143 resultados para 1995_12130153 LAPS-9


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合成了新的荧光衍生试剂1-[2-(对甲苯磺酸酯)乙基]-2-苯基咪唑[4,5-f]9,10-菲(TsEPIP),并将其作为柱前衍生化试剂,在Eclipse XDB-C:色谱柱上采用梯度洗脱实现了11种长链(C_(20)~C_(30))游离脂肪酸(FFA)衍生物的基线分离。利用柱后在线的串联质谱并以大气压化学电离源(APCI)的正离子模式实现了各组分的质谱定性。对土壤及3种苔醉(东亚毛灰鲜、锦丝鲜、羽平鲜)中FFA组分的定量结果表明,苔鲜植物从土壤中富集了大量的长链游离脂肪酸。荧光检测的激发波长和发射波长分别为260 nm和380 nm。线性回归系数大于0.9996,检测限为26.19~76.67 fmol。所建立的方法具有良好的重现性,对实际样品的测定结果令人满意。

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目的 研究藏药市场上9种“藏茵陈”植物中有效化学成分,根据所含成分的差异及其生理活性,确定这些植物的药用价值。方法 采用HPLC法测定7种成分的量。结果 9种植物的有效成分差异很大。结论 针对不同的化学成分用途,选择不同的植物,有效利用资源。[著者文摘]

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本文研究了青海葱属青甘韭 9个居群的染色体数目和核型。其中分布于湟源、西宁和共和海拔相对较低的地区的居群为 2倍体 ,核型公式为 2n =2x =16 =14m +2st (2SAT) (湟源居群和西宁居群 ) ,2n =2x =16 =12m +2sm +2st (2SAT) (共和居群 ) ;分布于玛沁、玉树、囊谦等高海拔地区的居群为 4倍体 ,核型公式为 2n =4x =32 =2 8m +4st (2SAT) (玉树居群 1和囊谦居群 1) ,2n =4x =32 =2 4m +4sm +4st (玛沁居群和玉树居群 3)和 2n =4x =32 =2 6m +2sm+4st (玉树居群 2 ) ;囊谦一个生长在林下的居群为8倍体,2n =8x =64 =54m +2sm +8st.讨论了居群间的核型分化和倍性与分布的关系。

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A pre-column derivatization method for sensitive determination of oligopeptides, using the tagging reagent 2-(9-carbazole)ethyl chloroformate (CEOC-Cl) followed by capillary electrophoresis (CE) with diode-array detection, has been developed. Maximum yield close to 100% were observed when a three to fourfold molar excess of reagent was used at pH 9.0-10.0. Excess reagent was extracted with n-hexane-ethyl acetate 9:1-10:1 (v/v); this enabled direct analysis using CE with no significant disturbance from the major fluorescent reagent degradation by-products. The effects on the results of buffer pH and of SDS and organic modifier concentrations were examined. Good baseline resolution in the separation of five CEOC-peptides was achieved with a 48.5-cm total length (effective length 40 cm) 50-mu m inner diameter capillary column.

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A pre-column derivatization method for the sensitive determination of amines using the labeling reagent 1,2-benzo-3,4-dihydrocarbazole-9-isopropyl chloroformate (BCIC-Cl) followed by high-performance liquid chromatography with fluorescence detection has been developed. Identification of derivatives is carried out by high performance liquid chromatography/atmospheric pressure chemical ionization (LC-APCl-MS-MS). The chromophore of 2-(9-carbazole)-ethyl chloroformate (CEOC) reagent is replaced by 1,2-benzo-3,4-dihydrocarbazole-9-isopropyl functional group, which results in a sensitive fluorescence derivatizing reagent BCIC-Cl. BCIC-Cl can easily and quickly label amines. Derivatives are stable enough to be efficiently analyzed by high-performance liquid chromatography and show an intense protonated molecular ion corresponding m/z [MH](+) under APCl in positive-ion mode. The collision-induced dissociation of protonated molecular ion formed a product at m/z 260 corresponding to the cleavage of CH2-OCO bond. Studies on derivatization demonstrate excellent derivative yields over the pH 9.0-10.0. Maximal yields close to 100% are observed with a 3 to 4-fold molar reagent excess. In addition, the detection responses for BCIC derivatives are compared with those obtained using CEOC and FMOC as derivatization reagents. The ratios of l(BCIC)/l(CEOC) and l(BCIC)/l(FMOC) are, respectively, 1.23-3.14 and 1.25-3.08 for fluorescent (FL) responses (here, l is relative fluorescence intensity). Separation of the derivatized amines had been optimized on reversed-phase Eclipse XDB-C-8 column. Detection limits are calculated from 1.0 pmol injection, at a signal-to-noise ratio of 3, are 10.6-37.8 fmol. The mean interday accuracy ranges from 94 to 105% for fluorescence detection with the largest mean %CV < 7.5. The mean interday precision for all standards is < 6.0% of the expected concentration. Excellent linear responses are observed with coefficients of > 0.9997.

