必需的

Vitamin K epoxide reductase generates vitamin K hydroquinone to sustain γ-carboxylation of many blood coagulation factors.

哺乳动物维他命K环氧化物还原酶催化对维他命K苯二酚的生成，这是维他命K循环中的决定性一步，是血液凝固所必需的。

To be considered a bona fide business expense, an expense must be both "ordinary and necessary ... in carrying on any trade or business."

被视为一个真正的业务费用，这笔费用必须是"普通和必需的，在任何贸易或业务的。。。。"

The research results indicated that the best base was KOH, the best acid was H3PO4 and their neutralizing products were the necessary nutrients for foliar fertilizer; 12.4 L of foliar fertilizer were obtained in per kg of shrimp offal, chitin was obtained in 13.8% yield, crude protein was obtained in 23.2% yield using this method; This multifuctional foliar fertilizer was an abundant nutritional multifunctional foliar fertilizer which contained 15 kinds of amino acids, shimp cephalin, astacein and many trace elements. The concentration of calcium was 38.9 mg/L, the concentration of magnesium was 55.4 mg/L, the concentration of potassium was 20.0 g/L, the concentration of nitrogen was 4.5 g/L and the concentration of phosphorus was

研究结果表明：(1)处理虾下脚料的最佳碱是KOH，最佳酸是H3PO4，其中和产物是叶面肥必需的营养素；(2)本工艺不仅每Kg虾下脚料可制备虾叶面肥12.4L，而且可回收13.8％甲壳素和23.2％粗蛋白质；(3)经分析测定虾叶面肥中，含钙(Ca2+)38.9 mg/L，含镁(Mg2+)55.4 mg/L，含钾20.0 g/L，含氮4.5 g/L，含磷 78.9 g/L，还含有15种氨基酸及虾脑磷脂、虾红素及多种微量元素等，是一种营养丰富的多功能叶面肥。

Histones, as basic components of nucleosome, are essential to chromatin structure and function.

组蛋白作为核小体的基本组分，是染色质的结构和功能必需的。

There are other classificatory systems which claim to be comprehensive, but in which the indispensable process of simplification has been carried so far that they are no longer true to the facts.

另一些分类系统声称是广泛的，但其必需的简化处理却过度了，以至于不再是真正的事实。

Potassium ions are required in high concentrations in the cell for efficient protein synthesis, and for glycolysis in which they are an essential cofactor for the enzyme pyruvate kinase.

在细胞中 K+需要维持较高的浓度，以便有效的进行蛋白质合成，另外在糖酵解中 K+也是丙酮酸激酶必需的辅助因子。

Life. That's not essential but it's much more than just having a better positive compulsion.

这并不是必需的但有一个更好的积极的冲动真的很更好。

A policy of confidentiality in each stage of development is also necessary.

在开发的每个阶段，保守机密的政策也是必需的。

Confiscation of property is the confiscation of part or all of the property personally owned by the criminal element.

没收全部财产的，应当对犯罪分子个人及其扶养的家属保留必需的生活费用。

Heavy bone is necessary to withstand the contact of the charge between man and dog.

强壮的骨骼在抵抗人和狗之间的侵犯接触是非常必需的。

However, as the name（read－only memory）implies, CD disks cannot be written onorchanged in any way.

然而，正如其名字所指出的那样，CD盘不能写，也不能用任何方式改变其内容。

Galvanizes steel pallet is mainly export which suits standard packing of European Union, the North America. galvanizes steel pallet is suitable to heavy rack. Pallet surface can design plate type, corrugated and the gap form, satisfies the different requirements.

镀锌钢托盘多用于出口，替代木托盘，免薰蒸，符合欧盟、北美各国对出口货物包装材料的法令要求；喷涂钢托盘适用于重载上货架之用，托盘表面根据需要制作成平板状、波纹状及间隔形式，满足不同的使用要求。