二价酸的

In acid and alkali soil, there are mainly indissoluble bivalent or trivalent phosphates, which cannot be utilized by plants.

在酸碱性土壤中，磷主要以植物难以吸收利用的难溶性二价或三价阳离子的形式存在。

Any of a group of five chemically related nonmetallic elements including fluorine, chlorine, bromine, iodine, and astatine.

酰亚胺源自氨的一种化合物，含有与一个二价酸基或者二个一价的酸基结合的氨基

In the presence of the combination of sulphuric and phosphoric acid, with sodium diphenylamine sulfonate as the indicator, standard solution of potassium dichromate was used to titrate total iron value.

试样以盐酸溶解后，在酸性介质中，先以氯化亚锡将三价铁大部分还原为二价，然后在钨酸钠指示下，再以三氯化钛将剩余的三价铁还原为二价，过量的三氯化钛以重铬酸钾氧化消除干扰，在硫磷混合酸存在下，以二苯胺磺酸钠为指示剂，用重铬酸钾标准溶液滴定全铁量。

Based on the biochemical analysis of the two proteins in vitro, the results of yeast two-hybrid experiment and protein-interaction in both wild type cells and C48 strain, we conclude HetR can form a homodimer through the Cys48 residue. We also show that the dimerization is required for heterocyst differentiation.

基于体外两种蛋白的性质比较和酵母双杂交的结果，并结合相应蓝细菌野生型和突变株C48A中HetR蛋白性质的体内研究表明：HetR蛋白可以通过第48位半胱氨酸残基形成共价结合的同源二聚体，该同源二聚体是异型胞正常分化所必需的。

After it was adjusted with ammonia until the test paper turned purple,in subacid medium of pH 6～7 ammonium acetate buffered solution,bivalent nickel was precipitated quantificationally by dimethylglyoxime.

试样以稀硝酸溶解高氯酸冒烟后，酒石酸掩蔽剂将铁等干扰元素配位掩蔽，以氨水调节至刚果红试纸呈紫色后，在pH6～7的乙酸铵缓冲溶液微酸性介质中，二价镍定量地被丁二酮肟沉淀。

It includes the following steps: extract trivalent iron ion and divalent iron ion in water phase through organic extractant, get predecessor of; absterge it with secondary distilled water for2-3 times and get pure load metal predecessor of organic phase; mix organic phase of Mg2 and Fe3 with mol rate of 1:2 and introduce them into autoclave, add distilled water according to the rate of 3:1 or 4:1 of organic phase and water phase and airproof it, and then mix it fiercely, stripping with hydrothermal method at temperature between 200 degree C and 300 degree C and make them react for 2.5 hours; cool it to the room temperature under natural condition, separate liquid and centrifugalize it, absterge it with absolute alcohol for 2-3 times and dry it at temperature of 50 degree C for 30-180 minutes, then get product of magnesium ferrite.

包括如下步骤：通过有机萃取剂来萃取水相中的三价铁离子和二价镁离子，制得有机相前驱物；用二次蒸馏水洗涤2-3次，获得纯净的负载金属有机相前驱物；按照Mg 2 和Fe 3 摩尔比1∶2将有机相混合均匀后引入高压釜中，按照有机相与水相的比例为3∶1或4∶1加入蒸馏水，密封后，对溶液进行强力搅拌，水热反萃的温度在200-300℃之间反应2.5小时；自然冷却至室温，分液，离心分离，用无水乙醇洗涤2-3次，在50℃下干燥30-180分钟，得铁酸镁产品。

In order to mimic this repair process of apoenzyme, we synthesized two model compounds, in which tryptophan and/or tyrosine was covalently linked to cyclobutane thymine dimer, and measured the splitting quantum yield of dimer under 295 nm light. By investigating the photosensitized splitting properties of the dimer, some new insights into the intramolecular electron-transfer process were gained.

为了模拟酶蛋白的这一修复过程，合成了色氨酸和/或酪氨酸与胸腺嘧啶二聚体共价连接的化合物，作为酶-底物复合物的模型，研究了它们在295 nm光照射下氨基酸残基光敏化二聚体裂解的性质，测定了二聚体裂解量子产率，获得一些新的结果并对其进行了分析。

The amount of Na(superscript +), NH4(superscript +), K(superscript +), Mg(superscript 2+), Ca(superscript 2+), Zn(superscript 2+) in fruits and juice (sports water, green tea , pear juice, carrot juice and carrot and orange juice) were respectively separated and detected by non-suppressed ion chromatography. And pyridine-2, 6-dicarbexylic was used as mobile phase to separated monovalent cations and pyridine-2, 6-dicarbexylic-ethylenedi-amine-oxalic acid was used as mobile phase to separated divalent cations.

采用非抑制型离子色谱法测定了水果以及饮料（运动型饮料、绿茶、水蜜桃汁、胡萝卜汁和胡萝卜橙汁）中Na、NH4、K、Mg(上标 2+)、Ca(上标 2+)、Zn(上标 2+)的含量，其中一价阳离子以吡啶－2，6-二羧酸为淋洗液测定，二价阳离子以吡啶－2，6-二羧酸+乙二胺+草酸为淋洗液测定。

The amount of Na+, NH4+, K+, Mg2+, Ca2+, Zn2+ in fruits and juice (sports water, green tea , pear juice, carrot juice and carrot and orange juice) were respectively separated and detected by non-suppressed ion chromatography.

采用非抑制型离子色谱法测定了水果以及饮料(运动型饮料、绿茶、水蜜桃汁、胡萝卜汁和胡萝卜橙汁)中Na+、NH4+、K+、Mg2+、Ca2+、Zn2+的含量，其中一价阳离子以吡啶-2，6-二羧酸为淋洗液测定，二价阳离子以吡啶-2，6-二羧酸+乙二胺+草酸为淋洗液测定。

The luminescent propetties of RE activated tungstates are dealt with in respect to mixed alkali earth metal tungstates,fluorotungstates,isopolytungstates,heteropoly tungstates.

本文从单钨酸盐、混合二价金属钨酸盐、卤钨酸盐、同多钨酸盐、杂多钨酸盐等方面综述了掺杂稀土离子钨酸盐的发光特性研究情况。

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。