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961.
On investigating the longitudinally driven GMI effect of the DC annealed Fe36Co36Nb4Si4.8B19.2 alloy ribbon, the current density was 3.2×10^7 A/m^2, the GMI effect responds sensitively (the sensitivity is as high as 2440.2%/(A-m^-1)) to weak magnetic field after a 600-second annealing. The experimental result shows that the sensitivity is closely related to annealing current density, driven current frequency and eroded thickness. GMI effect, current annealing, sensitivity, magnetic domain structure 相似文献
962.
YE GuiXiang CAO ZhiQiang LIN Lin CHEN DaYong LIU WenGuang 《科学通报(英文版)》2008,53(15):2307-2314
Previously we successfully prepared poly(vinyldiaminotriazine)(PVDT)-based non-viral vectors which complexed piasmid DNA via hydrogen bonding with adenine-thymine base pairs, in this report, surface charges and complex sizes of this system were further examined. The results showed that PVDT-based polymer could cover surface charges of DNA resulting in slightly negative or neutral complexes. It was also found that the complex sizes were governed by two events: the aggregation induced by the instability of neutral particles, and more compact complexes produced by PVDT-based polymers. In the study of cellular uptake, chlorpromazine and filipin III were used to inhibit clathrin-and caveolae-mediated endocytosis, respectively. We found that PVDT-based systems were transported into cells via a non-clathrin, non-caveolae mediated endocytosis. This special process was studied by temperature inhibition and kinetics assays. It was revealed that such a pathway was characterized by (i) a more en- ergy dependent process and (ii) a much slow transfection-effective internalization. 相似文献
963.
Ye Li 《科学通报(英文版)》2008,53(23):3615-3619
The photophysics of Zn(tetraphenylporphyrin,TPP), Zn(tetra-2,4,6-trimethylphenyl porphyrin, TMP), Zn (tetra-(o-dichlorophenyl) porphyrin, TPPCI8), Cu(tetraphenylporphyrin,TPP), Cu(tetra-2,4,6-trimethyl- phenyl porphyrin,TMP), and Cu(tetra-(o-dichlorophenyl) porphyrin, TPPCIE, TPPCI8) in several solvents have been investigated on steady state and time-resolved spectroscopy. The Cu(TPPCI8 ) is normal and shows no evidence of CT transition in the visible or near UV regions in nonpolar solvent. However, Cu(TPPCI8)shows a blue shift in the absorption spectrum and intramolecular CT bands at absorption spectra in polar solvent, which shows a fluorescence maximum emission at 650 nm and 8.4 ns lifetime. The reason can be attributed to two points. Firstly, the increase of solvent polarity can enlarge outer reorganisational energy, which is favorable to reduce the activation free energy of charger-transfer transition based on Marcus theory of electron transfer. Moreover, the internal heavy-atom effect on Cu(TPPCIE) is encouraging to stabilize the 2T1 state also, which increases the possibility of population to CT band from 2T1 state. This result is in accord with an earlier estimate of a 10 ns lifetime and CT absorption at 640 nm bands for the CT state of Cu (11) octethylporphyrins. Other possible reasons arousing unusual fluorescence like H-bonding, axial ligands, molecular aggregation are excluded. 相似文献
964.
光源调制全光纤电流互感器的研究 总被引:1,自引:1,他引:0
介绍了全光纤电流互感器的结构,分析了系统输出信号的特点,指出工频干扰及线性双折射效应是影响系统稳定性的主要问题.提出并实现了基于光源调制的抑制工频干扰方法.该方法利用2000 Hz的方波光源作为互感器的光驱动,系统的输出信息由原来的一路变成了两路,通过两路信息的融合有效地抑制了电路工频干扰.理论分析及实验结果表明,在不增加系统复杂性和硬件投入的条件下,该方法不仅抑制了电路中的低频干扰,还有效地抑制了工频干扰,提高了系统的信噪比,为提高全光纤电流互感器系统的稳定性和可靠性提供了新的方法. 相似文献
965.
