HNCO与 HF、HCl和HBr反应机理的理论化学研究

采用密度泛函B3LYP方法,在6-31 G(d,p)水平上研究和比较了HNCO与HF、HCl和HBr加成反应的反应机理.通过优化计算找到了反应的过渡态,且振动分析确认了过渡态的结构,并用内禀反应坐标方法确定了能量最低反应路径.计算结果表明3个反应都是放热反应,反应中伴随着一个σ键和一个π键断裂的同时有2个新σ键生成.过渡态是四元环结构,由于卤化氢中卤原子电负性的不同,四元环形状有比较明显的差异.过渡态最显著特征是氢原子的转移.     

HNCO与XCH2OH(X=CH3、NH2、OH、F)反应机理的理论研究

采用密度泛函(DFT)理论的B3LYP方法,在6-31 G(d,p)水平上按BERNY能量梯度解析全参数优化了HNCO和XCH2OH(X=CH3、NH2、OH、F)反应势能面上各驻点的几何构型,分别找到了这4个反应的过渡态,并通过振动频率分析确认了过渡态结构,通过内禀反应坐标(IRC)计算确认了最低能量反应途径(MEP).讨论了过渡态时的虚频振动模式,对各驻点进行了零点能(ZPE)校正,并计算了4个反应的活化能.研究结果表明,异氰酸的醇解反应是1个亲核加成反应,甲醇取代物和异氰酸分别是电子给体和电子受体,并且甲醇取代物的羟基氢在反应中发挥了重要作用;4个反应均为放热反应,反应中1个σ键和1个π键断裂,2个新的σ键生成;过渡态是四元环结构,由于CH3CH2OH、NH2CH2OH、OHCH2OH、FCH2OH分子中C、N、O、F原子电负性不同,四元环构型存在较明显的差异.     

X…Y(X=LiF,H3N,H2O; Y=HF,LiF)复合物中锂键、氢键的理论计算

在CCSD(T)/cc-pVTZ水平下，对X…Y(X=LiF,H3N,H2O; Y=HF, LiF)复合物的9个结构进行几何构型优化和红外振动频率计算. 根据定域化分子轨道、原子自然电荷、Wiberg键级的分析表明HFLiF分子中的H-F键是共价键, 而Li-F键则为离子键而非共价键. H3N…Y (Y=HF，LiF)、H2O…Y (Y=HF，LiF)中的氢键或锂键源于静电相互作用, 并非共用电子的共价键. 结合能的计算表明: 与HF相比, LiF与X (X=LiF, H2O, NH3)的结合能更高;结合能从高到低依次为 LiF > NH3 > H2O. 红外振动频率分析表明HF与NH3、H2O形成红移氢键,即 H-F键长增加, 相应的H-F伸缩振动频率降低. H3N…LiF的Li-F键键长增加同时伸缩振动频率减少. 而LiF与H2O形成锂键后，键长增加0.016 ?，而Li-F的伸缩振动频率反而增加了2 cm-1 , 即蓝移锂键.     

布洛芬分子手性转变裸反应机理及水分子的催化作用——基于羰基和苯环作H迁移桥梁

采用基于密度泛函理论的B3LYP方法和微扰理论的MP2方法,研究了布洛芬分子手性转变裸反应和水助质子从手性碳向羰基迁移的机理。分子结构分析表明:水助质子从手性碳向羰基迁移过程的8元环过渡态b TS2·2H_2O和10元环过渡态b TS2·3H_2O对应的氢键键角都远大于6元环过渡态b TS2·1H_2O;过渡态b TS2·2H2O的8元环结构基本共面,过渡态a_TS1·3H_2O和b TS2·3H_2O的10元环结构明显偏离平面。反应路径研究发现:标题反应有6条路径,分别是质子只以羰基氧、以甲基碳和羰基O及以羧基和苯环联合作桥,从手性C的一侧迁移到另一侧。势能面计算表明:质子以羧基和苯环联合作桥迁移的路径为优势反应路径,裸反应的决速步吉布斯自由能垒为287.1 k J·mol~(-1),2个水分子构成的链使决速步的吉布斯自由能垒降为144.9 k J·mol~(-1)。结果表明:布洛芬分子的手性转变存在多条可能的路径,水分子对布洛芬分子的H迁移异构反应有明显的催化作用,生命体内水分子的存在、温度的涨落、分子的频繁碰撞和某种酶的作用等综合因素,是导致左旋布洛芬旋光异构的原因。     

