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Mrnas: these provide protein coding information to ribosome. some snrnas: these function in a variety of nuclear processes, including rna splicing and processing. it is very sensitive to inhibition by -amanitin.

rna聚合酶ⅱ催化合成 mrna的前体核内不均一rna以及核内小分子rna.mrnas是核糖体翻译蛋白质的模板;核内小分子rna参与了核内的多种加工过程,包括rna的剪切加工。rna聚合酶ⅱ对α-鹅膏蕈碱高度敏感。

In the single crystal of C60 with a FCC structure,positron mainly appears outside the C60 molecule.The main annihilation space is the interspace between molecules.The calculated positron bulk lifetime in C60 is 352ps, which agrees with experiment value of 356ps in literature.In carbon nanotube bundles with different dimeters,as the diameter of carbon nanotubes increases,the main space where positron appears changes from the interspace of carbon tubes to the space inside carbon tubes,the radio between positron annihilation with valence eletrons and core eletrons becomes larger,the positron bulk lifetime in carbon nanotube increase rapidly first and come to be a constant at the end.The calculated positron lifetime of carbon nanotube with a dimeter of 0.8~1.6ns is 332~470ps,which agrees with the experiment value of 394ps.Positron annihilation has been studied in widly used compound semiconductors.

计算结果表明:在片层结构的石墨晶体中,正电子主要在石墨层间的空隙中湮没,计算出的石墨中的正电子寿命为208 pS,与文献中的实验结果215 ps符合很好;在金刚石单晶中,正电子主要在碳原子之间的空隙中存在并发生湮没,计算出的金刚石中的正电子寿命为115 ps,文献中的实验结果110 ps左右符合;在面心立方结构的C60晶体中,正电子主要在C60分子球壳内外侧及分子之间存在,C60球形分子中心正电子分布很少,正电子的湮没区域集中在C60分子之间的空隙区域,计算出的C60中的正电子寿命为352 ps与文献中的实验结果356ps相符合;对于不同管径碳米管束中的正电子分布,随着碳纳米管直径的增加,碳纳米管束中的正电子由主要在碳纳米管管间的区域出现转变为主要在碳纳米管管内中心的区域出现:碳纳米管束中的正电子与碳原子的价电子的湮没概率变得越来越大,与核心电子的湮没概率变得越来越小;碳纳米管束中正电子的湮没寿命先迅速增大,而后趋于一定值。

Objects in the thermal motion of molecules in a measure of average energy, it belongs to the molecular thermal motion of objects within the equilibrium molecular kinetic energy of the average statistics.

物体内分子的热运动平均能量的度量,它属于物体内的分子热运动平衡状态下分子动能的平均统计值。

It was found that the geometries of the studied materials were significantly affected by the ring size and intramolecular charge transfer. The HOMO level, LUMO level, and band gap of the studied model compounds were well controlled by the acceptor strength. However, the electronic properties of the studied polymer showed a significant different trend with the acceptor strength due to the geometrical transformation. The model compound of EDOT-TP and T-TP has the aromatic geometry but is transformed to the quinoid geometry for large intramolecular charge transfer. The small bond length alternation and large acceptor strength in the EDOT-BDP polymer also results in the smallest Eg of 0.7 eV among the studied polymers.

我们发现环的大小以及分子内电荷转移对结构有很大的影响,而小分子的HOMO、LUMO和能隙受到电子受体强度所控制,然而,高分子的电子特性与其构成分子却有明显不同的趋势,这主要是由於分子结构的转变,如小分子EDOT-TP以及T-TP因分子内电荷转移,使其高分子结构由aromatic转变成quinoid;而EDOT-BPP因其键长改变量小和良好的电子受体强度,使其能隙仅0.7个电子伏特。

