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101.
Dong Yu ZHAO Sheng Hua YANG Ming HU Xue Yi MA* Department of Chemistry National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 《中国化学快报》2003,14(2)
Andrographolide (Andro) (Figure 1) is a diterpene lactone isolated from Andrographis paniculate Nees1. It has showed several biological activities including analgesic, antipyretic and anti-inflammatory effects2. However, its poor water solubility and unstability towards oxygen restrained its application. In pharmaceutics, b-CD is used to increase solubility and stability3. We have prepared the inclusion compound of Andro/b-CD (Figure 2) under microwave irradiation4. It has been found… 相似文献
102.
以往关于资产组合选择的研究大多假设市场上存在无风险资产,但无风险资产实际上是不存在的.当不存在无风险资产时,假设投资者的效用定义在消费上,消费一直是投资者财富的一个固定比例,投资者的最优资产组合由两部分组成:短视的资产组合和对冲组合.假设只有股票和债券两种风险资产,当股票和债券的风险具有负的相关性时,投资者现在会消费更多,同时也会在股票上投资更多;两者正相关时,投资者无法降低风险,会减持股票并降低当前消费;两者不相关时,投资者持有的股票权重和存在无风险资产时一样.最后,还推导出了多种资产情况下最优消费和资产组合的解析表达式. 相似文献
103.
Kai Jun LIAO Xiao Hua YAN Dong Yun ZHAO Xue Yi MA* Department of Chemistry National Laboratory of Applied Organic Chemistry Lanzhou University Lanzhou 《中国化学快报》2002,(3)
Lappaconitine (Figure 1) is a diterpenoid alkaloid, naturally occurring in roots and rhizomes of Aconitum and delphinium1. Lap reveals bradycardic and hypotensive activity2. But its application is restrained owing to its poor water solubility, toxicity and side effects on humans. In a number of pharmaceutical studies, b-CD has been reported to interact with many drug molecules to form inclusion complexes for improving the water solubility of drugs, and reducing their toxicity3. We have p… 相似文献
104.
Ruo Jun SUN Hui JIANG Zhi Zhen HUANG* Department of Chemistry Zhejiang University Hangzhou 《中国化学快报》2003,(3)
Wittigreactionisoneofthemostimportantmethodfortheformationofcarbon-carbondoublebondandhasbeenwidelyusedinthesynthesisofnaturalproducts1,2.Recentlyitwasfoundthatalcoholscanundergoinsituoxidation-Wittigreactionwithphosponiumylidestogivecorrespondingolefinationproducts,whichhasgreatpotentialutilitiesinorganicsynthesis3.Tosimplifytheprocedureofthereactionfurther,weconsideredtocombinethedeprotonationofylide,oxidationofalcoholandWittigreactionintoonetandemreaction.Weutilizedphosphoniumorarsoniumsal… 相似文献
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IBONACCISEQUENCEANDCANTOR′STERNARYSETTONGJINGCHENGSAMONS,J.ManuscriptreceivedSeptember12,1994.RevisedDecember15,1996.Depar... 相似文献
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Characteristics of Flow around an Impulsively Rotating Square Cylinder via LB-DF/FD Method 下载免费PDF全文
Flow around an impulsively rotating square cylinder in a viscous fluid in range of 1 ≤ Re ≤ 300 is numerically investigated by the previously developed LB-DF/FD method, which combines the lattilce Boltzmann method (LBM) and direct-forcing fictitious domain (DF/FD) scheme. Results show that in total three kinds of transient characteristics depending on Re are observed: 1 ≤ Re ≤ 20, four vortices arising from the corners of the square cylinder separate from the surfaces and gradually become stable without vortex integration or shedding; 20 ≤ Re 〈 100, vortices integration is observed when they grow long enough, then separated from each other; Re ≥ 100, vortex shedding takes place in this regime. The shedding vortex joins the downstream vortex to form a new one. It is also found that vortex shedding happens more than one time when Re ≥ 160. Furthermore, each vortex shedding induces a fluctuation in the torque exerted on the cylinder. 相似文献