高效环保地膜多年应用对青花菜生长发育的影响

为了减少普通地膜连年使用造成的农田白色污染,为蔬菜生产选择高效环保地膜提供参考,以"耐寒优秀"青花菜为试材,研究高效环保地膜连续使用多年对青花菜生长发育的影响。结果表明:高效环保地膜连续使用3~4年,青花菜产量略有减少,但差异不显著;青花菜生长发育与对照普通黑色地膜和银灰色地膜2个处理没有明显差异;土壤容重有所降低;除草效果好于对照地膜,且回收容易,不易撕裂,没有残留,可以作为普通地膜的替代品。

Usefulness of coronary flow reserve measured by transthoracic coronary Doppler ultrasound in the elderly

The left anterior descending （LAD） coronary artery is the main vessel of human coronary circulation, and life-threa- tening consequences are seen when flow in this area is im- paired, Noninvasive measurement of coronary flow re- serve （CFR）, defined as the ratio of maximal to baseline coronary blood flow, has been repeatedly shown to be a feasible technique by ultrasound transthoracic Doppler （TTD） both in the LAD and, with some limitations, in the posterior descending （PD） coronary artery.