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A simple, sensitive, and mild method for the determination of amino compounds based on a condensation reaction with 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide hydrochloride (EDC-HCI) as the dehydrant with fluorescence detection has been developed. Amines were derivatized to their acidamides with labeling reagent 2-(2-phenyl-1H-phenanthro-[9,10-d]imidazole-1-yl)-acetic acid (PPIA). Studies on derivatization conditions indicated that the coupling reaction proceeded rapidly and smoothly in the presence of a base catalyst in acetonitrile to give the corresponding sensitively fluorescent derivatives with an excitation maximum at lambda(ex) 260nm and an emission maximum at lambda(em) 380nm. The labeled derivatives exhibited high stability and were enough to be efficiently analyzed by high-performance liquid chromatography. Identification of derivatives was carried out by online post-column mass spectrometry (LC/APCI-MS/MS) and showed an intense protonated molecular ion corresponding m/z [MH](+) under APCI in positive-ion mode. At the same time, the fluorescence properties of derivatives in various solvents or at different temperature were investigated. The method, in conjunction with a gradient elution, offered a baseline resolution of the common amine derivatives on a reversed-phase Eclipse XDB-C-8 column. LC separation for the derivatized amines showed good reproducibility with acetonitrile-water as mobile phase. Detection limits calculated from 0.78 pmol injection, at a signal-to-noise ratio of 3, were 3.1-18.2 fmol. The mean intra- and inter-assay precision for all amine levels were < 3.85% and 2.11%, respectively. Excellent linear responses were observed with coefficients of > 0.9996. The established method for the determination of aliphatic amines from real wastewater and biological samples was satisfactory. (c) 2006 Elsevier B.V. All rights reserved.

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A pre-column derivatization method for the sensitive determination of amino acids and peptides using the tagging reagent 1,2-benzo-3,4dihydrocarbazole-9-ethyl chloroformate (BCEOC) followed by high-performance liquid chromatography with fluorescence detection has been developed. Identification of derivatives was carried out by liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS/MS). The chromophore of 2-(9-carbazole)-ethyl chloroformate (CEOC) reagent was replaced by 1,2-benzo-3,4-dihydrocarbazole functional group, which resulted in a sensitive fluorescence derivatizing reagent BCEOC. BCEOC can easily and quickly label peptides and amino acids. Derivatives are stable enough to be efficiently analyzed by high-performance liquid chromatography. The derivatives showed an intense protonated molecular ion corresponding m/z (M + H)(+) under electrospray ionization (ESI) positive-ion mode with an exception being Tyr detected at negative mode. The collision-induced dissociation of protonated molecular ion formed a product at m/z 246.2 corresponding to the cleavage of C-O bond of BCEOC molecule. Studies on derivatization demonstrate excellent derivative yields over the pH 9.0-10.0. Maximal yields close to 100% are observed with a 3-4-fold molar reagent excess. Derivatives exhibit strong fluorescence and extracted detzvatization solution with n-hexane/ethyl acetate (10:1, v/v) allows for the direct injection with no significant interference from the major fluorescent reagent degradation by-products, such as 1,2-benzo-3,4-dihydrocarbazole-9-ethanol (BDC-OH) (a major by-product), mono- 1,2-benzo-3,4-dihydrocarbazole-9-ethyl carbonate (BCEOC-OH) and bis-(1,2-benzo-3,4-dihydrocarbazole-9-ethyl) carbonate (BCEOC)(2). In addition, the detection responses for BCEOC derivatives are compared to those obtained with previously synthesized 2-(9-carbazole)-ethyl chloroformate (CEOC) in our laboratory. The ratios AC(BCEOC)/AC(CEOC) = 2.05-6.51 for fluorescence responses are observed (here, AC is relative fluorescence response). Separation of the derivatized peptides and amino acids had been optimized on Hypersil BDS C-18 column. Detection limits were calculated from 1.0 pmol injection at a signal-to-noise ratio of 3, and were 6.3 (Lys)-177.6 (His) fmol. The mean interday accuracy ranged from 92 to 106% for fluorescence detection with mean %CV < 7.5. The mean interday precision for all standards was < 10% of the expected concentration. Excellent linear responses were observed with coefficients of > 0.9999. Good compositional data could be obtained from the analysis of derivatized protein hydrolysates containing as little as 50.5 ng of sample. Therefore, the facile BCEOC derivatization coupled with mass spectrometry allowed the development of a highly sensitive and specific method for the quantitative analysis of trace levels of amino acids and peptides from biological and natural environmental samples. (c) 2005 Elsevier B.V. All rights reserved.

