57 resultados para D., D. S. C. D. L. T.
em Chinese Academy of Sciences Institutional Repositories Grid Portal
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聚(ε┐己内酯)/聚(d,l┐丙交酯)共混物膜在酶促降解过程中的形态变化张杰甘志华*梁奇志景遐斌(吉林工业大学理学院应用化学系长春)(中国科学院长春应用化学研究所长春130022)关键词聚己酸内酯-聚丙交酯共混物,酶促降解,形态1997-10-30收…
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采用一种新型的稀土配位化合物Y(CF3COO)3/Al(i-Bu)3为催化剂,制备了不同组成的ε-己内酯/d,l-丙交酯共聚物,并用GPC、NMR和DSC表征了共聚物的结构.结果表明通过改变初始投料中两种单体的比例,可以调节共聚酯的化学结构,而共聚物的形态则受结构影响很大.
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本论文研究了从圆斑蛙蛇泰国亚种(Daboia russellii siamensis蛇毒中纯化的C型凝集素样蛋白Dabocetin和L氨基酸氧化酶DRSAO的理化性质、生物学活性和分子克隆。Dabocetin是分子量约为28扔。的异二聚体蛋白,它由分子量约为15.0kDa和14.5kDa的两个同源亚基以和p共价结合形成。N-末端氨基酸序列比较显示,Dabocetin与目前已知的蛇毒c型凝集素样蛋白有很高的同源性。即使在终浓度达50.0。叫而时,Dabocetin也不能直接诱导血小板聚集。此外,在终浓度为40.00μg/ml,Dabocetin几乎不能抑制由AdP,TMVA和stejnulxin诱导的血小板聚集。但是,Dabocetin呈剂量依赖地抑制瑞斯托霉素诱导的血小板凝集,其半数抑制率ICS。值为10.80ug/ml流式细胞仪分析表明,Dabocetin显著抑制单克隆抗体522与GPIba的结合,提示Dabocetin很可能是一个GPIb结合蛋白。从圆斑蛙蛇的毒腺中克隆到了7个编码不同蛇毒C型凝集素样蛋白亚基的七DNA(命名为DRs1至DRs7)。其中,DRsLS码Dabocetin的a亚基,DRS6编码Dabocetin的p亚基。DRs1和DRS2很可能是圆斑蛙蛇毒腺中表达的X因子激活剂的两条轻链LCZ和LCI的山NA。DRS3,DRS4和DRSL7可能是圆斑蛙蛇毒腺中表达的C型凝集素样蛋白p亚基的。NA。DRsLAO是一个新的L氨基酸氧化酶,比活力为1.98U加噶。十二烷基磺酸钠一聚丙烯酞氨凝胶电泳(SDs-PAGE)分析显示,该酶在还原和非还原条件下均呈现一条蛋白带,表观分子量约为58kDa。N-末端氨基酸序列比较显示,DRSAO与目前已知的蛇毒L氨基酸氧化酶有很高的同源性。该酶的最适底物为L亮氨酸,最适pH为8.8。DRsAo呈剂量依赖地抑制扔P和仆IvA诱导的血小板聚集,其半数抑制率ICS。值分别为32.8μg/ml32.3μg/mlDRS-LAO对金黄色葡萄球菌(灯Cc25923)和耐甲氧西林金黄色葡萄球菌有较强的抗菌作用。DRsAO对金黄色葡萄球菌必Tcc25923)的最低抑菌浓度卿C和最低杀菌浓度耐甲氧西林金黄色葡萄球菌的孤CS。和呱Cg。值分别为18.。林留时和36.0μg/mlDRSLAo对耐甲氧西林金黄色葡萄球菌的MBC50和MBCg。值分别为36.0μg/ml72.0μg/ml通过对DRSAO的分子克隆,得到了编码DRS-AO的部分cDNA序列。
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由于2酮L古龙酸还原酶(简称KGR)的存在,理论上造成了Vc合成前体2酮L古龙酸(简称2KLG)部分被还原成L艾杜糖酸[1,2],影响了Vc二步发酵的产率。而从L山梨糖到2酮L古龙酸的转化中,除被KGR催化的还原负反应外,均属...
