四种含抗生素类物质保鲜剂对非洲菊切花衰老的影响

文中用灰黄霉素、林可菌素、土霉素及红霉素四种抗生素对非洲菊鲜切花瓶插的综合保鲜效果进行了对比试验.通过切花外部形态、生理效应的观察测定结果表明,含林可霉素或红霉素的保鲜剂具有良好的保鲜效果.     

Does endurance training improve red blood cell aging and hemorheology in moderate-trained healthy individuals?

ObjectiveTo examine the impact of a 6-week endurance training on red blood cell (RBC) aging and deformability of healthy participants to detect possible improved hemorheological and performance-related adaptations.MethodsA total of 31 participants (17 females and 14 males) performed a 6-week moderate training protocol (three 1-h running sessions per week at 70% of maximal heart rate). Blood was sampled before and after the training. RBCs from each participant were fractioned according to density and age into 4 RBC subfractions. Subfractions were examined for changes of RBC properties, including aging distribution, RBC deformability, RBC microparticles, and phosphatidylserine concentrations. RBC and plasma nitrite levels were measured as indicators of nitric oxide metabolism.ResultsAerobic performance, peak oxygen consumption, ventilatory thresholds, velocity at the aerobic–anaerobic threshold, and lactate at exhaustion improved after training. The relative amount of both young RBCs and old RBCs increased, and the amount of the main RBC fraction decreased. Phosphatidylserine externalization and RBC-derived microparticles decreased. Overall deformability expressed as shear stress required to achieve half-maximum deformation to theoretical maximal elongation index at infinite shear stress improved in unfractioned RBCs (p < 0.001). Nitrite decreased in total (p = 0.001), young (p < 0.001), main (p < 0.001), and old (p = 0.020) aged RBCs and in plasma (p = 0.002), but not in very old RBCs.ConclusionThese results indicate that non-endurance-trained healthy participants benefit from a regular moderate running training program because performance-related parameters improve and a younger RBC population with improved RBC properties is induced, which might support oxygen supply in the microcirculation.     

改进的元胞自动机人员疏散仿真模型研究

近几年来,地震、火灾等自然灾害频繁发生,恐怖袭击事件突发频率也呈日益攀升之势,公共安全问题成为社会热点,灾难突发时人员疏散问题的建模与仿真技术成为研究热点。立足已有的元胞自动机模型,充分考虑了人员在疏散时的心理特点和行为特点,提出了一种改进的元胞自动机模型,通过改进的元胞自动机模型对人员疏散问题进行建模与仿真,更加真实再现了行为人在紧急疏散时表现出来的从众性和自组织性,其研究成果为人群疏散仿真研究提供了有力支持。     

具分布时滞和变系数的细胞神经网络概周期解的存在性

利用Tychonov不动点定理,研究一类具分布时滞和变系数的细胞神经网络的概周期解的存在性,得到了一个全新的结果.它与文献[8]的结果是互不包含的.     

Isolation and physiological characteristics of a premature senescence mutant in rice(Oryza sativa L.)

INTRODUCTION Leaf senescence is a kind of programmed cell death (PCD) in plants that is highly controlled by a genetically programmed process involving degrada-tion of cellular structures, decline of photosynthesis massive generation of active oxygen species (AOS) and mobilization of nutrients (Nam, 1997; Lim et al.,2003). Many environmental factors have been shown to play a role in causing the photosynthetic decline to lead to premature senescence. Leaves exposed to ultraviolet radia…     

水稻免耕栽培生理基础——Ⅴ.免耕水稻叶片衰老与根系活力

以威优64、陆青早1号为材料,免耕提高了根系的a—萘胺氧化量、呼吸强度、叶片老化指数,降低了功能叶的过氧化物酶含量,延缓了叶片的衰老;主分量分析表明,功能叶光台速率、呼吸速率、绿叶面积、叶绿素含量、可溶性蛋白质含量、叶片含氮量、根系活力等,都可任选其一作为叶片衰老指标。     

Isolation and physiological characteristics of a premature senescence mutant in rice （Oryza sativa L.）

A rice pse(t) (premature senescence, tentatively) mutant line, was isolated from 4500 independent T-DNA inserted transgenic lines. The symptoms of premature senescence appeared more severely than those of the control plants (Zhonghua 11,japonica) at the last development stage. To characterize the mutant and provide basic information on the candidate genes by mapping to a physical region of 220-kb, experiments were carried out in two phytotrons under controlled temperature of 24 ℃ and28 ℃, respectively. The content of chlorophyll, soluble protein and MDA (malondialdehyde), net photosynthesis, the antioxidant enzyme activities of SOD (superoxide dismuase) (EC 1.15.1.1) and POD (peroxidase) (EC 1.11.1.7) and the peptidase activities of leaves were measured from top to bottom according to the leaf positions at the flowering stage. Compared with the control plant,the mutant showed the following characteristics: (1) Higher net photosynthesis rate (Pn) appeared in the 1 st and 2nd leaves, contents of chlorophyll and soluble protein were also higher in the 1 st leaf; (2) The activities of SOD, POD and peptidase were higher according to the leaf position from top to bottom; (3) The symptom of premature senescence was accelerated in the mutant at 28℃treatment. The MDA content and the SOD and POD activities between the 24 ℃ and 28 ℃ treatment mutants were not significantly different. Content of chlorophyll and soluble protein of leaves mutant decreased rapidly at 28 ℃ treatment. The results show that pse(t) is sensitive to high temperature. The probable function of PSE(T) is discussed.     

数字式非循环侧抑制网络在联想记忆中的应用

提出了基于侧抑制理论和细胞神经网络(CNN)的数字式非循环侧抑制网络，给出其用于数字图象联想记忆的算法，并给出了仿真结果。     

三唑酮预处理对蚕豆离体幼苗衰老的延缓作用

以蚕豆为试材研究发现,在蚕豆离体幼苗(W W)衰老过程中,叶绿体色素和蛋白质含量均不断下降,而细胞膜透性逐渐升高.用质量浓度10mg/L的三唑酮浸种(T W)和浸种后在苗期喷施10mg/L的三唑酮(T T)处理可提高蚕豆幼苗叶片叶绿体色素和蛋白质的含量,并且两种处理尤其是T T处理方式均抑制蚕豆离体幼苗叶绿体色素和蛋白质含量的降低及细胞膜透性增加.表明三唑酮具有保护膜结构和延缓衰老的作用.     

p16INK4a基因对NIH3T3细胞衰老影响的研究

p16^INK4a是细胞周期负调控因子，在多种细胞的衰老过程中起着关键作用．为了研究p16^INK4a的表达对小鼠成纤维细胞即NIH3T3细胞生长增殖的影响，将真核表达载体PRetro-onpl6通过逆转录病毒介导的方法将其转染至NIH3T3细胞中，经嘌呤霉素筛选，获得整合有p16基因的稳定细胞株NIH3T3／pRetro-on-p16，并通过脱氧四环素的诱导，观察到NIH3T3／pRetro-on-p16衰老的显著特征：细胞宽大铺展、形状不规则、折射率低等，并且细胞生长速度明显减慢．