In March, President Obama ended restrictions on the use of federal money for research using human embryonic stem cells.

VOA: special.2009.04.07

There's a lot of interest in obtaining stem cells from the blood of the umbilical cord on birth.

从出生时的脐带血中取得一些干细胞,也很有趣

耶鲁公开课 - 生物医学工程探索课程节选

stem cell research can go on without the ethical dilemma provided by killing embryos.

干细胞研究者可以免受由于杀死胚胎而带来的道德困境。

干细胞和伦理 - SpeakingMax英语口语达人

Last year,President Obama ended restrictions on the use of federal money for studies of human embryonic stem cells.

VOA: special.2010.11.02

The new research shows that the buds on the side cannot export their auxin into the main stem because it is too full.

VOA: special.2009.10.13

Stem rust produces reddish-brown spots on the stems of infected plants.

VOA: special.2009.08.18

And until BP finds a way to stem the flow, no one can estimate the full effect of this disaster on BP, its shareholders,or employees.

VOA: standard.2010.06.18

"But a baby who has a defect in those brain stem circuits that use serotonin can't do that when challenged and they go on to die."

VOA: standard.2010.02.08

That was Wednesday. On Thursday the world leaders meet in working sessions to discuss what to do to stem the global recession and get back on the road to growth.

VOA: standard.2009.04.01

We have a big job on our hands,". Borlaug expressed concern about a new variety of wheat stem rust attacking wheat plants in Africa and advocated greater coordination of researchers around the world to stop its spread.

VOA: standard.2009.09.13

At a similar gathering last year, members of the so-called G20 set of advanced economies agreed on emergency spending to stem a global crisis brought on by the collapse of U.S.investment bank Lehman Brothers in late 2008.

VOA: standard.2010.06.05