共查询到15条相似文献,搜索用时 328 毫秒
1.
SUN Yan ZHOU Li SU Wei ZHOU YaPing 《科学通报(英文版)》2007,52(8):1146-1152
Hydrogen storage receives the worldwide attention due to its importance in sustainable energy and the solution of greenhouse effect.Adsorption provides an efficient way to compress gases and,therefore, has been applied to the development of hydrogen storage technology.However,hydrogen is a super- critical gas at the temperature of engineering interest and follows a different adsorption mechanism compared to the sub-critical gases.The present work shows why only monolayer coverage mechanism functions at above-critical temperatures and what consequences will result in the application study. Although there are pros and cons to this point of view,understanding the adsorption mechanism is,in- deed,essential for the research of hydrogen storage method since it claims that any storage material based on adsorption will not satisfy the practical need of on board storage no matter how novel the material is. 相似文献
2.
ZHU Tong lin FANG Suqin LI Zhiyuan LIU Yutao LIAO Hong YAN Xiaolong 《科学通报(英文版)》2006,51(19):2351-2361
The root system is an important organ for plants not only because it absorbs water and nutrients, but also because it provides anchorage against uprooting forces[1,2]. Root architecture is the spatial configuration of the root system in the growth medium[… 相似文献
3.
ZHI Lianhe ZHAO Xi SHAN Baoci PENG Silong YAN Qiang YUAN Xiuli TANG Xiaowei 《自然科学进展(英文版)》2006,16(11):1171-1176
The low signal to noise ratio (SNR) of functional MRI (fMRI) prefers more sensitive data analysis methods. Based on stationary wavelet transform and spectrum analysis, a new method with high detective sensitivity was developed for analyzing fMRI time series, which does not require any prior assumption of the characteristics of noises. In the proposed method, every component of fMRI time series in the different time-frequency scales of stationary wavelet transform was discerned by the spectrum analysis, then the components from noises were removed using the stationary wavelet transform, finally the components of real brain activation were detected by cross-correlation analysis. The results obtained from both simulated and in vivo visual experiments illustrated that the proposed method has much higher sensitivity than the traditional cross-correlation method. 相似文献
4.
系统研究了室温下Tb0.3Dy0.7(Fe1-xAlx)1.95(x=0,0.05,0.1,0.15,0.2,0.25,0.3,0.35)合金中金属Al替代Fe对磁性、磁致伸缩、自旋重取向和穆斯堡尔谱的影响.结果发现,x<0.4时,Tb0.3Dy0.7(Fe1-xAlx)1.95完全保持MgCu2立方Laves相结构.磁化强度和磁致伸缩测量发现,x<0.15时,添加少量Al有助于减小磁晶各向异性,并且随着Al替代量x增加,磁致伸缩λs、内禀磁致伸缩λ111和Curie温度Tc大幅度降低.多功能磁性测量系统PPMS的研究和M(o)ssbauer效应表明,Tb0.3Dy0.7(Fe1-xAlx)1.95合金的易磁化方向随成分和温度在{110}面逐渐偏离了立方晶体的主对称轴,即自旋重取向.室温下,当x=0.15时,Tb0.3Dy0.7(Fe1-xAlx)1.95合金中出现了少量非磁性相;x>0.15时,该合金完全呈顺磁性;而77K温度下x=0.2时合金仍然呈磁性相. 相似文献
5.
Thermodynamic analysis on the formation mechanism of MgO·Al<Subscript>2</Subscript>O<Subscript>3</Subscript> spinel type inclusions in casing steel
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MgO·Al2O3 spinel type inclusions in casing steel were analyzed by scanning electron microscope (SEM) and energy dispersive spectrometer
(EDS). The results show that there are three forms. One is pure MgO·Al2O3 spinel, another is the composite oxide of the Mg-Al-Ca-Si-O system, and the third is the complex with oxide as a core covered
by sulfide. The formation mechanisms were studied. The influences of slag basicity and vacuum degree on the magnesium content
during the vacuum treatment of molten steel and furnace lining in molten steel were calculated with the coexistence theory
of slag structure. The results show that the magnesium content increases with the increase in slag basicity and aluminum content
in molten steel, and decreases with the increase in CO partial pressure. 相似文献
6.
