983 resultados para 389


Relevância:

10.00% 10.00%

Publicador:

Resumo:

甲状腺素脱碘酶是能够催化甲状腺激素不同降解反应的一簇含硒酶 [1,2 ] ,由于其含量低 ,分离纯化困难等[3] ,严重阻碍了其生物化学性质和应用研究 .自 Lerner[4 ] 和 Schultz等 [5] 分别制备出了具有催化作用的抗体酶以来 ,抗体酶在天然酶的模拟研究中已展示了巨大潜力 ,有些抗体酶已达到或超过了天然酶的活力 [6 ] .我们曾用抗体酶技术制得具有脱碘酶活性的抗体酶 [7] .为进一步提高脱碘抗体酶活力 ,本文以疏水腔修饰法 [8] 为指导 ,用铜离子络合保护法设计合成了 3种甲状腺素衍生物半抗原和全抗原 ,并制备出了一种半抗原的单克隆抗体 .试剂和仪器 :五水甲状腺素钠 ( T4 )为 SIGMA产品 ;牛血清白蛋白 ( BSA )和卵清白蛋白( Ovalbumin) ,SIGMA分装 ;戊二醛 ,硫酸二甲酯 ,溴化苄 ,对硝基溴苄和其它试剂均为国产分析纯 .Finni- gan mat LCQ电喷雾多极串联质谱仪 ;KONTRON公司 92 2型紫外可见分光光度仪 ;德国Elementar Anallysensysteme Gmb H Vario EL元素分析仪 ;美国 Varian...

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本文采用助熔剂籽晶提拉法生长出了Nd:KWG激光晶体。化学组成和结构分析认为,所得的晶体是β-KGd(WO4)2。通过红外光谱和喇曼光谱判断了它的振动归属,通过紫外可见吸收光谱的测定得到了它的峰值吸收截面值。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

合成了K_2NiF_4结构的Ln_2CuO_4(Ln=La,Pr,Nd,Sm,Gd)类钙钛石型复合氧化物催化剂.研究了这些稀土取代的类钙钛石型复合氧化物的固态物理,化学性质.探讨了此类复合氧化物在苯酚羟化反应中的催化作用.考查了催化剂结构和组成与其苯酚羟化活性的关系,结果表明,在K_2NiF_4型复合氧化物中,A位稀土取代效应对复合氧化物的苯酚羟化催化活性有很大影响.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The preliminary work indicated that passive film is the most important factor influencing cell performance of carbon anode, and the carbon and solvent used govern cell performance by forming the passive film of different properties. A in situ XRD result is also presented.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The compound BaCuO2.5 Was obtained using BaO2 and CuO as starting materials, and its various properties were investigated. It belongs to the orthorhombic system with a = 8.55 angstrom, b = 10.56 angstrom, and c = 7.62 angstrom. The p-type semiconductor Ba

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The adsorption of cationic surfactant cetylpyridinium bromide (CPB) on a glassy carbon (GC) electrode surface has been studied by spectroelectrochemistry with a long optical path length thin-layer cell (LOPTLC) for the first time. A fine adsorption isotherm of CPB molecules from an aqueous solution containing 0.10 M KBr has been obtained over the range of (1.00-8.00) x 10(-5) M. From theoretical calculation and experimental data, adsorption of CPB on the GC electrode surface shows four distinct orientations and three large orientation transitions. Compared with the ordinary isotherm, the differential isotherm is more characteristic and would be suitable for the study of orientation transitions of organic compounds. With a theoretical treatment of the adsorption isotherm, four orientations of adsorbed CPB on a GC electrode surface coincide with the Frumkin-Langmuir type. From adsorption parameters the Frumkin-Langmuir equations, the adsorption free energy and, therefore, the equilibrium constants of orientation transitions of the CPB molecule can be obtained.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

本文用FTIR-ATR方法考察了线性低密度聚乙烯与天然橡胶(NR)及丁苯橡胶(SBR)两个共混体系,发现NR的835cm~(-1)和SBR的964cm~(-1)两个吸收峰因与聚乙烯共混而增高变窄,说明聚乙烯的非晶链段和橡胶分子之间存在一定程度的相互作用。

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Co-Mo 系催化剂由于其优越的耐硫性能和对水煤气变换反应的高活性,因此在制氢工业中日益得到重视。已知 Co-Mo-K/Al_2O_3催化剂是一种优良的水煤气变换催化剂,该催化剂在使用前须经硫化。实际上催化剂在反应时

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Arthropod defence responses (e.g. prophenoloxidase (proPO) activation and Toll pathway initiation) are mediated by serine proteinase cascades and regulated by serpins in haemolymph. A serpin (Fc-serpin) cDNA was cloned from the haemocytes of Fenneropenaeus chinensis by rapid amplification of cDNA ends (RACE) PCR and haemocyte cDNA library screening. The full-length cDNA consists of 1734 bp, encoding 411 amino acids with a calculated molecular mass of 46.55 kDa and a theoretical isoelectric point of 7.70. Fc-serpin contains a typical serpin-like homologue (serine proteinase inhibitors domain). The deduced protein contains a putative signal peptide of 19 amino acids and the serpin's signature sequence ((FHCNRPFLFLI389)-F-379). Fc-serpin showed some identity with Pacifastacus leniusculus serpin (42%) and Manduca sexta serpin-6 (34%). The reactive centre loop (RCL) sequences of Fc-serpin, P leniusculus serpin, M. sexta serpin-6 and Bombyx mori serpin-2 are highly similar. An Arg at the PI position of the reactive site indicates that Fc-serpin may have inhibitory activity against prophenoloxidase activating proteinase (PAP) and clotting enzyme. Transcripts of Fc-serpin mRNA were mainly detected in haemocytes and the lymphoid organ by RT-PCR. The variation of the mRNA transcription level in haemocytes followed by artificial infection with bacteria OF white spot syndrome virus (WSSV) was quantified by SYBR Green real-time PCR analysis. Expression profiles of Fc-serpin greatly fluctuated after challenge. This work represents the first report Of a serpin in penaeid shrimp. The data provide clues that Fc-serpin might play potential roles in the innate immunity of shrimp. (C) 2008 Elsevier Ltd. All rights reserved.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

A full-length cDNA encoding vitellogenin (Vg) was cloned from Chinese shrimp, Fenneropenaeus chinensis using RACE method. The full-length cDNA consist of 7,942 nucleotides including a 7,761 bp open reading frame, which encodes 2,587 amino acid residues. The deduced amino acid sequence showed high (from 94% to 37%) identity with other known crustacean Vgs. In addition, a consensus cleavage site (R-X-K/R-R) recognized by an endopeptidase and a member of subtilisin family of serine protease were identified in the deduced Vg precursor. RT-PCR analysis shown that Vg mRNA can be detected in both ovary and hepatopancreas of vitellogenic females but not in other experimental tissues including muscle, heart, lymph organ, gill, haemocytes and intestine. These results suggest that the Vg gene may be expressed exclusively in mature females, and both ovary and hepatopancreas are the possible tissues for Vg synthesis in F. chinensis. In addition, Vg gene is detected in genomic DNA of both females and males.