期刊文献+
共找到9篇文章
< 1 >
每页显示 20 50 100
Quasi-40-Day Oscillation and Its Teleconnection Structure together with the Possible Dependence on Conversion of Barotropic Unstable Energy of Temporal Mean Flow 被引量:1
1
作者 徐建军 《Advances in Atmospheric Sciences》 SCIE CAS CSCD 1993年第2期193-200,共8页
A study is made of the distribution of the diagnostic quantity vector E and the teleconnection structure of 30-50 (quasi-40) day oscillation, together with the dependence on the conversion of barotropic unstable energ... A study is made of the distribution of the diagnostic quantity vector E and the teleconnection structure of 30-50 (quasi-40) day oscillation, together with the dependence on the conversion of barotropic unstable energy of mean flow in terms of ECWMF daily 500 hPa grid data in winter, indicating that the energy transportation is closely associated with the westerly jet position, with zonal (meridional) propagation in the strong (weak) wind region, that considerable conversion of barotropic energy occurs at the jet exit region where low-frequency oscillation gains energy from the mean flow, leading to maximum kinetic energy for the oscillation observed there, which is marked by evident barotropy in striking contrast to the baroclinicity at low latitudes and that the teleconnection core is related to the center of action in the atmosphere and bound up with the pattern of the west wind. 展开更多
关键词 Quasi-40-Day Oscillation and Its Teleconnection structure together with the Possible Dependence on conversion of Barotropic Unstable Energy of Temporal Mean Flow
下载PDF
Chinese Conversation Structure
2
作者 刘燕 《海外英语》 2016年第16期230-232,共3页
This paper aims to describe the features of Chinese conversation structure. Specifically speaking, the structure will be analyzed from the following four aspects: openings and pre-sequence, adjacency pairs, pre-closin... This paper aims to describe the features of Chinese conversation structure. Specifically speaking, the structure will be analyzed from the following four aspects: openings and pre-sequence, adjacency pairs, pre-closing and closing. Generally speaking, Chinese conversation structure is similar to English conversation structure. But still a lot of differences are found due to cultural factors. 展开更多
关键词 Chinese conversation structure FEATURES DIFFERENCES cultural factors
下载PDF
Synthesis and Crystal Structure of a New Quinazolinone Compound 2,3-Dihydro-2-(2-hydroxyphenyl)-3-phenyl-quinazolin-4(1H)-one
3
作者 ZHANGGai LIANGYong-Qing ZHANGRong-Lan ZHANGWei-Hai ZHAOJian-She GUOZhi-An 《Chinese Journal of Structural Chemistry》 SCIE CAS CSCD 北大核心 2005年第7期783-788,737,共7页
A new quinazolinone compound 2,3-dihydro-2-(2-hydroxyphenyl)-3-phenyl- quinazolin-4(1H)-one 3 ([C20H16O2N2]?C2H5OH, Mr = 362.42) and compound 2-(2-hydroxy- benzylidene-amino)-N-phenyl-benzamide 2 (C20H16O2N2, Mr = 316... A new quinazolinone compound 2,3-dihydro-2-(2-hydroxyphenyl)-3-phenyl- quinazolin-4(1H)-one 3 ([C20H16O2N2]?C2H5OH, Mr = 362.42) and compound 2-(2-hydroxy- benzylidene-amino)-N-phenyl-benzamide 2 (C20H16O2N2, Mr = 316.34) were prepared from a precursor of 2-amino-N-phenyl-benzamide 1 (C13H12ON2, Mr = 212.25). Compound 3 was characterized by single-crystal X-ray diffraction analysis. The crystal belongs to orthorhombic, space group Pbca with a = 1.2889(11), b = 1.6170(14), c = 1.7729(15) nm, V = 3.695(6) nm3, Z = 8, F(000) = 1536, Mr = 362.42, Dc = 1.303 g/cm3, μ(MoKα) = 0.087 mm-1, R = 0.0447 and wR = 0.0879. The crystal structure analysis indicates that the title compound has a two-dimensional network structure formed by hydrogen bonds and electrostatic interactions. 展开更多
关键词 2 3-dihydro-2-(2-hydroxyphenyl)-3-phenylquinazolin-4(1H)-one synthesis crystal structure conversion mechanism of the structure
下载PDF
Turn-taking in Classroom Discourse and Implications for EFL Teaching
4
作者 黎畅 《海外英语》 2019年第23期261-262,共2页
