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QuEChERS联合UPLC-MS/MS和GC-MS/MS测定枸杞子中33种禁用农药残留
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作者 罗丽娟 周劲松 +3 位作者 马恩耀 孙心恒 梁朝鹏 谢珊珊 《中南农业科技》 2023年第11期49-52,共4页
以2020年版《中华人民共和国药典》农药残留量测定法第五法中的快速处理法(QuEChERS)作为前处理方法,采用UPLC-MS/MS和GC-MS/MS测定枸杞(Lycium barbarum L.)子中33种禁用农药的残留量。结果表明,该方法线性关系良好,相关系数≥0.9950,... 以2020年版《中华人民共和国药典》农药残留量测定法第五法中的快速处理法(QuEChERS)作为前处理方法,采用UPLC-MS/MS和GC-MS/MS测定枸杞(Lycium barbarum L.)子中33种禁用农药的残留量。结果表明,该方法线性关系良好,相关系数≥0.9950,加样回收率均在60%以上,20批枸杞子仅克百威检出,检出率为70%,合格率为60%。该方法灵敏度高,检测限低,可满足痕量分析要求。 展开更多
关键词 枸杞(lycium barbarum l.) 禁用农药 克百威 残留量 QUECHERS
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响应面法对超声波-螯合剂辅助提取石榴子多酚的优化 被引量:1
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作者 郭庆贺 吕远平 《湖北农业科学》 2015年第5期1159-1163,共5页
以石榴(Punica granatum L.)子为研究对象,以多酚得率为评价指标,通过单因素试验和响应面法分析,确定超声波-螯合剂辅助提取石榴子多酚的最佳工艺条件为乙醇体积分数50%、提取温度60℃、提取时间60 min、料液比1∶31(m:v)、螯合剂六偏... 以石榴(Punica granatum L.)子为研究对象,以多酚得率为评价指标,通过单因素试验和响应面法分析,确定超声波-螯合剂辅助提取石榴子多酚的最佳工艺条件为乙醇体积分数50%、提取温度60℃、提取时间60 min、料液比1∶31(m:v)、螯合剂六偏磷酸钠添加量0.15%。在此条件下,石榴子多酚得率可达9.375 mg/g。通过响应面法优化得出的回归方程具有一定的实践指导意义,为石榴子资源的开发提供了参考。 展开更多
关键词 石榴(Punica granatum l.) 多酚 提取 响应面分析
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Research on Rice Panicle L-system Model Based on Substructure Algorithm 被引量:1
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作者 周云辉 吴斌 +2 位作者 刘宏伟 曾超 邵延华 《Agricultural Science & Technology》 CAS 2010年第6期83-86,共4页
In order to decrease model complexity of rice panicle for its complicated morphological structure,an interactive L-system based on substructure algorithm was proposed to model rice panicle in this study.Through the an... In order to decrease model complexity of rice panicle for its complicated morphological structure,an interactive L-system based on substructure algorithm was proposed to model rice panicle in this study.Through the analysis of panicle morphology,the geometrical structure models of panicle spikelet,axis and branch were constructed firstly.Based on that,an interactive panicle L-system model was developed by using substructure algorithm to optimize panicle geometrical models with the similar structure.Simulation results showed that the interactive L-system panicle model based on substructure algorithm could fast construct panicle morphological structure in reality.In addition,this method had the well reference value for other plants model research. 展开更多
关键词 Rice panicle Substructure algorithm l-SYSTEM MODEl
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Effect of Metal Ions on Protease Activities in the Intestines and Hepatopancreas of Red-white Ornamental Carp (Cyprinus carpio L)
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作者 郭永军 魏东 +4 位作者 白东清 闫珊珊 吴旋 宁博 陆建权 《Agricultural Science & Technology》 CAS 2010年第3期104-106,122,共4页
[Objective] The aim of this study was to study effects of metal ions on the protease activities in digestive tissues and gland of red-white ornamental carp(Cyprinus carpio L).[Method] Effects of four kinds of metal ... [Objective] The aim of this study was to study effects of metal ions on the protease activities in digestive tissues and gland of red-white ornamental carp(Cyprinus carpio L).[Method] Effects of four kinds of metal ions (K+,Na+,Mg2+ and Ca2+) on protease activities in hepatopancreas,foregut,midgut,hindgut of red-white ornamental carp were studied by enzyme analysis method.[Result] Effects of four kinds of metal ions on protease activities of red-white ornamental carp were different in the range of experimental concentration from 25 mmol/L to 150 mmol/L.K+ could promote protease activities in hepatopancreas and hindgut at different levels.Especially,K+ had the promoting effect at low-concentration level,but the inhibitory effect at high-concentration level in midgut and the inhibitory effect in foregut.Na+ had the promoting effect on protease activities in hepatopancreas,foregut and hindgut at different levels,but the inhibitory effect in midgut.Mg2+ and Ca2+ had the inhibitory effect on protease activities in intestinal and hepatopancreas at different levels.[Conclusion] This study provides basic data and theoretical foundation for researches on the digestive physiology of red-white ornamental carp or the development and optimization of compound feed. 展开更多
