查询词典 asymmetric

In this thesis, two synthetic routes for the incorporation of sugar moiety into C5(5") or C3(3") of salicylaldehyde part of Salen Mn complex were designed and several corresponding compounds were prepared, as carbohydrate derivatives are widely used in asymmetric catalytic reactions.

鉴于糖类衍生物在不对称催化反应中的广泛应用，设计了两条分别在Salen Mn配合物水杨醛部分C5(5′)、C3(3′)位并入糖基的路线并合成了相应的化合物。

Results In 11 cases,5 cases were intracranial,and 6 cases intravertebral canal.MRI could effectively show similarly shuttle or long-round shape's abnormal signal imaging.The T1W imaging showed uniformity or asymmetric and low or equal signal.The borders were slighty low or equal signal intensity,some had spetum.The T2W imaging showed obviously high signal,and a few cases showed slightly high or equal signal,while the borders showed slightly low or equal signal imaging.The thin peripheral could be obviously enhanced,but without inner enhancement.

结果 11例中发生于颅内5例，椎管内6例，其 MRI 表现：断面上显示为在颅板下或椎管内的梭形或长圆形异常信号影， T1WI 上表现为均匀或不均匀的低、略低或等信号影，周边为略低或等信号的较厚边缘，少部分（2例）有分隔； T2WI 上多表现为较明显的高信号，少数呈等、略高信号，并可见略低或等信号的边缘；增强扫描病灶边缘明显强化，其内无明显强化或不强化，1例病灶呈较均匀的强化，1例病灶部分呈片状强化。

Chiral 3 methy 1,4 butanediol and its derivatives are the important intermediate of synthesis of chiral smectic liquid crystal polyesters and chiral natrual products with biological activity. In the paper, a new efficient route of 3 methyl 1,4 butanediol and its two derivatives, 2 methyl 4 tetrapyranyloxy 1 butanol and 2 methyl 4 tetrapyranylbutanal, was described, and the target products were synthesized by employing asymmetric hydroboration oxidation improved.

手性2－甲基－1，4－丁二醇及其衍生物是合成各种手性近晶型液晶材料以及手性天然生物活性物质的重要中间体，以3－甲基－3－丁烯－1－醇为原料利用改进的不对称硼氢化－氧化反应，成功地合成了－2－甲基－1，4－丁二醇以及其2种手性衍生物：－2－甲基－4－四氢吡喃氧基－1－醇和－2－甲基－4－四氢吡喃氧基丁醛。

A few spiro ligands have been successfully synthesized and applied in asymmetric catalysis .

手性螺环配体的合成及其在不对称催化反应中的应用是不对称合成和催化研究中重要的研究领域之一，一些手性螺环配体被合成出来并成功地应用于不对称催化反应中。

Biocatalysis has become one of the most promising and effective methods in the asymmetric synthesis for its outstanding stereochemical specificity.

生物催化因其高效和高度的立体选择性，成为手性合成最重要的方法之一。

The results of asymmetric transformation can also be affected by steric effect and electronic effect of substitute group of the substrate.

不同植物的细胞或同一种植物的不同细胞对底物的转化均具有不同的区域和立体选择性。

Influence of steric effect on asymmetric transformation is more prominent.

底物中取代基的空间效应和电子效应也影响不对称转化的结果，但空间效应的影响更加显著。

The facts indicate that apart from the asymmetric induction of chiral diamine backbone,sterically hindered substitute groups on the aromatic rings,and the presence of sp~3-hydridized amino donors and its N,N\'-disubstituted groups in chiral SalanCrX complexes all play important roles in controlling polymer stereochemistry and enantioselectivity.

研究发现除了手性二胺骨架的不对称诱导作用，苯环上的大位阻取代基、N，N\'-二取代基的位阻作用以及N原子上sp~3杂化的供电子效应都对调控聚合物的区域和对映体选择性有很大作用。

Ma 5(subscript 1-4) submember is an asymmetric long-term base level cycle which can be divided into five middle-term base level cycles and more than 26 short-term base level cycles.

马五(下标 1-4)亚段构成了一个长期基准面下降半旋回，其又可划分为5个中期基准面沉积旋回及多于26个短期基准面沉积旋回。

Stipules gradually deciduous, triangular, 1-2 mm, membranous; petiole often unequal in length, 0.5-7 cm; leaf blade dark green or green blue, ovate, lanceolate, or obovate-oblong, asymmetric, unequal or equal in size, 1-15 × 0.6-5 cm, thinly papery or submembranous, 3(or 5)-veined, lateral veins many, irregularly reticulate, external secondary veins anastomosing by margin, sometimes inconspicuous, cystoliths finely fusiform, conspicuous adaxially, base obliquely rounded or subcordate, sometimes cuneate, margin entire or sometimes undulate, apex shortly or long caudate-acuminate. Inflorescences solitary; male inflorescence a cymose panicle or racemelike, often longer than leaves; female cymes as long as or shorter than leaves, pedunculate.

逐渐落叶，三角形的托叶，1-2毫米，膜；叶柄通常不等长，0.5-7厘米；蓝色的深绿色的叶片或绿色，卵形，，或倒卵形长圆形，不对称，不等长或大小相等， 1-15 * 0.6-5 厘米，薄纸质的或近膜质， 3(或5)脉，侧脉很多，不规则网状，外部次脉网结的在边缘，有时不明显花序单生；雄花序一总状花序状的密伞圆锥花序或，通常长于叶；雌性聚伞花序等长或短于叶，有花序梗。

As she looked at Warrington's manly face, and dark, melancholy eyes, she had settled in her mind that he must have been the victim of an unhappy attachment.

每逢看到沃林顿那刚毅的脸，那乌黑、忧郁的眼睛，她便会相信，他一定作过不幸的爱情的受害者。

Maybe they'll disappear into a pothole.

也许他们将在壶穴里消失