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81.
简要介绍了润滑油添加剂的供需现状和发展预测,分析了推动润滑油添加剂升级换代的动力,阐述了即将推出的GF—4发动机油规格对添加剂的新要求。 相似文献
82.
1“居山”与”隐贵山居“
回想一下人类的聚居行为颇为有趣,当年我们的祖先拼命从险山恶水的自然环境中挣脱出来,为的是得到更加安全和便利的聚居条件,但似乎从那一刻起本能式的回归意识便时刻魂牵梦绕,隐隐作响。其实无论是脱离自然还是回归自然,对于现实而言两者皆是虚幻和理想的。 相似文献
83.
84.
女性自初潮开始到绝经的过程中,有30多年的时间需要避孕。如何在这样漫长的时间里安全避孕。是每位女性维护自身健康必不可少的一项措施。有人说:“怀孕是生命力的表现,如果我们不用避孕了,那一定不是老了就是病了。”因此。避孕对于女性来说,是一件甜蜜而又麻烦的事。如果因意外怀孕而不得不采取人工流产。不仅会给女性带来心灵上无法抚平的伤害,还可能由此引发不孕、感染以及妇科肿瘤等不良后果。因此了解各种避孕节育方法的有效性、优缺点,将有助于女性在人生的不同阶段,选择那些有效、安全、适合自己的避孕节育方法,降低避孕失败的风险。[编者按] 相似文献
85.
86.
OpenType字体技术是Type字体和TrueType字体“大战”的产物,也是响应Unicode字符编码标准的产物,更是Adobe与Microsoft公司合作的产物。单从时间概念上考虑,这种字体技术其实并不新,现在重提OpenType字体,是因为CS2套件对于OpenType字体的全面支持,以及OpenType字体具有许多最要的特征。 相似文献
87.
Meng Yan Minyu Yao Hongming Zhang Li Xia Ye Zhang 《Photonics Technology Letters, IEEE》2008,20(10):788-790
A novel en/decoder for spectral phase-coded optical code-division multiple-access system based on amplitude sampled fiber Bragg grating (FBG) is proposed. Both equivalent chirp and equivalent phase shift are achieved by amplitude sampling. Compared with previous en/decoder based on step chirped FBG, it is easier to fabricate. The performance of the proposed en/decoder is verified by both numerical simulation and experimental demonstration. 相似文献
88.
In the world energy about 26% of all was dedved from coal combustion. Nearly 80% of the electricity produced in China is generated from coal. Coal will play the most important role in the coming 50 years as the past century in China. However one consequentially of the mining and combustion of coal is the mobilization of trace elements, especially trace metals, which have environmental and human health significance. Information on concentrations and distributions of potentially toxic elements in coal, and information On the modes of occurrence of these elements and the relations of the minerals in coal can help to predict the behavior of the potentially toxic trace metals dudng cleaning, combustion, weathering, and leaching. 相似文献
89.
Yongxian Zhao Baochen Huang Wei Yao Hailin Cong Huafeng Shao Aihua Du 《应用聚合物科学杂志》2008,107(5):2986-2993
A new organic‐solvent‐free water‐phase suspension method was used to synthesize partially epoxidized high trans‐1,4‐polyisoprene (TPI) to improve its properties, including oil resistance and wet‐skid resistance. The epoxidation was conducted in an aqueous peracetic acid solution and on the TPI granules prepared by a bulk precipitation method with supported titanium catalyst. The effects of the synthesis conditions, including reaction temperature, reaction time, and pH value, on the epoxy content were investigated. Epoxidized trans‐1,4‐polyisoprene (ETPI) with epoxy contents between 10 and 80% were obtained within 4 h. Both the amorphous and crystalline regions of TPI were epoxidized. The crystallization properties decreased with increasing epoxy content. ETPIs possessed lower mechanical properties than TPI but could be enhanced by vulcanization. The oil resistance and wet‐skid resistance were significantly improved after epoxidation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
90.
A novel mixed‐mode expanded bed adsorbent with anion‐exchange properties was explored with benzylamine as the functional ligand. The cellulose composite matrix, densified with stainless steel powder, was prepared with the method of water‐in‐oil suspension thermal regeneration. High activation levels of the cellulose matrix were obtained with allyl bromide because of the relative inertness of the allyl group under the conditions of the activation reaction. After the formation of the bromohydrin with N‐bromosuccinimide and coupling with benzylamine, the activated matrix was derived to function as a mixed‐mode adsorbent containing both hydrophobic and ionic groups. The protein adsorption capacity was investigated with bovine serum albumin as a model protein. The results indicated that the prepared adsorbent could bind bovine serum albumin with a high adsorption capacity, and it showed salt tolerance. Effective desorption was achieved by a pH adjustment across the isoelectric point of the protein. The interactions between the cell and adsorbent were studied, and the bioadhesion was shielded by the adjustment of the salt concentration above 0.1M. Stable fluidization in the expanded bed was obtained even in a 2% (dry weight) yeast suspension. The direct capture of target proteins from a biomass‐containing feedstock without extra dilution steps could be expected with the mixed‐mode adsorbent prepared in this work, and this would be especially appropriate for expanded bed adsorption applications. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献