关键词 Red-white ornamental carp Metal ions Protease activities
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响应面法优化振摇提取百香果子中油脂及其脂肪酸成分分析 被引量:2
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作者 覃文霞 李昌宝 +5 位作者 辛明 王海波 郑娟梅 王警 王建刚 黄慧玲 《湖北农业科学》 2020年第12期134-139,共6页
以百香果(Passiflora coerulea L.)子油的得率作为评价指标,选择料液比、时间、温度进行单因素试验,在其基础上利用响应面法优化百香果子油的提取条件,并用气相色谱-质谱法(GC-MS)测定所提取油脂的脂肪酸组成。结果表明,最佳工艺条件为... 以百香果(Passiflora coerulea L.)子油的得率作为评价指标,选择料液比、时间、温度进行单因素试验,在其基础上利用响应面法优化百香果子油的提取条件,并用气相色谱-质谱法(GC-MS)测定所提取油脂的脂肪酸组成。结果表明,最佳工艺条件为料液比1∶30(m∶V),提取时间20 min,摇床温度23℃,此条件下百香果子油提取得率为22.37%。百香果子油中含有19种脂肪酸,其中不饱和脂肪酸相对含量为84.12%,饱和脂肪酸相对含量为15.88%,主要成分是亚油酸甲酯(60.51%)和反-9-十八碳烯酸甲酯(22.05%)。采用响应面法优化的条件进行提取,可得到较高的百香果子油得率,通过GC-MS分析所得百香果子油的脂肪酸成分不被破坏,这是一种简单、高效且对有效成分无损的方法。 展开更多
关键词 百香果(Passiflora coerulea l.) 提取 响应面法 脂肪酸 气相色谱-质谱法(GC-MS)
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PREPARATION AND CHARACTERIZATION OF WATER-SOLUBLE NEAR-INFRARED EMITTING PbS QUANTUM DOTS
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作者 曹洁 李杉 +1 位作者 邓大伟 顾月清 《Transactions of Nanjing University of Aeronautics and Astronautics》 EI 2010年第1期81-87,共7页
A new facile method for preparing water-soluble near-infrared (NIR)-emitting PbS quantum dots (QDs) is proposed by using N-acetyl-L-cysteine (NAC, a derivate of L-cysteine) as its stabilizer. The influence of th... A new facile method for preparing water-soluble near-infrared (NIR)-emitting PbS quantum dots (QDs) is proposed by using N-acetyl-L-cysteine (NAC, a derivate of L-cysteine) as its stabilizer. The influence of the precursor Pb/S molar ratio, the Pb/NAC molar ratio, and the pH of original solution on optical properties is explored. Results show that aqueous PbS QDs with strong NIR fluorescence can be prepared and their photoluminescence emission peaks can be tuned from 895 nm to 970 nm. Studies indicate that such aqueous QDs have a potential application in biomedical imaging, especially in noninvasive in vivo fluorescence imaging. In addition, the resulting PbS QDs are further characterized by a transmission electron microscopy and X-ray diffraction analysis. 展开更多
关键词 semiconductor quantum dots (QDs) biomedical imaging N-acetyl-l-cystelne(NAC) NEAR-INFRARED
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Experimental Study on Hydrodynamics of L-type Podded Propulsor in Straight-ahead Motion and Off-Design Conditions 被引量:4
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作者 Dagang Zhao Chunyu Guo +2 位作者 Yumin Su Pengfei Dou Tao Jing 《Journal of Marine Science and Application》 CSCD 2017年第1期48-59,共12页
Experimental tests were conducted to evaluate the hydrodynamic performance of an L-type podded propulsor in straight-ahead motion and off-design conditions using an open-water measuring instrument developed by the aut... Experimental tests were conducted to evaluate the hydrodynamic performance of an L-type podded propulsor in straight-ahead motion and off-design conditions using an open-water measuring instrument developed by the authors for podded propulsors, a ship model towing tank, and under water particle image velocimetry (PIV) measurement systems. Under the three types of conditions, the main parameters of an L-type podded propulsor were measured, including the propeller thrust and torque, as well as the thrust, side force, and moment of the whole pod unit.In addition, the flow field on the section between the propeller and the strut was analyzed. Experimental results demonstrate that the dynamic azimuthing rate and direction and the turning direction affect the forces on the propeller and the whole pod unit. Forces are asymmetrically distributed between the left and right azimuthing directions because of the effect of propeller rotation. The findings of this study provide a foundation for further research on L-type podded propulsors. 展开更多
