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1.
Impurity release from the first wall and components facing the hot plasma in Tokamak devices for controlled fusion research and the concomitant pollution of the plasma lead to enhanced energy losses and deuterium-tritium luel dilution. Both these effects can prevent reaching the ignition conditions. The recently developed technique for large areain situ deposition of boron carbide protective coatings by means of plasma-induced chemical vapor deposition enables one to significantly improve the purity of the fusion plasma. The prospects of approaching the scientific break-even in the large machines of the Tokarnak type has been increased.Extended version of an invited paper presented at the 10th International Symposium on Boron, Borides, and Related Compounds, Albuquerque, New Mexico, August 1990.The term Tokarnak is an abbreviation of the Russian name toroidal magnetic chamber.  相似文献   
2.
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   
3.
The impedance of zinc-rich polymer coatings on steel in a 3-% NaCl solution is studied. The electrochemical behavior of the electrode is satisfactorily described by an equivalent circuit that contains a constant-phase element, which reflects fractal properties of the zinc surface in the binder. From the results of calculations of the circuit elements for metal-rich electrodes with different zinc contents computed are fractions of the active area of the surface of the coating and its fractal dimensionality.  相似文献   
4.
应用中药材开发微量元素保健品   总被引:3,自引:0,他引:3  
介绍了用中药村开发几种微量元素保健品,有补锌,有助小儿生长,补硒抗癌,补铁钴养血,补铬治糖尿病和补锌铅的肝病滋补保健品。  相似文献   
5.
新的酚型开链冠醚及由其衍生的二苯并冠醚的合成   总被引:2,自引:0,他引:2  
孟杰  田宝芝  黄枢 《有机化学》1996,16(3):253-257
将水杨醛与碱和氯甲基甲基醚反应, 再经过NaBH4还原, 即制得邻(甲氧基甲氧基)苯甲醇, 然后将其在DMF中与NaH和二(或三)甘醇二对甲苯磺酸酯反应, 得开链冠醚1a和1b。1a和1b经稀酸水解, 即脱保护而分别生成新的酚型开链冠醚2a和2b。用2a与二甘醇二对甲苯磺酸酯和NaH在DMF溶液中反应, 合成顺型二苯并-20-冠-6(3); 而2a与环氧氯丙烷在NaOH水溶液中反应, 则合成了17-羟基二苯并-18-冠-5(4)。  相似文献   
6.
Glass-like sol-gel coatings have been investigated as corrosion protective coatings on stainless steel. Magnesium- and borosilicate coatings with thickness of about 100–700 nm and methyl-modified SiO2 coatings with a thickness of about 2 m were deposited on stainless steel plates by dip-coating. The coatings were densified between 400°C and 500°C in different atmospheres (N2, air) for 1 h. The corrosion protection against gaseous attack was investigated by accelerated corrosion tests, at 800°C in air for 1 h. A corrosion protection factor was calculated from the relation Fe/Fe2O3, determined by XRD on the surface of coated and uncoated samples. Methyl-modified SiO2 coatings showed a protection factor, which was 2 orders of magnitude higher than for the other coatings. Electrochemical investigations were performed on samples submerged in a NaCl solution for 200 h. The corrosion propagation, polarization resistance and impedance vector were measured. For accelerated corrosion tests, polarization intensity curves were determined for high potentials of up to 1 V. Again excellent results were obtained for the methyl-modified SiO2 coatings, which remained passive for 200 h. Results of the salt spray corrosion test, however, showed no corrosion protection by the sol-gel coatings. After 2000 h in the salt spray chamber the steel was corroded and the coatings peeled off. It is concluded that for the further development of these coatings an improved interfacial passivation will be required.  相似文献   
7.
肾脏缺血缺氧以及再灌注过程都将导致肾小管上皮细胞凋亡,使肾功能严重受损.肾脏的缺血再灌注损伤是移植肾功能延迟恢复的主要原因并能诱导急慢性排斥,影响肾存活率.近年来发现,衍生于促红细胞生成素(EPO)的B螺旋亚基亲水表面序列的肽链(HBSP),对肾脏缺血再灌注损伤具有显著的保护作用,但其在体内极短的半衰期(约2min)极大地限制了它的临床应用.因此,本研究采用构象约束、全D-构型氨基酸替换和N-端封闭策略,设计了3种类型的EPOB螺旋表面肽衍生物,旨在提高其代谢稳定性环肽的设计采用了对氧化还原稳定的硫醚键和相对刚性的亚砜键两种环合方式.在多肽的合成上,采用微波辅助多肽自动合成和手工合成两种模式有机结合;优化了硫醚环合工艺,应用微波加热进行硫醚环肽的合成,大大提高了产率和效率;利用圆二色(CD)谱确定了亚砜环肽的相对构型.活性实验表明,相对于线性母肽HBSP,本文设计合成的代谢稳定衍生肽对大/小鼠肾脏缺血再灌注损伤均有显著提高的保护作用,且硫醚和R-构型亚砜环肽的肾脏保护活性强于S-构型亚砜环肽.而且,环化确实提高了功能肽的血浆稳定性.因此,本文合成的硫醚环肽一周一次注射剂量等效于线性肽HBSP一日三次剂量对小鼠肾损伤的保护作用.  相似文献   
8.
We prepared highly flexible, transparent, conductive and antibacterial film by spin coating a silver nanowire suspension on a poly (ethylene terephthalate) (PET) substrate. The ZnO layer covered the conductive silver nanowire (AgNW) network to protect the metal nanowires from oxidization and enhance both wire-to-wire adhesion and wire-to-substrate adhesion. It is found that the number of AgNW coatings correlates with both the sheet resistance (Rs) and the transmittance of the AgNW/ZnO composite films. An excellent 92% optical transmittance in the visible range and a surface sheet resistance of only 9 Ω sq−1 has been achieved, respectively. Even after bending 1000 times (5 mm bending radius), we found no significant change in the sheet resistance or optical transmittance. The real-time sheet resistance measured as a function of bending radius also remains stable even at the smallest measured bending radius (1 mm). The AgNW/ZnO composite films also show antibacterial effects which could be useful for the fabrication of wearable electronic devices.  相似文献   
9.
金属锂因其具有极高的理论容量(3860 mAh·g?1)、最低的电极电位(?3.04 V vs.标准氢电极)和低的密度(0.534 g·cm?3),被认为是最具潜力的负极材料。但循环过程中不可控的枝晶生长及不稳定的固体电解质相界面膜所引起的安全隐患和电池库伦效率低等问题严重阻碍了锂金属负极的发展。通过在电极表面构建人造保护膜可以有效调控锂离子沉积行为,因此人造保护膜的构建是一种简单高效抑制锂枝晶生长的策略。本综述将从聚合物保护膜、无机保护膜、有机-无机复合保护膜和合金保护膜总结了人造保护膜的构建方法、抑制锂枝晶生长机理,为促进高比能锂金属电池的商业化应用提供借鉴参考作用。  相似文献   
10.
采用傅立叶变换红外光谱法对21个5种不同颜色的电线塑料护套样品进行了分析.从红外光谱图中可观察到样品特征峰的峰数、峰位、相对峰面积比均有差异,但可以归纳为两大类.其中同种颜色的不同样品在红外谱图中又反映出了不同的信息,这表明在外观颜色十分相近的情况下,采用此方法能够有效的为刑事案件现场遗留的各种塑料制品提供鉴别与比对.  相似文献   
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