1)  Necessary condition
必需条件
2)  essential
必需
1.
Analysis of the Principle-″essential, adequates″Elementary theory knowledge in HVTE;
对高职基础理论知识“必需·够用”的思辨
2.
Methods The four essential fatty acids of cord and venous blood on the 14th day after birth were measured in 16 breastfed and 12 formularfed full term normal delivered babies by gas chromatography.
目的　探讨不同喂养方式对新生儿必需脂肪酸水平的影响。
3)  Essential groups
必需基团
1.
The essential groups of three N acetylglucosaminyltransferases(GnTs) of rat kidney were studied by using chemical modification and substrate protection methods.
用化学修饰法和底物保护法研究了大鼠肾脏３种Ｎ－乙酰氨基葡萄糖转移酶（ＧｎＴ）的必需基团，发现氨基和吲哚基为ＧｎＴ－ＩＩ、ＧｎＴ－ＩＶ和ＧｎＴ－Ｖ共同的必需基团，其中氨基可能参与和共同供体底物ＵＤＰ－ＧｌｃＮＡｃ的结合，吲哚基对ＧｎＴ－ＩＩ和ＧｎＴ－ＩＶ可能是受体底物——七糖糖链Ｇｎ２Ｍ３Ｇｎ２－ＰＡ的结合基团，而对ＧｎＴ－Ｖ可能是不参与底物结合的必需基团。
4)  necessary elements
必需元素
1.
Cu, Se, Mn, Ni and V are necessary elements to plants growth .
铜、硒、锰、镍和钒是植物生长的必需元素。
2.
The find drinking water demand a little or nought chemical and toxic elements, in the same time contain necessary elements.
饮用水中有机物与有毒元素含量是单向限值 ,在小于限值的前提下越低越好 ;而必需元素含量应是双向阈值 ,低于阈值下限或高于阈值上限都是对人体健康不利的。
5)  essential element
必需元素
1.
The animal experiments showed that manganese can increase or hamper the absorption,distribution and excretion of some essential elements,such as Zn,Cu,Fe,Co and Ca.
动物实验发现 ,锰可促进或妨碍某些必需元素如 Zn、Cu、Fe、Co和 Ca等的吸收、分布与排泄。
6)  Essential elements
必需元素
1.
Effect of aluminum chelating agent on liver zymogram and on essential elements of rats induced by aluminum;
铝螯合剂对染铝大鼠肝酶谱及必需元素影响
2.
[Objective] To study the relationship between essential elements and GST genetic polymorphisms in patients with chronic benzene poisoning.
[目的]探讨谷胱甘肽硫转移酶(GST)基因多态与慢性苯中毒患者血清中必需元素的关系。
参考词条
补充资料：半必需氨基酸
分子式：
CAS号：

性质：仅仅在某些特定情况下才是必需氨基酸，或者可以部分地代替一种必需氨基酸的氨基酸。如成年哺乳动物合成足够需要的精氨酸，但生长猪却只能合成所需量的60%～75%，对于猪和家禽蛋氨酸需要量的50%可用胱氨酸代替，苯丙氨酸需要量的30%可用酪氨酸代替，家禽甘氨酸需要量的一部分可用丝氨酸代替，精氨酸、胱氨酸、酪氨酸和丝氨酸就是半必需氨基酸。

说明：补充资料仅用于学习参考，请勿用于其它任何用途。