LIUShuhua ZHANGXuegong SUNSuqin 《科学通报(英文版)》2005,50(2):179-184
With the traditional Chinese medicine herbs angelicae dahuricae radix (ADR or Baizhi) and salviae miltiorrhizae radix (SMR or Danshen) as two examples, this work studies the automatic discrimination of the geographic origins of the herbs using near infrared (NIR) reflectance spectroscopy. Multi-class support vector machine (SVM) is utilized for the purpose, and recursive SVM is utilized to select the feature spectral segments that are decisive for the discrimination. With only 5 and 8 short spectral segments, discriminative accuracies of 92% are achieved on independent test sample sets. This work not only provides a prototype of accurate rapid discriminating systems for quality control of herbal medicines, but also opens new possibilities in studying subtle differences in the chemical compositions of herbs from different cultivation conditions and investigating their associations with the effectiveness of the herbs. 相似文献
7.
In this paper we investigate the relationship between the convergence of cascade algorithm and orthogonal (or biorthogonal) multiresolution analysis on the Heisenberg group. It is proved that the (strong) convergence of cascade algorithm together with the perfect reconstruction condition induces an orthogonal multiresolution analysis and vice versa. Similar results are also proved for biorthogonal multiresolution analysis. 相似文献
8.
Comprehensive analysis of the impact of climatic changes on Chinese terrestrial net primary productivity 总被引:4,自引:0,他引:4
Recent climatic changes have affected terrestrial net primary productivity (NPP). This paper presents an investigation of the impact of climatic changes on Chinese terrestrial vegetation NPP by analyzing 18 years’ (1982 to 1999) climatic data and satellite observations of vegetation activity. Results indicate that climatic changes in China have eased some critical climatic constraint on plant growth. (1) From 1982 to 1999, modeled NPP increased by 1.42%·a-1 in water-limited regions of Northwest China, 1.46%·a-1 in temperature-limited regions of Northeast China and Tibet Plateau, and 0.99%·a-1 in radia- tion-limited regions of South China and East China. (2) NPP increased by 24.2%, i.e. 0.76 petagram of carbon (Pg C) over 18 years in China. Changes in climate (with constant vegetation) directly contrib- uted nearly 11.5% (0.36 Pg C). Changes in vegetation (with constant climate) contributed 12.4% (0.40 Pg C), possibly as a result of climate-vegetation feedbacks, changes in land use, and growth stimula- tion from other mechanisms. (3) Globally, NPP declined during all three major El Ni-o events (1982 to 1983, 1987 to 1988, and 1997 to 1998) between 1982 and 2000, but Chinese vegetation productivity re- sponded differently to them because of the monsoon dynamics. In the first three events (1982 to 1983, 1987 to 1988, and 1992), Chinese vegetation NPP declined, while in the later two events (1993, 1997 to 1998) increasing obviously. 相似文献
9.
LI Haiyan TANG Beisha* XIA Kun CAO Guifang SHEN Lu JIANG Hong PAN Qian SONG Yanmin CAI Fang 《自然科学进展(英文版)》2005,15(8)
Benignfamilialneonatalconvulsions(BFNC)is arareautosomaldominantinheritedepilepsysyn dromecharacterizedbyunprovokedpartialorgeneral izedseizures.Theseizuresusuallyoccurfromthesec onddayofbirthtothesixthmonthandremitsponta neouslyafterseveralweekstomonths.Mostindivid ualsareseizure freebytheageofsixmonths.The serumchemistryandneuroradiologicalexaminations,interictalelectroencephalogram(EEG),andpsy chomotordevelopmentareusuallynormal.However,10%to15%ofpatientshavetheriskofseizurere currencela… 相似文献
10.