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A simple and sensitive method for the determination of short and long-chain fatty acids using high-performance liquid chromatography with fluorimetric detection has been developed. The fatty acids were derivatized to their corresponding esters with 9-(2-hydroxyethyl)-carbazole (HEC) in acetonitrile at 60 degreesC with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride as a coupling agent in the presence of 4-dimethylaminopyridine (DMAP). A mixture of esters of C-1-C-20 fatty acids was completely separated within 38 min in conjunction with a gradient elution on a reversed-phase C-18 column. The maximum fluorescence emission for the derivatized fatty acids is at 365 nm (lambda (ex) 335 nm). Studies on derivatization conditions indicate that fatty acids react proceeded rapidly and smoothly with HEC in the presence of EDC and DMAP in acetonitrile to give the corresponding sensitively fluorescent derivatives. The application of this method to the analysis of long chain fatty acids in plasma is also investigated. The LC separation shows good selectivity and reproducibility for fatty acids derivatives. The R.S.D. (n = 6) for each fatty acid derivative are <4%. The detection limits are at 45-68 fmol levels for C-14-C-20 fatty acids and even lower levels for

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Alcohols were derivatised to their carbazole-9-N-acetic acid (CRA) esters with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC . HCl) as the dehydrating agent. Studies on derivatisation conditions indicated that the coupling reaction proceeded rapidly and smoothly in the presence of a base catalyst in acetonitrile to give the corresponding sensitively fluorescent derivatives. The retention behaviour of alcohol derivatives was investigated by varying mobile phase compositions (ACN-water and MeOH-water). The parameters from the equation log k'=A-BX were evaluated by retention data of derivatives using an isocratic elution with different mobile phases. The results indicated that the parameters derived allowed computation of retention factors in good agreement with experiments. At the same time, a general equation was derived that makes possible predictions of partition coefficient in binary mobile phases with different proportions of organic solvent to water based on some simple regression analysis. The LC separation for the derivatised alcohols containing higher carbon alcohols showed good reproducibility on a reversed-phase C-18 column with gradient elution. The detection limits (excitation at 335 nm, emission at 360 nm) for derivatised alcohols (signal-to-noise ratio=3:1) were in the range of 0.1-0.4 pg per injection. (C) 2001 Elsevier Science B.V. All rights reserved.

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Research on naïve biology investigates children spontaneous understanding of biology objects, phenomena and function. Previous researches focus mostly on biology phenomena. Little has done on organism’s function, such as eating food. Many research in this field found that children were unable to categorize food by nutrition criterion, but rely on physical cues. In order to investigate the development of children’s naïve understanding of food and to find if they can classify food by nutrition criterion, three age groups (5-year-olds, 7-year-olds, and 9-year-olds) were included in this study. Varies experimental tasks were also used to explore the children’s understanding of food and its function. The results showed as the followings: 1) A few 5-year- old children can classify food by nutrition criterion when they take the spontaneous classification task. However, more and more children can realize what make a kind of food different from another can be the nutrition it contains. 2) Kindergarteners can find the relation between food and its output. When they become older, more and more children can explain the relation by consistent theory. It can be said that 9-year-old children have already have a profound understanding of nutrition. They gradually developed naive theory of biology on nutrition level. 3) Even kindergarteners can understand the concept of “food balance”. However, with development there was a significant age increase in food balance choice. 4) Children’s knowledge of food balance grows with age, but urban and rural educational background influence cognitive performance.

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Research on children's naive concepts has previously tended to focus on the domains of physics and psychology, but more recently attention has turned to conceptual development in biology as a core domain of knowledge. Because of its familiarity, illness has been a popular topic for researchers in this domain. However, they have only studied the children’s understanding of its causes. Other aspects of illness, such as treatment and prognosis, have received little attention. This research addresses the development of 5- to 9-year-old children’s understanding of the causes of illness and their probabilities via open-ended and forced choice interviews. The results of this research are: 1) Most of the 5- to 7-year-old children used behavioral causes to explain illness, and the 9-year-old children primarily used biological causes to interpret illness. With age, more and more children selected psychological causes to explain illness. 2) Pre-school children did not over-generalize contagions to non-contagious illnesses. They used behavioral and biological causes to explain contagious illnesses. For non-contagious illnesses, they chose only behavioral causes. 3) Most of the children used only one kind of cause to explain illness. 4) Some preschool-aged children viewed outcomes of familiar causes of illness as probabilistic. With age, more and more could make uncertain predictions of illness. 5) The children’s understanding of the causes’ probabilities appeared to be based on naïve biology. 5- to 9-year-old children often made probabilistic predictions by analyzing a single cause of illness. 6) Children coming from higher educational backgrounds outperformed their counterparts coming from lower educational backgrounds with respect to understanding illness. 7) Specific knowledge acquired could generally improved the preschoolers’ understanding of causes of illness and their probabilities.