The strike of registered nurses against the Washington Hospital Center entered its 13th day today with no bargaining sessions scheduled and each side calling upon the other to make some movement in the stalled negotiations.

Dottie Hararas, president of the hospital center's unit of the District of Columbia Nurses' Association, said at a press conference yesterday that the union "cannot bare-bone our issues any more."

"We'd rather be inside taking care of patients than outside doing strike duty," said Hararas. She charged that "the input we're getting from inside the hospital" is that the hospital is admitting patients for unnecessary stays in order to generate more income.

"They're admitting people for overnight stays" who should be having minor surgery performed in physicians' offices or at the hospital on an in-and-out basis, she said.

The hospital center, which is operating at just about 50 percent of its 911 bed capacity - experts say 80 and 85 per cent of capacity is the bread-even point.

Jane Snyder, spokeswoman for the hospital center, vehemently denied the charge and said that the center currently is following the same criteria for admissions that have always been used.

"I assure you we are only admitting patients that doctors say should be admitted," said Snyder. 'If the nurses are questioning the medical judgments of physicians admitting patients . . . I can't respond to that.

"We're willing to talk at any time," said Snyder. We have made compromises and I have no doubt we'll make more compromises. We want to sit down in a spirit of goodwill, ignoring the news media and other outside influences."

The key issues still separating the two sides are.

Rotating shifts, with the union now asking that a joint nurse-physician committee be created to write a plan within 90 days that would permit some nurses to work fixed day shifts, rather than rotating between days, evenings and nights. The hospital center has offered to establish a committee that would report back within two months of the expiration of the contract being negotiated. The report of the committee would be the first item of negotiations when the contract expires.

Union shop, with the hospital center offering to give nurses freedom to make a binding choice to join or not join the union, and the nurses demanding that any nurse hired prior to June 1 of this year be given a choice, but all nurses hired after that date be required to join.

Seniority, with the nurses asking that seniority, and the traditional last-hired, first-fired rule be applied on a hospital-wide basis, while the hospital center is insisting that seniority only be applied within a nurse's area of specialty, that is a coronary care nurse would have seniority within coronary care, but would lose it if she transfered to a phychiatric unit.

The nurses have demanded the right to see their personnel files on demand and the hospital has rejected that demand.

Sick leave, with the hospital center offering the nurses a total of 29 combined vacation and sick leave days after nine years, and 30 extra leave days a year that may be used only for hospitalization and convalesence following hospitalization. The nurses have demanded more sick leave and also demanded that the days not be tied to hospitalization.

Most other issues, including raises, have been settled. The nurses were given a 6 percent raise to take effect Oct. 1. The nurses now start at $12,528 and earn $14,679 after five years.