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Yields, correlation shapes, and mean transverse momenta p(T) of charged particles associated with intermediate-to high-p(T) trigger particles (2.5 < p(T) < 10 GeV/c) in d + Au and Au + Au collisions at root s(NN) = 200 GeV are presented. For associated particles at higher p(T) greater than or similar to 2.5 GeV/c, narrow correlation peaks are seen in d + Au and Au + Au, indicating that the main production mechanism is jet fragmentation. At lower associated particle pT < 2 GeV/c, a large enhancement of the near- (Delta phi similar to 0) and away-side (Delta phi similar to pi) associated yields is found, together with a strong broadening of the away-side azimuthal distributions in Au + Au collisions compared to d + Au measurements, suggesting that other particle production mechanisms play a role. This is further supported by the observed significant softening of the away-side associated particle yield distribution at Delta phi similar to pi in central Au + Au collisions.
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Balance functions have been measured for charged-particle pairs, identified charged-pion pairs, and identified charged-kaon pairs in Au + Au, d + Au, and p + p collisions at root s(NN) = 200 GeV at the Relativistic Heavy Ion Collider using the STAR detector. These balance functions are presented in terms of relative pseudorapidity, Delta eta, relative rapidity, Delta y, relative azimuthal angle, Delta phi, and invariant relative momentum, q(inv). For charged-particle pairs, the width of the balance function in terms of Delta eta scales smoothly with the number of participating nucleons, while HIJING and UrQMD model calculations show no dependence on centrality or system size. For charged-particle and charged-pion pairs, the balance functions widths in terms of Delta eta and Delta y are narrower in central Au + Au collisions than in peripheral collisions. The width for central collisions is consistent with thermal blast-wave models where the balancing charges are highly correlated in coordinate space at breakup. This strong correlation might be explained by either delayed hadronization or limited diffusion during the reaction. Furthermore, the narrowing trend is consistent with the lower kinetic temperatures inherent to more central collisions. In contrast, the width of the balance function for charged-kaon pairs in terms of Delta y shows little centrality dependence, which may signal a different production mechanism for kaons. The widths of the balance functions for charged pions and kaons in terms of q(inv) narrow in central collisions compared to peripheral collisions, which may be driven by the change in the kinetic temperature.
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We report a measurement of high-p(T) inclusive pi(0), eta, and direct photon production in p + p and d + Au collisions at root s(NN) = 200 GeV at midrapidity (0 < eta < 1). Photons from the decay pi(0) -> gamma gamma were detected in the barrel electromagnetic calorimeter of the STAR experiment at the Relativistic Heavy Ion Collider. The eta -> gamma gamma decay was also observed and constituted the first eta measurement by STAR. The first direct photon cross-section measurement by STAR is also presented; the signal was extracted statistically by subtracting the pi(0), eta, and omega(782) decay background from the inclusive photon distribution observed in the calorimeter. The analysis is described in detail, and the results are found to be in good agreement with earlier measurements and with next-to-leading-order perturbative QCD calculations.
