That vector is called a "null vector".

那种矢量就叫做”零矢量“。

An expressing vector of major outer-membrane protein of Chlamydia psittaci was constructed.

构建了鹦鹉热衣原体主要外膜蛋白的表达载体。

This research intended to construct a eukaryotic expression vector with a site-directed mutation of porcine MSTN propeptide gene.

本研究旨在构建具有猪 MSTN 前肽基因定点突变的真核表达载体。

I experience a vector quantity.

我经历了一个矢量的量变。

It's a vector, perpendicular.

一个与半径垂直的矢量。

Now, what's the gradient vector?

现在，梯度向量是什么呢？

These involve vector quantities.

这些则包括向量。

Well, you know the normal vector.

那么当然知道它的法向量。

Remember this-- this is a vector.

记住它，这是个矢量。

Of course, it's not a real vector.

显然，这不是一个实际意义上的向量。

What is the normal vector?

那么法向量又是什么呢？

We have this vector field.

这是向量场。

Now, how do we get this unit vector?

那我们怎么得到这单位矢量呢？

A I call this vector vector a.

我称之为矢量。

It is not a unit vector.

它不是单位向量。

So, the acceleration vector is;.

那加速度就是。

That was a vector field in the plane.

它是一个在平面上的向量场。

This makes it a vector.

它构成一个矢量。

What about vector BP?

向量BP是什么？

This is that vector.

就是这个矢量。

Why else would you know a normal vector?

还有什么原因你会知道法向量？

We dot our favorite vector field with it.

用我们喜欢的向量场来点乘它。

So, this vector field is not conservative.

所以，这个向量场不是保守场。

First, code a needle using vector drawing.

首先，为使用矢量图的指针编写代码。

That means your normal vector points down.

那意味着法向量指向下。

Add the access point to your location vector.

将访问点添加到位置向量中。

That corresponds to normal vector pointing up.

那相当于法向量指向上。

Then, if I choose any vector in that tangent plane.

那么如果我选择了任何位于切平面的向量。

BP Now, let's think about vector ab and vector BP.

现在我们来考虑向量ab和向量。

And, the direction is essentially that of a vector.

方向基本和这里的单位切向量一致。