查询词典 covalent

Covalent modification of four isolated alkannin derivatives (alkannin, acetylalkannin,β,β dimethylacrylalkannin and β acetoxyisovalerylalkannin, respectively) on rabbit muscle latate dehydrogenase and yeast Alcohol Dehydrogenase has been studied.

为研究紫草萘醌类化合物的细胞毒性作用机制，从新疆软紫草根中分离出四种紫草萘醌类化合物β，β二甲基丙烯酰阿卡宁(1)，乙酰阿卡宁(2 )，β乙酰氧基异戊酰阿卡宁(3)和阿卡宁(4)。

It can be seen that the bulk modulus depends mainly on electrons per atomic volume and mass density, while covalent structure of chemical bonding and N content make more contribution to theoretical hardness, and appropriate content N—N covalent bonding in the same direction tends to increase the shear modulus of nitrides.

说明在Tc的氮化物中，其体弹模量与材料的晶体结构、平均每个原子上的电荷密度和材料的质量密度有关；化学键的共价性结构和氮元素的含量对理论计算硬度有正作用；而剪切模量的极大值则与其层状结构及体系中一定量的方向基本一致的N—N键相关。

The method involves exposing the cells to a compound having the formula I in which: w is a nucleic acid x is a non-amino acid or non-peptide nucleic acid binding group y is a spacer having a chain length equivalent to 1-30 carbon-carbon single covalent bonds or is absent R4 is H or halogen or CH2O-R3; and R1, R2 and R3 are the same or different and are either hydrogen, methyl, ethyl, alkyl, alkenyl, hydroxylated alkyl, hydroxylated alkenyl groups or ether containing alkyl, alkenyl, hydroxylated alkyl or hydroxylated alkenyl groups optionally being an acyl group having a carbon chain length equivalent to 3-24 carbon atoms saturated or unsaturated, with the proviso that at least one of R1, R2 or R3 includes a group having a carbon chain of 3-24 carbon atoms saturated or unsaturated, or to a compound having the formula II in which: w is a nucleic acid x is a non-amino acid or non-peptide nucleic acid binding group y is a space having a chain length equivalent to 1-30 carbon-carbon single covalent bonds or is absent, R5 is alkyl, alkenyl, hydroxylated alkyl, hydroxylated alkenyl group or ether containing alkyl, alkenyl, hydroxylated alkyl or hydroxylated alkenyl group optionally being an acyl group having a carbon chain length equivalent to 3-24 carbon atoms saturated or unsaturated, with the proviso that R5 includes a group having a carbon chain of 3-24 carbon atoms saturated or unsaturated.

该方法包括使细胞暴露于具有式的化合物，在式中：w是核酸，x是非氨基酸或者非肽核酸结合基团，y是具有等于1―30个碳―碳单共价键的链长的间隔基或者不存在，R4是H或者卤素或者CH2O－R3；R1、R2和R3是相同的或者不同的并且是氢、甲基、乙基、烷基、链烯基、羟基化烷基、羟基化链烯基或者包含烷基、链烯基、羟基化烷基或羟基化链烯基的醚，任选地是来源于具有等于3―24个碳原子的碳链长的饱和或不饱和脂肪酸的酰基，其条件是R1、R2或者R3的至少一个包括具有3―24个碳原子的饱和或不饱和碳链的基团，或者使细胞暴露于具有式的化合物，在式中：w是核酸，x是非氨基酸或者非肽核酸结合基团，y是具有等于1―30个碳―碳单共价键的链长的间隔基或者不存在，R5是烷基、链烯基、羟基化烷基、羟基化链烯基或者包含烷基、链烯基、羟基化烷基或羟基化链烯基的醚，任选地是具有等于3―24个碳原子的饱和或不饱和碳链的链长的酰基，其条件是R5包括具有3―24个碳原子的饱和或不饱和碳链的基团。

At last, adsorbent and covalent Ag nanoparticles modified electrodes were prepared by adsorbent and covalent method, respectively. The electrochemical behaviours of SCN-, brilliant cresyl blue and nicotinamide adenine dinucleotide on modified electrode were studied by Cyclic voltammetry, differential pulse voltammograms and electrochemical impedance spectroscopy.

