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991.
该项工程的开挖爆破中,采用塑料导爆管非电起爆技术等措施,成功地解决了复杂环境条件下的爆破安全问题,为同类工程施工提供了可借鉴的经验。 相似文献
992.
We describe an innovative concept of synthesizing a novel hybrid bimodal network elastomer with high strength–high ductility combination involving utilization of functionalized nanocrystalline titania as short-chain cross-links between neighboring elastomer chains. This subject is germane both fundamentally and from an application viewpoint. Silicone rubber is selected as the model elastomer. The short-chain cross-links are acrylic acid functionalized nanocrystalline titania that are an integral component of bimodal network structure of the elastomer. To delineate and separate the effects of functionalization from nanoparticle effects, a relative comparison is made between silicone rubber–titania nanocomposite (i.e. containing dispersion of titania as a reinforcement filler) and silicone rubber–titania hybrid network elastomer (i.e. titania as short chain cross-links). An important finding is that the effect of functionalized titania present as short chain cross-links is far more significant than non-functionalized titania present as reinforcement filler, on mechanical behavior. This is presently ascribed to the double bonds introduced to nanocrystalline titania via functionalization with acrylic acid that provide active sites for the cross-linking reaction resulting in inorganic bridging chains. The basic physical mechanisms that govern elastic recovery in hybrid bimodal network elastomer with short chain cross-links of functionalized nanocrystalline inorganic particles are discussed. The hypothesis of the study described here is that the hybrid bimodal network elastomer with short chain cross-links of functionalized nanocrystalline inorganic particles modifies the unimodal long chain network elastomer with consequent increase in modulus and high strength–ductility combination. 相似文献
993.
DNA methylation is one of the major epigenetic modifications and has been involved in a number of biological processes in mammalian cells. Yeast is widely used as a model organism for studying cell metabolism, cell cycle regulation, and signal transduction. However, it remains controversial whether methylated cytosine (5-methylcytosine, 5mC) exists in the yeast genome. In the current study, we developed a highly sensitive method based on gas chromatography/mass spectrometry (GC/MS) and systematically examined the incidence of 5mC in 19 yeast strains, which represent 16 yeast species. Our results showed that DNA methylation is widespread in yeast and the genome-wide DNA methylation of the studied yeast strains ranged from 0.014 to 0.364%, which were 1 to 2 orders of magnitude lower than that in mammalian cells (i.e., 3-8%). Furthermore, we found that the 5mC content in yeast varied considerably at different growth stages and DNA methylation inhibitor 5-azacytidine could induce a decrease in genome-wide DNA methylation as that in mammalian cells. The demonstration of the universal presence of DNA cytosine methylation in yeast constituted the first and essential step toward understanding the functions of this methylation in yeast. 相似文献
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995.
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997.
提出一种基于不完全模态测量数据同时修正有限元质量矩阵与刚度矩阵的有效数值方法。运用代数特征值反问题的理论与方法,得到了满足正交关系及特征方程的最逼近有限元质量矩阵及刚度矩阵的唯一的修正质量矩阵与刚度矩阵(最优修正矩阵)。该方法有一个简洁的表达式,修正过程简单而且容易实现。数值算例表明,修正模型与模态试验数据具有非常好的一致性。 相似文献
998.
Scanning Nanowelding Lithography for Rewritable One‐Step Patterning of Sub‐50 nm High‐Aspect‐Ratio Metal Nanostructures 下载免费PDF全文
Guoqiang Liu Lina Chen Jin Liu Meng Qiu Zhuang Xie Jian Chang Yaokang Zhang Peng Li Dang Yuan Lei Zijian Zheng 《Advanced materials (Deerfield Beach, Fla.)》2018,30(35)
The development of a new nanolithographic strategy, named scanning nanowelding lithography (SNWL), for the one‐step fabrication of arbitrary high‐aspect‐ratio nanostructures of metal is reported in this study. Different from conventional pattern transfer and additive printing strategies which require subtraction or addition of materials, SNWL makes use of a sharp scanning tip to reshape metal thin films or existing nanostructures into desirable high‐aspect‐ratio patterns, through a cold‐welding effect of metal at the nanoscale. As a consequence, SNWL can easily fabricate, in one step and at ambient conditions, sub‐50 nm metal nanowalls with remarkable aspect ratio >5, which are found to be strong waveguide of light. More importantly, SNWL outweighs the existing strategies in terms of the unique ability to erase the as‐made nanostructures and rewrite them into other shapes and orientations on‐demand. Taking advantages of the serial and rewriting capabilities of SNWL, the smart information storage–erasure of Morse codes is demonstrated. SNWL is a promising method to construct arbitrary high‐aspect‐ratio nanostructure arrays that are highly desirable for biological, medical, optical, electronic, and information applications. 相似文献
999.
1000.
Jun Yan Yigang Chen Qingling Yuan Song Yu Wencai Qiu Chengguang Yang Zhigang Wang Jianfeng Gong Kaixing Ai Qi Zheng Jianan Li Shaoxiang Zhang Xiaonong Zhang 《Journal of materials science. Materials in medicine》2013,24(6):1515-1525
To evaluate the ability of Mg–6Zn to replace titanium nails in the reconstruction of the intestinal tract in general surgery, we compared the Mg–6Zn and titanium implants with respect to their effects on rat’s intestinal tract by biochemical, radiological, pathological and immunohistochemical methods. The results indicated that Mg–6Zn implants started to degrade at the third week and disintegrate at the fourth week. No bubbles appeared, which may be associated with intestinal absorption of the Mg–6Zn implants. Pathological analyses (containing liver, kidney and cecum tissues) and biochemical measurements, including serum magnesium, creatinine, blood urea nitrogen, glutamic–pyruvic–transaminase and glutamic–oxaloacetic–transaminase proved that degradation of Mg–6Zn did not harm the important organs, which is an improvement over titanium implants. Immunohistochemical results showed that Mg–6Zn could enhance the expression of transforming growth factor-β1. Mg–6Zn reduced the expression of tumor necrosis factor at different stages. In general, our study demonstrates that the Mg–6Zn alloy had good biocompatibility in vivo and performed better than titanium at promoting healing and reducing inflammation. It may be a promising candidate for stapler pins in intestinal reconstruction. 相似文献