首先我们看“at all”的用法：

1、At all is a Negative Polarity Item (NPI). That means it is one of a long list of English words, phrases, idioms, and constructions that can only occur grammatically in a Negative environment.

at all functions as an intensifier of the negation, meaning something like 'in even the most insignificant manner'. But without a negative environment to license it, at all makes no sense at all.

The only way the sentence "That makes sense to me at all" makes sense to a native English speaker is if spoken sarcastically, with heavy emphasis on either "that" or "me", such that the actual meaning is "that does not make sense to me".

来源：http://english.stackexchange.com/questions/63718/at-all-vs-not-at-all-in-negated-sentences

2、Question: A student in China asked, “Can at all be used in a positive context?”

Answer

The expression at all is used to intensify a statement or question—that is, to make it stronger.

It is common in negative statements and questions, where it means “in any way” or “even slightly.” It is also used occasionally in positive statements, where it means something like “absolutely.”

Below are some example sentences with at all.

Negative

I wasn't tired at all. (While someone who utters this sentence may be expressing a positive thought, the sentence is still grammatically negative.)

This chair is not at all comfortable.  

“Did she say anything?” “No, nothing at all.”

He hardly thinks about himself at all. (This sentence is negative because of hardly, which has a negative sense.)

Question

Are you at all interested in seeing a movie tonight?

John hasn't been studying at all?

Positive

This cell phone can be used anywhere at all. (=absolutely anywhere)

来源：http://www.learnersdictionary.com/qa/how-to-use-at-all

3、“In the first place the forces known in classical electrodynamics are inadequate for the explaination of the remarkable stability of atoms and molecules, which is necessary in order that the materials may have any definite physical and chemical properties at all.”

As used here, "at all" serves as a way of emphasizing "any."

来源：http://forum.wordreference.com/showthread.php?t=1583834

爱因斯坦从小讲话就晚，第一次考大学时因为语文和历史而没有通过，移居美国后，其英语和德语拼写能力极差（Einstein was a horrible speller.  After moving to the US, Einstein became completely bilingual but could never recall how to spell words correctly in both German and English.），所以，我怀疑他的信最后一句——“The astonishing thing is that those discoveries were made at all.”可能也是有问题的。因为“at all”一般用在否定句中，你老爱用在肯定句中是什么意思？

爱因斯坦回信的原文是：

Development of Western science is based on two great achievements: the invention of the formal logical system (in Euclidean geometry) by the Greek philosophers, and the discovery of the possibility to find out causal relationships by systematic experiment (during the Renaissance). In my opinion one has not to be astonished that the Chinese sages have not made those steps. The astonishing thing is that those discoveries were made at all.