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991.
以三(2-巯吡啶基)甲烷(L)为配体合成了2个Cd(Ⅱ)和Zn(Ⅱ)的配合物:Cd(L)4(NO3)2和Zn(L)4(ClO4)2, 发现在配合物中配体的C-S键发生了断裂, 通过紫外、质谱手段研究并预测了其反应机理。单晶X-射线衍射的结果显示, 配合物1和2中金属原子均处于扭曲的四面体配位环境中, 分子间π-π堆积作用将配合物1的分子结构延伸为二维网状结构。 相似文献
992.
993.
Chinese regional energy efficiency change and its determinants analysis: Malmquist index and Tobit model 总被引:2,自引:0,他引:2
China becomes the largest energy consumer in 2010 but its energy productivity is well below the world average. To meet China’s fast growing energy using, energy efficiency should be especially emphasized under China’s energy policy. This paper focuses on the regional level of energy efficiency change in China. And we analyze total factor energy efficiency for 30 Chinese provinces over the period 1998–2009 using Malmquist index method and Tobit analysis. The Malmquist estimation results suggest there is a dropping change trend of energy productivity growth. Chinese energy efficiency still faces with huge regional disparity, but the energy technical efficiency reflects convergence in the nationwide and west region. As a result of Tobit regression, we find that industrial structure, energy consumption structure and institutional factor have different influences on energy efficiency. 相似文献
994.
By Petersen's Theorem, a bridgeless cubic graph has a 2-factor. Fleischner(Discrete Math.,101, 33–37(1992)) has extended this result to bridgeless graphs of minimum degree at least three by showing that every such graph has an even factor without isolated vertices. Let me 0 be even and mo 0 be odd. In this paper, we prove that every m e-edge-connected graph with minimum degree at least me + 1 contains an even factor with minimum degree at least m e and every(m o + 1)-edge-connected graph contains an odd factor with minimum degree at least m o, which further extends Fleischner's result. Moreover, we show that our results are best possible. 相似文献
995.
In this paper, we study gradient solitons to the Ricci flow coupled with harmonic map heat flow. We derive new identities on solitons similar to those on gradient solitons of the Ricci flow. When the soliton is compact, we get a classification result. We also discuss the relation with quasi-Einstein manifolds. 相似文献
996.
Numerical discretization-based kernel type estimation methods for ordinary differential equation models 下载免费PDF全文
We consider the problem of parameter estimation in both linear and nonlinear ordinary differential equation(ODE) models. Nonlinear ODE models are widely used in applications. But their analytic solutions are usually not available. Thus regular methods usually depend on repetitive use of numerical solutions which bring huge computational cost. We proposed a new two-stage approach which includes a smoothing method(kernel smoothing or local polynomial fitting) in the first stage, and a numerical discretization method(Eulers discretization method, the trapezoidal discretization method,or the Runge–Kutta discretization method) in the second stage. Through numerical simulations, we find the proposed method gains a proper balance between estimation accuracy and computational cost.Asymptotic properties are also presented, which show the consistency and asymptotic normality of estimators under some mild conditions. The proposed method is compared to existing methods in term of accuracy and computational cost. The simulation results show that the estimators with local linear smoothing in the first stage and trapezoidal discretization in the second stage have the lowest average relative errors. We apply the proposed method to HIV dynamics data to illustrate the practicability of the estimator. 相似文献
997.
Qiu‐Yan Chen Xian Cheng Tao Wang Zi‐Hao Yu Chong Zhang Shu‐Kun Lin Hao‐Hong Li Zhi‐Rong Chen 《无机化学与普通化学杂志》2014,640(2):439-443
A new low‐dimensional benzyl viologen/iodoargentate hybrid, [(BV)2(Ag5I9)]n ( 1 ) (BV2+ = benzyl viologen) was prepared. In 1 , (Ag6I9)n2– chain exhibits a new type of one‐dimensional chain constructed from vertex‐sharing of Ag5I10 units, and its two‐dimensional layer structure was constructed from C–H ··· I hydrogen bonds. Strong luminescence at 404 nm can be detected in 1 . DFT calculation suggests that 1 displays a reduced bandgap, which is led by a more dispersed LUMO band of BV2+ compared with MV2+ in [MV(Ag2I4)]n. 相似文献
998.
Jayachandran Jayakumar Kanniyappan Parthasarathy Yi‐Hsiang Chen Tai‐Hua Lee Shih‐Ching Chuang Chien‐Hong Cheng 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2014,126(37):10047-10050
A new method for the synthesis of highly substituted naphthyridine‐based polyheteroaromatic compounds in high yields proceeds through rhodium(III)‐catalyzed multiple C H bond cleavage and C C and C N bond formation in a one‐pot process. Such highly substituted polyheteroaromatic compounds have attracted much attention because of their unique π‐conjugation, which make them suitable materials for organic semiconductors and luminescent materials. Furthermore, a possible mechanism, which involves multiple chelation‐assisted ortho C H activation, alkyne insertion, and reductive elimination, is proposed for this transformation. 相似文献
999.
Genetic profile characterization and population study of 21 autosomal STR in Chinese Kazak ethnic minority group 下载免费PDF全文
Xiao‐Ye Wang Chun‐Mei Shen Wen‐Juan Liu Jiang‐Wei Yan Hong‐Dan Wang Hong‐Wei Pu Yan‐Li Wang Guang Yang Yu‐Dang Zhang Hao‐Tian Meng Hang Jing Bo‐Feng Zhu 《Electrophoresis》2014,35(4):503-510
Short tandem repeat loci have been recognized as useful tools in the routine forensic application and in recent decades, more and more new short tandem repeat (STR) loci have been constantly discovered, studied, and applied in forensic caseworks. In this study, we investigated the genetic polymorphisms of 21 STR loci in the Kazak ethnic minority as well as the genetic relationships between the Kazak ethnic minority and other populations. Allelic frequencies of 21 STR loci were obtained from 114 unrelated healthy Kazak individuals in the Ili Kazak Autonomous Prefecture, Xinjiang Uigur Autonomous Region of China. We observed a total of 159 alleles in the group with the allelic diversity values ranging from 0.0044 to 0.5088. The highest polymorphism was found at D19S433 locus and the lowest was found at D1S1627. Statistical analysis of the generated data indicated no deviation from Hardy–Weinberg equilibriums at all 21 STR loci. In order to estimate the population differentiation, allelic frequencies of all STR loci of the Kazak were compared with those of other neighboring populations using analysis of molecular variance method. Statistically significant differences were found between the studied population and other populations at 2–7 STR loci. A neighbor‐joining tree was constructed based on allelic frequencies of the 21 STR loci and phylogenetic analysis indicates that the Kazak has a close genetic relationship with the Uigur ethnic group. The present results may provide useful information for forensic sciences and population genetics studies, and can also increase our understanding of the genetic background of this group. The present findings showed that all the 21 STR loci are highly genetically polymorphic in the Kazak group, which provided valuable population genetic data for the genetic information study, forensic human individual identification, and paternity tests. 相似文献
1000.