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971.
季延红 《西安交通大学学报(医学版)》2012,33(3):261-265
重组激活基因(recombination activating gene)1和2编码的RAG1和RAG2蛋白通过对V(D)J重组起始阶段的调节作用,使得抗原受体基因重排严格地按组织、细胞发育阶段进行。本文将就RAG蛋白结合和催化断裂抗原受体基因机制作简要介绍。这些新发现明确了体内V(D)J重组发生的部位以及其出现错误时可能发生的地方,提示V(D)J重组机制不仅对淋巴细胞正常发育起关键性作用,而且对基因组不稳定性和淋巴系统恶性肿瘤的发生也具有重要意义。 相似文献
972.
《西安交通大学学报(医学版)》2016,(5):689-692
目的探讨核苷酸切除修复交叉互补基因(excision repair cross complementation 1,ERCC1)、3型β微管蛋白编码基因(ClassⅢβ-tubulin,TUBB3)和DNA拓扑异构酶Ⅱα(TopoisomeraseⅡA,TOP2A)mRNA在小儿肾母细胞瘤组织中的表达及临床意义。方法收集18例肾母细胞瘤组织标本及14例癌旁组织标本,通过分支-DNA液相芯片法检测标本中ERCC1、TUBB3、TOP2A mRNA的表达水平,并分析上述基因表达与肾母细胞瘤临床病理的关系。结果肾母细胞瘤组织中ERCC1、TUBB3和TOP2A高表达率分别为44.4%、50.0%和66.7%,均显著高于癌旁组织的7.1%、7.1%和14.3%,差异有统计学意义(P<0.05)。ERCC1高表达率与肾母细胞瘤临床分期和病理类型有关(P<0.05),TOP2A高表达率与肾母细胞瘤临床分期相关(P<0.05)。结论小儿肾母细胞瘤组织中ERCC1、TUBB3和TOP2A mRNA表达高于癌旁组织,可能参与肾母细胞瘤的发生发展过程。 相似文献
973.
Xander Olsthoorn 《运输规划与技术》2013,36(1):105-133
Transport accounts for about 25% of global CO 2 emissions. Transport activities are on the rise in the coming decades. Would associated CO 2 emissions move upwards as well, and at what rate? The present paper explores the future of these CO 2 emissions, starting from four scenarios for global transport. Considering fuel consumption, energy efficiencies in transport, occupancy rates of transport means, size of cars on the market, and possible environmental policies we find CO 2 emissions are persistently increasing, especially in the less wealthy areas of the world. In Europe, policies that attempt to control mobility and also limit CO 2 emissions may succeed in reducing emissions growth by about 30%. Efforts to increase energy efficiency of transport, in particular road transport, would contribute most to such reduction. 相似文献
974.
使用热硫化热补方式,修理皮带撕裂工作量大,维修时间长,严重影响企业生产.新的皮带机修补技术T2胶枪应运而生.阐述了该T2胶枪的技术原理、T2胶枪的结构、特点和使用工序.通过应用实例,证明该技术取得良好的经济效益,为用户提供了一种创新的维修理念. 相似文献
975.
Cristina Misic Michela Castellano Nicoletta Ruggieri Anabella Covazzi Harriague 《Journal of Marine Systems》2008,73(1-2):123-137
The variations in the expression of two hydrolytic ectoenzymes (leucine aminopeptidase – LA – and β glucosidase — BG) were studied in the southern Tyrrhenian Sea during spring 2004. This area is characterised by a complex morphology and hydrodynamism, which generate significant differences between different sectors, particularly in the 0–100 m layer. However, the area generally exhibits oligotrophic features such as low autotrophic pigment and organic matter concentrations and a higher bacterial biomass than the phytoplanktonic one. Despite this general bottom-up pressure, adaptations by the microbial consumers were indicated by the ectoenzymatic activities and by the relationships between the enzymes, their organic substrates and their producers (namely the bacteria). In particular, bacteria were able to exploit the inorganic N supply (nitrite + nitrate provided by irregular intrusions of intermediate waters) to escape the bottom-up limitation and produce enzymes such as BG devoted to the degradation of cellulose remnants and, therefore, also able to take advantage on this refractory organic matter. In the 200–800 m layer, where trophic limitation was strong due to the low values of potentially-labile organic matter (namely proteins), the peculiar hydrodynamism led to the formation of nepheloid layers rich in organic matter, which provided the bacteria with substrates and allowed the development of a significant correlation between LA activity and its own organic substrate. Furthermore, a reduction of the bottom-up pressure was also indicated by a higher mean bacteria cell size in the entire water column of the central and eastern sectors, and a significantly increased expression of BG related to the increase in the cell size.The ectoenzymatic activities, therefore, suggested that the southern Tyrrhenian Sea should be considered as a mosaic of subsystems, where the peculiar hydrological features stimulate bacterial adaptations and enhance the channelling of energy embedded in refractory materials into the food web. 相似文献
976.
阐述站内一体化轨道电路的由来以及我国高速铁路和客运专线将采用的站内ZPW-2000一体化轨道电路的技术方案;从轨道电路和CTCS-2级列控系统安全性的角度,对站内一体化轨道电路列控信号电流减弱、道岔跳线断线、绝缘节破损、短轨道区段对列控车载设备工作的影响、站内轨道电路电气连接和电缆使用等方面的问题进行了分析,并提出一些解决方案或思路。 相似文献
977.
ABSTRACTRisk assessment in maritime domain is one of the most cited topics since maritime transportation poses potential hazard for human life, marine environment and property. To mitigate risk and enhance safety awareness in maritime transportation, safety researchers have been seeking proactive solutions. This article prompts a quantitative risk-based approach combining interval type-2 fuzzy sets (IT2FSs) with failure mode and effect analysis (FMEA) to perform a comprehensive risk analysis. Thus, potential failure modes and their effects are revealed by calculating risk prioritisation numbers (RPNs). Whilst the FMEA method provides a robust risk analysing tool with relevant control options, the IT2FSs deals with ambiguity and vagueness of linguistic assessment of decision-makers through the FMEA. Hence, expert’s linguistic assessment in risk assessment can be transformed into useful information in terms of enhancing safety and pollution prevention in maritime industry. To demonstrate the proposed approach, potential failures and effects of a real shipboard oil spill case are handled. The findings show that incomplete information exchanged with local maritime authorities, malfunction of oil skimmer and poor organization of shoreline clean-up team are the most important failures during case of oil spill. The proposed approach provides not only theoretical insight into the maritime transportation industry but also practical contributions to chemical/oil tanker safety and environmental protection by mitigating risk in terms of technical or operational aspects. 相似文献
978.
979.
模拟40 t轴重矿石车的牵引梁下盖板与枕梁下盖板的对接焊缝形式,采用单面焊双面成型(加陶瓷衬垫)的工艺方法进行试验,并通过对焊接接头的力学性能检验、微观组织观察和分析,证明了该工艺的可行性,现已应用于出口澳大利亚铁路货车的批量生产中. 相似文献
980.
算法首先将离散点与约束边界点一起进行Delaunay三角剖分,形成初始Delaunay三角网,然后将约束边界上的各条约束线段通过局部更新依次嵌入已有的三角网,最后再删除多余的三角形,从而得到带内外边界约束的平面点集Delaunay三角剖分. 相似文献