Silicon Valley venture capital firm, Venrock Associates, is deepening its focus on biotech and healthcare, by hiring two seasoned professionals. It has also promoted two other partners.

Finally, is also opening offices in China and Israel over the “next few months,” the firm told us yesterday.

The two new partners are “venture partners,” generally understood as partners who help find companies to invest in and then advise the companies, but who are not full managing members of a firm — with all the management duties, and profit sharing that full membership entails.

The firm promoted of Bryan Roberts and Brian Ascher, both based in the firm’s Menlo Park office. Roberts, who joined Venrock in 1997, has been named a managing general partner, and focuses on healthcare. Brian Ascher joined the firm in 1998 and now has the title of general partner, again, not quite the status of a “managing partner,” but still more duties than a “venture partner.” These definitions are getting confusing, in part because each firm uses the terms differently, and they are also changing as lawyers push the firms to use proper terminology to make clear what the roles are. Ascher’s focus is in consumer Internet, enterprise applications and wireless technology, the firm said.

Venrock also has offices in New York and Cambridge, Mass.