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在维生素 C 二步发酵中,第二步发酵为混菌发酵。氧化葡萄糖酸杆菌为产酸菌,巨大芽孢杆菌为伴生菌。巨大芽孢杆菌和氧化葡萄糖酸杆菌纯化培养的生物学特性不同于其在混菌培养中的生物学特性。种子液的组成和生物量影响 2-酮基-L古龙酸的合成。在发酵过程中,采采取适宜的调控措施有利于产酸。Na~+和 H~+可诱导对数生长期的巨大芽孢杆菌发生自溶,Na~+诱导的自溶作用可被 Ca~++抑制。200mM Na~+ 可抑制 2-酮基-L古龙酸的合成。H~+可抑制稳定期的巨大芽孢杆菌衰亡。本文建立了简便易行的巨大芽孢杆菌的筛选模型,并获得两株耐低 pH 和 2-酮基-L古龙酸的突变株 Bn 和 B5,与氧化葡萄糖酸杆菌混合培养,发酵转化率可分别提高 4.1%和 3.8%。Bn和 B5 生长的最适 pH 值为 6.0~8.0,可促进氧化葡萄糖酸杆菌的生长,表现为延迟期缩短,稳定期延长。苏云金芽孢杆菌 B529 作为伴生菌与氧化葡萄糖酸杆菌组成的新混合菌系,具有抗污染、稳定高产的特性。B529 和巨大芽孢杆菌释放的分子量在 30~50kDa 和 >100kDa 的组份均可促进氧化葡萄糖酸杆菌产酸,其中 30~50kDa 的组份是促进产酸的关键物质。二菌所释放的活性物质经 Sephadex G-150 柱层析呈现不同的洗脱图谱,说明二菌释放的活性物质成分可能不同。B529 的培养上清液可增强氧化葡萄糖酸杆菌的细胞酶活力和 L山梨糖胶氢酶的活性。新混全菌系的最适发酵条件被确定,在4M~3 发酵罐中连续被批发酵,平均糖酸转化率提高了 6.4%,发酵周期缩短 7.3h。
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维生素C步发酵混菌生产中,第一步由单菌发酵将D-山梨醇转化为L-山梨糖,第二步由产酸菌氧化葡萄糖酸杆菌与伴生菌巨大牙孢杆菌混菌发酵将L-山梨糖转化为2-酮基-L-古龙酸(维生素C前体物).利用离子注入技术,采用N<'+>离子束为诱变源,诱变维生素C步混菌发酵中的产酸菌氧化葡萄糖酸杆菌.通过建立的维生素C产菌筛选方法,以2-酮基-L龙酸为筛选标记,获得一株维生素C产菌株D14,其与生产用伴生菌巨大牙孢杆菌组成维生素C混合菌系ND14,平均醇酸转化率比生产用混菌提高3.3个百分点.维生素C产菌株D14及维生素C混合菌系ND14生长特性及发酵特性为:维生素C产菌株D14生长能力明显增强;维生素C混合菌系D14于种子培养基中稳定期延长8-12小时,总生物量增加;在发酵过程中ND14生长明显快于CK,菌体总生物量增加.利用均匀设计的方法对新混合菌系ND14发酵培养基进行了优化,其结果为:最适玉米浆浓度为1.6%、最适尿素浓度为1.6%、最适MgSO<,4>浓度为0.03%、最适KH<,2>PO<,4>浓度为0.06%.
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该文对维生素C二步发酵法”第二步混合发酵中伴生菌对产酸菌——氧化葡萄糖酸杆菌作用机制进行了研究.除巨大芽孢杆菌外,还选用另外几种芽孢杆菌及酵母菌作为产酸菌的伴生菌.各伴生菌及其胞外液对产酸菌生长和2-酮基-L-古龙酸合成能力均有刺激作用,表明产酸菌的伴生菌具有广谱性.利用膜超滤浓缩、柱层析及电泳等技术,从伴生菌B2980胞外液中分离纯化出达电泳均一纯的高纯度活性蛋白质样品,并对其部分基本特性进行分析.结果表明:该活性物质是分子量为36300道尔顿,等电点为4.75的酸性蛋白质,并且是由一个亚基构成的单体蛋白.活性蛋白质的结晶呈规则的菱形形状,其水溶液显著提高产酸菌中SDH酶活性.试验中依伴生菌胞外液对产酸菌中SDH酶活性的作用,建立了该研究中目标活性物质的快速检测方法.
