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1.
Lizbeth Laureano-Prez R. Coll R. Fitzgerald Iisa Outola L. Pibida 《Applied radiation and isotopes》2007,65(12):1368-1380
A new radioactivity solution standard of 210Pb has been developed and will be disseminated by the National Institute of Standards and Technology (NIST) as standard reference material (SRM) 4337. This new 210Pb solution standard is contained in a 5 mL flame-sealed borosilicate glass ampoule, consists of (5.133±0.002) g of a nominal 1 mol L−1 nitric acid solution, has a density of (1.028±0.002) g mL−1 at 20 °C, has carrier ion concentrations of about 11 μg Pb2+ and 21 μg Bi3+ per gram of solution, and is certified to contain a massic activity (9.037±0.22) kBq g−1 as of the reference time 1200 EST, 15 June 2006. All of the uncertainties cited above correspond to standard uncertainties multiplied by a coverage factor k=2. The standardization for the 210Pb content of the solution was based on 4πβ liquid scintillation (LS) measurements using CIEMAT/NIST 3H-standard efficiency tracing (CNET). Confirmatory determinations were also performed by high-resolution HPGe γ-ray spectrometry, by 2π spectrometry with a Si surface barrier detector of separated 210Po, and by 4πβ(LS)–γ(NaI) anticoincidence counting. 相似文献
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Gallyas F Csordás A Schwarcz A Mázló M 《Experimental brain research. Experimentelle Hirnforschung. Expérimentation cérébrale》2005,160(4):473-486
Dark neurons were produced in the cortex of the rat brain by hypoglycemic convulsions. In the somatodendritic domain of each affected neuron, the ultrastructural elements, except for disturbed mitochondria, were remarkably preserved during the acute stage, but the distances between them were reduced dramatically (ultrastructural compaction). Following a 1-min convulsion period, only a few neurons were involved and their environment appeared undamaged. In contrast, 1-h convulsions affected many neurons and caused swelling of astrocytic processes and neuronal dendrites (excitotoxic neuropil). A proportion of dark neurons recovered the normal structure in 2 days. The non-recovering dark neurons were removed from the brain cortex through two entirely different pathways. In the case of 1-h convulsions, their organelles swelled, then disintegrated and finally dispersed into the neuropil through large gaps in the plasma membrane (necrotic-like removal). Following a 1-min convulsion period, the non-recovering dark neurons fell apart into membrane-bound fragments that retained the compacted interior even after being engulfed by astrocytes or microglial cells (apoptotic-like removal). Consequently, in contrast to what is generally accepted, the dark neurons produced by 1-min hypoglycemic convulsions do not die as a consequence of necrosis. As regards the case of 1-h convulsions, it is assumed that a necrotic-like removal process is imposed, by an excitotoxic environment, on dark neurons that previously died through a non-necrotic pathway. Apoptotic neurons were produced in the hippocampal dentate gyrus by intraventricularly administered colchicine. After the biochemical processes had been completed and the chromatin condensation in the nucleus had reached an advanced phase, the ultrastructural elements in the somatodendritic cytoplasm of the affected cells became compacted. If present in an apparently undamaged environment such apoptotic neurons were removed from the dentate gyrus through the apoptotic sequence of morphological changes, whereas those present in an impaired environment were removed through a necrotic-like sequence of morphological changes. This suggests that the removal pathway may depend on the environment and not on the death pathway, as also assumed in the case of the dark neurons produced by hypoglycemic convulsions. 相似文献
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目的 评估我国吸烟人群因吸烟所致内照射剂量并与其他国家进行比较。方法 收集并分析国内外香烟中210Po/210Pb辐射水平,推荐主流烟雾中210Po/210Pb份额,进行我国吸烟者因吸烟所致内照射剂量估算。结果 2015年中国15岁及以上成人现在吸烟者为3.2亿,日平均吸烟量为15.2支;按文献中香烟品牌数量加权的210Po /210Pb活度均值分别为28.2 mBq/支和39.3 mBq/支;在剂量估算中,210Po主流烟雾份额采用模拟装置和志愿者实验结果均值20%,210Pb主流烟雾份额采用模拟装置实验结果10%。根据我国日平均吸烟量和现在吸烟者人数估算的我国现在吸烟者年有效剂量为126 μSv·a-1,集体有效剂量为40746 人·Sv。结论 我国香烟中210Po/210Pb含量约为其它国家香烟的2~3倍,但由于本文采用的主流烟雾份额和210Po/210Pb剂量转换系数不同于其它文献,所以本文估算的我国吸烟人员吸20支烟所受剂量低于部分国家。 相似文献
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细胞培养中支原体污染的去除 总被引:1,自引:0,他引:1
在运用细胞培养手段的生物学研究和生物工程产品中,支原体污染仍是一个颇为棘手的问题。11株人的细胞SPC-A1、K562、HUT-102、BT-325、6T-CEM、NKM-45、CNE、HL-60、QGY-7701、QZG、人羊膜细胞;3株小鼠细胞P388-1、YAC-1、P815;1株绒猴细胞B95-8;和一株杂交瘤QKT3等,已污染了支原体的细胞经MC-210 1μg/ml处理7天,支原体污染 相似文献
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Young semi-domesticated pigeons captured or hatched from eggs gathered in Bratislava during 1989–1991 were examined for complement fixing antibodies to Chlamydia psittaci and agglutinating antibodies to Coxiella burnetii. Antibodies to Ch. psittaci were present in 76% of birds younger than 24 h, in 47.7% between 1 and 10 days of age and in 12% of nestlings over 10 days old. Antibodies to Ch. psittaci were also detected in crop milk of 4.1% of 1 to 10 day old birds and in 4.5% of specimens older than 10 days. Antibodies to C. burnetii were not found in juvenile birds under 24 h old, but antibodies against this agent were present in 16.4% birds between 1 and 10 days old and in 18% over 10 days old. Antibodies to C. burnetii were also detected in crop milk collected from crops of 2% of the young birds between 1 and 10 days. 相似文献
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目的探讨大黄-丹参通过miRNA-155对脓毒症大鼠血清中炎症因子水平的影响。方法 Wistar大鼠分为正常对照组、脓毒症模型组、大黄-丹参中药组、miRNA-155抑制剂组,每组15只。除正常组大鼠外,其余大鼠建立脓毒症模型,在此基础上给予相应的药物干预。在造模3 h后检测大鼠血清中IL-6、IL-10水平;应用RT-PCR检测大鼠血清中miRNA-155的表达。结果脓毒症模型组大鼠血清miRNA-155表达、IL-6和IL-10水平较正常对照组高(P0.05),大黄-丹参中药组和miRNA-155抑制剂组的miRNA-155表达、IL-6和IL-10水平均较脓毒症模型组低(P0.05),大黄-丹参中药组和miRNA-155抑制剂组的miRNA-155表达、IL-6和IL-10水平差异无统计学意义(P0.05)。结论大黄-丹参或可通过miRNA-155降低脓毒症大鼠血清IL-6、IL-10水平,从而减轻脓毒症炎症反应。 相似文献
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目的 探讨miR-4319与泛素特异性蛋白酶2(USP2)表达的相关性以及miR-4319靶向USP2通过核转录因子κB(NF-κB)信号通路对乳腺癌细胞侵袭的影响.方法 实时荧光定量PCR(qRT-PCR)检测miR-4319在正常乳腺癌上皮细胞(MCF10A)、低侵袭性乳腺癌细胞(MCF7)和高侵袭性乳腺癌细胞(M... 相似文献