* China signals support for growth, boosts global shares
* Blue chips DuPont, United Tech lift Dow index
* Apple due to report after the bell
* Indexes: Dow up 0.3 pct; S&P up 0.1 pct; Nasdaq up 0.1 pct
By Angela Moon
NEW YORK, July 23 (Reuters) - U.S. stocks edged up on Tuesday, with the S&P 500 less than 3 points away from the 1,700 level, helped by solid earnings from blue-chips DuPont and United Tech and by China's efforts to avoid a hard landing for its slowing economy.
With earnings season in full swing, Apple Inc is due to report after the closing bell. The tech giant is expected to post a smaller quarterly profit and its financial report may come under intense scrutiny. The stock was down 0.3 percent at $425.31 in early trade.
Chemical maker DuPont Co, a Dow component, said it was looking to sell or spin off its performance chemicals unit to insulate itself from flagging sales of paint pigments that have weighed on profits. The stock jumped 4.7 percent to $59.91.
United Technologies Corp, the world's largest maker of elevators and air conditioners, raised the bottom end of its 2013 earnings forecast, citing its growing confidence after a jump in aerospace orders and cost cuts. The stock rose 2.4 percent to $104.72.
The Dow Jones industrial average was up 44.08 points, or 0.28 percent, at 15,589.63. The Standard & Poor's 500 Index was up 1.80 points, or 0.11 percent, at 1,697.33. The Nasdaq Composite Index was up 3.23 points, or 0.09 percent, at 3,603.62.
Wall Street has moved higher in 11 of the past 12 market days. The S&P 500 closed at a third straight all-time high on Monday, and is now up about 20 percent for the year.
"Could the upward run continue? Yes," said David Brown, CEO at Sabrient Systems, an independent equity research firm in Santa Barbara, California.
"Funds continue to flow from money market and longer-term fixed income funds into the equity market. Valuations have not exceeded reasonable variations from the norm, a tad high here and there but with bargains remaining. The gains have not been powerful, large up days on large volume indicating a blow-off top."
Among the day's decliners, Netflix Inc shares fell 1.1 percent to $259.15, a day after the online-entertainment firm reported that its show "Arrested Development" lured new subscribers in the second quarter but not enough to impress investors.
United Parcel Service Inc posted a smaller quarterly profit as customers chose slower, cheaper shipping services, especially on international routes. The stock fell 0.1 percent to $87.49.
China must deepen reforms to address a slew of challenges confronting it, President Xi Jinping said in comments published on Tuesday that emphasize the government's determination to restructure the slowing economy. China shares listed in Hong Kong posted their biggest rise in nearly seven months on Tuesday.