Firstly,this paper introduces the characteristics and classes of search engine,then anatomizes it s system architecture,and analyzes the processes of index and search among them.

Study of the search engine of magnetic resonance imaging journals in medline;

Study of the search engine of nuclear medicine journal online;

Development and study of " search engine of genetics journals;

Searching for national medical examination information by search engines;

Application of Cross-Language Information Retrieval on Internet Search Engines;

Realization of web search engine based on XML;

New source of information come to the fore everyday in Internet,thus bringing a high request to web search engine.

The design and implementation of the intelligent Web search engines for special topics were discussed in this article.

To remove dissymmetry of the movement of monitor image under some conditions when image guided missile adopting guided search,two factors causing this dissymmetry are found,viz,the angular velocity of line of sight and the lead speed of the missile.

For an image guided missile,adopting guided search can increase the probability of target entering the instantaneous field of view of the seeker,but it may cause dissymmetry of the monitor image under some conditions.

To remove the dissymmetry of horizontal movement speed of monitor image caused by image guided missile adopting guided search and the search law with one-dimension visual effect,pitching and yawing signals of the search law with one-dimension visual effect are designed again under the condition of ensuring no blind area and only horizontal movement of monitor image.