Tokyo stocks opened higher Thursday, with the Nikkei index climbing to a new all-time intraday high, buoyed by Wall Street gains overnight after the Federal Reserve chair indicated again that the central bank will cut its key interest rate this year. In the first 15 minutes of trading, the 225-issue Nikkei Stock Average rose 227.35 points, or 0.57 percent, from Wednesday to 40,318.13. The broader Topix index was up 16.84 points, or 0.62 percent, at 2,747.51. On the top-tier Prime Market, gainers were led by insurance, bank, and oil and coal product issues. At 9 a.m., the U.S. dollar fetched 14…