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101.
102.
900 MHz 1H NMR (nuclear magnetic resonance) spectroscopy was used to analyze metabolites in allantoic fluid of the chicken embryo in
the 9th incubation day without any chemical or physical sample separation. The result showed that superhigh spectral dispersion
and sensitivity at 900 MHz are useful in directly analyzing a complex mixture, particularly in resolving the overlapped NMR
resonances. In this study, we had assigned 61 metabolites and 26 chemical fragments in the allantoic fluid. The relative concentrations
of the major metabolites were also measured. Among the assigned metabolites, some were detected by NMR in chicken embryo allantoic
fluids for the first time. The biological functions of these compounds were briefly discussed.
Authors' address: Maili Liu, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute
of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, People's Republic of China 相似文献
103.
Hua Zhang Nabil A. Amro Robert Elghanian Joseph Fragala 《Applied Surface Science》2006,253(4):1960-1963
A method, combining micro-contact printing (μCP), wet chemical etching and reactive ion etching (RIE), is reported to fabricate microstructures on Si and SiOx. Positive and negative structures were generated based on different stamps used for μCP. The reproducibility of the obtained microstructures shows the methodology reported herein could be useful in Micro-Electro-Mechanical Systems (MEMS), optical and biological sensing applications. 相似文献
104.
105.
根据塑料挤出的特点,在编程实现对型材截面轮廓凸凹性自动判断的基础上,采用射线法与比例间隔法相结合的方法,确定流道入口圆周上型值点的位置.以三次多项式作为流道模腔型曲线的数学模型,依据流线型要求给出的初始、边界条件,得出型曲线的数学方程.构建了挤出模流道的三维参数化曲面模型.有限元分析结果显示,该方法创建的流线型流道模型,其流动稳定性和平顺性都优于直线型流道. 相似文献
106.
运用一种新的动力学突变检测方法——排列熵(permutation entropy,PE)算法,计算并分析了中国华北地区52个站点1960年—2000年逐日平均气温资料的排列熵演化情况,发现中国华北地区气温在20世纪70年代中期、80年代初均发生了较大突变;进一步用经验模态分解(empirical mode decomposition,EMD)方法对排列熵序列进行逐级平稳化处理,结果发现这一地区的气温突变与准10年这一年代际时间尺度的周期变率密切相关,其原因与太阳黑子活动有着密切联系.
关键词:
华北
突变
排列熵算法
经验模态分解 相似文献
107.
We report viscometric data collected in a Couette rheometry on dilute, single‐solvent polystyrene (PS)/dioctyl phthalate (DOP) solutions over a variety of polymer molecular weights (5.5 × 105 ≤ Mw ≤ 3.0 × 106 Da) and system temperatures (288 K ≤ T ≤ 318 K). In view of the essential viscometric features, the current data may be classified into three categories: The first concerns all the investigated solutions at low shear rates, where the solution properties are found to agree excellently with the Zimm model predictions. The second includes all sample solutions, except for high‐molecular‐weight PS samples (Mw ≥ 2.0 × 106 Da), where excellent time–temperature superposition is observed for the steady‐state polymer viscosity at constant polymer molecular weights. No similar superposition applies at a constant temperature but varied polymer molecular weights, however. The third appears to be characteristic of dilute high‐molecular‐weight polymer solutions, for which the effects of temperature on the viscosity curve are further complicated at high shear rates. The implications concerning the relative importance of hydrodynamic interactions, segmental interactions, and chain extensibility with increasing polymer molecular weight, system temperature, and shear rate are discussed. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 787–794, 2006 相似文献
108.
J. Jiang B.Y. Jiang C.X. Ren F.M. Zhang T. Feng X. Wang X.H. Liu S.C. Zou 《Applied Surface Science》2006,252(10):3642-3646
Hafnium and platinum were deposited onto molybdenum grids by ion-beam assisted deposition method. Electron-emission characteristics from molybdenum grids with Hf and Pt films, which were contaminated by active electron-emission substances (Ba, BaO) of the cathode, were measured using analogous diode method. The surfaces of grids were analyzed by X-ray diffraction. The results revealed that the reaction between BaO and Hf formed BaHfO3 compound, which greatly reduced the accumulation of BaO on the surface and accordingly decreased grid emission. In contrast, Ba were formed by the decomposition of BaO on the surface of Pt film under high temperature and re-evaporated from its surface, which reduced the active electron-emission substances on the surface of the grid and effectively restrained grid emission. Their mechanisms for grid-emission suppression are discussed and a good method to develop new grid-coating materials is suggested. 相似文献
109.
110.