But in the economic evaluation to the gas reserves, we are always difficult to carry on the accurate valuation because of lacking the related material.
而油气田在对天然气储量经济性评价中，由于受资料的限制，往往难以进行准确的评价。
Also it is the valuation criterion of material price dynamic variation and basis of the material valuation for bidding bottom of construction bid and tender quotation.
同时，它也是材料价格动态变化的计价依据，施工招标标底、投标报价的材料费计价的基础。
Methods The forest ecosystem service is evaluated by the method of material valuation, the ARCVIEW geographic information system technique, and the observation on the spot in the different regions.
方法应用物质量和价值量相结合的方法，借助ARCVIEW地理信息系统技术，根据不同林分在不同区域的实地观测值进行估算。
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