由于遗传资源狭窄，有利重组体的数量受到限制，使育种工作进展缓慢，甚至停滞不前。
Because the heredity resources is narrow, the restrict that the quantity of the beneficial reorganization suffer, make the breeding work progress slowly, even bog down.
但是现在，即便在全国一流的不育诊所婴儿出生率的增加速度已经有所减缓甚至停滞不前。
But now, improvements in the "take-home-baby rate" have slowed or even plateaued at the nation's top infertility clinics.
但是由于当时测序工具的停滞不前和高成本，很多后续研究进程都十分缓慢甚至停滞不前。
But because of the balky sequencing tools of the day and their high cost, much of the subsequent research progressed slowly or stalled.
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