查询词典 elimination by substitution

Cellulose acetate butyrate with high or low degree of butyryl substitution was synthesized in heterogeneous system(butyric acid/ acetic acid/ butyric anhydride/ sulfuric acid) using the "free solvent" method. The effect of activation time, esterification time, the molecular weight of cellulose and the content of the organic acid or anhydride on the degree of acetyl and butyryl substitution of cellulose was discussed.

在非均相体系中进行酯化反应，采用&反应性溶剂&，以硫酸作为催化剂合成出从高丁酯含量到低丁酯含量的纤维素醋酸丁酸酯，研究有机酸以及酸酐的添加量、活化时间、酯化反应时间以及原料纤维素的分子量对酯化产物纤维素醋酸丁酸酯的影响。

In the second chapter , four new tetra-O-substitution of calix[4]arene derivatives are synthesized by condensation and two steps of substitution reaction from p-tert-phenol and formaldehyde.

本文第二章对Calix[4]arene进行了功能化，通过三步反应，合成了四种新的混醚。

The barley chromosome in wheat was identified by genomic in situ hybridization in which biotin labelled total genomic DNA of barley betzes was used as probe and the unlabelled total DNA of common wheat Chinese Spring as blocking DNA. A series of wheat materials were tested as follows; two disomic alien substitution and monosomic alien addition lines, 2n=43; two monosomic alien substitution lines.

用生物素(Biotin-16-dUTP)标记的大麦Betzes基因组DNA作探针，以普通小麦中国春总DNA作封阻进行基因组原位杂交(Genome in situ hybridiz ation，简称GISH)，从13株小麦-大麦杂交后代中鉴定出2个含有3条大麦B etzes2H染色体的材料(2n=43)；2个2H单体异代换系(2n=42)；7个2H二体异代换系(2n=42)。

With increasing the percent of azide substitution, maximum temperature of thermal degradation is also increscent, a linear relationship exists between the glass transition temperature of B and percent of azide substitution.

随着叠氮化反应程度的加深，最大热分解温度升高，不同程度叠氮化取代率的叠氮聚醚多元醇的玻璃化温度与叠氮化取代率成线性关系。

The feldspars of topaz-lepidolite granite in Yashan late stage are P-rich albite and Kfeldspar, and the phosphorus goes into feldspar structure in the form of PAlSi〓 substitution. The phosphorus contents of feldspars vary according to their crystal habitus. In general, the feldspars of later generation have the higher average phosphorus content than that of earlier generation, and the albite contains higher phosphorus than the K-feldspar in the same generation. The zircon is highly rich in Hf, U, P and Al. The phosphorus enters the zircon structure mainly by the form of〓P〓〓Si〓, Al〓P〓Si〓 or P〓Al〓Si〓, Zr〓 substitution. The P-rich zircon is the production of the highly evolved magma, and it might be one of the important characteristic minerals of the high-P subtype granite. The manganocolumbite, manganotantalite, wodginite and titanowodginite are the main niobium and tantalum minerals.

雅山晚阶段黄玉锂云母花岗岩的长石矿物是富磷长石，磷以PAlSi〓替换方式进入长石结构中，并且在长石中的分布很不均一，一般是晚结晶的长石比早结晶的长石的磷含量高，同期结晶的钠长石比钾长石的磷含量高；锆石矿物为高度富铪、铀、磷和铝的锆石，磷主要以(Y， HREE， Fe)〓P〓〓〓Si〓〓、Al〓P〓Si〓〓、P〓Al〓Si〓〓Zr〓〓等替换方式进入锆石晶格中，富磷锆石是岩浆高度演化的结果，是高磷花岗岩的特征矿物之一；雅山含有丰富的磷锂铝石，是高磷花岗岩的主要磷酸盐矿物；铌—钽矿物主要有铌锰矿—钽锰矿、锡锰钽矿—钛锰钽矿、细晶石等。

Density Functional Theory method was used to optimize the geometries of 209 PCDE molecules, 209 PBDE molecules and 75 PCDD molecules at the B3LYP/6-31G* level. Using computed structural parameters as theoretical descriptors, the forward stepwise multiple regression technique was adopted to obtain QSPR models of environmental partition properties for these POPs by using GQSARF 2.0 and SPSS12.0 for windows programs. The obtained QSPR models are as follows:(1) QSPR models for predicting subcooled liquid vapor pressure, n-octanol/water partition coefficients lgK_(ow and subcooled liquid water solubilities -lgS_(w,l of PCDEs, of which correlative coefficients (R~2) are 0.988, 0.958 and 0.959 and the root-mean-square-error of estimation are 0.134, 0.116 and 0.327 respectively.(2) QSPR models of lgPL and n-octanol/air partition coefficients lgK_(oa for PBDEs, which both contain three structural parameters. The values of R2 for the two models are both 0.997 while the values of RMSEE are 0.073 and 0.062 respectively.(3) QSPR models of lgKow and–lgS_ for PCDEs, which both have one variable (mean molecular polarizability,α). The values of R~2 for the two models are 0.978 and 0.866 and the values of RMSEE are 0.300 and 0.270 respectively.(4) The molecular structures of 24 substituted naphthaline compounds were optimized using Hartree-Fock and DFT methods at four different levels and the same means was used to obtain four three-parameter (EHOMO, q~+ andα) QSPR models of lgK_. The model at the HF/6-311G** level is the best one of which R2 is 0.9662 and RMSEE is 0.380.(5) QSPR study for environmental partition properties of PCDEs was also performed using position of Cl substitution method in which simple parameters of substitution position were taken as descriptors. The multiple linear regression was performed with GQSARF 2.0 and SSPS 12.0 for windows programs to obtain QSPR models of lgP_L, lgK_ and–lgS_ for PCDEs of which R~2 are 0.991, 0.983 and 0.965 and RMSEE are 0.311, 0.100 and 0.300 respectively.

