排序方式: 共有73条查询结果,搜索用时 296 毫秒
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Lorenzo CaggianoDamiano Castoldi Raphael BeumerPau Bayón Joachim TelserCesare Gennari 《Tetrahedron letters》2003,44(43):7913-7919
During the course of our synthetic studies towards simplified eleuthesides, we have found that p-methoxyphenyl (PMP) protected allylic alcohols are compatible with the RCM reaction and can give better yields than the corresponding free allylic alcohols. 相似文献
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Jorge M.M. Verkade Peter J.L.M. Quaedflieg Floris L. van Delft 《Tetrahedron letters》2006,47(46):8109-8113
Mild and efficient procedures for deprotection of the amine nitrogen protecting p-methoxyphenyl (PMP) group are described. Periodic acid and trichloroisocyanuric acid (TCCA) were found to be particularly effective in realizing amine liberation using 1 and 0.5 equiv of the oxidant, respectively. Extension of the periodic acid-mediated conditions to simultaneous alcohol oxidation by combination with a catalytic amount of sodium dichromate led to smooth conversion of PMP-protected Mannich products into the corresponding β-amino acids in a one-pot procedure. 相似文献
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We develop a fully calibrated positive mathematical programming model for Hawaii's local food systems—which captures the production and the consumer sides of the market. Then we use the model to assess two proposed policies—a general excise tax (GET) exemption on locally produced foods, and an investment in agricultural infrastructure. For the GET exemption case, our results indicate an economic gain of $118 per $100 cost. On the other hand, an investment in 1,200 acres of land injected to support local production may generate an economic gain of up to $357 per $100 annual cost of the investment. However, these estimates should be considered preliminary, and thus viewed with caution. Although the model is used to capture Hawaii's local food systems, we believe that our model is generalizable and can be adopted by other economies to assess their respective food localization policies. Recommendations for Resource Managers
- Local food policies need to be based on quantitative terms instead of mere armchair speculation because often their potential outcomes may vary significantly.
- The current modeling framework demonstrates the potential of using positive mathematical programming (PMP) in capturing the intricacies of local food systems. However, this exploratory exercise should be viewed as preliminary in nature and the ensuing results were taken with caution because many important factors such as labor availability may have been left out.
- Thus, further model refinements are necessary to better capture the complexities of local food systems such as farm heterogeneity, availability of farm labor, water availability, and interisland transportation of farm products in the case of Hawaii.
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Gareth J. Rowlands Author Vitae 《Tetrahedron》2010,66(9):1593-501
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本文提出一种利用复合光栅进行相位测量轮廓术的方法,将三个有一定相移的条纹合成一个彩色光栅,用此光栅进行投影完成相位测量轮廓术.该方法具有单帧测量、无相移误差的优点.文中给出了理论分析和计算机模拟. 相似文献
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采用D类放大器可延长电池供电终端产品的工作时间,并产生更少的热量,因此高效率D类音频功率放大器正越来越多地被用在移动电话、智能电话、PDA及其他类似便携式应用中,以取代AB类放大器。简单陈述了D类功放的原理,并以TI公司的芯片TPA2012D2为例,着重介绍了该芯片在便携式媒体播放器(PMP)中的应用实例。该例在实际应用中得到较好的音频播放表现。 相似文献
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