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81.
带关闭期和启动期的GI/M/1排队及其应用 总被引:1,自引:0,他引:1
本研究了带关闭期和启动期的GI/M/1排队,给出了稳态队长分布和等待时间分布的随机分解,展示了它在计算机通讯网络中的应用。 相似文献
82.
广义区间估计及其最优性(Ⅳ) 总被引:1,自引:0,他引:1
陈乃辉 《数学的实践与认识》2003,33(6):55-62
本文在提出了广义区间估计以及其上的最优性概念之后 ,证明了广义区间估计与假设检验的最优性之间的关系 ,推演了一个重要区间估计的最优性 相似文献
83.
利用宇宙线直接测量结果对初级宇宙线能谱参数的调整 总被引:1,自引:0,他引:1
由JACEE?,RUNJOB和SOKOL等宇宙线直接测量结果和刚度截断模型,对于1014—1016eV能区的初级宇宙线微分能谱参数进行调整.利用调整后的能谱与选取QGSJET模型的CORSIKA程序进行EAS模拟,同HD,PD谱进行对比研究.采用相同的标准对模拟数据与实验数据进行分析.结果表明,调整后的谱和HD谱的模拟结果与甘巴拉山乳胶室实验结果符合较好,而PD谱的模拟结果与实验结果偏离较大. 相似文献
84.
Low valent titanium was used to deoxygenate triphenylarsine oxide to triphenylarsine. 相似文献
85.
Jin Cui Ming Jie Zhang Xiang Qian Wang Nai Jing Cui 《中国化学快报》2008,19(3):311-313
By the addition of rice wine koji, enhancement of the reactivity was observed for the baker's yeast reduction of β-keto esters into (S)-β-hydroxy esters with high enantiomeric purity (73-98%). 相似文献
86.
Hong‐Wei Liu Man‐Yuan Wang Xue‐Ying Song Ying Xia Yi‐Song Zhao Xiao‐Hong Song Miao‐Miao Jiang Xue Zhang Hao Gao Nai‐Li Wang Xin‐Sheng Yao 《Helvetica chimica acta》2008,91(9):1704-1711
Three new escin‐like triterpene saponins, assamicins VI ( 1 ), VII ( 2 ), and VIII ( 3 ), were isolated from the seeds of A. assamica, together with a known saponin, isoescin Ib ( 4 ). Their structures were established as 28‐O‐acetyl‐21‐O‐(3,4‐di‐O‐angeloyl‐6‐deoxy‐β‐glucopyranosyl)‐3‐O‐{O‐β‐glucopyranosyl‐(1→2)‐O‐[β‐glucopyranosyl‐(1→4)]‐β‐glucopyranuronosyl}protoaescigenin ( 1 ), 21‐O‐angeloyl‐3‐O‐{O‐α‐rhamnopyranosyl‐(1→2)‐O‐[β‐glucopyranosyl‐(1→3)]‐β‐glucopyranuronosyl}protoaescigenin ( 2 ), and 21‐O‐angeloyl‐3‐O‐{O‐[β‐glucopyranosyl‐(1→3)]‐β‐glucopyranuronosyl}protoaescigenin ( 3 ) on the basis of spectroscopic analysis (protoaescigenin=(3β,4β,16α,21β,22α)‐olean‐12‐ene‐3,16,21,22,23,28‐hexol; angelic acid=(2Z)‐2‐methylbut‐2‐enoic acid). 相似文献
87.
Yanwei Jing Xueying Nai Donghai Zhu Li Dang Yabin Wang Wu Li 《Surface and interface analysis : SIA》2016,48(3):126-131
Aragonite whiskers (AWs) were treated with several fatty acid surfactants and silane coupling agent in order to determine the optimal modifier by using contact angle measurements. The results revealed that the AWs modified by fatty acids showed more remarkable increase in the contact angle than by silane, suggesting the former were preferentially applied in modifying AWs. While the samples coated with fatty acids exhibited hydrophobicity with contact angles ranging from 104.08° to 137.87° with increasing of carbon chain length. Therefore, the highest contact angle of AWs treated by oleic acid was discussed in detail as an example, which was characterized by field emission scanning electron microscope (FESEM), transmission electron microscopy (TEM), thermo‐gravimetry analyses (TGA), X‐ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR). FESEM and TEM results showed a thin layer coated on the modified sample surface. Both the results of TGA and XPS confirmed organic groups existed in the sample of AWs treated by oleic acid. FTIR demonstrated that calcium dioleate was formed in the modification process. Further, modification mechanism was proposed based on the obtained results. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
88.
89.
DNA hypermethylation of CpG islands plays an important role in gene regulation during cancer development. Many techniques have been developed to detect global DNA methylation in cancer cells compared to normal tissues. This knowledge helps us to better understand cancer progression and also aids in the development of new biomarker for early cancer detection. New prognostic tools for monitoring drug efficacy during cancer treatment can also be developed. In this review, we will examine the different techniques that have been used to study DNA methylation, as well as the emerging high resolution, high throughput techniques for identification of methylated regions to defining cancer related genes in the cancer methylome. 相似文献
90.
Shang NG Papakonstantinou P Sharma S Lubarsky G Li M McNeill DW Quinn AJ Zhou W Blackley R 《Chemical communications (Cambridge, England)》2012,48(13):1877-1879
Bulk quantities of graphene nanosheets and nanodots have been selectively fabricated by mechanical grinding exfoliation of natural graphite in a small quantity of ionic liquids. The resulting graphene sheets and dots are solvent free with low levels of naturally absorbed oxygen, inherited from the starting graphite. The sheets are only two to five layers thick. The graphene nanodots have diameters in the range of 9-29 nm and heights in the range of 1-16 nm, which can be controlled by changing the processing time. 相似文献