关键词 l-type podded propulsor off-design condition flow field particle image velocimetry PROPEllER HYDRODYNAMIC experimental test
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METHOD OF CONSTRUCTING BORNOLOGICAL SPACES FROM L~*-VECTOR SPACES
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作者 张志尧 《Transactions of Tianjin University》 EI CAS 2001年第2期137-139,共3页
A new method of constructing bornological vector topologies for vector spaces is discussed.In general,the convergent sequence and bounded set are concepts only in topological spaces.However,in this paper,it is first i... A new method of constructing bornological vector topologies for vector spaces is discussed.In general,the convergent sequence and bounded set are concepts only in topological spaces.However,in this paper,it is first introduced sequential convergence C and L * space which is a vector space giving some relation:x mCx between sequences and points in it,then the bounded set is defined in vector space.Let C be a sequential convergence,T(C) be a vector topology on X determined by C and B(C) be the collection of bounded sets determined by C.Then B(C)=B(T(C)).Furthermore,the bornological locally convex topological vector space is constructed by L * vector space. 展开更多
关键词 convergent sequence bounded set l %MUl% space additive filterbase bornological space
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Studies on Enhancing Yield of Embryos in Microspore Culture of Brassica napus L. 被引量:1
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作者 李浩杰 蒲晓斌 +2 位作者 张锦芳 蒋俊 蒋梁材 《Agricultural Science & Technology》 CAS 2009年第4期37-40,共4页
In ecological zone of Chengdu, Sichuan, microspore culture was carried out in Brassica napus L. to study the influencing factors on microspore culture. The results showed that the temperature on microspore formation s... In ecological zone of Chengdu, Sichuan, microspore culture was carried out in Brassica napus L. to study the influencing factors on microspore culture. The results showed that the temperature on microspore formation stage, day and night temperature, disinfection solution of buds, cultivation concentration on microspore and strain-age were both important influencing factors on microspore culture. At a temperature below 5 ℃ or above 20 ℃, the material had a much lower embryo producing rate or even could not produce any embryo, but at the optimum temperature of 10 -15 ℃ the embryo yield was up to 300 pieces per bud; the best cultivation effect appeared when 0. 1% HgCl2 was used for disin- fection; the best density of microspore was 3 -4 buds per dish; In 2009, while strain-age was from 125 d to 150 d, the microspore embryo yield increased as strain-age increased. When stain-age was 150 days, the microspore embryo yield was up to the highest, but the yield declined after 150 days. 展开更多
关键词 Brassica napus l. Isolated microspore culture Technical system Stain-age Embryo yield
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Amino acid-assisted synthesis of TS-1 zeolites containing highly catalytically active TiO_(6)species 被引量:2
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作者 Yuyao Wang Li Li +4 位作者 Risheng Bai Shiqin Gao Zhaochi Feng Qiang Zhang Jihong Yu 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 2021年第12期2189-2196,共8页
