The variation trends of natural gas price and selection of stand-by gas sources for piped natural gas are analyzed.
分析了天然气价格变化趋势及管输天然气备用气源的选择。
The comprehensive response of first frost and latest frost to climate change showed that the extened variation trends have obvious regional differences.
初霜、终霜对气候变化的综合响应表现在无霜期的延长变化趋势存在明显的区域性差异。
The recent developments of modified pitch in China are introduced. The new manufacturers for pitch, improvement for technological process as well as its variation trends of standard are reviewed.
阐述了国内改质沥青的一些最新进展；介绍了一些新的改质沥青企业、生产技术的完善情况以及改质沥青的标准变迁情况。
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