多步的

Up to 3 voxels may be processed in one step and no accumulated error is made. The discriminator used in this algorithm is well refined, so that few calculations are required and the algorithm is simple and compact in form.

该算法是一个多步整数遍历算法，每一步可以遍历最多3个体素，且所用的判断公式非常精炼，不仅计算量很小而且没有累计误差。

It was considered that the multi-functional catalysts,in which the active sites were combined in nano/micro scale,was one of the promising methods for the integration of multi-step chemical reactions.

认为催化剂活性相以纳微尺度复合的多功能催化剂是实现多步反应一步化的有效方法之一。

In fact, it has been claimed and proved by Dahlquist and Krieg that there does not exist any second-order accurate, unconditionally stable explicit method with in the class of linear multi-step integration methods.

事实上，学者Dahlquist和Krieg曾提出并且证明在多步的逐步积分法中具有二阶精确度的无条件稳定外显式积分法是不存在的。

Otherwise, we construct an exponential fitting schur product multistep method based on schur product multistep method and exponential fitting method.

数值实验表明，该方法与传统方法相比，在同等步长下，方法的计算精度远远高于传统方法。另外，本文将此类指数拟合方法与Schur积多步方法结合起来，构造了一类指数拟合Schur积多步方法。

The synthesis of the pentacyclic skeleton of Et-743 and the construction of the five chiral centers thereof.1. The core pentacyclic skeleton of phthalascidin was constructed with L-dopa as the starting material via thirteen steps. First, two basic synthons, the C-1 functionalized tetrahydroisoquinoline compounds 8 and N-protected Z-dopa derivative 9, were prepared from L-dopa. They were coupled via amide bond to form the dipeptide compounds 10, which were the first key intermediates. Then the primary hydroxyl groups were transformed into the corresponding amino aldehydes 11 via Swern oxidation. Followed by the intramolecular Pictet-Spengler cyclization, the pentacyclic compounds 12 were synthesized.

五环骨架的构建及五个正确手性中心的确立：1.1我们以L-多巴为起始原料，经过多步官能团保护和转化合成了基本结构单元8然后和苯丙氨酸衍生物9，通过缩合反应生成酰胺中间体10，经Swern氧化得到醛化合物11，然后再次利用分子内改良的Pictet-Spengler反应一步构建c，d两环，得到五环骨架化合物12，最后，实现了21-位羰基向氰基的转化，得到了C-1位官能化的化合物14，化合物14不但具有和Et-743一致的五环骨架，而且分子中五个手性中心立体构型也与其完全相同：其中，3，位和13，位的手性中心由原料L-多巴带入，而1，位，11，位和21，位手性中心则通过不对称诱导而确立。

The amphoteric fatliquor of N-amidel- polyethylene polyamine -β-aminopropionic acid types has been synthesized by nature oil and fat reaction with polyethylene polyamine and acrylic acid .

用天然油脂、多乙烯多胺和丙烯酸合成制得N -酰胺基多乙烯多胺-β-氨基丙酸型两性加脂剂，最佳合成条件分两步的反应温度分别控制在 10 0℃及 12 0℃、两步反应时间分别为 2h和 4h ，天然油脂与多乙烯多胺及丙烯酸的物质量的比为 1：0 。

The result proved that this tripart H-beta zeolite capsule catalyst was effective, especially for the consecutively multistep reaction.

反应结果表明这种三分结构的沸石胶囊催化剂是非常有效的，特别对于那些连续、多步的化学反应体系。

The result proved that this tripart Hbeta zeolite capsule catalyst was effective, especially for the consecutively multistep reaction.

反应结果表明这种三分结构的沸石胶囊催化剂是非常有效的，特别对于那些连续、多步的化学反应体系。

Now he was less than twenty feet above the elves and could see them clearly, their cloaks streaming behind them.

现在，他和这些精灵只有20多步的距离，已经可以清晰的看到他们，以及他们身后的斗篷。

There were more than 1000 steps to get to the top of it .looking up at the old men in front of us ,we exceed our speed .eventually ,we made it .there was a huge monument of workers and farmers .on the top stand the symbol , the sickle and hammer,both of them are made of gold and brass.

有一千多步的石阶才能爬上去。看看前面的老爷爷们，我们加紧了步伐。终于爬上去了，这里有一个巨大的碑，顶上是工农红军的标志，镰刀和锤子，都是金铜铸就的。

They weren't aggressive, but I yelled and threw a rock in their direction to get them off the trail and away from me, just in case.

他们没有侵略性，但我大喊，并在他们的方向扔石头让他们过的线索，远离我，以防万一。

In slot 2 in your bag put wrapping paper, quantity does not matter in this case.

在你的书包里槽2把包装纸、数量无关紧要。