Tailoring the Ti coordination states in titanosilicate zeolites to simultaneously improve feedstock conversion and maximize the target product selectivity remains a challenge in the pursuit of high-performance catalys... Tailoring the Ti coordination states in titanosilicate zeolites to simultaneously improve feedstock conversion and maximize the target product selectivity remains a challenge in the pursuit of high-performance catalysts for selective oxidation reactions.Herein,we provide a facile strategy to synthesize hierarchical anatase-free TS-1(MFI-type)zeolites with tetrahedrally coordinated(TiO_(4))and octahedrally coordinated Ti species(TiO_(6)).The TiO_(4)species provide high epoxide selectivity,while the TiO_(6)species afford improved alkene conversion.This strategy is achieved by synergistically using an L-lysine-assisted approach and a two-step crystallization;the two-step crystallization approach prevents the formation of anatase TiO_(2),while L-lysine stabilizes the TiO_(6)species and ensures efficient incorporation of TiO_(6)into the anatase-free TS-1 zeolites.Compared with their conventional counterparts,which only contain TiO_(4)species,the as-prepared TS-1 zeolites(Si/Ti=36.9)result in a higher 1-hexene conversion(33%),higher TON value(153),and comparable epoxide selectivity(95%).This synthetic strategy provides avenues to tailor the amount and distribution of Ti species in titanosilicate zeolites to achieve high catalytic performances in various processes. 展开更多
关键词 TS-1 zeolites Ti species l-lysine-assisted approach 1-Hexene epoxidation
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Quantum mechanic study on cyclic molecul formation from ethynyl radical (C2H) and ethyne (C2H2)
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作者 INDARTO Antonius 《Journal of Chemistry and Chemical Engineering》 2009年第1期55-60,共6页
The first cyclic molecule formation reactions from ethyne (C2H2), initiated by ethynyl radical (C2H), were studied by theoretical quantum mechanic. The study included the competition reaction between structure re-... The first cyclic molecule formation reactions from ethyne (C2H2), initiated by ethynyl radical (C2H), were studied by theoretical quantum mechanic. The study included the competition reaction between structure re-arrangement for the favourable ring-closure mechanism and ethyne addition in each step. The analysis was done by evaluating the energy difference of activation (AE), entalphy (AH), Gibbs (AG) of the optimized stable and transition molecules. The reaction temperatures were set at normal (T = 298 K) and combustion (T = 1200 K) condition. 展开更多
关键词 ethynyl radical ETHYNE quantum mechanic
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Enzymatic Synthesis of Halogen Derivatives of Aromatic Amino Acids Labeled with Hydrogen Isotopes
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作者 Elzbieta Winnicka Matgorzata Pajak Katarzyna Patka Katarzyna Czerwiflska Marianna Kafiska 《Journal of Chemistry and Chemical Engineering》 2014年第1期54-60,共7页
The isotopomers of halogenated amino acids (2'-F-L-phenylalanine, 3'-F- and 3'-Cl-L-tyrosine, as well as 5'-F-, 5'-Br-and 6'-F-L-tryptophan) specifically labeled with deuterium at α- and 13-carbon atom of the... The isotopomers of halogenated amino acids (2'-F-L-phenylalanine, 3'-F- and 3'-Cl-L-tyrosine, as well as 5'-F-, 5'-Br-and 6'-F-L-tryptophan) specifically labeled with deuterium at α- and 13-carbon atom of the side chain were synthesized by enzymatic catalyzed H/D exchange in fully deuteriated incubation medium. The extent and site of deuterium incorporation were confirmed by ^1H NMR (proton nuclear magnetic resonance) spectra. 展开更多
关键词 DEUTERIUM HAlOGEN PHENYlAlANINE TRYPTOPHAN tyrosine.
