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排序方式: 共有9141条查询结果,搜索用时 15 毫秒
961.
Don Woong Choi Jee Yeun Kim Seon Hee Choi Hee Su Jung Hyo Joo Kim So Yean Cho Chan Soon Kang Seung Yeup Chang 《Food chemistry》2006
Although it has been known that pomegranate (Punica granatum L.) contains several steroid hormones, concrete experimental proofs about that have not been published until now. In order to identify and evaluate the contents of steroid hormones including estrone in pomegranate, we analyzed pomegranate seed, fruit juice and commercial preparations. We developed a reproducible and sensitive method for separation and identification of steroid hormones in pomegranate samples using both high performance liquid chromatography (HPLC)–PDA and gas chromatography (GC)–MS. In case of HPLC, an isocratic elution method using 35% aqueous acetonitrile solution at 1.0 ml/min with photodiode-array (PDA) detection at 225 nm and 254 nm was found to optimally separate and identify the steroid hormones from the pomegranate samples with a run time of less than 30 min. The pomegranate samples were comparatively analyzed to the HPLC results by GC/FID or GC/MS detection on a HP-1 (30 m length, 0.32 mm I.D.) with helium as carrier gas under the oven temperature control as follows: start 220 °C for 5 min, raising 5 °C per min, final 280 °C for 10 min. The HPLC and GC methods were successfully applied to the identification of steroid hormones in pomegranate samples. Our results suggested that there were no steroid estrogens including estrone, estradiol and testosterone in pomegranate seed, fruit juice and preparations. Consequently, we assumed that the previously reported analysts of pomegranate were misunderstood their analytical results according to either the estrogen-like effects or similarity of peak retention time and Rf values in experiments. 相似文献
962.
Concept development of an underground research tunnel for validating the Korean reference HLW disposal system 总被引:5,自引:0,他引:5
Sangki Kwon W.J. Cho P.S. Han 《Tunnelling and Underground Space Technology incorporating Trenchless Technology Research》2006,21(2):203-217
In order to dispose of high-level radioactive waste (HLW) safely in geological formations, it is necessary to assess the feasibility, safety, appropriateness, and stability of the disposal concept at an underground research laboratory (URL) constructed in the same geological formation as the host rock. In this study, minimum requirements and the conceptual design for an efficient construction of a small scale URL were derived based on a literature review. To confirm the validity of the conceptual design for construction at KAERI, a geological survey including a seismic refraction survey, electronic resistivity survey, borehole drilling, and in situ and laboratory tests were carried out. The mechanical stability of the URL was investigated with a consideration of the surface topography, tunnel geometry, tunnel slope, sequential excavation, in situ stress ratio, erosion effect, and rock property variation along the tunnel using the three-dimensional code, FLAC3D. From the study, it was possible to conclude that the small scale URL will be effectively constructed in a granite mass at KAERI and will satisfy the minimum requirements. 相似文献
963.
Shin K. Weize Xiong Chung Yeung Cho Cleavelin C.R. Schulz T. Schruefer K. Patruno P. Smith L. Tsu-Jae King Liu 《Electron Device Letters, IEEE》2006,27(8):671-673
The impact of stress induced by biaxial mechanical bending on multiple-gate FET (MuGFET) performance is studied. For relatively low levels of bending-induced surface strain (/spl sim/ 0.1%), significant enhancements in the driving current can be achieved and maintained with gate-length scaling. This makes package strain a potentially attractive approach to enhancing MuGFET-based CMOS performance at low cost. For bending-induced strain, the enhancements in electron mobility and [110] hole mobility are well predicted by the piezoresistance model using the coefficients for bulk-Si, but the impact of stress on (100) hole mobility is more complex. 相似文献
964.
Martini R. Bethea C. Capasso F. Gmachl C. Paiella R. Whittaker E.A. Hwang H.Y. Sivco D.L. Baillargeon J.N. Cho A.Y. 《Electronics letters》2002,38(4):181-183
Experimental results for an optical free-space high-speed link using direct modulated mid-infrared (λ = 8.1 μm) quantum cascade lasers are presented. A total of 800 digitally encoded multimedia channels were transmitted. The reliability of the system against weather influence (fog) was experimentally compared to that of a near-infrared (λ = 0.85 μm) link 相似文献
965.
