Development of the expressed immunoglobulin μ chain repertoire during maturation of mice B cells

In the bone marrow and spleen, the developing B cell populations undergo both negative and positive selections to shape their B cell receptor repertoire. To gain insight into the shift of the immunoglobulin heavy (IgH) chain repertoire during B cell development, we undertook large scale Ig μ chain repertoire analysis of pre-B, immature B and spleen B cell populations. We found that the majority of V_H gene segments, V_H families, J_H and D gene segments, were observed to have significantly different usage frequencies when three B cell populations were compared, but the usage profile of the V_H, D, and J_H genes between different B cell populations showed high correlations. In both productive and nonproductive rearrangements, the length of CDRH3 shortened significantly on average when B cells entered the periphery. However, the CDRH3 length distribution of nonproductive rearrangements did not follow a Gaussian distribution, but decreased successively in the order 3n-2, 3n-1 and 3n, suggesting a direct correlation between mRNA stability and CDRH3 length patterns of nonproductive rearrangements. Further analysis of the individual components comprising CDRH3 of productive rearrangements indicated that the decrease in CDRH3 length was largely due to the reduction of N addition at the 5′ and 3′ junctions. Moreover, with development, the amino acid content of CDRH3 progressed toward fewer positively charged and nonpolar residues but more polar residues. All these data indicated that the expressed Ig μ chain repertoire, especially the repertoire of CDRH3, was fine-tuned when B cells passed through several checkpoints of selection during the process of maturation.     

降雨条件下黏性土坡微结构动态环境能场分析

【目的】研究降雨条件下黏性土坡位移场、应变场、微结构动态环境能场的变化及对土坡稳定性的影响。【方法】通过室内土坡模型试验,用读数显微镜观测降雨前后土坡内45个测点的位移,特意选择并全程观测斜坡面(1个)、坡脚(2个)、坡底(1个)的4个测点的位移,研究侧向位移和竖向位移随时间的变化,利用反分析方法分析土坡的位移场与应变场的变化,从宏观、中观、微观角度上分析黏性土坡微结构动态环境能场及外部环境条件变化与其内在介质环境变化之间的关系。【结果】降雨条件下坡顶和坡脚处土体的损伤程度较大,最大竖向位移发生在坡脚处;用常规方法分析土坡变形时会低估瞬时变形而夸大固结变形;由斜坡面、坡脚和坡底的蠕变曲线可见,降雨初期的瞬时竖向位移和侧向位移增长较快,但随着降雨时间的延长,土坡微结构受到损伤,竖向位移和侧向位移的增长变慢,最后趋于稳定。【结论】降雨引发的土坡滑移大多数是瞬时的,土坡的蠕变既是土体损伤的过程,也是土坡微结构能量耗散的过程。因降雨劈裂力的作用,在坡顶及斜坡面上会出现裂缝,而斜坡面和坡脚是最容易诱发险情的部位。     

供热计量中的几个问题

论述了供热计量中的温控阀设置、热计量户内系统、恒压差、恒流量装置等问题,值得业内有关工程技术人员借鉴。     

关于黑龙江省五常市城乡一体规划的若干认识

我国城乡规划随着经济社会的发展而不断得以重视,根据发展的需求,针对五常市城乡一体化结合情况进行了说明研究;并对五常市城乡一体化规划内容和方法进行了探讨。     

Effects of variable retention logging in the boreal forest on the bumble bee-influenced pollination community,evaluated 8–9 years post-logging

Boreal forests are currently facing intensified logging pressures, yet we know little about impacts of logging on the pollination community. This study extends research done immediately before and after logging, to consider its longer term effects. We censused bumble bee and flower communities 8–9 years after experimental variable retention logging. Harvest treatments left 0%, 10–20%, 50–75%, or 100% of the original trees after logging. Total bumble bee and floral abundances were increased by all forms of logging; however the floral community in retention cuts (i.e., 10–20% and 50–75% of trees remaining) was more similar to undisturbed controls than was the community in clearcuts. Bumble bees in low-retention treatments (i.e. 10–20%) were in an ideal free distribution (IFD) with their floral resources, which allows for equal per-flower rate of visitation, regardless of local flower density. In clearcuts (i.e. 0%) and high-retention areas (i.e. 50–75%) bees were at an IFD with respect to the density of their floral resources, but undermatched (in 50–75% treatments) or were resource-independent (in 0% treatments) with respect to the energetic value of their floral resources. Bees in unlogged forest controls (i.e., 100%) deviated from an IFD by undermatching. Overall, low-retention logging (10–20%) was an improvement over clearcutting, because there was less change to the floral community, while still allowing for the achievement of an ideal free distribution. However, unlogged forest appeared to be negatively affected (in the lack of an IFD) by the presence of adjacent logged forests: numerical responses of bees to flowers were altered, with implications for bee foraging success and plant pollination service. Forest reserves should therefore incorporate buffer zones when adjacent to logged forest, to preserve the inter-relationships in their bee-influenced pollination community.     