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RAPID DETERMINATION OF L-GLUTAMIC ACID WITH AN ENZYME REACTOR OF L-GLUTAMIC DECARBOXYLASE IMMOBILIZED ON ION EXCHANGE RESIN
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作者 WUGuoqi LING Daren +1 位作者 WANG Fan SONG Guoqiang 《Chinese Journal of Reactive Polymers》 2001年第2期160-167,共8页
The preparation and characterization of an immobilized L-glutamic decarboxylase (GDC) were studied. This work is to develop a sensitive method for the determination of L-glutamate using a new biosensor, which consists... The preparation and characterization of an immobilized L-glutamic decarboxylase (GDC) were studied. This work is to develop a sensitive method for the determination of L-glutamate using a new biosensor, which consists of an enzyme column reactor of GDC immobilized on a novel ion exchange resin (carboxymethyl-copolymer of allyl dextran and N.N?methylene-bisacrylamide CM-CADB) and ion analyzer coupled with a CO2 electrode. The conditions for the enzyme immobilization were optimized by the parameters: buffer composition and concentration, adsorption equilibration time, amount of enzyme, temperature, ionic strength and pH. The properties of the immobilized enzyme on CM-CADB were studied by investigating the initial rate of the enzyme reaction, the effect of various parameters on the immobilized GDC activity and its stability. An immobilized GDC enzyme column reactor matched with a flow injection system-ion analyzer coupled with CO2 electrode-data collection system made up the original form of the apparatus of biosensor for determining of L-glutamate acid. The limit of detection is 1.0×10-5 M. The linearity response is in the range of 5×10 -2-5×10 -5 M . The equation of linear regression of the calibration curve is y= 43.3x + 181.6 (y is the milli-volt of electrical potential response, x is the logarithm of the concentration of the substrate of L-glutamate acid). The correlation coefficient equals 0.99. The coefficient of variation equals 2.7%. 展开更多
关键词 Immobilized enzyme reactor l-glutamic decarboxylase Glutamate acid Ion exchanger..
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Bandwidth Numerical Analysis of Triangular Patch Antenna Fed by L-Shaped Probe
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作者 刘毅军 黎滨洪 +1 位作者 张亚斌 陈兴义 《Journal of Shanghai Jiaotong university(Science)》 EI 2004年第1期60-62,共3页
A single layer triangular patch antenna fed by an L-shaped probe was investigated numerically by using FDTD (Finite Difference Time Domain) method. It achieves >40% impedance bandwidth (VSWR<2) and stable radiat... A single layer triangular patch antenna fed by an L-shaped probe was investigated numerically by using FDTD (Finite Difference Time Domain) method. It achieves >40% impedance bandwidth (VSWR<2) and stable radiation pattern across the passband. The triangular patch antenna with two orientations of L-shaped probe has almost the same characteristics, such as impedance bandwidth and radiation pattern. The bandwidth vs feeding position was also investigated, the broadband characteristic can be observed when the feeding position is only in a small segment along the centerline. 展开更多
关键词 FDTD triangular patch antenna l-shaped probe
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Effects of Solvent and Impurities on Crystal Morphology of Zinc Lactate Trihydrate
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作者 杨芗钰 钱刚 +2 位作者 张相洋 段学志 周兴贵 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2014年第2期221-226,共6页
The crystal morphology of zinc lactate trihydrate in the absence or presence of impurities(viz.succinic acid,L-malic acid and D-malic acid)is investigated by molecular simulation based on surface docking model and COM... The crystal morphology of zinc lactate trihydrate in the absence or presence of impurities(viz.succinic acid,L-malic acid and D-malic acid)is investigated by molecular simulation based on surface docking model and COMPASS force field.Combing simulation results with our previous experimental results,it is found that the solvent mainly has an inhibition effect on the(0 0 2)surface,and succinic acid impurity will inhibit the growth of(0 0 2)and(0 1 1)surfaces while two enantiomers of malic acid impurity will inhibit the(0 0 2)and(1 0 0)surfaces,which are in good agreement with the experimental results. 展开更多
关键词 crystal morphology molecular simulation solvent effect impurity adsorption
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Modified DIX model for ion-exchange equilibrium of L-phenylalanine on a strong cation-exchange resin 被引量:3
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作者 Jinglan wu Pengfei Jiao +2 位作者 Wei Zhuang Jingwei Zhou Hanjie Ying 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2016年第10期1386-1391,共6页
