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991.
波性是原子或分子中电子的重要性质,但结构化学教材对电子波性概念的解释不够详尽。为降低学生在学习该概念时的难度,结合教学实践,尝试将电子波性的物理特征描述为微观环境中电子的运动没有确定的轨迹。通过详细的分析与讨论,多数学生较好地理解了电子波性的物理特征,并认识到正是电子的波性与粒性在不同条件下的转换,才产生了能同时体现出电子波粒二象性的衍射图谱。 相似文献
992.
以有机合成路线图题的命制为例,展示如何挖掘并整合教材内容为命题素材,如何基于SOLO分类理论进行设问而命制成试题。 相似文献
993.
以N-异丙基-9H-咔唑为起始原料,经取代、氧化、环合、酰化4步反应合成了7个新型2-取代氨基-5-(N-异丙基-9H-咔唑-2-基)-1,3,4-噻二唑类化合物(1a~1g),其结构经1H NMR, 13C NMR, MS(ESI)和元素分析表征。采用MTT法测定了1a~1g对5种肿瘤细胞的体外抗增殖活性。结果表明:1a~1g对人正常VEC细胞的抑制活性弱于5-FU。 1d和1e对人白血病细胞(K562)和人结肠癌细胞(HCT-8), 1e对人肺癌细胞(A549细胞),以及1g对人结肠癌细胞(HCT-8)的抑制活性(IC50≤9.28 μmol·L-1)均与5-FU相当。 相似文献
994.
DAI Jianan LIU Bengen WEI Zhonglin CAO Jungang LIANG Dapeng DUAN Haifeng LIN Yingjie 《高等学校化学研究》2019,35(2):216-220
A straiglitforward and efficient synthetic method of 2′-(dialkylammo)-l-alkyl-4′H-spiro[indoline-3,5′-oxazole]-2,4′-diones and 2-(dialkylamino)-5,6-dihydro-4H-naphtho[2,1-e][1,3]oxazin-4-one-derivatives have been developed from a-hydroxy andβ-carbonyl amides and various Vilsmeier salts.A wide range of heterocyclic compounds were obtained in excellent yields(up to 97%),which will provide promising candidates lor chemical biology and drug discovery. 相似文献
995.
996.
This paper presents the planar Fiber Bragg Grating (FBG) hydrophone probe sensing principle, and theoretically and experimentally researches the probe structure sensitivity, the receiving sensitivity frequency response characteristic and the acceleration response property. Planar sheet is made of stainless steel, its thickness is 0.15 mm, its diameter is 15mm, and the length of hollow circular shell is 20 mm. For this size of the structure, the probe structure sensitivity is up to 23 fm/Pa, which is about 7300 times of the value of the bare fiber. The resonance frequency is 6.5 kHz, and the amplitude-frequency curve of the receiving sensitivity response is relatively flat within the frequency range of 100 Hz to 5.5 kHz. The output yielded by one unit acceleration (1m/s2) is equivalent to (2.52 to 3.26 Pa) acoustic pressure acting output. This probe structure is easy to form FBG hydrophone array by multiplexing technique. The research shows that this planar structure not only can form FBG hydrophone probe, but also can constitute optical FBG laser hydrophone probe. The structure can realize different bandwidth, different range acoustic pressure measurement by adjusting the geometrical size of the sheet. 相似文献
997.
We present the generation of six-particle Greenberger Horne-Zeilinger (GHZ) states via deterministic entanglement concentration and generalize the scheme to the case of 2N particles. We show that arbitrary 2N-particle GHZ states can be obtained with certain probability via entanglement concentration. This may provide a new perspective for the preparation of multi-particle GHZ states. This study is also an exploration on the theory of deterministic entanglement concentration. 相似文献
998.
Comparison of Laser Performances of 5at.% Yb:Gd2xY2(1-x)SiO5 Crystals between Different Cutting Directions 下载免费PDF全文
YU Hai-Bo LIANG Xiao-Yan HE Jin-Ping LENG Yu-Xin LI Ru-Xin XU Zhi-Zhan ZHENG Li-He ZHAO Guang-Jun SU Liang-Bi XU Jun 《中国物理快报》2008,25(7):2496-2499
We investigate the laser actions of 5at.% Yb:Gd2xY2(1-x)SiO5 (Yb:GYSO; x=0.1) crystals with different cutting directions, parallel and vertical to the growth axis. Our results show that the cutting direction of the sample plays an astonished role in the laser operation. The sample cut vertically to the growth axis possesses the favourable lasing characteristics. Its output power reaches 3.13W at 1060nm with a slope efficiency of 44.68% when the absorbed pump power is 8.9,W. In contrast, the sample cut parallel reaches only 1.65W at 1044nm with a slope efficiency of 33.76% with absorbed pump power of 7.99W. The absorption and emission spectra of the two samples are examined and the merit factor M is calculated. Our analysis is in agreement well with the experimental results. The wavelength tuning range of the superior sample covers from 1013.68nm to 1084.82nm. 相似文献
999.
Electronic Energy Levels in an Asymmetric Quantum-Dots-in-a-Well Structure for Infrared Photodetectors 下载免费PDF全文
Theoretical calculation of electronic energy levels of an asymmetric InAs/InGaAs/GaAs quantum-dots-in-a-well (DWELL) structure for infrared photodetectors is performed in the framework of effective-mass envelope-function theory. Our calculated results show that the electronic energy levels in quantum dots (QDs) increase when the asymmetry increases and the ground state energy increases faster than the excited state energies. Furthermore, the results also show that the electronic energy levels in Q Ds decrease as the size of QDs and the width of quantum well (QW) in the asymmetric DWELL structure increase. Additionally, the effects of asymmetry, the size of QDs and the width of QW on the response peak of asymmetry DWELL photodetectors are also discussed. 相似文献
1000.
Realization of Ultraviolet Electroluminescence from ZnO Homojunction Fabricated on Silicon Substrate with p-Type ZnO:N Layer Formed by Radical N2O Doping 下载免费PDF全文
ZnO homojunction light-emitting diodes are fabricated on Si(100) substrates by plasma assisted metal organic chemical vapour deposition. A p-type layer of nitrogen-doped ZnO film is formed using radical N2O as the acceptor precursor. The n-type ZnO layer is composed of un-doped ZnO film. The device exhibits desirable rectifying behaviour with a turn-on voltage of 3.3 V and a reverse breakdown voltage higher than 6 V. Distinct electrolumineseence emissions centred at 395nm and 490nm are detected from this device at forward current higher than 20mA at room temperature. 相似文献