982 resultados para 559


Relevância:

10.00% 10.00%

Publicador:

Resumo:

A high performance liquid chroatography-electrospray ionization-mass spectrometric method was developed for analysis and identification of ginsenosides from the decoction of ginseng, ginseng with trogopteroum feces and ginseng with semen raphani. Ten ginsenosides were separated and detected. The content variation of these ginsenosides was researched. The experimental results showed, that ginsenosides were less in compatible decoction than in separate one expect Ro. the stripping of ginsenosides were restrained by semen raphani and during combination of ginseng with trogopteroum feces, the precipitates were produced by ginsenosides.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In this article, two schemes are suggested based on three exons of beta-globin gene belonging to 10 species for comparison of DNA primary sequences. At first, the positions of four nucleic acid bases were extracted, and then based on the information, as the numerical characterization of DNA sequences, the sequence invariants were derived. Sequences comparisons of 10 species selected in this work by using these invariants were performed. The results, especially with scheme 2, are quite satisfactory.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Reactions of freshly prepared M(OH)(2-2x)(CO3)(x) (.) yH(2)O (M = Mn, Zn) and 4,4'-bipyridine (bpy) with succinic acid (H2L) or famaric acid (H2L') in CH3OH-H2O afforded [Mn(H2O)(4)(bpy)]L (.) 4H(2)O, 1, [Mn(H2O)(4)(bpy)]L' (.) 4H(2)O, 2 and [Zn(H2O)(4)(bpy)]L (.) 4H(2)O, 3. The three coordination polymers are isostructural and consist of (1)(infinity)[M(H2O)(4)(bpy)(2/2)](2+) cationic chains, crystal H2O molecules and dicarboxylate anions (succinate or fumarate anions). Within the chains, the metal atoms are each octahedrally coordinated by four aqua oxygen atoms and two pyridyl nitrogen atoms from two 4,4'-bipyridine ligands. The crystal H2O molecules are hydrogen bonded to dicarboxylate anions to form ribbon-like anionic chains. The cationic and anionic chains are interconnected via hyqrogen bonds to generate a 3D network. Crystal data: 1 triclinic, P (1) over bar, a = 7.235(1), b = 7.749(2), c = 10.020(2) Angstrom, alpha = 79.95(3), beta = 88.79(3), gamma = 71.39(3)degrees, V = 523.9(2) Angstrom(3) and D-cal = 1.494 g cm(-3) for Z = 1; 2 triclinic, P (1) over bar, a = 7.127(1), b = 7.800(2), c = 9.945(2) Angstrom, alpha = 80.26(3), beta = 87.86(3), gamma = 72.69(3)degrees, V = 520.2(2) Angstrom(3) and D-cal = 1.498 g cm(-3) for Z = 1; 3 triclinic, P (1) over bar, a = 7.189(1), b = 7.764(2), c = 9.843(2) Angstrom, alpha = 79.16(3), beta = 87.80(3), gamma = 71.29(3)degrees, V = 510.9(2) Angstrom(3) and D-cal = 1.559 g cm(-3) for Z = 1.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The interfacial behavior of sec-nonylphenoxy acetic acid (CA-100) at various diluents/(H, Na)Cl interfaces was examined using the Du Nouy ring method. Different adsorption isotherms such as the Gibbs and Szyszkowski were in good agreement with the experimental data. The values of interfacial excess at saturated interface increase in the following order: n-heptane > kerosene > cyclohexane > CCl4 > toluene > benzene > chloroform. The effects of temperature, acidity, and ionic strength of the aqueous phase on the interfacial activity of CA- 100 were also examined. The interfacial-activity data were used to discuss the mechanism and kinetics of yttrium (Y) extraction.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

众所周知 ,聚合物的光电性质依赖于聚合物链的构象和 (或 )组成 ,通过在聚合物上引入手性单元 ,采用圆二色谱 ( CD)和圆偏振荧光光谱 ( CPL)等方法可表征聚合物结构 [1] .近年来 ,由于圆偏振光可用作光数据存储和液晶显示器背景光 [2 ] ,人们开始注重共轭聚合物圆偏振光材料的研究 .共轭聚合物的光致和电致圆偏振光的现象由一种带手性侧链的聚噻吩[3 ] 和一种带手性侧链的聚 (对苯撑乙烯 ) [4 ]产生 ,但它们的圆偏振荧光度 (用不对称因子 glum=2 ( IL-IR) / ( IL+IR)表示 ,IL 和 IR 分别指左圆偏振光强度和右圆偏振光强度 )相对较低 (绝对值 <0 .0 1 ) .最近报道一种带手性侧链聚芴[5] 的圆偏振荧光度可达 -0 .2 5,这可归结于其独特的液晶行为 ,使分子远程有序排列 .到目前为止 ,用圆偏振荧光研究的旋光共轭聚合物大都局限于带手性侧链的聚合物 ,而对主链旋光共轭聚合物的圆偏振荧光研究还未见文献报道 .含手性联萘基共轭聚合物已被认为是一类旋光构型热稳定性很好的化合物 [6 ,7] .本文合成了一种含手性联萘基的类似 PPV结构的新型旋光共轭聚合物...

