Can alcohol and salt lengthen the shelf life of vegetables in room temperature?
No, it won't help you at all. Your vegetables aren't being eaten by bacteria or similar (and this is a good thing, foods which are rendered unsafe by bacteria shouldn't be kept more than 4 hours at room temperature). They are simply wilting. 

There is no way to stop the wilting process. It is the plant cells dying off and stopping being able to "take care of themselves". You have to buy vegetables more frequently if you want them to be pleasantly fresh. The only thing you can do is to cool them, which slows down their metabolism and so prolongs the time they have left until they die. For a few types of vegetable, providing water helps, e.g. carrots or any bunch of leafy herbs, but this is an exception.