对从7个不同地方采集的7份辣木(Moringa)材料进行了ISSR 标记分析.结果表明,被测材料间ISSR标记多态性较高.从18个ISSR 引物中筛选出6个可扩增出清晰的且具多态性的条带的引物,共扩增出75条带,其中59条具有多态性, 占总扩增带数的78.67 %,其中每个引物可扩增出4~14条多态性带,平均10.17条.ISSR 标记遗传相似性系数(GS) 变异范围为0.557 0~0.836 7,平均值为0.687 6±0.080 9.聚类分析表明,7份辣木材料可以聚为四类,其中MS2为单独一类.ISSR 标记可以有效地评价辣木植物遗传分化并为辣木种类的鉴别提供一定的理论依据. 相似文献
966.
967.
正弦激励线性预测声码器子带清浊音模糊判决 总被引:1,自引:0,他引:1
为了解决目前正弦激励线性预测声码器中各子带的清浊音硬判决使得语音帧间产生明显过渡感的问题,提出一种子带清浊音模糊判决算法,直接采用自相关函数对各子带的清浊音度进行描述,矢量量化后传输至解码端,用于激励信号的产生.测试结果表明: 采用子带清浊音模糊判决算法,能够消除语音帧间的过渡感,能够使各种速率正弦激励线性预测声码器的平均主观意见得分提高约0.05以上. 相似文献
968.
Non-invasive measurement and validation of tissue oxygen saturation covered with overlying tissues 总被引:1,自引:0,他引:1
Yichao Teng Haishu Ding Lan Huang Yue Li Quanzhong Shan Datian Ye Haiyan Ding Jenchung Chien Betau Hwang 《自然科学进展(英文版)》2008,18(9):1083-1088
In this paper, the biological tissue oxygen saturation (rSO2) is obtained non-invasively and in real time based on near infrared spectroscopy (NIRS) using two emitting wavelengths and two detectors, where the tissue is covered with overlying tissues. Our group developed an NIRS oximeter based on the above principle independently, and validated it using liquid tissue model calibrations and animal experiments. The results indicate that (1) in the normal range of tissue oxygen saturation (40-70%), the rSO2 measured by NIRS is accurate enough and little influenced by the background absorptions (such as the absorption of water) and overlying tissues (such as fat); (2) during cerebral hypoxia and recovery of three piglets, there is excellent correlation (p 〈 0.001) between cerebral rSO2 and jugular venous oxygen saturation (SjO2), meaning that the rSO2 can be indicated by the SjO2 to a large extent; during the death of the three piglets induced by heart beat stopping, cerebral rSO2 decreases continuously to significantly low levels (〈25%) because cerebral blood supply does not exist any more. All the above results are of explicit physiological importance. 相似文献
969.
The brain and the thoracic ganglion of a crustacean can synthesize and secrete gonad-stimulating hormone (GSH) which stimulates the maturation of gonad. In the previous experiments, sex steroid hormones (estradiol, testosterone, progesterone, etc.) have been detected from the crustacean. However, the feedback regulation of sex steroid hormones on the brain and the thoracic ganglion of the crustacean has not been reported so far. In the present experiment, monoclonal antibodies were applied to investigate the immunorecognition of estrogen receptor (ER) and androgen receptor (AR) in the brain and the thoracic ganglion mass of Scylla paramamosain. The results showed that the distribution of the immunopositive substances of ER and AR was extremely similar. They distributed in the protocerebrum, deutocerebrum and tritocerebrum of the brain, and mainly in protocerebrum. In the thoracic ganglion mass, immunopositive substances distributed in the subesophageal ganglion, thoracic ganglion and abdominal ganglion, and mostly in subesophageal ganglion. Immunopositive substances of ER and AR mostly existed in the cytoplasm of neurons. The present study will provide morphological evidence for the origin and the evolution of ER and AR. In addition, the immunoreactivities of ER and AR suggested that the estrogen and androgen may be involved in the feedback regulation of crustacean neuroendocrine. 相似文献
970.
This paper presents a method for detecting weak fault signals in chaotic systems based on the chaotic dynamics reconstruction technique and the fuzzy neural system (FNS). The Grassberger-Procaccia algorithm and least squares regression were used to calculate the correlation dimension for the model order estimate. Based on the model order, an appropriately structured FNS model was designed to predict system faults. Through reasonable analysis of predicted errors, the disturbed signal can be extracted efficiently and correctly from the chaotic background. Satisfactory results were obtained by using several kinds of simulative faults which were extracted from the practical chaotic fault systems. Experimental results demonstrate that the proposed approach has good prediction accuracy and can deal with data having a -40 dB signal to noise ratio (SNR). The low SNR requirement makes the approach a powerful tool for early fault detection. 相似文献