KC Park KH Kim SW Youn JH Hwang KH Park JS Ahn YG Kim SD Kim DY Lee JH Choe JH Chung KH Cho 《Canadian Metallurgical Quarterly》1998,139(6):1087-1091
Bowenoid papulosis (BP) of the genitalia, characterized by the histological findings of a squamous cell carcinoma, follows a largely benign clinical course. The detection of oncogenic human papilloma viruses (HPV) from BP points to an aetiological role of these viral infections. A 47-year-old man with multiple genital skin lesions was seen over a 10-year period with the diagnosis of BP. Recently, he attended again with a recurrent genital tumour that was diagnosed as squamous cell carcinoma. His genital lesions progressed and became polymorphic in appearance, from a wart-like tumour to a reddish invasive plaque. To screen for the presence of different HPV sequences from different skin lesions and to correlate each HPV type with distinct clinical manifestations, polymerase chain reaction and single-strand conformational polymorphism (PCR-SSCP) were performed. PCR-SSCP revealed the presence of several types of HPV from different genital lesions. Sequencing results disclosed that he had a mixed infection of HPV6b, HPV16, HPV18 and HPV33, respectively. Interestingly, the clinical findings were fairly well correlated with the oncogenic potential of HPV found from each lesion. 相似文献
966.
The behaviors of concentric-double inclusions dispersed in continuous media are investigated theoretically to find some possibilities
of improving toughness of composite materials by dispersing double-inc’usions instead of single-inclusions. The general solutions
of the Stokes equation, expressed in terms of the spherical harmonics, are used for analyzing the problems that are related
to the concentric-double inclusions. From the analysis, it is found that the pressure and stress fields inside and outside
the inclusion can be modified by changing the modulus ratios and the thickness of shell layer. Especially, the positions of
the minimum pressure points and the maximum stress points turn out to be controllable with some degree of freedom. 相似文献
967.
968.
SH Cho JY Seo DC Choi HJ Yoon YJ Cho KU Min GK Lee JW Seo YY Kim 《Canadian Metallurgical Quarterly》1996,26(10):1210-1219
BACKGROUND: There have been many studies concerning pathological changes in bronchial mucosa from asthmatics; however, few studies has been carried out to evaluate pathological changes according to the severity of asthma. OBJECTIVE: This study was designed to evaluate the cellular components in bronchoalveolar lavage fluid (BALF) and histological abnormalities in asthmatics according to the severity of asthma. METHODS: Bronchoalveolar lavages, bronchoscopic biopsies and ultrastructural examinations were performed in 13 asthmatics and 11 (BAL) or four (biopsies) non-asthmatic controls. The proportions of epithelial cells and correlations with PC20Meth which reflects bronchial hyperresponsiveness. Light microscopic examination revealed loss of epithelium, inflammatory cell infiltrations and thickening of the basement membrane which also showed significant correlation with PC20Meth. Hypertrophy of airway smooth muscles and hyperplasia of mucous glands were prominent in asthmatics but there was no difference according to the severity of asthma. Ultrastructural examination revealed that basement membrane thickening on light microscopic examination is due to the increased subepithelial collagen deposition with normal thickness of basal lamina. CONCLUSION: These data suggest that loss of epithelial cells, infiltration of inflammatory cells, especially eosinophils, and increased deposition of subepithelial collagen play major roles in determining the severity of asthma and non-specific bronchial hyperresponsiveness. 相似文献
969.
Ketones react with primary amines in dioxane at 180 °C in the presence of a catalytic amount of a ruthenium catalyst to give the corresponding α-alkylated ketones in moderate to good yields. With alkyl(methyl) ketones, the alkylation takes place exclusively at less-hindered methyl position over α-methylene. 相似文献
970.
Young-Gyu Kim Seok-Beom Cho Pil-Jong Kim Boo-Kil Kwon 《Journal of Mechanical Science and Technology》2006,20(3):329-334
This paper presents the evaluation of LPG (Liquefied petroleum gas) regulators for home use. For the evaluation, several properties
of the regulators were experimentally analyzed, such as the operation of safety device, the adjusting and lock-up pressure,
the adjusting spring and the diaphragm, with respect to the used time of the regulators. Experimental results showed that
the initial operation performances of regulators were degraded with increase of the service time and also showed that the
degradation of the performance and material property could become serious after about six-year-use of the regulators. 相似文献