IntroductionThe Agreement on Textiles and Clothing ( ATC) wason effect worldwide on January1,2005, which indicatedthe post-quota era of global textile and clothing (T & C)trade . After that ,according tothe regulation of Clause242( Textiles-Specific Safeguard Clause , TSSC) , some ofAmerican associations and organizations put forward thedemand of resetting li mits on seven textile and clothingproducts exporting to America from China based on thestatistics in the three to four months af… 相似文献
11.
ZHAO Weijuan LI Guoxia GAO Zhengyao ZHANG bin LI Rongwu WU Xiaoli YAO Guifang JIA Xiuqin HAN Song HUANG Zhongxiang 《科学通报(英文版)》2000,45(20)
The content of 30 kinds of coloring elements in Guan porcelain in the Southern Song Dynasty has been determined by neutron activation analysis (NAA). Iron is the major coloring element. M(o)ssbauer spectroscopy has shown that the iron of the glaze exists in the form of structural iron (Fe2+, Fe3+). The quantitative relationship between the main wavelength of every color glaze and the relative content (Fe2+/Fe3+) of structural iron has been determined. Thus the coloring mechanism of Guan porcelain in the Southern Song Dynasty has been revealed entirely. 相似文献
12.
Rongwu Li Lei Yang Guoxia Li Weijuan Zhao Zhengyao Gao Jianzhong Xie Jin Chen Bin Zhang Xinmin Sun Songlin Feng Xiuqin Jia Song Han Zhongxiang Huang 《科学通报(英文版)》2002,47(14):1163-1166
The characteristic spectrum and its main wavelength of Ru porcelain glaze are measured by color difference instrument to determine the relations between glaze color and its main wavelength. The content of the 30 coloring elements in Ru porcelain is determined by neutron activation analysis (NAA), which showed that iron is the major coloring element. Mössbauer spectroscopy analysis shows that the iron element in the glaze exists in the form of structural iron (Fe2+, Fe3+). The quantitative relationship between the main wavelength of glaze in various colors and the relative content of structural iron (Fe2+/Fe3+) is determined. Thus the coloring mechanism of Ru porcelain is investigated entirely. 相似文献
13.
LI Rongwu YANG Lei LI Guoxia ZHAO Weijuan GAO Zhengyao XIE Jianzhong CHEN Jin ZHANG Bin Sun Xinmin FENG Songlin JIA Xiuqin HAN Song HUANG Zhongxiang 《科学通报(英文版)》2002,47(14)
The characteristic spectrum and its main wavelength of Ru porcelain glaze are measured by color difference instrument to determine the relations between glaze color and its main wavelength. The content of the 30 coloring elements in Ru porcelain is determined by neutron activation analysis (NAA), which showed that iron is the major coloring element. M?ssbauer spectroscopy analysis shows that the iron element in the glaze exists in the form of structural iron (Fe2+, Fe3+). The quantitative relationship between the main wavelength of glaze in various colors and the relative content of structural iron (Fe2+/Fe3+) is determined. Thus the coloring mechanism of Ru porcelain is investigated entirely. 相似文献
14.
中国古代音乐体裁是中国音乐史中的重要领域,从古至今的研究和其本身的艺术价值是其研究的动因,而现代科学的历史研究法引入其中所产生的诸多成果是其研究的立论基础,而由此提出的研究框架是历史之选择,也是当代学人面对历史遗产时的勇敢姿态。以导引的形式对这一研究进行宏观、全揽的内容和方法关照,以期引起更多人的关注。 相似文献
15.
采用文献资料法、调查法和实验法等研究方法,通过对上海市中小学体育教师专业发展和上海师范大学体育师范生培养中存在的主要问题进行调查分析,探索和研究了"卓越体育教师"培养机制,制定并实施了相应的实践工程,提出了有针对性的对策措施,为研究上海市一流体育师资培养提供参考. 相似文献