Do anyone know if it exists a professional English-Chinese and Chinese-English Technical Dictionary?
Based on your comment:
Technical dictionaries are dictionaries with terminology in the fields of technology and science, in which you can find names that you do not find in "classical dictionaries", because they are very technical.
I would highly recommend the 21st Century English-Chinese Dictionary
blurb from Amazon:
The English-Chinese dictionary collects more than 70,000 entries. It includes over 10,000 new words. The phonetic is referred to the new edition from U.K. & U. S. Appendix includes the information of five countries: United Kingdom, United States, Canada, Australia & New Zealand; the military ranks of U.K. & U.S.; international famous companies; chemical elements; punctuation; the usage of numeral, date & time; comparison of metric system & metrology of U.K. & U.S.
entry-wise I'm not sure why Amazon only mentions 70,000 entries as Pleco calls it:
the 280,000-entry 21st Century English-Chinese Dictionary
I used http://www.mdbg.net/ to translate a number of terms in the theory of differential equations. Later I checked the translations with a native Chinese mathematician who works in the UK, and he said that they were mostly good. That's a limited set of evidence, but suggestive.