解读“生长素既不促进也不抑制生长”

<正>在浙科版生物必修三中提到:植物激素作用的一个特点是低浓度促进作用,高浓度抑制作用。如图1所示,即为生长素浓1度小于c时,促进植物生长(b点之前,随着生长素浓度的增大,促进作用逐渐增强,b点促进作用最大;b点之后,随生长素浓度的增大,促进作用逐渐减弱);生长素     

知微见著——关于卢瑟福原子模型的估算分析

于细微处发现真理,在科学发现史上常有之.卢瑟福原子模型的提出就是一个典型的例子.在α粒子散射实验中,α粒子约有八千分之一的概率被靶原子反射回来.这一微小的反射概率却让卢瑟福惊讶不已,进而否定了早前的汤姆孙原子模型.根据动量定理和库仑定律,本文估算了α粒子与靶原子核之间的相互作用力,推算出原子核的合理大小约为原子大小的万...     

Basic fibroblast growth factor alleviates brain injury following global ischemia reperfusion in rabbits

The aim of this study was to explore the protective effect of basic fibroblast growth factor (bFGF) on brain injury following global ischemia reperfusion and its mechanisms. Brain injury following global ischemia was induced by four vessels occlusion and systemic hypotension. Twenty-four rabbits were randomized into three groups: group A, only dissection of vessels; group B, intravenous infusion of normal saline after reperfusion for 6 h; group C, 30 μg/kg bFGF injected intravenously at the onset of reperfusion, then infused with 10 μg/(kg·h) for 6 h. Serum neuron specific enolase (NSE), S-100B, tumor necrosis factor-α(TNF-α), interleukin-1 (IL-1), interleukin-8 (IL-8) were measured before ischemia, 30 min after ischemia, 0.5, 1, 3, 6 h after reperfusion. Brain water content was determined and cerebral histopathological damages were compared. NSE and S-100B were increased 1 h after reperfusion and reached their peaks 6 h after reperfusion, but were much higher in group B than those in group C 3, 6 h after reperfusion. In groups B and C, TNF-a was increased after ischemia and IL-1 and IL-8 were increased significantly 0.5 h after reperfusion, then reached their peaks 6 h, 3 h, 6 h after reperfusion respectively. TNF-a and IL-8 at the time points of 1 h and 3 h and IL-1 at 3 h and 6 h in group C were correspondingly lower than those in group B. These indices in group A were nearly unchanged. There were less severe cerebral histopathological damages in group C compared with group B, but no difference in brain water content. It could be concluded that bFGF alleviates brain injury following global ischemia and reperfusion by down-regulating expression of inflammatory factors and inhibiting their activities.     

游泳训练及联合补充线粒体营养素α-硫辛酸对wistar2型糖尿病大鼠血脂代谢及脂质过氧化水平的影响

目的:观察2型糖尿病(T2DM)模型大鼠,经8周游泳训练后,血脂代谢、血清氧化应激、血糖(FBG)、胰岛素敏感性(ISI)及肝脏组织二相酶活性变化,检测联合作用方式(游泳训练及联合补充α硫辛酸)对wistarT2DM大鼠血脂代谢及脂质过氧化水平的影响,并探讨其内在影响机制。方法:实验材料wistar大鼠60只,造模完成后随机分成4组,对照组(CON);α硫辛酸(LA);游泳运动组(SEX);α硫辛酸+游泳运动组(LA+SEX),每组15只。进行游泳训练共计8周,观察各组大鼠血脂代谢水平、FBG、ISI及肝脏组织二相酶活性变化。结果:经联合作用方式可极显著性降低wistar大鼠血清总胆固醇和甘油三酯水平,降低LDL-C含量和FFA水平,提高HDL-C;在降低FBG,提高ISI作用上存在叠加效应(P<0.01),对胰岛素水平无显著性影响;在改善血清氧化应激水平作用上(降低ROS和提高SOD),存在增强作用(P<0.01);对肝脏组织二相酶的影响,在对谷胱甘肽-S-转移酶(GST)和谷胱甘肽过氧化物酶(GPX)存在增强作用,对醌氧化还原酶1(NQO-1)则无此作用。结论:联合作用方式可以有效降低血清及肝脏脂质过氧化水平,纠正血脂代谢异常,提高ISI。其保护作用可能是通过降低机体氧化应激水平,维持机体血脂正常代谢水平,减少氧化应激而实现。提示,联合作用方式可以为治疗T2DM提供新思路。     

