86 resultados para 595
Resumo:
Thionine-containing chemically modified electrode (cme) was constructed with glassy carbon substrate by potential sweep oxidation, electrodeposition and adsorption procedures, and electrocatalytic reduction of hemoglobin was carried out and characterized at the cme under batch and flow conditions. Comparison of the catalytic response toward hemoglobir obtained at the cme was made mainly in terms of the potential dependence, the detectability and long-term stability. When used in flow injection analysis (FIA) experiments with the detector monitored at a constant potential applied at -0.35 V vs sce, detection limit of 0.15-1.5 pmol level of hemoglobin injected was achieved at the cme, with linear response range over 2 orders of magnitude. All the cme s retained more than 70% of their initial hemoglobin response level over 8 h of continuous service in the flow-through system.
Resumo:
用动态光散射法(DLS)直接测定了镍系顺丁橡胶(NiBR)在环己烷溶液中溶胶分子的扩散系数D_0和流体力学半径R_h,求得两者与(?)_w的关系分别为:D_0=2.39×10~(-4)(?)_w~(-0.595),R_h=9.979×10~(-10)(?)_w~(0.595);分析了含凝胶的NiBR与钴系BR(CoBR)溶液中粒子的D及R_h的变化,结果看出,微凝胶的粒径比溶胶的粒径大1~2个数量级。
Resumo:
聚偏氟乙烯(PVF_2)具有丰富的晶相结构,在四种晶相中(α、β、γ和δ相),β晶相最为重要,因其与PVF_2的压电性和热电性直接相关。近年来,对PVF_2β相结构的研究引起人们的关注。 聚甲基丙烯酸甲酯(PMMA)是少数与PVF_2热力学相容的聚合物之一。对其共混体系相容性的研究较为广泛,但对其晶相结构的研究却少见报道。本工作用傅里叶变换红外光谱(FTIR)和透射电子显微镜(TEM)方法研究了不同分子量PMMA对高取向PVF_2薄膜β相结晶的影响。
Resumo:
An assimilation data set based on the GFDL MOM3 model and the NODC XBT data set is used to examine the circulation in the western tropical Pacific and its seasonal variations. The assimilated and observed velocities and transports of the mean circulation agree well. Transports of the North Equatorial Current (NEC), Mindanao Current (MC), North Equatorial Countercurrent (NECC) west of 140degreesE and Kuroshio origin estimated with the assimilation data display the seasonal cycles, roughly strong in boreal spring and weak in autumn, with a little phase difference. The NECC transport also has a semi-annual fluctuation resulting from the phase lag between seasonal cycles of two tropical gyres' recirculations. Strong in summer during the southeast monsoon period, the seasonal cycle of the Indonesian throughflow (ITF) is somewhat different from those of its upstreams, the MC and New Guinea Coastal Current (NGCC), implying the monsoon's impact on it.
Resumo:
Analytical representations of the high frequency spectra of ocean wave and its variation due to the variation of ocean surface current are derived from the wave-number spectrum balance equation. The ocean surface imaging formulation of real aperture radar (RAR) is given using electromagnetic wave backscattering theory of ocean surface and the modulations of ocean surface winds, currents and their variations to RAR are described. A general representation of the phase modulation induced by the ocean surface motion is derived according to standard synthetic aperture radar (SAR) imaging theory. The detectability of ocean current and sea bottom topography by imaging radar is discussed. The results constitute the theoretical basis for detecting ocean wave fields, ocean surface winds, ocean surface current fields, sea bottom topography, internal wave and so on.
Resumo:
本文以山东近海野生和养殖牙鲆Paralichthys olivaceus(T.& S.)为研究对象,采用同工酶电泳和随机扩增多态性DNA(RAPD)两种方法,进行了群体遗传学研究;另外,用PCR扩增了牙鲆、桂皮斑鲆Pseudorhombus cinnamomeus(T.& S.)、石鲽Kareius bicoloratus,Basilewsky和大菱鲆Psetta maxima 4种鲽形目鱼类mtDNA 16s rRNA基因区的部分片段,采用生物信息、学方法构建了鲽形目分子系统树。主要结果如下:1.首先建立了适于牙鲆同工酶分析的水平淀粉凝胶和垂直聚丙烯酰胺凝胶电泳系统;对获得的牙鲆15种同工酶基本酶谱进行了生化遗传分析,进而对自然和养殖群体的生化遗传结构进行了分析,共记录了29个基因座位,发现了9个多态座位。2.野生群体的生化遗传参数多态基因座位比例(31.O%)、等位基因平均数(1.38)和群体平均杂合度(0.0802)都明显高于养殖群体(24.1%,1.28,O.0788);在野生群体中有9个多态基因座位,而养殖群体仅7个多态基因座位;其中,除了Cat和Idhp-1(仅养殖群体)(P < 0.05)有显著差异、Ldh-C(P < O.01)完全偏离Hardy-Weinberg定律外,其余多态座位基因频率均符合Hardy-Weinberg遗传平衡定律。野生和养殖群体的遗传相似性系数(I)为0.9877,它们的遗传距离(D)是0.0124;两群体间的遗传分化系数G_(st)为0.0681,D_m为0.01,表明总变异中的6.8%的遗传变异产生于群体间的基因差异。3.采用11个随机引物对20个野生个体和24个养殖个体进行了RAPD群体遗传多样性分析,分别扩增出88条和86条DNA带,片段大小在200-2500bp之间,平均每个引物扩增的带数是7.8-8.0。两个群体的多态座位比例分别是43.2%和34.9%,平均杂合度是0.2739和0.2255,而Shannon遗传多样性指数表明两群体的遗传变异中有88.12%的遗传变异来自种群内,只有11.88%的变异来自群体间。遗传分化指数G_(st)的结果也验证了Shannon遗传多样性指数的结果:总群体的遗传变异中约有12%是由两群体间的基因差异产生的。4.本文对牙鲆两个群体的同一批样品分别采用经典的同工酶方法和RAPD方法进行了较系统的比较分析。发现,RAPD所显示的多态性要比同工酶的高得多,因为大部分RAPD的变异是源于非编码区和重复DNA,可以遍布整个基因组,而同工酶仅是功能基因的产物,只表现编码区的变异。因此,自然选择在同工酶编码区的作用要多于RAPD标记。在遗传相似性系数(I)和遗传距离(D)上,RAPD的分析结果与同工酶的分析结果也是有差异的,用同工酶分析两个群体遗传距离只有0.0124,而用RAPD研究可达0.0508。遗传分化指数的差异也很大,同工酶为0.0681,RAPD为0.1237。5.RAPD和同工酶的分析结果是类似的,即自然群体的多态座位比例和平均杂合度要比养殖群体高,降低幅度在同工酶中界于1.7~22.3%之间,在RAPD中则界于15.9~19.2%之间。这充分证明了养殖群体的遗传多样性水平已有明显的丧失,值得我们注意。6.构建了鲽形目鱼类mtDNA 16S rRNA基因的分子系统树。通过分子克隆法将牙鲆、桂皮斑鲆、大菱鲆和石鲽mtDNA 16S rRNA目的基因片段连接到质粒载体上,经MegaBACE测序仪测序,分别获得了590、595、582和590bp序列,通过生物信息学方法对其进行了序列分析和核酸变异比较,结合NCBI上6种鲽形目鱼类的同源序列探讨了这4种鱼类在鲽形目中的遗传分化和分子系统进化,构建了系统树,其中,桂皮斑鲆的16S rRNA基因在系统树中的位置与物种形态资料的系统演化不相符,而其它三种很好地呈现了它们在鲽形目中的系统位置。同时,可以看出mtDNA 16S rRNA基因片段可以构建一个相对准确的树,特别是NJ树和ML树比较接近,更为客观一些。由比对序列获得的物种之间的遗传距离也基本可以反映种、属、科间的不同变异水平。
Resumo:
青海地道中药材"西宁大黄"野生资源濒临枯竭,人工种植规模不断扩大.定期采集青海西宁及邻近地区两年生种植大黄,跟踪分析了其微量无素铜、锌、铁、锰、铬,为地道西宁大黄资源的可持续开发和利用提供科学依据.研究表明,种植大黄中微量元素铁、锌、铜、锰的有效积累以及土壤地球化学环境中的微量元素锌、锰、铜对种植大黄的生长具有重要的作用和意义.
Resumo:
Genomic constitutions of three taxa of Hystrix Moench, H. patula, H. duthiei ssp. duthiei and H. duthiei ssp. longearistata, were examined by meiotic pairing behavior and genomic in-situ hybridization. Meiotic pairing in hybrids of H. patula x Pseudoroegneria spicata (St), H. patula x Elymus wawawaiensis (StH), H. patula x H. duthiei ssp. longearistata, H. patula x Psathyrostachys huashanica (Ns(h)), H. duthiei ssp. duthiei x Psa. huashanica, H. duthiei ssp. longearistata x Psa. huashanica, Leymus multicaulis (NsXm) x H. duthiei ssp. longearistata averaged 6.53, 12.83, 1.32, 0.29, 5.18, 5.11 and 10.47 bivalents per cell, respectively. The results indicate that H. patula has the StH genome and H. duthiei ssp. duthiei and H. duthiei ssp. longearistata have the NsXm genome. Results of genomic in-situ hybridization analysis strongly supported the chromosome pairing data; therefore it is concluded that the type species of Hystrix, H. patula, should be included in Elymus, and that H. duthiei ssp. duthiei and H. duthiei ssp. longearistata should be transferred to Leymus.
Resumo:
A rapid capillary electrophoresis method for the separation of five natural pharmacologically active compounds from extracted Rhodiola, namely salidroside, tyrosol, rhodionin, gallic acid and ethyl gallate has been developed. The separation of five natural pharmacologically active compounds was carried out in a fused-silica capillary with 14 mM boric acid, 30 mM SDS and 2.5% acetonitrile, adjusted to pH 10.7 with NaOH. Applied potential was 21 kV. The temperature of the capillary was maintained at 25 degreesC by the instrument thermostating system, with the correlation coefficients of 0.9805-0.9989 for migration time, and relative standards of < 3.52% for peak areas. The established method is rapid and reproducible for the separation of five natural pharmacologically compounds from extracts of Rhodiola with satisfactory results.
Resumo:
该文介绍了机器人迭代学习控制的研究进展,指出了存在的问题及今后的研究方向。
Resumo:
本文系统地阐述了国内外有关金矿床同位素定年方面的最新进展和古地磁法,天然裂变径迹法的基本原理,并对常用同位素定年法的适用性和局限性进行了评述。