X…Y(X=LiF，NH3，H20;Y=HF，LiF) 复合物中锉键、氢键的理论计算

在CCSD(T)/cc-pVTZ水平下,对X...Y(X=LiF,NH3,H2O; Y=HF,LiF)复合物的9个结构进行几何构型优化和红外振动频率计算根据定域化分子轨道、原子自然电荷、Wiberg键级的分析表明HFLiF分子中的H-F键是共价键,而Li-F键则为离子键而非共价键H3N...Y (Y=HF,LiF),H2O...Y (Y=HF,LiF)中的氢键或铿键源于静电相互作用,并非共用电子的共价键结合能的计算表明:与HF相比,LiF与X (X=LiF,H2O,NH3)的结合能更高;结合能从高到低依次为LiF gt; NH3 gt;H2O红外振动频率分析表明HF与NH3,H2O形成红移氢键,即H-F键长增加,相应的H-F伸缩振动频率降低H3N...LiF的Li-F键键长增加同时伸缩振动频率减少而LiF与H2O形成铿键后,键长增加0.001 6nm,而Li-F的伸缩振动频率反而增加了2c;m,即蓝移铿键.     

F2＋2HCl=2HF＋C12反应机理的密度泛函理论（DFT）研究

用密度泛函理论(DFT)B3LYP方法，在6-3l1G^**基组下，计算研究了反应F2 2HCl=2HF Cl2的机理。求得各可能反应途径的系列过渡态，并通过振动分析和内禀反应坐标(IRC)分析加以证实。比较反应能垒(理论计算活化能)发现，题称反应若以分子与分子作用机理进行，则需克服的最大能垒为l50．63kJ／mol；若以F2分子先裂解为F原子再反应的机理进行，则需越过能垒154．82kJ／mol。求得反应F HCl→HF Cl的线形和三角形两种过渡态，以三角形较稳定；求得反应HCl Cl→H Cl2的两种过渡态，以线形较稳定。     

甲酰胺热分解反应机理的理论探讨

对甲酰胺的热分解反应进行了精确理论研究,在CAS（6,6）／6－21G优化构型的基础上,用CASPT2法做了单点能量校准,推测反应有2种途径：反应I经三元环过渡态形成NH3和CO产物,反应II经四元环过渡态形成H2和HNCO产物,这2个反应为一对竞争反应,并且有B3LYP,MP2和HF方法进行了对比分析。     

硝基甲烷正、负带电离子氢转移反应位垒的计算研究

采用DFT（UB3LYP）方法，在6—311＋＋G^＊＊基组水平上，计算研究了硝基甲烷2种带电结构[CH3NO2]^＋和[CH3NO2]^-分子内H原子向O原子转移后的O-N键的解离机理和反应位垒．结果表明，[CH3NO2]^＋发生氢转移后，O-N键的断裂是2步反应，第一步是分子内的H原子转移到O原子上，生成中间体[CH2N（OH）O]^＋，反应位垒为106．5kJ／mol；第二步是中间体中O-N键断裂，这步的反应位垒为105．5kJ／mol，理论计算得出的产物带电状态与实验一致．[CH3NO2]^-中H原子向O原子转移及O-N键断裂反应一步完成，生成一氢键复合物（H-Complex），该反应位垒为176．2kJ／mol，H—Complex进一步解离成CH2NO自由基和OH^-，或是OH自由基和[CH2NO]^-．     

