It is defined as a clinical condition which is characterized by narrowing of blood vessels due to excess contraction of muscular wall of the vessels. The medicine that causes constriction of blood vessels is known as vasoconstrictors. Generally vasoconstrictors are given to increase the blood pressure. Vasoconstriction occurs due to the high concentration of calcium in vascular smooth muscle.The impact factor of journal provides quantitative assessment tool for grading, evaluating, sorting and comparing journals of similar kind. It reflects the average number ofÂ citationsÂ to recent articles published inÂ science and social science journals in a particular year or period, and is frequently used as aÂ proxyÂ for the relative importance of a journal within its field. It is first devised byÂ Eugene Garfield, the founder of theÂ Institute for Scientific Information.The impact factor of a journal is evaluated by dividing the number of current year citations to the source items published in that journal during the previous two years.
Last date updated on September, 2014