最后，用吸附法和共价键合法制备了吸附型和共价自组装银纳米修饰电极，采用循环伏安法、示差脉冲伏安法和交流阻抗谱等电化学方法研究了SCN-、灿烂甲酚蓝和还原型烟酰胺腺嘌呤二核苷酸的电化学行为。

Due in large part to relativistic effects this element possesses unique properties such as a higher than expected electron affinity and the formation of strong covalent bonds to soft elements like the heavier halogens and sulfur.

在大的部分由于这元素拥有独特特性的相对论性效应象那样一高，期望电子密切关系和对象更沉重的卤和硫一样的柔软的元素的强大的covalent 契约的形成。

The bonding energy of the mixed covalent/metallic Ti-Al bond for the Ti-terminated Al/TiB_2 interface is larger than that of the polar covalent Al-B bond with partial ionic-like feature for the B-terminated interface. Metallic bond between Al atoms forms across the Al/AlB_2 interface, which results in weaker interfacial adhesion than that for the Al/TiB_2 interface. The interfacial energy for Al/TiB_2 depends on the interfacial chemical potential.

Al熔体中仅存在TiB_2粒子，而无多余溶质Ti时，α-Al在TiB_2粒子上异质形核产生的Al/TiB_2界面能大于α-Al从Al熔体中直接形核时的液-固界面能，不满足TiB_2粒子充当α-Al有效异质形核核心的能量条件，这从理论上解释了Al熔体内仅存在TiB_2粒子时无晶粒细化效果的实验现象。

Reversible covalent modification The activity of many enzymes is alterd by the reversible making and breaking of a covalent bond between the enzyme and a small nonprotein group.

可逆共价修饰许多酶的活性随酶和小的非蛋白质基团之间共价键可逆性的生成和断裂而改变。

The results show that the major contribution to DOS of Mg and Pb are the 2p orbit of Mg and the 5d orbit of Pb, followed by the 3s orbit of Mg and the 6p orbit of Pb, the 6s orbit of Pb is the smallest one. There are a large number of charges around Mg, it has the characteristics of typical metal bond. Mg and Pb share some charges to form covalent bond, but the distortion of the charge at the junction is little; the proportion of covalent bond is less than the metal bond, Mg2Pb is semimetal. The elastic modulus and shear modulus of Mg2Pb are 68.6 and 27.9 GPa, respectively. Based on Pugh empirical criterions and Poisson's ratio, Mg2Pb is brittle in nature.

结果表明：Mg和Pb对态密度的贡献主要是Mg的2p轨道和Pb的5d轨道，其次为Mg的3s轨道和Pb的6p轨道，Pb的6s轨道贡献最小；在Mg原子周围有大量的电荷存在，呈典型的金属键特征，Mg、Pb之间存在共用的电荷，有较强的离域性，以共价键形式存在，但交界电荷的畸变不大，故共价键所占比例较少，金属键所占比例较大，Mg2Pb化合物呈半金属性；Mg2Pb的弹性模量和切变模量分别为68.6和27.9 GPa，Pugh经验判据和泊松比均表明Mg2Pb具有脆性。

The weak base anion exchange resin with covalent bond side chains which contain donator atom N offering unshared electron pairs, is able to form a coordinative covalent bond to heavy metal in which unsaturated vacant orbits exist in its electron shells.

在天然淡水水体的环境下，重金属被树脂吸附源于树脂胺基官能团上的N原子有孤对电子，水中所含重金属的价电子层有空轨道。

The approaches taken to prepare NO releasing polymers are classified into three catogories:(1)doping discrete NO nonors within polymer matrix;(2)covalent attachment of NO resealing moieties on the filler particles of the polymer to provide NO releasing properties and then dispersion them into the polymer backbone;(3) covalent linkage of NO donors to polymer molecules.

制备可释放NO聚合物材料的方法主要有3种：（1）通过物理掺杂的方式将小分子的NO供体分散到聚合物材料中；（2）对聚合物材料的填料微粒进行化学改性，得到可释放NO的填料粒子，再将其填充到聚合物材料中；（3）通过共价键将可释放NO的基团连接到聚合物主链及侧链上。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。