Turn-taking is one of the basic mechanism in conversation.Learners of English may find it difficult to take their turns appropriately,this paper gives the description of turn-taking in classroom discourse and some fac... Turn-taking is one of the basic mechanism in conversation.Learners of English may find it difficult to take their turns appropriately,this paper gives the description of turn-taking in classroom discourse and some factors pertaining to it,and explores its implication for EFL teaching so as to apply it into the practice of the classroom discourse. 展开更多
关键词 TURN-TAKING classroom discourse conversational structure EFL
下载PDF
Voice conversion using structured Gaussian mixture model in cepstrum eigenspace 被引量:2
5
作者 LI Yangchun YU Yibiao 《Chinese Journal of Acoustics》 CSCD 2015年第3期325-336,共12页
A new methodology of voice conversion in cepstrum eigenspace based on structured Gaussian mixture model is proposed for non-parallel corpora without joint training. For each speaker, the cepstrum features of speech ar... A new methodology of voice conversion in cepstrum eigenspace based on structured Gaussian mixture model is proposed for non-parallel corpora without joint training. For each speaker, the cepstrum features of speech are extracted, and mapped to the eigenspace which is formed by eigenvectors of its scatter matrix, thereby the Structured Gaussian Mixture Model in the EigenSpace (SGMM-ES) is trained. The source and target speaker's SGMM-ES are matched based on Acoustic Universal Structure (AUS) principle to achieve spectrum transform function. Experimental results show the speaker identification rate of conversion speech achieves 95.25%, and the value of average cepstrum distortion is 1.25 which is 0.8% and 7.3% higher than the performance of SGMM method respectively. ABX and MOS evaluations indicate the conversion performance is quite close to the traditional method under the parallel corpora condition. The results show the eigenspace based structured Gaussian mixture model for voice conversion under the non-parallel corpora is effective. 展开更多
关键词 LPCC Voice conversion using structured Gaussian mixture model in cepstrum eigenspace ES GMM
原文传递
Modification of CaO-based sorbents prepared from calcium acetate for CO_2 capture at high temperature 被引量:8
6
作者 Xiaotong Liu Junfei Shi +2 位作者 Liu He Xiaoxun Ma Shisen Xu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第5期572-580,共9页
CaO-based sorbent is considered to be a promising candidate for capturing CO_2 at high temperature. However,the adsorption capacity of CaO decreases sharply with the increase of the carbonation/calcination cycles. In ... CaO-based sorbent is considered to be a promising candidate for capturing CO_2 at high temperature. However,the adsorption capacity of CaO decreases sharply with the increase of the carbonation/calcination cycles. In this study, CaO was derived from calcium acetate(CaAc_2), which was doped with different elements(Mg, Al,Ce, Zr and La) to improve the cyclic stability. The carbonation conversion and cyclic stability of sorbents were tested by thermogravimetric analyzer(TGA). The sorbents were characterized by N_2 isothermal adsorption measurements, scanning electron microscopy(SEM) and X-ray diffraction(XRD). The results showed that the cyclic stabilities of all modified sorbents were improved by doping elements, while the carbonation conversions of sorbents in the 1st cycle were not increased by doping different elements. After 22 cycles, the cyclic stabilities of CaO–Al, CaO–Ce and CaO–La were above 96.2%. After 110 cycles, the cyclic stability of CaO–Al was still as high as 87.1%. Furthermore, the carbonation conversion was closely related to the critical time and specific surface area. 展开更多
关键词 CO2 capture CaO-based sorbent Carbonation conversion Cyclic stability Critical time Mesoporous structure
下载PDF
A RGB LED Driving Structure and Signal Processing Based on Tone-to-Color Conversion
7
