The article overviews the principles , methods , the effect factors of the tip meristem culture of sweet potatoes and its research progress , and points out the problem that it is unknown widely , its composition of culture medium is different because of varietal difference , virus infects sweet potatoes again and production cost is high 摘要综述了甘薯茎尖分生组织培养的原理、方法、影响因素及其研究进展，指出了茎尖组织培养存在的未被广泛认识、由于品种差异造成的培养基成分不同、病毒再侵染、生产成本高等问题。
The agent may be used to recommend wines given a set of constraints ( such as a meal being served ) , the agent may find information about a particular wine or a particular class of wines , it may look for appropriate accessories for a wine ( such as a particular kind of glass suited for that wine varietal , etc . ) 主体能够根据给定的许多约束条件（例如要提供的餐宴）推荐合适的葡萄酒，能够找到关于某种特定的葡萄酒或者某种特定的葡萄酒的类别的信息，它还能够为一种葡萄酒找出合适的附属品（例如为某个品种的葡萄酒找到合适的特定种类的杯子等） 。
When analyzing agricultural market , agricultural policies , and agricultural trade , the paper exercise contrast analysis method , according to wto agreement , to refer operational agricultural protection measures . at the same time , on the basis of qualitative analysis , the paper constructs mathematical models on how th e open trade affects farm produce and establishes agricultural industrial structure and agricultural product ' s varietal structure . through the analysis of computer software , it determines the aims and measures of hebei agricultural economy 在撰写过程中作者运用了众多的研究方法：在深入分析我省农业市场、农业政策、农业外贸等状况时，本文运用对比分析法，比照wto的《农业协议》及相关条款，提出了适合我省的可操作的农业保护措施；同时本文在定性分析的基础上，构造了贸易开放对农产品影响的数学模型，建立了农业产业结构和农产品品种结构模型以及农产品优劣势评价指标体系，通过运用计算机数据处理软件进行分析，确定了河北省农业经济的调整目标和措施。
It could improve carcass quality meat quality , reproductive ability of livestock , and was indispensible matter for normal elaboration of livestock ' s varietal performance . up till now , biotin could only be gained by the method of chemical synthesis and only imported from the foreign countries , and its price was very expensive and seriously restricted the development of our country ' s animal husbandry 由于生物素能够提高家畜胴体质量和改善肉质，提高家畜繁殖力，是家畜品种性能正常发挥所必需的物质。目前，生物素只能通过化学合成方法获得，且均从国外进口，价格昂贵，制约了我国畜牧科技和产业的发展。