Relevância:

10.00% 10.00%

Publicador:

Resumo:

It is important to detect the aromaticity of structures during the process of structure elucidation and output. In this paper, an alogrithm was proposed to detect the aromaticity of structures by the use of algorithm on ring identification. The results show that it could be used to identify most of the aromatic structure. It have been used as constraints of Expert System on Elucidation Structure of Organic Compounds(ESESOC) and a good result has been achieved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

研究了La2CaB10O19∶Eu3+红色发光材料的高分辨发射光谱和UV VUV激发光谱。根据发射光谱和荧光寿命,认为进入晶格的Eu3+占据了两种格位,一种Eu3+占据了与O2-离子十配位的La3+的格位,另一种Eu3+则占据了与O2-离子八配位的Ca2+的格位。又从激发光谱的分析中,得到Eu3+的电荷迁移带(CTB)是峰值位于244nm的宽带,而位于130~170nm之间的成份复杂的宽带包括硼酸盐基质的吸收带和Eu3+的f d跃迁的结论。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

以图论为基础,从化合物的二维连接表出发,在环识别算法的约束下,对分子中的节点进行判断.结果表明,该算法能够识别大多数化合物中的芳香性.作为约束条件,把芳香性的识别算法应用于ESESOC系统中结构的穷举生成,得到了较好的结果.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Cp2SmCl(THF) reacts with 0.5 equivalent disodium salts of trans-(+/-)-N,N'-bis(salicylidene)-1,2-cyclohexanediamine give the title complex [(eta(5)-C5H5)Sm(mu-OC20H20N2O)](2)(mu-THF)(THF)(2) (1). X-ray crystal determination shows that the molecule is a dimer, in which two (eta(5)C(5)H(5))Sm(mu-OC20H20N2O) units are connected via a THF oxygen and two bridging oxygen atoms of Schiff base ligands. The average Sm-C distance is 2.78(7) Angstrom, while those of Sm-O (bridging THF oxygen) and Schiff base oxygens are 2.79(3) and 2.43(4) Angstrom; respectively. (C) 1998 Elsevier Science Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本文建立了丙烯酰胺水溶液聚合的潜在型引发体系;研究了在碳酸盐法聚合体系中,添加不同量氨、尿素、EDTA—2Na,以及聚合体系pH、单体浓度、聚合水浴温度对聚合产物分子量及其溶解性能的影响规律和原因;解决了产物高分子量与产生不溶聚合物之间的矛盾;指出了获得高分子量阴离子型速溶粉末产品的关键.从而,用碳酸盐法得到了溶解性能优异的[η]高达28dl/g的胶体产品和[η]高达22dl/g的速溶粉末产品.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

牙鲆在中国北方沿海地区形成了大规模的工厂化养殖,成为我国海水养殖的一大重要产业。然而疾病的频繁发生严重阻碍了这一产业的发展,为了保证牙鲆产业稳定、健康、持续地发展,开展鱼类免疫系统的基础研究,提高鱼类抵抗病原菌侵害的能力,本研究从牙鲆免疫系统的个体发育过程入手,克隆了其rag(recombination activating gene)基因,在此基础上对其组织特异性表达进行了分析。 研究结果表明牙鲆rag1基因由4个外显子和3个内含子组成,第一个外显子位于5’非翻译区,这一外显子存在两种不同的剪切方式。牙鲆rag1基因编码1068个氨基酸。牙鲆rag2基因的编码区序列长为1602 bp,编码533个氨基酸,没有在牙鲆rag2基因编码区内发现内含子的存在。rag基因间序列长为3128 bp,两个基因共用一段3’非编码区。 本试验通过RT-PCR检测发现,牙鲆的rag1和rag2基因在头肾和体肾中均有表达。整装原位杂交结果表明,牙鲆在受精后第8天开始起有rag1和rag2基因的表达,主要在胸鳍前面,腮背部的部位表达,这个区域与后来胸腺出现的位置相一致。冰冻切片结果显示,rag是在靠近咽部的区域有表达。石蜡切片原位杂交结果显示,rag基因在胸腺中的表达显示出不均一性,着色较深的为皮层区,而着色比较浅的为髓部。 将牙鲆rag1基因的一部分(编码559个氨基酸)和rag2全基因序列(编码533个氨基酸)插入到表达质粒pProEXTM HTa上,在大肠杆菌E. coli BL-21中进行体外表达与分析,结合BD TALONTM Metal Affinity Resins亲和柱纯化了RAG2蛋白。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

高原314春小麦新品种在青海省乐都县川水地区突出表现为产量高、品质优、落黄好,可以作为现有水地春小麦替代品种大面积推广应用.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

短管兔儿草为典型的高山植物 ,具较强的光合能力 ,但光合效率较低。叶片具有发达的通气贮气组织 ;栅栏组织发达 ,叶绿体基粒片层较少。短管兔儿草光合作用特性易受生长环境因素的影响。低温胁迫使短管兔儿草光合速率、光合量子产额降低。低温下的光照加剧了光合作用受抑制的程度。本研究表明 ,短管兔儿草具较强的抗冻能力 ,是研究植物抗冻机理及筛选抗冻基因的理想材料