The test pieces(主语）// were loaded（谓语）// with a weight（状语）// according to// （介词宾语从句）what is described in the standard methods（状语）.

解析：融合型关系代词/复合型连接代词what=the thing/content that引导的介词宾语从句。

according to what is described in the standard methods(what引导介词宾语从句，并在宾语从句作主语成分）

=according to the thing/content that is described in the standard methods（that引导定语从句，并在定语从句作主语成分）

参考译文：根据/按照标准方法中所描述的内容。

(1)load A with B “用B把A装满”

Mr. Dambar had loaded his plate with lasagne. 

丹巴尔先生盛了一大盘千层面。

(2)A be loaded with B “A被装满了B”

Now no spaceship cannot be loaded with man.  

现在没有任何宇宙飞船不能载人了.

(3)according to 据…所说；按…所载

Philip stayed at the hotel, according to Mr Hemming.

据亨明先生所说，菲利普住在旅馆里。

He and his father, according to local gossip, haven't been in touch for years.  

当地风传，他和父亲已多年未联系了

依据，根据，依照 （原则等）

They both played the game according to the rules.

他们俩都依章行事。

They must take their own decision according to their own legal advice.  

他们必须根据各自律师的意见自行决定。

(4)试样，制取试样的金属块，钢材取样

In addition, still checked other helminth in ground test piece egg.  

此外, 在土样中还查到了其它寄生虫卵.

Introduce a method of analyzing ferro alloy test piece by fluorescent X - ray.  

介绍了 X 射线荧光分析铁合金试样的制备方法.

Becomes test piece is a good deed?  

难道成为实验品是一件好事 吗 ?