conspicuously, after a cycle of cooling and heating, the unit cell does not return to its initial volume. 相似文献
2.
Du Young Choi Long Mei Jin Dexian Wang Kyung Ho Row 《Korean Journal of Chemical Engineering》2005,22(3):465-469
High-performance frontal analysis (HPFA) was used for a protein binding study of isoflavones (daidzein, genistin, and genistein),
enantiomers of perillyl alcohol and S-ibuprofen to human serum albumin (HSA). The analyses were performed on a Develosil and
Inertsil 100-Diol-5 column (10 cm×4.6mm). Sodium phosphate solution (pH 7.4, ionic strength 0.17) was used as the mobile phase
at a flow rate of 1 ml/min. To ensure the drug to be eluted as a trapezoidal peak with a plateau, injection volumes were each
fixed up the zonal profile with an evident plateau appears. The unbound drug concentration was determined from a plateau height
of the plateau region after that experimental data were fitted by Scatchard equation. The binding constants (K) and total
binding affinities (nK) of drugs to HSA were calculated, respectively. 相似文献
3.
The loading effects of the superstrate with various thickness on the circular polarisation (CP) performances of a cross-slot-coupled microstrip antenna are first investigated. Then, for improving the shifted centre frequency, the bad impedance matching, and the increased axial ratio, which are due to the superstrate effects, the key dimensions of the loaded antenna are adjusted to regain or even enhance the original unloaded CP performances. From the obtained experimental results, it is found that the CP bandwidth of the loaded antenna can be increased when the thickness of the superstrate is properly selected. 相似文献
4.
The amounts of isoflavones extracted from Korean soybean by various ultrasonic waves were compared using 60% aqueous ethanol
solution. The effect on extraction yield of variations in solvent composition, temperature, and extraction time was investigated.
The experimental results confirmed that ultrasonic waves are a desirable method to extract isoflavones from Korean soybean.
The highest yield of aglycone isoflavones was obtained by ultrasonic waves with a frequency of 20 KHz and an extraction time
of 10 min, which produced yields of glycoside and aglycone isoflavones three-fold greater than those by dipping method. 相似文献
5.
正你有没有发现,很多大型购物中心正在增加儿童业态的比重?在零售逐渐失去吸引力的时候,购物中心开始惦记着这一新生代,甚至开辟出超过15%-25%的经营面积专供儿童业态。拿北京来举例,北京最著名的王府井商圈,这两年逐渐调整成了亲子友善的消费场景。拥有200多年历史的英国哈姆雷斯玩具店之前在王府井百货大楼开设了全球最大旗舰店;apm王府井店引入了美国品牌Toys"R"Us(玩具反斗城);新中国儿童用品商店也调整了商场的总体布局, 相似文献
6.
Mi Soon Yeo Duk Hui Kang Se Kyung Kim Hyun Shik Yun Yoon Mo Koo Youn-Woo Lee Kyung Ho Row 《Korean Journal of Chemical Engineering》2002,19(5):815-817
Ceramide was prepared by the cultivation ofSaccharomyces cerevisiae from cell extracts by solvent exfraction and analyzed by NP-HPLC using a UV detector. The mobile phase was composed of hexane,
methanol, and IPA. From the experimental conditions, the composition of mobile phase was 72/5/23 (hexane/IPA/methanol, vol%).
Quantitative analysis of ceramide was performed. Based on the analytical conditions, the effect of cultivation temperature
for the production of ceramide was investigated and the optimum cultivation temperature was found to be 35°C.
This paper is dedicated to Dr. Youn Yong Lee on the occasion of his retirement from Korea Institute of Science and Technology. 相似文献
7.
Kyung Ho Row 《Korean Journal of Chemical Engineering》1989,6(4):347-349
The use of Reversed-Phase High Performance Liquid Chromatography (RP-HPLC) was investigated for the separation of oligonucleotides.
By the gradient elution with the mobile phase of methanol, 0.1 M KH2PO4 and 0.02 M MaCl2, the mixtures could be separated in a 250 mm × 4.6 mm I.D. column. The number of theoretical plates and resolution were compared
belween this technique and Micellar Electrokinetic Capillary Chromatography (MECC). The charged nucleic acid constituents
in the RP-HPLC were relatively better separated than in the MECC. 相似文献
8.
The effects of sample size, liquid loading, particle size, column length, and column temperature on retention volumes were
studied and separation factor, column efficiency, partition coefficient, and heat of solution were also obtained by gas-liquid
chromatography. The feed materials were chosen by similar boiling points as diethylether, dimethoxymethane and dichloromethane.
The relations between retention volume and above mentioned various variables were obtained. Separation factor was more affected
by column temperature than other variables, and decreased with the temperature. HETP increased almost linearly with sample
size. From the exponential relationship between partition coefficient and column temperature heat of solution of each material
was calculated. 相似文献
9.
A single-fed reconfigurable microstrip antenna that can provide various polarization diversities is presented in this paper. The antenna is excited by a microstrip feed line through aperture coupling. When two PIN diodes are used to respectively reconfigure the coupling slot and the open stub of the feed line, the polarization of the microstrip antenna can be switched between vertical and horizontal polarizations. For the reconfigurable antenna with the linear polarization diversity, it can be converted to a circularly-polarized antenna with switchable polarization sense by introducing a perturbation segment. Moreover, an antenna with the quadri-polarization diversity, including dual orthogonal linear polarizations and two circular polarizations, is also developed from the structure of the switchable circular polarization microstrip antenna, and only three diodes are required. Details of the antenna design are shown, and the measured results for the constructed prototype are also exhibited and discussed. 相似文献
10.
A microstrip antenna with broadband circular polarisation (CP) is presented. The proposed microstrip antenna has a circular patch and is excited by a series microstrip-line-feed configuration through the coupling of a ring slot in the ground plane. The broadband operation is achieved by coupling two CP resonant elements, which are due to the circular patch and the ring slot, respectively. A typical prototype using foam material of thickness 5 mm as the antenna substrate is constructed. Measured results show the 3 dB-axial-ratio bandwidth centred at 2500 MHz is more than 10%. 相似文献