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991.
Jin Yan Dong Ye Gao Chen Hong Chuan Song Yan Ping He Lei Li Yong Ping Zhong Yan Hui Zhu Jie Cao Luo Wang Ke Qin Zhang Laboratory for Conservation Utilization of Bioresources Yunnan University Kunming China Department of Chemistry Yunnan Normal University Kunming China Provincial Key Lab of Rural Energy Engineering Yunnan Normal University Kunming China 《中国化学快报》2007,18(2):165-167
Microbial transformation of nigranoic acid by Caryospora carllicarpa YMF1.01026 afforded the new derivative 6β-hydro-xynigranoic acid. Its structure was elucidated by spectroscopic methods. 相似文献
992.
Xin Gen Luo Hai Sheng Chen Shuang Liang Mao Huang Wei Dong Xuan Li Jin College of Pharmacy Second Military Medical University Shanghai China Department of Pharmacy Guangzhou Military General Hospital Guangzhou China Center of New Drug Evaluation Institute of Basic Medical Sciences Second Military Medical University Shanghai China 《中国化学快报》2007,18(6):697-699
Six indole alkaloids were isolated from the stems of Ervatamia yunnanensis. Among them, yunnanensine (I) is new. The other five are known alkaloids, namely: 19,20-E-vallesamine (II), 19s-heyneanine (HI), ibogaine (IV), ibogamine (V), coronaridine (VI). The structural elucidation of the alkaloids was based on spectral means. 相似文献
993.
A novel near infrared (NIR) modeling method—Laplacian regularized least squares regression (LapRLSR) was presented, which can take the advantage of many unlabeled spectra to promote the prediction performance of the model even if there are only few calibration samples. Using LapRLSR modeling, NIR spectral analysis was applied to the online monitoring of the concentration of salvia acid B in the column separation of Salvianolate. The results demonstrated that LapRLSR outperformed partial least squares (PLS) significantly, and NIR online analysis was applicable. 相似文献
994.
Wei Luo Xiang Kai Fu Li Hua Ma 《中国化学快报》2007,18(7):883-886
The high quality TiO2, MoO3-doped WO3 electrochromic film was prepared by the sol–gel method for the first time. The sol, which has hydrogen peroxide (H2O2) and oxalic acid (H2C2O4), was very stable at room temperature and quite suitable for the deposition of films. The WO3 electrochromic film prepared from this doped sol had excellent performance, such as short response time, no cracks, good adhesion to the substrate, high coloring efficiency and longevity of service. 相似文献
995.
Electrodeposition of nanocrystalline zinc from acidic sulfate solutions containing thiourea and benzalacetone as additives 总被引:1,自引:0,他引:1
Mou Cheng Li Li Li Jiang Wen Qi Zhang Yu Hai Qian Su Zhen Luo Jia Nian Shen 《Journal of Solid State Electrochemistry》2007,11(4):549-553
Nanocrystalline zinc coatings were produced by pulse electrodeposition in acid sulfate bath containing thiourea and benzalacetone
additives and characterized by X-ray diffraction and scanning electron microscopy techniques. The influence of benzalacetone
concentration and pulse peak current density on the grain size and crystallographic orientation of zinc deposits was investigated.
Zinc electrodeposited from additive-free solutions or with one of the two additives is not composed of nanosized crystals.
The mixture additives of thiourea and benzalacetone give rise to the formation of particle-like nanocrystalline zinc with
a (10ī1) random orientation. A change in peak current density from 2 to 1 A/cm2 only increases the grain size from 60 to 62 nm. 相似文献
996.
Four new tirucallane triterpenoid saponins, named munronosides I–IV ( 2 – 5 ), along with three known triterpenoids, sapelin B ( 1 ), melianodiol, and (3β)‐22,23‐epoxytirucall‐7‐ene‐3,24,25‐triol, were isolated from the EtOH extract of the whole plants of Munronia delavayi Franch by chromatographic methods. On the basis of spectroscopic evidences, the structures of 2 – 5 were elucidated as (20S,23R,24S)‐21,25‐epoxy‐29‐{{O‐β‐d‐ glucopyranosyl‐(1→3)‐O‐[α‐l‐ rhamnopyranosyl‐(1→6)]‐β‐d‐ glucopyranosyl}oxy}‐23,24‐dihydroxytirucall‐7‐ene‐3,21‐dione ( 2 ), (3β,20S,23R,24S)‐21,25‐epoxy‐29‐{{O‐β‐d‐ glucopyranosyl‐(1→3)‐O‐[α‐l‐ rhamnopyranosyl‐(1→6)]‐β‐d‐ glucopyranosyl}oxy}‐3,23,24‐trihydroxytirucall‐7‐en‐21‐one ( 3 ), (20S,23R,24S)‐24‐(acetyloxy)‐21,25‐epoxy‐29‐{{O‐β‐d‐ glucopyranosyl‐(1→3)‐O‐[α‐l‐ rhamnopyranosyl‐(1→6)]‐β‐d‐ glucopyranosyl}oxy}‐23‐hydroxytirucall‐7‐ene‐3,21‐dione ( 4 ), and (3β,20S,23R,24S)‐24‐(acetyloxy)‐21,25‐epoxy‐29‐{{O‐β‐d‐ glucopyranosyl‐(1→3)‐O‐[α‐l‐ rhamnopyranosyl‐(1→6)]‐β‐d‐ glucopyranosyl}oxy}‐3,23‐dihydroxytirucall‐7‐en‐21‐one ( 5 ). 相似文献
997.