职业技能鉴定中的题库建设和命题技术研究

以化学检验工职业技能鉴定为例,对职业技能鉴定题库建设和试题编码、命题格式和命题要求等命题技术进行了系统的分析研究,提出了在合理制定鉴定要素细目表编码基础上,根据职业技能鉴定要素表命题,按照理论知识鉴定要素细目表和技能操作鉴定要素细目表中的代码进行全代码编码的编码方法,十分便于电脑随机抽取组合试卷。     

基于Shapley值的组合预测方法在福建省农业总产值预测中的应用

提出了基于Shapley值的农业总产值的组合预测方法。算例结果表明,该方法可有效提高农业总产值的预测精度。     

新梢生长势与果穗施用B9对巨峰葡萄坐果的影响

经3 a试验,调查巨峰葡萄新梢生长势与果穗施用B9对花的生长发育、受精能力、坐果及花朵营养状况的影响。结果表明:在花前用B9处理果穗对新梢生长没有明显影响,但有缩短旺梢果穗长度的倾向,对弱梢没有什么影响;B9能使旺、弱梢有籽果的坐果率显著提高,对无籽果坐果率则影响不大;新梢生长势与B9都影响花中的含氮量与含糖量,花前用B9处理果穗可提高花期花朵的蛋白质及全氮含量而糖含量皆因B9处理而下降。     

两种不同药性中药注射液对内毒素性肾衰的防治作用

摘要：以家兔为试验动物,研究复方金银花注射液和茵陈五苓注射液对内毒素所致急性肾功能衰竭的防治作用。将32只雄性健康成年家兔随机分为阴性对照组、模型组、复方金银花防治组和茵陈五苓防治组,每组各8只。模型组和各防治组家兔一次性静脉注射大肠杆菌O111B4内毒素生理盐水溶液,剂量为100μg/kg。两防治组家兔注射等剂量内毒素24h后静脉注射剂量为100μg/kg的中药注射液,阴性对照组静脉注射等量生理盐水。注射内毒素（或生理盐水）1h后开始通过膀胱瘘管收集尿液,每1h收集一次,共收集6h。末次收集尿液后心脏采血。结果表明,模型组家兔发生急性肾功能衰竭,其各项肾功能指标均与阴性对照组有显著或极显著差异（P<0.05,P<0.01）。与模型组比较,复方金银花组家兔的尿量以及肌酐、尿素氮和尿钠排出量显著或极显著增加（P<0.05,P<0.01）,肾衰指数和钠排泄分数显著降低（P<0.05）,内生性肌酐清除率、尿渗透压和尿血渗比及渗透物质清除率显著或极显著升高（P<0.05,P<0.01）,游离水清除率极显著降低（P<0.01）。结果表明,复方金银花注射液对内毒素性肾衰具有防治作用。茵陈五苓组家兔的尿量、肌酐和尿素氮随尿排出量、渗透物质清除率和内生性肌酐清除率在试验后期也较模型组显著改善。     

不同浓度2,4-D对罗布麻茎尖诱导成活率的影响

采用MS基本培养基,分别添加不同浓度的2,4-D、6-BAI、BA,筛选适合罗布麻组织培养的最佳培养基。结果表明:最适合罗布麻诱导分化的培养基为C(MS+2,4-D 0.9 mg/L+6-BA 1.5 mg/L+琼脂8 g/L+蔗糖30 g/L)、D(MS+2,4-D 1.1 mg/L+6-BA 1.5 mg/L+琼脂8 g/L+蔗糖30 g/L)。