L-phenylalanine, one of the nine essential amino acids for the human body, is extensively used as an ingredient in food, pharmaceutical and nutrition industries. A suitable equilibrium model is required for purificati... L-phenylalanine, one of the nine essential amino acids for the human body, is extensively used as an ingredient in food, pharmaceutical and nutrition industries. A suitable equilibrium model is required for purification of L-phenylalanine based on ion-exchange chromatography. In this work, the equilibrium uptake of L-phenylalanine on a strong acid-cation exchanger SH11 was investigated experimentally and theoretically. A modified Donnan ion-exchange (DIX) model, which takes the activiW into account, was established to predict the uptake of L-phenylalanine at various solution pH values. The model parameters including selectivity and mean activity coefficient in the resin phase are presented. The modified DIX model is in good agreement with the experimental data. The optimum operating pH value of 2.0, with the highest t-phenylalanine uptake on the resin, is predicted by the model. This basic information combined with the general mass transfer model will lay the foundation for the prediction of dynamic behavior of fixed bed separation process. 展开更多
关键词 Ion-exchange equilibrium l-phenylalanine Mathematical modeling Chromatography Mean ionic activity coefficient
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Isolation and characterization of the murine Nanog gene promoter 被引量:13
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作者 DaYongWU ZhenYAO 《Cell Research》 SCIE CAS CSCD 2005年第5期317-324,共8页
Nanog protein is expressed in the interior cells of compacted morulae and maintained till epiblasts but downregulated by implantation stage. It is also expressed in embryonic stem cells, embryonic carcinoma cells and ... Nanog protein is expressed in the interior cells of compacted morulae and maintained till epiblasts but downregulated by implantation stage. It is also expressed in embryonic stem cells, embryonic carcinoma cells and embryonic germ cells but disappeared in differentiated ES cells. In this study, we have isolated, sequenced, and performed the first characterization of the Nanog promoter. The transcription start sites were mapped by primer extension analysis. Two promoter regions were found upstream the transcription start sites and the expression of major Nanog promoter/ reporter gene construct is abolished in differentiated F9 EC cells as compared to the undifferentiated counterpart. We also showed that a putative octamer motif (ATGCAAAA) is necessary for the major promoter activity. Gel shift and supershift assays showed that Oct-1, Oct-4 and Oct-6 protein selectively bind to the octamer motif. 展开更多
关键词 NANOG PROMOTER F9 EC cells Oct-1 OCT-4 Oct-6.
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Notes on the Heat Diffusion Semigroup in a Riemannian Manifold
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作者 卢克平 《Chinese Quarterly Journal of Mathematics》 CSCD 1992年第1期89-95,共7页
In this paper, the properties of the heat diffusion semigroup {e^(t△)}_(t≥0) generated by the Hodge-deRham operator in a Riemannian manifold are discussed.
关键词 Riemannian manifold Hodge-deRham operator Heat semigroup
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Berry Phases for the L—S Coupled System in a Time—Dependent Magnetic Field
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作者 YANFeng-Li YANGLin-Guang 《Communications in Theoretical Physics》 SCIE CAS CSCD 2001年第5期527-530,共4页
By the unitary transformation method, the instantaneous energy eigenstates of the L-S coupled system in a time-dependent magnetic field, hence the Berry phases, are calculated.
关键词 l-S coupled system instantaneous energy eigenstate Berry phase
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Finite Type Non-Minimal Submanifolds
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作者 宋鸿藻 吴报强 《Chinese Quarterly Journal of Mathematics》 CSCD 1992年第4期76-83,共8页
The notion of finite type submanifolds was introduced by B. Y. Chen. In this paper we consider the characteristics and the classifications of finite type non-minimal submanifolds. The characteristic theorems of 2-type... The notion of finite type submanifolds was introduced by B. Y. Chen. In this paper we consider the characteristics and the classifications of finite type non-minimal submanifolds. The characteristic theorems of 2-type Chen submanifolds,mass-symmetrie hypersurfaces and Dupin hypersurfaces in E_3~m are obtained. The classification theorems of 3-type hypersurfaces and null 2-type curves in E_3~m are also proved. 展开更多
关键词 Finite Type Submanifolds Minimal Submanifolds
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