我国优秀女子射箭运动员赛前脑地形图指标的分析

采用神经电生理学与运动心理学相结合的方法,记录安静状态、运动表象、过度换气诱发试验和恢复期的脑电信号,对我国14名健将级优秀女子射箭选手的赛前脑电地形图指标进行了分析。结果表明赛前女子优秀射箭运动员的大脑应激水平提高,大脑的唤醒水平较高,注意力集中程度高,表现出中枢神经适应专项要求的调节能力较强,说明赛前运动员专项能力较强。同时提示:我国优秀女子射箭运动员神经系统承受长时间的负荷训练和比赛的耐受力略有欠缺。     

EFFECT OF EXERCISE ON THE ACTIVITY OF 5α-REDUCTASE IN THE CYTOSOL OF LIVER,KIDNEY AND PROSTATE

It has a different change in androgen in serum and some special tissue after exercise, and it is according to the sensate and time of exercise. It is necessary to study the metabolism of teststerrone in some tissue after exercise, This experiment is using the technology of thin chromatography to analyse the 5α-reductase in tissue and calculated the rate of T metabolism. Because of the activity of 5α-reducatase that is too low, that the activity of 5α-reducatase in muscle and brain has not been tested. The exercise could develop the activity of 5α-reducatase in liver, kidney and express the activity of 5α-reducatase in prostate.     

从Nα到Bμ空间的复合算子

介绍解析函数空间H（D）上的两个子空间Nα和Bμ构造Nα中的检测函数,结合解析函数φ：D→D的函数性质,研究了从Nα到Bμ及其子空间Bμ,0刚之间的复合算子的有界性与紧性．     

耐力训练和注射丙酸睾酮对雄性大鼠肝脏、心脏和腓肠肌 PPARα表达的影响

探讨持续性运动和耐力训练或注射丙酸睾酮对雄性大鼠体重增长、血脂水平以及肝脏、心脏及腓肠肌细胞内过氧化物体增殖活化受体α（PPARα）及其靶酶-酰基辅酶A氧化酶（AOX）的mRNA和PPARα蛋白量的影响。将40只SD大鼠随机分为4组：A为对照组，B为丙酸睾酮组，C为运动训练组，D为运动训练＋丙酸睾酮组。丙酸睾酮给药方式：每天皮下注射5mg／kg，每周6d，共6周。运动方式：采用跑台，速度为25m／min，每天1h，每周6d，共7周。结果发现：（1）B组和D组，实验后体重增长明显少于A组和C组（P〈0．05）；（2）D组的血清甘油三酯浓度，与A组相比，有降低的趋势（P〉0．05），而明显低于C组（P〈0．05）。总胆固醇、高密度脂蛋白胆固醇和低密度脂蛋白胆固醇浓度，各组之间无明显差异；（3）各组间的PPARα和AOX的mRNA表达均无明显差异：（4）在肝脏和心脏，C组与D组的PPARα水平明显高于A组（均为P〈0．001）。在腓肠肌，各组间PPARα水平无明显差异。结果表明：（1）注射丙酸睾酮和运动训练加注射丙酸睾酮可以明显控制体重的增长。这种作用可能与血清甘油三酯水平降低有关；（2）持续性运动在翻译及翻泽后水平上调了心脏和肝脏PPARα基因的表达，对腓肠肌PPARα基因的表达无明显作用；（3）丙酸睾酮对心脏、肝脏和腓肠肌PPARα水平无明显调节作用．可能通过其他机制发挥作用。     

Ti-80钛合金冲击韧性及力学性能异常原因探析

Ti-80是一种近α型钛合金,应用非常广泛,检测一组Ti-80冲击试样时,发现冲击韧性存在差别,分析了出现差别的原因.根据分析,初生α相含量以及形状不同,是导致冲击韧性出现差别的主要原因,而导致初生α相含量以及形状不同的可能原因则是Ti-80钛合金在热处理时温度不均.     

Blogα空间到QT,s空间的积分型算子的有界性

对Bαlog空间到QT,s空间的积分型算子为有界算子进行等价刻画.利用|f|(z)的估计讨论了Bαlog空间到QT,s空间的积分型算子(CΦJτf)(z)=∫0Φ(z)f(ξ)τ′(ξ)dξ和(CΦJτf)(z)=∫0z(f°Φ)(ξ)τ′(ξ)dξ的有界性,并给出了Bαlog空间到QT,s空间的积分型算子有界的充分必要条件.