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91.
对小学科学课程标准与五年制专科小学教育专业“科学·化学”教学大纲中对化学知识内容的要求,以及小学《科学》和高等专科学校《科学·化学》教材中涉及的化学知识内容进行了对比。同时就五年制专科层次小学教育专业化学课程存在的问题进行了讨论,并提出了选择合适的课程教学内容、加强化学实验和化学教材建设、建立理论课程和实验教学新体系模块等建议。 相似文献
92.
Qi Teng Wenxiu Mao Dong Chen Zhen Wang Chen‐Ho Tung Zhenghu Xu 《Angewandte Chemie (International ed. in English)》2020,59(6):2220-2224
A rhodium(I)‐BINAP‐catalyzed highly enantioselective [2+2+2] cycloaddition of enynes with alkynes has been developed. Diverse fused tricyclic hydronaphthofuran scaffolds with three consecutive stereogenic centers were constructed in one step from easily available materials with excellent chemo‐, regio‐, diastereo‐, and enantioselectivity. Notable features of these reactions include 100 % atom economy, very broad scope, and mild reaction conditions. 相似文献
93.
Chen Wu-Hua Xiong Jin-Hua Teng Xue Mi Jin-Xiao Hu Zhi-Biao Wang Haifeng Chen Zuofeng 《中国科学:化学(英文版)》2020,63(12):1825-1836
Science China Chemistry - A novel CoII-Fenton-like heterogeneous catalyst, (H3O)2[CoII(phen)(H2O)2]2[MoVI5O15(PO4)2]·4H2O (phen=1,10-phenanthroline, C12N2H8) (1), is synthesized and utilized... 相似文献
94.
Teng Xia Ju 《数学学报(英文版)》2009,25(5):831-844
In this paper, we show that if H is a finite-dimensional Hopf algebra such that H and H^* are semisimple, then gl.dim(A#σH)=gl.dim(A), where a is a convolution invertible cocycle. We also discuss the relationship of global dimensions between the crossed product A^#σH and the algebra A, where A is coacted by H. Dually, we give a sufficient condition for a finite dimensional coalgebra C and a finite dimensional semisimple Hopf algebra H such that gl.dim(C α H)=gl.dim(C). 相似文献
95.
Teng Fu Tao Wang Hongfang Sun Yida Xu Zhen Dong Xiangke Guo Luming Peng Yan Zhu Zhaoxu Chen Weiping Ding 《中国科学:化学(英文版)》2018,61(8):1014-1019
A new mechanism of catalyst has been demonstrated in this article. With the interaction between carbon nitride (CN) and encapsulated nickel, the CN in the catalyst has been endowed with new active sites for the adsorption and activation of hydrogen while nickel itself is physically isolated from the contact with reactive molecules. For the selective hydrogenation of acetylene in large amount of ethylene, the catalyst shows excellent ethylene selectivity than the nickel catalyst itself, which is almost totally unselective. Meanwhile, the CN itself is inactive for the reaction. The results of characterization demonstrate that pyridinic nitrogen doped in the carbon matrix should be the active sites for hydrogen dissociative adsorption. The theoretical calculations further confirm the results and provide with the detail in the electron transfer between nickel and CN in the catalyst. The current results supply a new concept for design of high performance catalyst. 相似文献
96.
Hongxiao Hu Zhidong Teng Haijun Jiang 《Nonlinear Analysis: Real World Applications》2009,10(4):2420-2433
We study the permanence of a class of nonautonomous two-species Lotka–Volterra competitive systems with infinite delay and feedback controls. New results on the permanence of solutions are obtained. The corresponding results given in [F. Chen, Z. Li, Y. Huang, Note on the permanence of a competitive system with infinite delay and feedback controls, Nonlinear Anal. RWA 8 (2007) 680–687] are improved and extended. 相似文献
97.
Hendargo HC Bower BA Reinstein AS Shepherd N Tao YK Izatt JA 《Optics Communications》2011,284(19):4847-4851
Spectral domain phase microscopy (SDPM) is an extension of spectral domain optical coherence tomography (SDOCT) that exploits the extraordinary phase stability of spectrometer-based systems with common-path geometry to resolve sub-wavelength displacements within a sample volume. This technique has been implemented for high resolution axial displacement and velocity measurements in biological samples, but since axial displacement information is acquired serially along the lateral dimension, it has been unable to measure fast temporal dynamics in extended samples. Depth-Encoded SDPM (DESDPM) uses multiple sample arms with unevenly spaced common path reference reflectors to multiplex independent SDPM signals from separate lateral positions on a sample simultaneously using a single interferometer, thereby reducing the time required to detect unique optical events to the integration period of the detector. Here, we introduce DESDPM and demonstrate the ability to acquire useful phase data concurrently at two laterally separated locations in a phantom sample as well as a biological preparation of spontaneously beating chick cardiomyocytes. DESDPM may be a useful tool for imaging fast cellular phenomena such as nervous conduction velocity or contractile motion. 相似文献
98.
Liang Zhang Jinghua Teng Soo Jin Chua Eugene A. Fitzgerald 《Applied Physics A: Materials Science & Processing》2011,103(3):827-830
Linearly polarized light from InGaN green light emitting diode grown on (0001) oriented sapphire is demonstrated by using
subwavelength metallic nanogratings. Polarization ratio can reach 7:1 (∼88%), the highest ever reported from a single light
emitting device. We discuss the design and fabrication of this device in detail. 相似文献
99.
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