π‐Allyl (η3‐C3H5), a four‐electron donor, was used as a ligand model to replace η5‐C5Me4SiMe3 in DFT calculations on the tetranuclear yttrium polyhydrido complex (η5‐C5Me4SiMe3)4Y4H8 containing a Y4H8 tetrahedral core structure, which may separate the four π‐allyl groups and hence suppress the allyl ligand coupling during the computation. In terms of the calculated core geometry, isomerization energy barrier, charge population, and frontier orbital features of the complex, the η3‐C3H5 ligand model is comparable to η5‐C5H5. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
998.
Chen Luo Chenggang Zhou Jinping Wu T. J. Dhilip Kumar Naduvalath Balakrishnan Robert C. Forrey Hansong Cheng 《International journal of quantum chemistry》2007,107(7):1632-1641
Structures and physical properties of small palladium clusters Pdn up to n = 15 and several selected larger clusters were studied using density functional theory under the generalized gradient approximation. It was found that small Pdn clusters begin to grow 3‐dimensionally at n = 4 and evolve into symmetric geometric configurations, such as icosahedral and fcc‐like, near n = 15. Several isomers with nearly degenerate average binding energies were found to coexist and the physical properties of these clusters were calculated. For several selected isomers, relatively moderate energy barriers for structural interchange for a given cluster size were found, implying that isomerization could readily occur under ambient conditions. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 相似文献
999.
考察了Ni/Al_2O_3,Ce和Pr改性Ni/Al_2O_3催化剂在甲醇水蒸气重整制氢过程中的性能。研究结果表明:稀土的添加可增加H2的选择性并降低CO的选择性。Pr改性Ni/Al_2O_3催化剂表现出最好的催化性能,Ni的最佳负载量为10%(质量分数)。在相同的反应条件下(反应温度为350℃和水醇摩尔比=3∶1),Ni/Al_2O_3与Pr改性的Ni/Al_2O_3催化剂的甲醇转化率相当,但Pr改性的Ni/Al_2O_3催化剂H_2的选择性从64.5%提高到了75.6%,相应的CO选择性则从31.4%降低到了4.5%。H2选择性随着水醇摩尔比的增加而升高,当水醇摩尔比为6∶1时,几乎没有CO产生。XRD和TPR表征结果表明:Pr的添加不仅促进了Ni在载体上的分散而且促进了Ni的还原,从而有利于催化性能的改善。 相似文献
1000.
In this study, multiwalled carbon nanotubes (MWCNTs) were used to encapsulate a model anticancer drug, doxorubicin (Dox). Then, the drug-loaded MWCNTs (Dox/MWCNTs) with an optimized drug encapsulation percentage were mixed with poly(lactide-co-glycolide) (PLGA) polymer solution for subsequent electrospinning to form drug-loaded composite nanofibrous mats. The structure, morphology, and mechanical properties of the formed electrospun Dox/PLGA, MWCNTs/PLGA, and Dox/MWCNTs/PLGA composite nanofibrous mats were characterized using scanning electron microscopy (SEM), Fourier transform infrared spectroscopy, and tensile testing. In vitro viability assay and SEM morphology observation of mouse fibroblast cells cultured onto the MWCNTs/PLGA fibrous scaffolds demonstrate that the developed MWCNTs/PLGA composite nanofibers are cytocompatible. The incorporation of Dox-loaded MWCNTs within the PLGA nanofibers is able to improve the mechanical durability and maintain the three-dimensional structure of the nanofibrous mats. More importantly, our results indicate that this double-container drug delivery system (both PLGA polymer and MWCNTs are drug carriers) is beneficial to avoid the burst release of the drug and able to release the antitumor drug Dox in a sustained manner for 42 days. The developed composite electrospun nanofibrous drug delivery system may be used as therapeutic scaffold materials for post-operative local chemotherapy. 相似文献