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991.
以羊软骨为实验材料,用不同体积分数的二甲基亚砜(Me2SO)作为保护剂,在4、-20、-30、-70℃温度下研究对羊软骨细胞存活率和琥珀酸脱氢酶(SDH)活性的影响.实验结果表明,Me2SO对细胞的存活率和SDH活性的影响受温度和体积分数的影响较大.在4~20℃时,Me2SO作为单独冷冻保护剂的最佳初始体积分数为10%~20%.在-20~-70℃时,Me2SO作为羊软骨细胞保护剂的最佳应用体积分数为10%~45%. 相似文献
992.
GALS(全局异步、局部同步)架构适用于NoC的时钟分布,但现有的GALS需要定制地设计异步包装电路,不利于验证和集成.采用通用的数字ASIC设计流程,在仅使用已有标准单元的情况下,提出了一种新的基于FIFO的异步包装.通过此包装电路,实现了一个信号传输只需2步操作,提高了通信吞吐率.实验结果表明该包装电路在吞吐率和延迟上获得了显著改进. 相似文献
993.
郭庆广 《浙江大学学报(理学版)》2011,38(4):477-482
原本方物流成本和第三方物流成本会因各自条件明显欠缺而难以集中并进行会计核算.尽管如此,却可以运用统计方法对它们进行估算,即在理清物流成本结构的基础上,分别对物流需求者和物流经营者总体的有关特征进行抽样推断,进而估算出原本方物流成本和第三方物流成本以及由它们合成的物流供给成本.抽样推断方法具有科学性和可操作性,能有效解决物流成本估算问题,其应用成果为制定物流发展规划或设计物流建设方案提供了依据,为解决物流卫星账户构建之瓶颈问题奠定了重要基础. 相似文献
994.
A partially orthonormal basis is constructed with better conditioning properties for tetrahedral H(curl)-conforming Nédélec elements.The shape functions are cla... 相似文献
995.
Two new 1,3-dithiole derivatives, 4,4'-{9-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-9H-fluorene-2,7- diyl} dipyridine(2a) and 3,3'-{9-[4,5-bis(methylthio)-1,3-dithiol-2-ylidene]-9H-fluorene-2,7-diyl} dipyridine(2b) were synthesized and characterized by Fourier transform infrared(FTIR), 1H NMR, 13C NMR and mass spectroscopies. The crystal structure of compound 2b was also studied. The optimized conformations and molecular orbital diagrams of compounds 2a and 2b were illustrated via density functional theory(DFT). By the time-dependent DFT(TD-DFT) method, electronic absorption spectra of compounds 2a and 2b were predicted and the results achieved were in good agreement with the experimental data. The formation of the cationic radical during the electrochemical oxidation process was also proposed. 相似文献
996.
TANG Yan ZHAO Xiaoli CHU Linya SUN Ning LIU Renxiao DENG Congliang GE Guanglu 《高等学校化学研究》2014,30(1):23-26
Magnetic nanoparticles show great potential in RNA enrichment and separation for rapid detection of viral infection.Fundamental studies on the interaction between RNA and nanoparticles with uniform size and surface property are necessary for designing better adsorbent and optimizing the conditions.In this study,monodispersed superparamagnetic magnetite(Fe3O4) nanoparticles were synthesized by thermal decomposition and modified with tetramethylammonium hydroxide[N(CH3)4OH,TMAOH] that become highly dispersible and stable in water.High-efficiency plant viral RNA adsorption onto TMAOH/Fe3O4 nanoparticles in the extracted solution of plant leaves was demonstrated.The changes of surface charge of TMAOH on the Fe3O4 nanoparticles with pH contribute to the RNA adsorption and elution.Separating viral RNA with magnetic nanoparticles could be a simple,quick andhighly efficient method. 相似文献
997.
We reported a dripping solvothermal method for synthesizing metal-organic framework-5(MOF-5). It started from separately dissolving Zn(NO3)2 and terephthalic acid(H2BDC) in dimethyl formamide(DMF), and then dripping one solution into the other. Results of SEM, XRD and laser particle size distribution show that regular cubic-shaped and micro-crystallite powder of MOF-5 can be obtained. The d0.5(volume-median-diameter) values are 4.32 μm for particles prepared by dripping Zn(NO3)2 into H2BDC(ZH) and 9.32 μm for those prepared by dripping H2BDC into Zn(NO3)2(HZ), much smaller than 22,7 μm that of particles prepared by the traditional adding water solvothermal method(L). The standard deviations of the particle size distributions fitted by the GaussAmp model are 2.49, 4.38 and 15.4 respectively for ZH, HZ and L, further revealing narrower size distributions of particles prepared by the dripping method. In addition, the Langmuir specific surface areas are 923 m^2/g for ZH and 868 m^2/g for HZ. The TGA results present mass losses of 4.18% and 3.62% at 105 ℃, 17.19% and 14.78% at 245 ℃, 39.04% and 34.85% at 600℃ separately for ZH and HZ, which correspond to the removal of H20, DMF and the decomposition of MOF-5. This indicates that MOF-5 has a strong adsorption ability for small molecules. Besides, the mass loss of 48.39%(ZH) and 41.02%(HZ)between 400 ℃ and 600 ℃ are less than the theoretical value of 57.81% for MOF-5 decomposition to ZnO, suggesting that an impure phase with an extra amount of ZnO may exist in the cavities of MOF-5. 相似文献
998.
ZHANG Yu ;DONG Kaiyue ;QIU Qianqian ;XU Kangzhen ;HE Fei ;SONG Jirong ;ZHAO Fengqi 《高等学校化学研究》2014,30(4):672-675
The thermal behavior and non-isothermal decomposition kinetics of [Cu(en)2H2O](FOX-7)2·H2O (en=ethylenediamine) were studied with DSC and TG-DTG methods.The kinetic equation of the exothermal process is dα/dt=(10^17.92/β)4α^3/4exp(-1.688×10^5/RT).The self-accelerating decomposition temperature and critical temperature of the thermal explosion are 163.3 and 174.8 ℃,respectively.The specific heat capacity of [Cu(en)2H2O](FOX-7)2·H2O was determined with a micro-DSC method,with a molar heat capacity of 661.6 J·mol^-1·K^-1 at 25 ℃.Adiabatic time-to-explosion was also estimated as 23.2 s.[Cu(en)2H2O](FOX-7)2·H2O is less sensitive. 相似文献
999.
LI Ling HU Yanna WANG Kailiang WANG Qingmin 《高等学校化学研究》2014,30(4):619-623
A mild synthetic method of a series of phenanthrenes with different substituents on the phenanthrene ring is described.The method involves intramolecular oxidative coupling with 2,3-dichloro-5,6-dicyanobenzoquinone (DDQ)/trifluoroacetic acid(TFA) as oxidant to produce phenanthrenes in high yields and is fit for large-scale preparation.Furthermore,DDQ can be regenerated by a simple oxidation.The present approach solves a key step for the synthesis of polycyclic structures related to an alkaloid tylophorine. 相似文献
1000.
Strong law of large numbers for pair-wise extended lower/upper negatively dependent random variables
Fengyang CHENG 《Frontiers of Mathematics in China》2014,9(5):1019-1031
We establish some strong limit theorems for a sequence of pair-wise extended lower/upper negatively dependent random variables and give some new examples of dependent random variables. 相似文献