In a quiet, almost pastoral setting in suburban Schenectady, one of the biggest and most sophisticated corporate research and development centers in the country painstakingly goes about the business of developing the technology of the 21st century.

This is where the General Electric Co. brainstorms the wonders of the microelectronic silicon chip, which has compresed the computing power of massive machines into tiny, silver-thin pieces of material.

It is also a center of development for electric automobiles and plastics as tough as metal, and for highly sophisticated, coal-powered utility plants that burn fuel more efficiently. Real diamonds were concocted in a laboratory here, not pulled from the depths of the earth.

In a move that made headlines worldwide last year, the center developed an "oil-eating" bacterium.

All-along, General Electric's research and development center has been doing the kind of thing that economists say all U.S. companies must do today if the nation is to regain its technological edge in the world. It cuts a leading path in technology and works with the company's corporate strata to introduce newly developed products to the marketplace.

"U.S. business today finds itself challenged by aggressive overseas competitors," John Welch, GE's new chairman and chief executive officer, said in the company's 1980 annual report. "National productivity has been declining, and, in industry after industry, product leadership is moving to other nations.

"Companies that refuse to renew themselves, that fail to cast off the old and embrace new technologies, could well find themselves in serious decline in the 1980s," he wrote. "We are determined that this shall not happen to General Electric."

As a corporate-level organization, the mission of the GE R&D center is to concentrate its resources on broad, company-wide needs by performing fundamental, longer-range reasearch. It complements applied R&D efforts at more than 100 other GE laboratories nationwide associated with specific product operations.

The center also encompasses more than 2,000 people, nearly 800 of them scientists or engineers, in their R&D components. These are electronics science and engineering, energy science and engineering, materials science and engineering, and the chemical laboratory.

The money committed to all this is mind-boggling, although GE studies have shown that the company has garnered much of it back in the way of profits. Including the work at its satellite laboratories, GE last year spent $1.6 billion on R&D.

The company provided $760 million of the money. The rest -- $838 million -- came from the U.S. government, the Electric Power Research Institute, the research arm of the nation's electric utilities, and other sources.

The results of all this spending have been bountiful. Year after year, GE wins more patents than any other American company. Last year GE was awarded 796, of which 219 came from Niskayuna. That was four more than the number garnered by Union Carbide and only three fewer patents than Exxon picked up.

The research center doesn't operate out of an ivory tower, however. Roland Schmitt, GE's vice president of corporate research and development, takes pride in noting that his facility has always responded to "fire fighting" problems throughout the company.

When a former GE "heavy water" plant in Port Hawkesbury, Canada, was producing only 80 percent of its design output, Schmitt sent a Niskayuna team there to investigate the problem. That led to redesign of parts of the plant, boosting the production of water for use in nuclear reactors to full capacity.

The fruits of GE's R&D endeavors are acknowledged readily by outside analysts, who note that other firms are now following GE's lead in the integration of R&D into corporate strategic planning. Unless companies also spend money on the plants and equipment needed to reap the results of new technology, they say, R&D is virtually meaningless.

"Research and development has enabled GE to develop many new processes and new products over the years," says Bruce S. Old, a retired senior vice president and consultant to Arthur D. Little Inc., a prominent management consulting firm in Cambridge, Mass.

Of late, the biggest R&D thrust at GE has been microelectronics, reflecting the compnay's contention that by the mid-1980s, two-thirds of its sales will feel the impact of the electronics content in its diversified product lines.

Late in 1979, GE broke ground on a $50 million expansion of its corporate R&D center, with more than half of the building program devoted to construction of one of industry's most modern electronics laboratories. The laboratory, which is scheduled for completion in 1982, will inlcude facilities for electronic materials research and a semiconductor processing area.

Last August, GE also broke ground on a $55 million microelectronics center in the Research Triangle Park in Raleigh, N.C.

GE's Schmitt says that the leading edge in micorelectronics development in recent years has shifted from the makers of electronic circuitry to the manufactrurers of final systems in which the circuitry is used. GE intends to keep the momentum moving, he adds.

With the increasing need to custom-design circuitry to better fit the finished product, the company also is moving rapidly into the direct manufacture of microelectronic components and equipment.

Last February, the comapny paid $235 million for Intersil Inc., a leading supplier of advanced integrated circuits and data acquisition and memory products. In April, it paid $100 million, with additional compensation contingent on sales, to buy the Calma Co., a supplier of interactive graphic systems and a former subsidiary of United Telecommunications Inc.

But the biggest paydirt should come from the computer chip. In the coming decade, GE says there will be nearly as many computers in a typical home as motors. That amounts to 40 or 50, taking into account the likes of electric can openers, washing machines, dishwahers and electric furnaces.

Nonetheless, electronics is really only a small piece of the entire story in Niskayuna.

In the chemical area, GE devotes most of its resources to developing, improving and reducing the cost of polymers, or long chains of organic chemical materials used in the manufacture of highly sophisticated plastics.

Frank Williams, manager of GE's chemical laboratory, says these plastics began netting the company $1 billion a year in sales in 1978, and he projects that figure will double by 1983. "We're changing the image of GE as an electrical company into one that is heavily involved in the development and manufacture of high-performance materials," he boasts.

In chemicals, GE perhaps is best known for the development of Lexan, used as a tough substitute for windows on trains and in the manufacture of helmets for the National Football League. Noryl, another proprietary GE plastic highly resistant to steam and water, is commonly found in dishwasher components, water pumps and automobile wheel coverings.

There is also silicone, a highly versatile polymer manufactured at GE's Waterford complex, and Williams says a fourth super plastic may be ready for commercial introduction next year. He won't say much about it, except that it's resistant to high temperatures and flame retardant.

In materials science and engineering, GE scientists focus on developing jet engines increasingly resistant to high temprature, various forms of power-generation technology, and the development of ever more efficient lamps and a sodium sulfur battery to store electricity at night.

The materials section -- and probably the entire center -- is best known for the development in 1955 of industrial-grade diamonds used in factory-cutting operations. GE also artificially developed gem-grade diamonds in the late 1960s, although they wound up costing five to 10 times as much as natural diamonds and never came to market.

In energy science and engineering, the R&D center is working to develop a new form of highly sophisticated transistors -- dubbed Mosfets -- that would make it economically feasible to install variable speed motors in industrial and consumer product applications, saving fantastic quantities of energy.

Work also is progressing on a U.S. government-funded project to produce two advanced "hybrid" automobiles for the Department of Energy, which have both a gasoline engine and electric motor under the hood.

There is also work on development of a coal-powered utility plant that would rely on both gas and steam turbines to boost the conversion factor of coal into electricity while maintaining environmental standards.

In this system, the coal is the first gasified, then cleaned of pollutants and burned to produce electricity in a highly efficient gas turbine, steam turbine combined system. GE says the system should be 20 percent to 25 percent more efficient than a conventional coal-burning plant with stack gas scrubbers.

"Our overall mission here is to establish a leadership position in energy-related technologies," says Michael Jefferies, manager of the energy science and engineering sector. "We have to find ways of reducing the nation's dependence on premium fuels."