In this thesis,the AM1,MNDO,MINDO/3(mainly AM1)and INDO/S-CI semiempirical MO methods were used toinvestigate the excited-state intramolecular protontransfer reactions of salicylic acid derivatives—salicylic acid,methyl salicylate,salicylaldehyde,o-hydroxyaceto-phenone,salicylamide and 3-hydroxy-picolinamide (6 conformers and 2-3 anion species);2-(2'-hydroxy-5' methylphenyl) benzotriazole(4 conformers),2-(2' hydroxyphenyl) benzimidazole (3 conformers and 3anion species),Bis-2,5-(2-benzoxazolyl)hydroquinone(3 conformers),2-(2'-hydroxyphenyl)benzothiazole(2conformers) and 7-azaindole dimer (2 conformers).Theinvestigations were described as follows.Geometry optimization,relative stability andhydrogen bonding energy First,for sylicylic acid derivative molecules,the AM1,MNDO and MINDO/3 methods were used toinvestigate ground-state geometry optimization,energies,relative stabilities and hydrogen-bondingenergies on the five kinds of the molecules(designing 6 conformers and 2-3 anion species).Comparing with experimental data,the optimizedgeometry,the order of stability,the hydrogen-bonding energies and the distances between O-O in O-H..O hydrogen bonds by AM1 method were in agreementwith the experimental data,however,the C-C bondlengths optimized by MNDO and MINDO/3 were longer,C-O and O-H bond lengths were shorter;for C-N bondlengths,the results opitimized by MNDO method werethe same as those by AM1 method,nevertheless the C-Nbond lengths given by MINDO/3 method were muchshorter.For some sylicylic acid derivatives(e.g.methyl salicylate,salicylamide),the order ofstabilities on the conformers given by MNDO andMINDO/3 methods were not in agreement with theexisting conformers deduced by experimental methods,and the hydrogen bonding energies calculated by MNDO.and MINDO/3 methods were smaller.Second,the studyon the other systems found that the optimizedgeometry of the proton-transfered product with INDOmethod could not be obtained,only could theoptimized geometry of reactant be obtained,and thecalculated hydrogen bonding energies were greater.Many results of calculation indicated that the studyon the excited-state intramolecular proton transferreaction system using AM1 method was suitable andreliable.

本论文用AM1、MNDO、MINDO/3(主要是AM1)和INDO/S-CI半经验分子轨道方法对水杨酸衍生物系列——水杨酸、水杨酸甲酯、水杨醛、O-羟基乙酰苯酮、水杨酰胺和3-羟基吡啶酰胺(6种异构体和2-3种阴离子);2-(2'-羟基-5'-甲基苯基)苯并三〓唑(4种异构体);2-(2'-羟基苯基)苯并咪唑(3种异构体和3种阴离子);2,5-二间氮杂氧茚氢醌(3种异构体);2-(2'-羟基苯基)间〓杂硫茚(2种异构体)和7-〓吲哚二体(2种异构体)的激发态分子内质子转移反应在以下几个方面进行了较系统的理论研究:几何构型优化和相对稳定性及氢键能首先以水杨酸衍生物系列分子为例,用AM1、MNDO和MINDO/3方法考察了5种分子(每种分子设计6种异构体和2-3种阴离子)的基态几何构型优化,能量、相对稳定性和氢键能计算,通过和实验数据进行比较,AM1方法给出的优化几何构型、稳定性次序、氢键能和O—H。。。O氢键的0—0距离与实验数据吻合最好,MNDO和MINDO/3方法优化的C-C键长偏长,C-O键和O-H键长偏短;对于C-N键长,MNDO和AM1优化结果差别不大,而MINDO/3给出了过短的C-N键长,MNDO和MINDO/3方法给出的有些水杨酸衍生物分子(如水杨酸甲酯和水杨酰胺)异构体的稳定性次序和实验上推测的可存在异构体结果不一致,MNDO和MINDO/3方法给出的氢键能偏低,对其他体系的研究发现INDO方法常常不能得到质子转移产物的优化几何构型,只能得到反应物的优化构型,并且估算的氢键能偏高,大量的计算结果表明AM1方法对本论文研究的激发态分子内质子转移反应体系是适宜和可靠的。

The dissertation is focused on the research of organic supramolecular self-assembly and molecule folding. It consists of four parts. In the first part, three new model molecules for investigating intramolecular coaggregation behavior have been designed and synthesized. Fluorescence studies reveal that intramolecular coaggregation of these molecules take place with the increase of the solvent polarity because of hydrophobic-lipophilic interaction .

本论文主要对有机超分子自组装和分子折叠做了一些研究,共分四个部分:第一部分中,我们设计并合成了一个新的研究分子内自簇集的模型,用荧光光谱法对该模型进行了研究,研究表明,在促簇能力较强的溶剂体系中,这一类模型分子可在疏水亲脂作用的驱动下发生分子内自簇集而形成卷曲的构象。

The dissertation mainly consists of two parts:1. The Reaction Chemistry of Alkynes under Palladium Catalysis Part 1 studies the reaction α,β-unsaturated carbonyl compounds with alkenylpalladium intermediate generated by nucleopalladation, and discovered 1 the Pd-catalyzed tandem addition reaction of halides, alkynes and α,β-unsaturated carbonyls,2 the four-component tandem addition reaction of halides, alkynes and α,β-unsaturated carbonyls, 3 the tandem intramolecular oxypalladation-conjugate additionreaction of alkynoic acids with α,β-enals. These new reactions provide notonly efficient highly stereoselective methods for the synthesis of γ,δ-unsaturated,polyunsaturated carbonyl compounds and γ-lactonic aldehydes, but also thebasic transformations for a number of C-C bond formation reactions which can be usedto design synthesis of many acyclic, cyclic or polycyclic compounds.

