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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.
Low valent titanium was used to deoxygenate triphenylarsine oxide to triphenylarsine. 相似文献
83.
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
84.
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
85.
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
86.
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
87.
通过对猪卵母细胞的电激活进行系统研究,结果表明:对于体外成熟卵母细胞,电场强度为 1 250 V/cm ,脉冲时程为40、60 μs时,效果较好,一次脉冲激活率可达85.3% 和87.1% ;而对于体内成熟卵母细胞,电场强度为1 500 V/cm ,脉冲时程为40、60 μs 时,效果较好,一次脉冲激活率达85.7% 和88.2% ;增加脉冲次数并不能显著提高激活率,反而使卵母细胞裂解率显著增加;激活液选用0.3 m ol/ L甘露醇(含0.1 m m ol/ L Mg S O4 )时,添加 0.1 m m ol/ L Ca Cl2 ,获得较好的激活率(87.8% )电脉冲激活卵母细胞后进一步培养,体内和体外成熟卵母细胞的发育率并无显著差异 相似文献
88.
This work focuses on the characteristics of the Rayleigh-Taylor Instability (RTI) of the interfaces formed by two semi-infinitely distributed fluids and one interlayer. In consideration of the coupling effects between the interfaces, the expression of the growth rate is obtained. The result reveals that the instability growth rate depends on the density and thickness of the interlayer. It is found that /f the interlayer thickness is less than 0.6 times of the disturbing wavelength, the coupling effects should be considered. 相似文献
89.
在100—4000 cm-1范围内,研究了十四个稀土三螯合噻吩甲酰三氟丙酮二水络合物RE(TTA)3·2H2O的傅里叶红外光谱。对照前人工作对络合物的谱带作了指认。观察到六个RE—O振动,两个在中红外区(456—475)和489—508cm-1),四个在远红外区(173—190、213—228、362—374和396—408cm-1)。中红外区456和489cm-1附近的谱带随稀土原子序数的变化呈“四分组”效应。羰基及不饱和碳碳键吸收峰都比噻吩甲酰三氟丙酮低60多个波数。 相似文献
90.
类胡萝卜素是一类奇特的色素,由高等植物和微生物光化学合成,作为防止单线氧通过光敏反应产生危害的必要基团,类胡萝卜素最近受到了关注。类胡萝卜素联于富勒烯上,既可大大增加在可见光区域光诱导电子转移的有效吸收断面,又可抑制富勒烯敏化单线氧的危害能力。合成了类胡萝卜素的相关化合物,报道的某些反应条件先进且简洁。 相似文献