作者 LUO Guizhou QI Kejun XIONG Xiaodong 《Wuhan University Journal of Natural Sciences》 CAS CSCD 2017年第3期252-256,共5页
In order to solve the uncertainty of voice-to-color conversion in which one of the three voice features(loudness, tone, rhythm) is applied to control LED color, a linear conversion solution is proposed. And a chroma... In order to solve the uncertainty of voice-to-color conversion in which one of the three voice features(loudness, tone, rhythm) is applied to control LED color, a linear conversion solution is proposed. And a chromaticity diagram is defined by using hue definition on hue-saturation-lightness(HSL) hue ring and the normalization of CIE xyY which is a color standard defined by International Commission on Illumination(CIE). The chromaticity diagram shows a linear relation between pitch and color, which is referred to conversions of other physical parameters as well. Based on the solution, red(R), green(G) and blue(B) LEDs, the driving structure of a conversion circuit is designed and set up. The results indicate that signal processing of tone-to-color conversion is effective, from 30 Hz to 3 kHz with a resolution of 10 Hz mapped to the chromaticity diagram. 展开更多
关键词 International Commission on Illumination(CIE) hue-saturation-lightness(HSL) chromaticity diagram tone-to-color conversion RGB LED driving structure
原文传递
Facile synthesis of nitrogen-doped graphene aerogels functionalized with chitosan for supercapacitors with excellent electrochemical performance 被引量:3
8
作者 Yong Zhang Jia-Yi Zhu +2 位作者 Hong-Bo Ren Yu-Tie Bi Lin Zhang 《Chinese Chemical Letters》 SCIE CAS CSCD 2017年第5期935-942,共8页
Three-dimensional porous nitrogen-doped graphene aerogels(NGAs) were synthesized by using graphene oxide(GO) and chitosan via a self-assembly process by a rapid method.The morphology and structure of the as-prepar... Three-dimensional porous nitrogen-doped graphene aerogels(NGAs) were synthesized by using graphene oxide(GO) and chitosan via a self-assembly process by a rapid method.The morphology and structure of the as-prepared aerogels were characterized.The results showed that NGAs possesed the hierarchical pores with the wide size distribution ranging from mesopores to macropores.The NGAs carbonized at different temperature all showed excellent electrochemical performance in 6 mol/L KOH electrolyte and the electrochemical performance of the NGA-900 was the best.When working as a supercapacitor electrode,NGA-900 exhibited a high specific capacitance(244.4 F/g at a current density of 0.2 A/g),superior rate capability(51.0% capacity retention) and excellent cycling life(96.2% capacitance retained after 5000 cycles). 展开更多
关键词 Nitrogen-doped graphene aerogels Hierarchical porous structure Carbonizing temperature Supercapacitors Energy storage and conversion
原文传递
D-A structural protean small molecule donor materials for solution-processed organic solar cells 被引量:1
9
作者 Qiong WU Dan Deng +1 位作者 Kun Lu Zhi-Xiang Wei 《Chinese Chemical Letters》 SCIE CAS CSCD 2017年第11期2065-2077,共13页
Under the synergistic effect of molecular design and devices engineering, small molecular organic solar cells have presented an unstoppable tendency for rapid development with putting forward donor- acceptor (D-A) s... Under the synergistic effect of molecular design and devices engineering, small molecular organic solar cells have presented an unstoppable tendency for rapid development with putting forward donor- acceptor (D-A) structures. Up to now, the highest power conversion efficiency of small molecules has exceeded 11%, comparable to that of polymers. In this review, we summarize the high performance small molecule donors in various classes of typical donor-acceptor (D-A) structures and discuss their relationships briefly. 展开更多
关键词 Small molecule donor materials Bulk heterojunction solar cells Donor-acceptor structures Molecule design Power conversion efficiency
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部