采用密度泛函理论方法在B3LYP/6-31G*水平上对PCDEs、PBDEs和PCDDs的分子结构进行了全优化计算，以计算得到的量子化学参数作为理论描述符，采用GQSARF 2.0和SPSS 12.0 for windows统计程序进行正向逐步回归分析，建立了这些POPs的环境分配性质的QSPR模型：(1) PCDEs的过冷液体蒸汽压、正辛醇/水分配系数lgK_(ow和水溶解度-lgS_(w，l的QSPR模型，这3个QSPR模型的相关系数(R2)分别为0.988、0.958和0.959，估计的均方根误差分别为0.134、0.116和0.327；(2) PBDEs的lgPL和正辛醇/空气分配系数lgK_(oa的QSPR模型，这两个模型都包含三个分子结构参数，其R~2都为0.997，RSMEE分别为0.073和0.062；(3) PCDDs类化合物的lgK_和-lgS_w的QSPR模型，两个模型都只含一个变量，其R~2分别为0.978和0.866，RSMEE分别为0.300和0.270；(4)采用Hartree-Fock和DFT方法，在4种不同水平上优化计算了24个取代萘系列化合物的分子结构，采用上述同样的方法分别建立了四种水平上的三变量lgK_模型，通过比较得到，在HF/6-311G**水平计算得到的模型最好，R为0.966，RSMEE为0.380；(5)同时，采用氯原子取代位置方法对PCDEs的环境分配性质进行QSPR研究，建立了PCDEs的lgPL、lgK_和-lgS_的QSPR模型，其R~2分别为0.991、0.983和0.965，RSMEE分别为0.110、0.100和0.300。

Some residues are subject to conservative substitution of one residue by another with similar properties, others to nonconservative substitution where one amino acid residue is replaced by another with different propertied.

某些塞住的嘴基属于保守的取代，即一个残基被别一个相似性质的残基取代；其它为非保守的取代，即一个氨基酸残基被另一个不同性质残基取代。

However, in different primate groups, as well as in different CCR5 gene regions, synonymous substitution rate Ks and nonsynonymous substitution rate Ka were obviously different.

通过使用不同的时间标尺，我们估计了Ka和Ks在不同灵长类类群中的进化速率，并与它们在啮齿类中的进化速率比较。

The nonsynonymous substitution sites were more than synonymous substitution sites in human, house mouse and pig obviously.

人、家鼠和猪的非同义替换位点数明显高于同义替换位点数。

The results show that although both Ni substitution and Mg vacancies are effective in desorbing hydrogen at lower temperatures, the substitution of Ni at the Mg site is energetically more favorable than the formation of Mg vacancies. The Ni atoms of NiF2 can replace some Mg atoms of MgH2 systems, the reaction of NiF2+3MgH2=MgF2+Mg2NiH4 during mill process is accelerated, thus, MgH2 with the higher stability can be changed into Mg2NiH4. Because of a ternary hydride Mg2NiH4 with lower stability forming, the dehydrogenating properties on Ni doped MgH2 systems are improved.

结果表明：Ni替代Mg和创造Mg空位对MgH2体系解氢而言，均发挥有益作用，而形成Mg空位所需能量(6.51 eV)高于Ni替代Mg所需能量(2.12 eV)，表明低温下Ni替代Mg对MgH2体系解氢而言更有利，至此NiF2中的Ni替代MgH2中的Mg，有利于加速化学反应NiF2+3MgH2=MgF2+Mg2NiH4向右进行，使结构稳定的MgH2发生转变，生成结构不稳定的Mg2NiH4，这样体系解氢过程不是通过MgH2，而是转变为通过Mg2NiH4进行，因此，Ni掺杂提高了MgH2体系的解氢性能。

Although translator has turned from being a crystal ball by which the original culture can unrestrainedly penetrate to another crystal ball by which the target culture can freely traverse, the translator's personal embodiment, in the process of cognitive act, are still absent in translation studies. Translators are still subjects without body or simply disembodied subjects.

译者虽然由原语文化可以自由穿透的玻璃球变成了译语文化可以自由穿越的玻璃球，但译者认知过程中的个体体验在翻译研究中依然缺席，译者依然仅仅是一个没有躯体体验的主体。

Chillingly, he claimed our technology is 'not nearly as sophisticated' as theirs and "had they been hostile", he warned 'we would be been gone by now'.

令人毛骨悚然的，他声称我们的技术是'并不那么复杂，像他们一样，和"如果他们敌意"，他警告说，'我们将现在已经过去了。