本论文的主要工作分为两个部分:一、钯催化下炔烃的反应化学在本小组前人工作的基础上,我们详细研究了炔烃亲核钯化产生的烯基钯中间体与α,β-不饱和羰基化合物的反应,发现两价钯催化下卤离子-炔烃-α,β-不饱和醛酮的串联加成反应、卤离子-炔烃-α,β-不饱和醛酮的西组分串联加成及炔酸分子内氧钯化-串联Michael型加成反应;由此发展了γ,δ-不饱和醛酮、多不饱和羰基化合物和带有醛酮基侧链的γ-丁内酯衍生物的高立体选择性合成方法,这一过量卤离子存在下的烯基钯对α,β-不饱和羰基化合物共轭加成反应的发现,为大量碳-碳键形成反应的实现提供了基础,使我们能够从这一基本反应出发,设计和开发多种分子内、分子间的碳碳成键反应,以好的立体、区域选择性组建开链、环状及多环类型的化合物。

Because of little and not well-distributed suction power of gas molecule to liquid molecule, there is surface tension between the liquid and gas in alveoli(a kind of suction power or concentric force souced from surface).

肺泡内液气界面存在着表面张力(一种表面能来源与分子间的吸引力或内聚力),是由于气体分子对肺泡内面表面液气分子吸引力很小,液体分子各向受力不匀的表现。

A one-step method for the synthesis of aromatic indolizine derivatives byintramolecular 1,5-dipolar cyclization reaction of 2-(2-arylethenyl)pyridinium N-ylidesin the presence of an oxidant has been studied for the first time. In the presence ofelectron-deficient olefins, however, 2-(2-phenylethenyl)pyridinium N-ylides underwent1,3-dipolar cycloadditions and then aromatized in situ by TPCD to produce indolizinederivatives, indicating 1,3-dipolar cycloaddition proceed more readily than 1 ,5-dipolarcyclization in these conditions. Pyridinium disubstituted N-ylides, readily obtainedfrom corresponding pridinium and β-chlorovinyl ketone, underwent thermalintramolecular 1,5-dipolar cyclization to give indolizine derivatives easily.Indolizinecarbaldehyde derivatives were synthesized starting from 2-pyridinecarbaldehyde in four-steps involving 1,3-dipolar cycloaddition reaction.

本文首次研究了2-(2-芳基乙烯基)吡啶N-叶立德在氧化剂存在下的分子内1,5-偶极环化反应,采用一锅法合成了中氮茚衍生物;研究了这些N-叶立德的1,5-偶极环化和1,3-偶极环加成反应的选择性,发现当有缺电子烯烃存在时,优先进行1,3-偶极环加成反应,而不再发生分子内1,5-偶极环化反应;由β-氯乙烯酮方便地得到了烯丙基N-叶立德,他们在加热时进行分子内1,5-偶极环化反应而得到中氮茚衍生物;由2-吡啶甲醛为起始原料,通过1,3-偶极环加成反应等四步反应,得到了重要的中氮茚甲醛衍生物,这些反应都具有条件温和和操作简便的特点,是合成中氮茚衍生物的新方法。

The immune system reacts powerfully to a surprising variety of the patient's molecules, ranging from targets exposed at the surface of cells to some inside of cells to even some within a further sequestering chamber, the cell nucleus.

狼疮患者的免疫系统会对体内许多分子产生强烈反应,种类多到令人惊讶,从暴露在细胞表面的分子到细胞内的分子,甚至是包在细胞核内的分子。

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The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应,而且减少跟风的可能性。

The new PS20 solar power tower collected sunlight through mirrors known as "heliostats" to produce steam that is converted into electricity by a turbine in Sanlucar la Mayor, Spain, Wednesday.

聚光:照片上是建在西班牙桑路卡拉马尤城的一座新型PS20塔式太阳能电站。被称为&日光反射装置&的镜子将太阳光反射到主塔,然后用聚集的热量产生蒸汽进而通过涡轮机转化为电力