The solar system began as a disk of dust and gas swirling around the young sun. 太阳系一开始是一个由灰尘和气体组成的圆盘,围绕年轻的太阳旋转。
The PQR shall include the composition and flow rate of the shielding and inert gas backing, when used. 焊接工艺评定记录单上应包括封底焊时所用的惰性保护气体组成成分和流率。
A new method for recognizing gas components in air based on nonlinear fluorescence spectra combined with a neural network model was proposed. 提出利用物质的荧光光谱联合人工神经网络识别大气中杂质气体成分的新方法。