Using I Lab via ChemSketch 

8.  As soon as the results are received, the Results of ACD/NNMR DB v7.0 dialog box appears 

containing the 10 records best matching the query: 

Note 

If the Show results on receiving check box in the ACD/I Lab Options dialog box 

is not selected, the results are not displayed, but can be found in the Task 

Manager dialog box (I Lab menu). 

9.  Browse through the entries by clicking the lines in the Structures list. 

10. If you want to insert any entry into the ChemSketch window, highlight it in the list and click 

Insert. 

3.7.1.1 Similarity Coefficients 

The similarity coefficient should be used to provide a quantitative measure of structural 

relatedness between a pair of structural representations.  The similarity coefficient determines a 

numerical measure of similarity (or conversely, the distance) between two objects, each 

characterized by a common set of attributes.  Now we are going to review the coefficients that 

have found widespread use in chemical information systems. 

Each structure is represented as a binary vector containing n attributes. 

Let 

 and 

 be similarity and distance between the structures A and B respectively. 

Let 

X

{x , x ;..., x ,..., x }

X

{x , x ;..., x ,..., x }

A

1A

2 A

jA

nA

 and 

B

1B

2 B

jB

nB

be binary vectors 

describing the structures A and B respectively. 

X

1 X

0

iA

iA

 if the structure object number 

i

 is present (absent) at the structure A. 

Structure objects are generated automatically depending on DB structures type. 

Let  and  be similarity and distance between the structures A and B respectively. 

ACD/I Lab via ChemSketch  

User's Guide 

21