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本文利用分批培养数据构建了维生素C步发酵过程的数学模型关对模型方程中参数进行了估算。首先用2-酮基-L古龙酸产生株 2980(G.oxydan s 8c B. megaterium)在2.6L控发酵罐上进行了维生素C批发酵实验,并确认该发酵属于发酵动力学分类的Gaden第II型。在此基础上,提出了有关菌体增长(x)、基质消耗(s)和产物形成(p)的模型方程。然后,分别利用拟线性化方法及辨识方法对其中的参数进行估算。结果表明,拟线性化的方法只适合于求取参数的初值,需要利用其它估计方法进一步调整参数;而通过系统辨识求得的参数使模型仿真数据和实验数据符合得经较理想,基本反映了发酵过程中x. sp的变化特征。
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The effect of C-12(6+) heavy ions bombardment on mutagenesis in Salvia splendens Ker-Gawl. was studied. Dose-response studies indicated that there was a peak of malformation frequency of S. splendens at 200 Gy. Abnormal leaf mutants of the bileaf, trileaf and tetraleaf conglutination were selected. Meanwhile, a bicolor flower chimera with dark red and fresh red flower was isolated in M1 generation of S. splendens. Random amplified polymorphic DNA (RAPD) analysis demonstrated that DNA variations existed among the wild-type, fresh and dark red flower shoots of the chimera. The dark red flower shoots of the chimera were conserved and cultivated at a large-scale through micropropagation. MS supplemented with 2.0 mg/L BA and 0.3 mg/L NAA was the optimal medium in which the maximum proliferation ratio (5.2-fold) and rooting rate (88%) were achieved after 6 weeks. Our findings provide an important method to improve the ornamental quality of S. splendens.
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<div class="abut_top partOrAlls">
target="_blank">环境流体力学――它的意义,内容与方法 李家春
target="_blank">用于大气环流模式的陆面物理过程参数化研究进展 戴永久,曾庆存,欧阳兵
target="_blank">植被-陆面过程耦合模式的动力框架 欧阳兵
<div class="allContent" style="display: block">target="_blank">第二部分均匀下垫面的陆面过程
target="_blank">干旱地区陆面过程的研究 李家春,姚德良,沈卫明
target="_blank">阿克苏地区陆面蒸发的数值研究 沈卫明,姚德良,李家春
target="_blank">塔里木盆地陆气水热交换数值模拟 姚德良,沈卫明,李家春
target="_blank">植物固沙区土壤水热运移耦合模型研究 姚德良,李家春,沈卫明
target="_blank">在植物耗水条件下土壤水分动态的数值模拟 姚德良,邱克俭,冀伟,孙菽芬
target="_blank">干旱地区陆面过程耦合模式及其应用 李家春,姚德良,沈卫明
target="_blank">Modelling of terrestrial ecosystem B.Ouyang
target="_blank">森林生态系统生物循环过程的耦合模型(BCM)及其数值模拟 欧阳兵
target="_blank">森林生态系统生物能流的瞬态分析 欧阳兵
target="_blank">第三部分非均匀下垫面的陆面过程
target="_blank">Turbulence in the atmosphere and ocean J.C.Li
target="_blank">非均匀下垫面上大气边界层的研究进展 徐大鹏
target="_blank">非均匀植被的群体蒸发 徐大鹏
target="_blank">第四部分 区域尺度以上的陆面过程与水文模型
target="_blank">估算区域蒸发的能量法研究 聂松媛,徐丰
target="_blank">用卫星数据估算区域水资源蒸发研究 聂松媛
target="_blank">负轮分析法在水环境规划与管理中的应用 聂松媛
target="_blank">第五部分 陆面过程观测的指标体系
target="_blank">Mathematical modelling and index system in ecology J.C.Li
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A new dye, 2,7-bis(4-methoxystyryl)-9,9-bis(2-ethylhexyl)-9H-fluorene, has been synthesized, which is a D-pi-D symmetrical-type fluorene derivative. The two-photon absorption (TPA) of this new dye has been experimentally studied by comparable two-photon-induced fluorescence method. This new dye has a TPA cross-section of 84 x 10(-50) cm(4) s/photon at 790 nm/13 fs. (c) 2004 Elsevier GmbH. All rights reserved.