Proceedings of the Biological Society of Washington.

v. 6 (1890-1891)

Proceedings of the Biological Society of Washington.

v. 5 (1888-1890)

Proceedings of the Biological Society of Washington.

v. 13 (1899-1900)

Proceedings of the Biological Society of Washington.

v. 15 (1902)

Proceedings of the Entomological Society of Philadelphia.

v. 6 (1866-1867)

Catalogue of scientific papers, 1800-1863 [to 1884-1900]. Compiled by the Royal Society of London.

v. 14

Proceedings of the Biological Society of Washington.

v. 4 (1886-1888)

Proceedings of the Biological Society of Washington.

v. 12 (1898)

Proceedings of the Linnean Society of New South Wales.

v.45=no.177-180 (1920)

Annual report of the secretary of the State Horticultural Society of Michigan.

1894

Annual report of the State Horticultural Society of Missouri.

37, 1895

Annual report of the secretary of the State Horticultural Society of Michigan.

1882

Annual report of the secretary of the State Horticultural Society of Michigan.

1890

Flows of knowledge from universities and federal laboratories: Modeling the flow of patent citations over time and across institutional and geographic boundaries

The extent to which new technological knowledge flows across institutional and national boundaries is a question of great importance for public policy and the modeling of economic growth. In this paper we develop a model of the process generating subsequent citations to patents as a lens for viewing knowledge diffusion. We find that the probability of patent citation over time after a patent is granted fits well to a double-exponential function that can be interpreted as the mixture of diffusion and obsolescense functions. The results indicate that diffusion is geographically localized. Controlling for other factors, within-country citations are more numerous and come more quickly than those that cross country boundaries.