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本文系统的介绍了国际计量局(BIPM)2005~2007年度组织世界各国初级标准实验室放射性剂量的比对和刻度情况,以及BIPM到2009年的放射性剂量的比对和刻度计划. 相似文献
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XY Jiao E Tanczos T Dodic M Voigt J Haberstroh GB Stark 《Canadian Metallurgical Quarterly》1999,103(1):138-144
This study investigated the feasibility of prefabrication of a bilaminar-epithelialized flap by using a tissue expander and cultured keratinocytes, for reconstruction of perforate defects in the oral cavity and upper aerodigestive tract. In each of six rats, a 10-ml volume expander was implanted under the inferior epigastric flap and a thin silicon catheter was introduced into periexpander space. Seven days after implantation, 10 x 10(6) cultured keratinocytes, isolated from inbred donor rats, were suspended in fibrin glue and injected into the periexpander space through the catheter (n = 4 of 6). The expansion was started immediately after cell inoculation and lasted at least 3 weeks at the speed of 2 to 3 ml every 5 to 7 days. At the end of expansion, the periexpander space was opened and the capsule around the tissue expander was found to be covered completely with a neoepithelium. Thus, a bilaminar-epithelialized flap based on femoral vessels was elevated and successfully transferred to cover the excisional perforate defect in the oral cavity with the neoepithelial side as inner lining. All flaps treated with 10 x 10(6) cultured keratinocytes survived with complete wound healing during a 1-week follow-up (n = 4 of 6). Both macroscopic and histologic findings demonstrated that a bilaminar-epithelialized composite flap can be fabricated by using a tissue expander and keratinocyte-fibrin glue suspension. 相似文献
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EMLC1 is a hematopoietic stem cell line that depends on stem cell factor (SCF) for growth and generates lymphoid, erythroid and myeloid progenitors in the presence of different cytokines. We have studied signaling events leading to cell proliferation and differentiation of EMLC1 mediated by interleukin (IL)-4 and IL-9. It was found that IL-9 enhances SCF-induced cell proliferation and promotes erythropoietin (EPO)-dependent erythroid differentiation of EMLC1 cells. However, IL-9 alone cannot support the growth of this cell line. In contrast, IL-4 by itself is sufficient to promote the growth of EMLC1 cells, even in the absence of SCF. Antiphosphotyrosine immunoblots of total cell lysates demonstrated that IL-4 and IL-9 induce tyrosine phosphorylation of different cellular substrates. Both IL-4 and IL-9 stimulated tyrosine phosphorylation of SHP-2, whereas the 90-kD tyrosine phosphorylated protein induced by IL-9 stimulation is Stat3. We have also shown that IL-4 is much more potent than IL-9 in inducing the expression of primary response gene c-myc. It was further determined that c-myc antisense oligodeoxynucleotide blocked IL-4 supported cell growth. Taken together, these results indicate that IL-4 may serve as a growth-promoting factor for hematopoietic stem cells, and IL-9 enhances both growth and erythroid differentiation of primitive hematopoietic progenitors. The results also suggest that differences in tyrosine phosphorylation induced by IL-4 and IL-9 may in part determine their distinct biological functions. 相似文献
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Bovine serum albumin (BSA) labeled with 9,10-anthraquinone (AQ) shows a greatly enhanced photochemical fluorometric activity compared with that of free AQ. The spectral characteristics of the photoreduction product of conjugated AQ was investigated and large blue shifts in the excitation and emission bands compared with those of free AQ were observed. The enhancement in the photochemical reactivity can be employed for sensitive detection of labeled BSA by a simple in-situ photochemical kinetic fluorimetric method. The kinetic behavior of the photochemical reaction and the effects of some experimental conditions were investigated. The calibration graph was linear over the range 0-1.8 x 10(-7) M BSA. The detection limit was 1.2 x 10(-10) M BSA and the relative standard deviation was 2.24% for the 1.42 x 10(-8) M BSA (n = 7). 相似文献
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