降低地下卷取机助卷辊冲击负荷的措施

在理论分析和试验研究的基础上，找出地下卷取机助卷辊冲击负荷过大 的主要原因。通过调整工艺参数和设备状况，使助卷辊的冲击负荷显著降低。     

The effect of splenectomy on the development of experimental pyelonephritis

Summary Although an unusually high incidence of a variety of infections in infants who had undergone splenectomy has been reported by a number of investigators the subject remains somewhat controversial. In the present experiments the role of the spleen in the protection of rats against experimentally induced hematogenous pyelonephritis was studied. The results of this study suggest that the spleen has an important preventive function against bacterial infection.     

Intragenic tandem repeats generate functional variability

Tandemly repeated DNA sequences are highly dynamic components of genomes. Most repeats are in intergenic regions, but some are in coding sequences or pseudogenes. In humans, expansion of intragenic triplet repeats is associated with various diseases, including Huntington chorea and fragile X syndrome. The persistence of intragenic repeats in genomes suggests that there is a compensating benefit. Here we show that in the genome of Saccharomyces cerevisiae, most genes containing intragenic repeats encode cell-wall proteins. The repeats trigger frequent recombination events in the gene or between the gene and a pseudogene, causing expansion and contraction in the gene size. This size variation creates quantitative alterations in phenotypes (e.g., adhesion, flocculation or biofilm formation). We propose that variation in intragenic repeat number provides the functional diversity of cell surface antigens that, in fungi and other pathogens, allows rapid adaptation to the environment and elusion of the host immune system.     

Fermentation of xylose to produce ethanol by recombinant <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> strain containing <Emphasis Type="Italic">XYLA</Emphasis> and <Emphasis Type="Italic">XKS1</Emphasis>

Fermentation of the pentose sugar xylose to produce ethanol using lignocellulosic biomass would make bioethanol production economically more competitive. Saccharomyce cerevisise, an efficient ethanol producer, cannot utilize xylose because it lacks the ability to convert xylose to its isomer xylulose. In this study, XYLA gene encoding xylose isomerase (XI) from Thermoanaerobacter tengcongensis MB4T and XKS1 gene encoding xylulokinase (XK) from Pichia stipitis were cloned and functionally coexpressed in Saccharomyces cerevisiae EF-326 to construct a recombinant xylose-utilizing strain. The resulting strain S. cerevisiae EF 1014 not only grew on xylose as sole carbon source, but also produced ethanol under anaerobic conditions. Fermentations performed with different xylose concentrations at different temperatures demonstrated that the highest ethanol productivity was 0.11 g/g xylose when xylose concentration was provided at 50 g/L. Under this condition, 28.4% of xylose was consumed and 1.54 g/L xylitol was formed. An increasing fermentation temperature from 30℃ to 37℃ did not improve ethanol yield.     

生命表理论与方法

本文给出了寿命分布的极大似然估计, 从而给出了现时人口寿命各参数的严格的概率意义, 并利用1990年人口普查10%抽样数据, 求得中国人口寿命表和简略寿命表。     

关于两个随机变量序列共同收敛性的一个充分条件

本文简要的论证了在一定的条件下一个随机变量序列的某种收敛性可以由另一个随机变量序列的这种收敛性得到,从而为判断一个随机变量序列的这种收敛性提供了一种较为简便的方法。     

退火温度对NiCo2O4纳米材料析氧性能的影响

电催化水分解过程中,动力学缓慢的阳极氧析出反应,制约了全水分解制备氢气的效率,因此,制备高效、稳定的析氧催化剂是十分必要的.通过溶剂热和热处理的方法制备了 NiCo2O4纳米颗粒,研究了退火温度对材料电催化析氧性能的影响.通过XRD,Raman,SEM,TEM以及极化曲线测试等研究了不同退火温度下得到材料的结构、形貌和...     

骨桥蛋白在免疫中的作用

骨桥蛋白（OPN）是一种多功能的磷酸化糖蛋白,其涉及多种病理生理学过程.近来研究发现骨桥蛋白通过不同的翻译起始位点产生两种形式的蛋白,即分泌型骨桥蛋白（ sOPN,secreted OPN）和胞内型骨桥蛋白（iOPN,intracellular OPN）.本文主要介绍了sOPN及iOPN在免疫应答中的作用.     

宁夏贺兰山东麓扬黄新灌区土壤质量的演变

为系统认识宁夏贺兰山东麓扬黄新灌区土地在利用变化背景下,土壤质量演变的一般规律,用空间换时间的田间取样方法,分别从利用方式、土壤分层、利用年限的角度构建数据体系.结果表明,相对未利用对照地,耕地土壤中有机碳和盐分发生表聚现象,园地20～60cm土层中有机碳和盐分明显富集;随利用年限的延长,早期耕地和园地表层中有机碳和盐分含量都呈现先降后升的格局,但后期变化趋势出现分异.园地和耕地表层土壤中wC/N,wC/P随利用年限的延长表现出近似的变化趋势,但后期土壤中wC/N开始趋近于未利用对照地,土壤中C-N循环并未发生实质性改变.耕地、园地各自具有其独特的土地退化防治价值,但是园地具有更突出的生态适宜性,耕地长期利用下的次生退化问题依然需要关注.     

低周反复荷载下再生混凝土框架边节点受力性能试验研究

文章对再生混凝土框架边节点的受力性能进行了研究,通过2榀边节点试件在低周反复荷载下的试验,了解节点的破坏过程、承载能力、滞回曲线、耗能性能和延性指标,分析节点核心区剪切破坏和梁端弯曲破坏2种破坏模式对构件承载能力和延性性能的影响。研究表明,再生混凝土框架边节点构件发生梁端弯曲破坏时,纵向钢筋屈服,截面充分转动,滞回曲线丰满,具有良好的耗能能力,可满足抗震性能要求。