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251.
梁光裕 《广东微量元素科学》1998,5(1):63-65
为探讨Ge-132的毒副反应,对服用Ge-132的肺癌患者3083例进行长期观察。结果发现各项观察指标,治疗组与对照组均无明显差异,可认为在合理剂量下,临床长期应用Ge-132是安全的。 相似文献
252.
Xi-Shang Sun Xing-Heng Wang Hai-Yan Tao Liang Wei Chun-Jiang Wang 《Chemical science》2020,11(40):10984
In this study, we developed an efficient Ir-catalyzed cascade umpolung allylation/2-aza-Cope rearrangement of tertiary α-trifluoromethyl α-amino acid derivatives for the preparation of a variety of quaternary α-trifluoromethyl α-amino acids in high yields with excellent enantioselectivities. The umpolung reactivity empowered by the activation of the key isatin-ketoimine moiety obviates the intractable enantioselectivity control in Pd-catalyzed asymmetric linear α-allylation. In combination with quasi parallel kinetic resolution or kinetic resolution, the generality of this method is further demonstrated by the first preparation of enantioenriched quaternary trifluoromethyl β-, γ-, δ- and ε-amino acid derivatives.In this study, we developed an efficient Ir-catalyzed cascade umpolung allylation/2-aza-Cope rearrangement for the preparation of a variety of quaternary trifluoromethyl α-ε-amino acids in high yields with excellent enantioselectivities. 相似文献
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The cover picture shows a typical building within the Campus of Xiamen University displaying Chen Jiageng (Tan Kah Kee)'s style. Just like many beautiful buildings designed and constructed by human, Nature “designs and constructs” a huge number of useful molecules with fascinating structures called natural products. Many natural products possess a fused six or seven‐membered carbocyclic unity. On page 315–322, the Huang's group disclosed a three‐step “[2+n]” annulation method for the construction of fused six and seven‐membered carbocyclic enimines and enones. The method starts from simple cyclic ketones and terminal olefinic amides, and relies on both the Suzuki coupling reaction and the olefin‐amide based Friedel‐Crafts type acylating reaction, a method developed by Huang and coworkers.
257.
Adsorption, desorption and activities of acid phosphatase on various colloidal particles from an Ultisol 总被引:1,自引:0,他引:1
Adsorption, desorption and activity of acid phosphatase on various soil colloidal particles and pure clay minerals were studied. Higher adsorption amounts and low percentage of desorption of acid phosphatase were found on fine soil clays (<0.2 μm). Electrostatic force and ligand exchange are the major driving forces that are involved in the adsorption of enzymes on soil clays. More enzyme molecules were adsorbed on soil clays in the presence of organic components. However, enzymes on organic clays were more easily released. One-third of the enzyme on goethite was adsorbed via ligand exchange process. Some other interactions, such as van der Waals force, hydrophobic force and hydrogen bonding may be more important in the adsorption of enzyme on kaolinite and the enzyme in this system cannot be easily removed. Coarse clays (0.2–2 μm) and inorganic soil clays had higher affinities for enzyme molecules than fine clays and organic clays, respectively. The activity of enzyme bound on soil clays was inhibited and the thermal stability was increased in the presence of organic matter. Data obtained in this study are helpful for a better understanding of the interactions of enzymes with inorganic and organic constituents in soil and associated environments. 相似文献
258.
使用疏水作用色谱研究蛋白质的构象变化 总被引:2,自引:0,他引:2
研究了高效疏水作用液相色谱中(HIC)色谱条件改变对蛋白质构象的影响。发现固定相配体的疏水性、温度及流动相中盐的阴离子、阳离子和pH值都影响蛋白质的构象。 相似文献
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Shen YH Li SH Li RT Han QB Zhao QS Liang L Sun HD Lu Y Cao P Zheng QT 《Organic letters》2004,6(10):1593-1595
Both coriatone (1). a novel highly oxygenated picrotoxane-type sesquiterpene, and corianlactone (2). with an unprecedented sesquiterpene basic skeleton, named coriane, were isolated from Coriaria nepalensis Wall. The structures of 1 and 2 were determined by analysis of their two-dimensional NMR data, and the structure of 2 was confirmed by X-ray analysis. Compounds 1 and 2 showed no remarkable inhibitory activity toward K(562) cells. They are cytotoxic with IC(50) > 50 microg/mL (cis-platinim: IC(50) = 0.49 microg/mL). 相似文献