四

Bisbenzimidazolium salts were used as a tetrahydrofolate coenzyme model, and thus the biomimetic synthesis of twenty-four acyclic diketones as precursors for macrocyclic ketones was successfully accomplished by using the addition-hydrolysis reaction of the bisbenzimidazolium salts with alkyl magnesium halide, wherein six diketones have not been reported in literature.

在本文中，受四氢叶酸辅酶的一碳单元转移反应的启发，作者以双苯并咪唑盐作为四氢叶酸辅酶模型，利用格利雅试剂与双苯并咪唑盐的加成-水解反应，成功合成了二十四种作为麝香酮及类似大环酮重要前体的长链二酮，同时，提供了一种麝香酮及类似大环酮的仿生合成新方法。

Main products: the accurate four pillars automatic balance oil pressure bias cutting machine ,the accurate four pillars planer-type oil pressure bias cutting machine,rocker arm oil pressure bias cutting machine,oil pressure flat embossing machine,vertical four pillars oil pressure bias cutting machine, portable bias cutting machine,belt embossing machine, one spindle oil pressure bias cutting machine,sponge ball grinder, splitting machine,thicknesser,hammer machine,gluing machine,flanging machine,etc.

主要产品有：精密四柱自动平衡油压裁断机、精密四柱龙门式油压裁断机、摇臂式油压裁断机、油压平面压花机、立式四柱油压裁断机、箱式裁断机、皮带压花机、单头式油压裁断机、海绵磨球机、片皮机、刨板机、锤仔机、上胶机、折边机等。

Ballad stanza: A type of four-line stanza. The first and third lines have four stressed words or syllables; the second and fourth lines have three stresses.

民谣体诗节：一种四行诗节，第一、三行由四个重读单词或音节组成，二、四行由三个重音组成。

As to the mate lag problems in loom beat up mechanism,comparing traditional four bar linkages with quick return four bar linkages beat up mechanism,the latter can solve the lag problems effectively.A CAD method of designing the quickreturn four bar linkages beat up mechanism is pointed out,and the design mathematics model and the kinematic analysis model are also presented.

针对现有织机打纬机构和开口机构在运动配合上存在的滞后问题，比较了传统的四连杆打纬和具有急回特性的四连杆打纬机构，基于后者能有效地改善配合上的滞后问题，提出了精确设计具有急回特性的四连杆打纬机构的CAD方法，给出了设计的数学模型、机构运动分析的数学模型。

A UV method was adopted to analyze the furanocoumarin content in four types of citrus essential oils: orange oil, lemon oil, grapefruit oil and bergamot oil. A liquid-liquid separation technology was investigated to remove these furanocoumarins, and then furancoumarin free essential oils were obtained.

采用UV技术测定了四种市售芳香疗法用柑橘类精油：橙油、柠檬油、葡萄柚精油与佛手柑精油中呋喃香豆素的含量，并使用液－液萃取分离技术对这四种精油进行了脱呋喃香豆素类化合物试验，开发研制了四种脱敏精油。

Four vine-shielded soldiers, each with a vine shield in the left hand and a short knife in the right hand, engage four other soldiers who hold three-toothed forks, broad-bladed knives, spears or woolen sticks, and they take turns to fight according to the battle arrays.

四名藤牌兵左手执藤牌，右手执短刀，与四名攥三齿叉、大片刀、长矛或木棍者，按阵法轮番打斗；实战时藤牌阵法变化无穷，常见的有&一字长蛇阵&、&八卦连环阵&&梅花五方阵&&四门迷魂阵&&八门穿心阵&等，阵容可随实战需要扩大到成千上万人。

The four clutches are used to distribute the driving force generated by the electric motor and combustion engine via four fixed ratios and two electric variable ratios to all four wheels on the 4MATIC permanent all-wheel-drive system, depending on the driving situation.

四离合器用于分发的驱动力所产生的电电动机和内燃机通过四个固定比率和两个电动可变比率所有四个车轮上的4MATIC永久全轮驱动系统，根据驾驶状况。

In order to study the intake air flow characteristics in four-valve diesel engines, in this dissertation hot-wire anemometer and PIV twodimension instantaneous measuring technique are used. Extensive experimental study on two intake valve exit flow fields and longitudinal section flow field in cylinder are performed for different type of diesel engines. Great researching progress have been made on the interaction between two intake ports, and the formation process of in-cylinder swirl and flow field structure of cross and longitudinal section for four valve diesel engines. These results are presented in China for the first time and without such kind of research work reported abroad as detailed and deepgoing as this dissertation. The author designs and makes a set of hot wire measuring velocity device to measure the velocity distribution around the intake valve annulus and the cross section flow field in cylinder.

为了研究四气门柴油机进气过程中气体流动的变化规律，本文利用热线测速和PIV二维瞬态测速技术，对四气门柴油机两进气门出口全圆周流速场和缸内横、纵剖面的气体流动流场进行了大量的试验研究，在四气门柴油机两进气道之间相互影响的变化规律，缸内涡流的形成过程及缸内横、纵剖面流场结构等方面取得了重大的研究进展，这一研究工作在国内尚属首次，在国外也未见有如此全面、深入的研究报道。

No need to dwell on the legendary beauty of the cornerpieces, the acme of art, wherein one can distinctly discern each of the four evangelists in turn presenting to each of the four masters his evangelical symbol, a bogoak sceptre, a North American puma (a far nobler king of beasts than the British article, be it said in passing), a Kerry calf and a golden eagle from Carrantuohill.

至于堪称艺术顶峰的四个角落的旷世之美，就毋庸赘述了。观者足以清清楚楚地辨认出，四部福音书的作者分别向四位大师赠送福音的象征：一根用泥炭栎木制成的权杖，一头北美洲狮（附带说一句，它是比英国所产高贵得多的百兽之王），一头凯里小牛以及一只卡朗突奥山的金鹰。

In Chapter 4 a new method to determine carbaryl in effluent was given and the hydrolysis of carbaryl in effluent with the aid of three-order calibarion was studied.

第四章应用四线性平行因子分析方法检测了农业污水中西维因的含量，同时利用四线性分解的优势，同时对其水解过程进行研究，得到了满意的结果。

Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).

呼气，收缩臀部肌肉；拱起身体，尽量抬起头来，右腿伸直朝向天花板（膝微屈，以避免肌肉紧张）。

The cost of moving grain food products was unchanged from May, but year over year are up 8%.

粮食产品的运输费用与5月份相比没有变化，但却比去年同期高8％。