Fragment code selection

A particularly good selection of physical properties may be spectra, because they are known to depend strongly on the chemical structure. In fact, different types of spectra carry different kinds of structural information, NMR spectra characterize individual carbon atoms in their molecular environment. They therefore correspond quite closely to fragment-based descriptors, as underlined by the success of approaches to predict NMR spectra by fragment codes (see Section 10.2.3). 

Select the fragment sequences by clicking on the ID code. Select Delete Selected Sequences from the Edit menu. 

Table 2 Selected Parts of the Derwent Fragmentation Code ...

Fig. 3 Typical ICT probes (left) and representative spectroscopic responses toward selected metal ions (right). Color code (left) coordinating atoms in blue, bridgehead atom of the fluorophore that takes part in complexation in orange, formal donor fragment in red, formal acceptor fragment in green (right) hypsochromic shifts in red, bathochromic shifts in green, fluorescence enhancement in violet, fluorescence quenching in blue. Symbols in table Aabs, 7em,

No numerical codes are used by the system. A search for a specific subject can be carried out by entering the subject word itself. If the word mass is entered, searches for 7 terms (all those containing the fragment mas i.e. mass spectra, mass discrimination, mass measurement, etc.) are conducted and the user is asked to select the one of interest. In this way knowledge of the correct subject words or of their correct spelling is not necessary. 

Plants will have a specific DNA bar code, which will be a useful forensic tool. The DNA bar code is made up of a standard short region (or regions) of DNA selected from one or more of the genomes. It can be applied universally across land plants but is also variable enough to provide individual identification at species level. The bar code system can be applied to access a database for identification of known plants. It can be used to identify unknown samples from fragments of plant material by comparing them to the known standards and has applications for verification of material in natural products like herbal medicines and foodstuffs. 

---