CH3与HO2自由基反应途径及位垒的计算研究

采用量子化学从头算中的QCISD方法,在cc-pvdz和cc-pvtz基组水平上对CH3 HO2反应机理进行了计算研究,结果表明,CH3与HO2双分子自由基反应是一个复杂反应,反应可以在不同的电子态下经数个产物通道进行．在HOz自由基上的H直接转移到甲基自由基生成CH4 O2的反应途径上,存在一个低于反应物能量8．49kJ／mol的分子复合物．直接氢转移反应的计算位垒为3．07kJ／mol。与实验值零位垒相近．由CH3OOH生成CH2O和H2O反应的过渡态呈四元环构型,且具有Cs对称性,基于IRC计算,证明了该过渡态引导CH3OOH生成CH2O和H2O的反应机理是一个分子内氢迁移和H2O消除的协同过程．对由反应物生成CH3O和OH自由基的反应,除存在协同机理外,还提出了另一可能的通道,即反应物沿单线态位能面经过一个分步反应完成．也即反应物先经无位垒过程产生CH3OOH及其异构体CH3(O)OH,其中CH3(O)OH发生解离反应生成CH3OH和单线态原子氧,然后原子氧转化为三线态再与CH3OH进行反应生成CH3O和OH．     

氨基氰氢-迁移异构化反应的理论研究

利用Gaussian03程序,在B3LYP/6-311G＊＊的水平下对氨基氰分子的腈式、亚胺式异构体构型,氨基氰.H2O复合物的腈式、亚胺式异构体构型,氨基氰.HF复合物的腈式、亚胺式异构体构型,氨基氰.NH3复合物的腈式、亚胺式异构体构型的稳定构型、以及氢-迁移异构化反应过程中可能过渡态（TS）的结构进行全参数优化.根据主要几何构型参数,比较其对应物的相对稳定性;结果表明各复合物腈式结构较亚胺式稳定,氨基氰分子分别与H2O、HF、NH3形成复合物后,进行氢-迁移引起的互变异构反应的活化能大大降低,使反应较易进行;在298.15 K和1.0×10^5Pa下,气相氨基氰与甲二亚胺分子间的异构反应,各催化剂小分子的催化效能顺序为：NH3〉H2O〉HF.     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

橡胶颗粒沥青混合料低温抗裂性试验研究

以AC-13级配为基础,将橡胶颗粒代替部分集料掺入混合料中,以低温弯曲试验为评价方法对不同橡胶颗粒掺量下沥青混合料的低温抗裂性进行研究,并引入应变能密度值对混合料的低温抗裂性进行综合评价.试验结果表明:橡胶颗粒沥青混合料试件的破坏微应变均超过2 300,满足冬寒区的技术指标;无论是否掺加橡胶颗粒,随着温度的下降,沥青混合料破坏时的最大弯拉强度增大,弯拉应变降低,劲度模量增大;弯曲应变能密度在胶粒掺量为1%左右时具有较大的弯曲应变能密度值,此时橡胶颗粒沥青混合料具有较好的低温抗裂性.     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

Quantitative trait loci （QTLs） for quality traits related to protein and starch in wheat

Quality traits in wheat （Triticum aestirum L.） were studied by quantitative trait locus （QTL） analysis in a recombinant inbred line （RIL） population, a set of 131 lines derived from Chuan 35050 × Shannong 483 cross （ChSh）. Grains from RILs were assayed for 21 quality traits related to protein and starch. A total of 35 putative QTLs for 19 traits with a single QTL explaining 7.99-40.52% of phenotypic variations were detected on 10 chromosomes, 1D, 2A, 2D, 3B, 3D, 5A, 6A, 6B, 6D, and 7B. The additive effects of 30 QTLs were positive, contributed by Chuan 35050, the remaining 5 QTLs were negative with the additive effect contributed by Shannong 483. For protein traits, 15 QTLs were obtained and most of them were located on chromosomes 1 D, 3B and 6D, while 20 QTLs for starch traits were detected and most of them were located on chromosomes 3D, 6B and 7B. Only 7 QTLs for protein and starch traits were co-located in three regions on chromosomes 1D, 2A and 2D. These protein and starch trait QTLs showed a distinct distribution pattern in certain regions and chromosomes. Twenty-two QTLs were clustered in 6 regions of 5 chromosomes. Two QTL clusters for protein traits were located on chromosomes 1D and 3B, respectively, three clusters for starch traits on chromosomes 3D, 6B and 7B, and one cluster including protein and starch traits on chromosome 1D.     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.