全文获取类型
收费全文 | 100篇 |
免费 | 17篇 |
国内免费 | 12篇 |
专业分类
化学 | 103篇 |
晶体学 | 2篇 |
力学 | 5篇 |
数学 | 6篇 |
物理学 | 13篇 |
出版年
2024年 | 1篇 |
2023年 | 3篇 |
2022年 | 5篇 |
2021年 | 1篇 |
2020年 | 7篇 |
2019年 | 1篇 |
2018年 | 1篇 |
2017年 | 6篇 |
2016年 | 4篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 9篇 |
2012年 | 13篇 |
2011年 | 10篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 8篇 |
2007年 | 1篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 2篇 |
2003年 | 2篇 |
2002年 | 3篇 |
1999年 | 4篇 |
1998年 | 2篇 |
1993年 | 1篇 |
1990年 | 1篇 |
排序方式: 共有129条查询结果,搜索用时 31 毫秒
1.
Chuncheng Hao Zuolin Cui Yansheng Yin Zhikun Zhang 《Journal of nanoparticle research》2002,4(1-2):107-110
Nanostructured Fe3Al intermetallic compounds were produced by using hydrogen arc plasma method. The transmission electron microscopy experiments showed that the average particle size of the as-synthesized was about 40-nm. The change in hardness of Fe3Al nanostructured intermetallic compounds with annealing temperatures was observed and evaluated. 相似文献
2.
Xiaoqing Liu Chuncheng Li Dong Zhang Yaonan Xiao 《Journal of Polymer Science.Polymer Physics》2006,44(6):900-913
This article investigated the melting behaviors, crystallization kinetics, and spherulitic morphologies of poly(butylene succinate) (PBS) and its copolyester (PBSR) modified with rosin maleopimaric acid anhydride, using wide‐angle X‐ray diffraction, differential scanning calorimeter (DSC), and polarized optical microscope. Subsequent DSC scans of isothermally crystallized PBS and PBSR exhibited two melting endotherms, respectively, which was due to the melt‐recrystallization process occurring during the DSC scans. The equilibrium melting point of PBSR (125.9 °C) was lower than that of PBS (139 °C). The commonly used Avrami equation was used to describe the isothermal crystallization kinetics. For nonisothermal crystallization studies, the model combining Avrami equation and Ozawa equation was employed. The result showed a consistent trend in the crystallization process. The crystallization rate was decreased, the perfection of crystals was decreased, the recrystallization was reduced, and the spherulitic morphologies were changed when the huge hydrogenated phenanthrene ring was added into the chain of PBS. The activation energy (ΔE) for the isothermal crystallization process determined by Arrhenius method was 255.9 kJ/mol for PBS and 345.7 kJ/mol for PBSR. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 900–913, 2006 相似文献
3.
Visible light induced photocatalytic reaction of rhodamine B dye via 12-tungstosilicic acid in water
Using 12-tungstosilicic acid (SiW124-) as the catalyst, rhodamine B (RhB) dye in an aerated aqueous solution can undergo an effective photocatalytic stepwise N-deethylation process under visible light irradiation, and dioxygen is reduced to hydrogen peroxide by the reducedSiW12 4-. This provides the potential for moving polyoxometalate-based photocatalytic processes from the near-UV into the visible region of the spectrum. 相似文献
4.
CHENG Mingming SUN Zhenying MA Wanhong CHEN Chuncheng ZHAO Jincai WANG Zhengping 《中国科学B辑(英文版)》2006,49(5)
The organic-inorganic layered solid catalyst Fe(bpy)32+-laponite was able to photodegrade Rhodamine B (RhB) by activation of dioxygen under visible irradiation (λ>420 nm), while the homogeneous aqueous solution Fe(bpy)32+ showed no photoactivity. The catalyst could be repeatedly used and retained its reactivity. The hybrid catalyst could be separated from the suspension by centrifugation or sedimentation. The TOC removal yield of RhB was measured. Reactive oxygen species (ROS) formed during degradation was detected by EPR. A possible mechanism was proposed on the basis of the experimental results. 相似文献
5.
Mechanism of TiO2-assisted photocatalytic degradation of dyes under visible irradiation: photoelectrocatalytic study by TiO2-film electrodes 总被引:3,自引:0,他引:3
Photoelectrocatalytic degradation of various dyes under visible light irradiation with a TiO(2) nanoparticles electrode has been investigated to reveal the mechanism for TiO(2)-assisted photocatalytic degradation of dyes. The degradation of both cationic and anionic dyes at different biases, including the change in the degradation rate of the dyes and the photocurrent change with the bias potential, the degraded intermediates, the voltage-induced adsorption of dyes, the accumulation of electrons in the TiO(2) electrode, the effect of various additives such as benzoquinone (BQ) and N,N-dimethyl aniline (DMA), and the formation of active oxygen species such as O(2)(*-) and H(2)O(2) were examined by UV-visible spectroscopy, HPLC, TOC, and spin-trap ESR spectrometry. It was found that the dyes could controllably interact with the TiO(2) surface by external bias changes and charging of dyes. The cationic dyes such as RhB and MG underwent efficient mineralization at negative bias, but the N-dealkylation process predominated at positive bias under visible light irradiation. The discolorations of the anionic dyes SRB and AR could not be accelerated significantly at either negative or positive bias. At a negative bias of -0.6 V vs SCE, O(2)(*-) and dye(*+) were formed simultaneously at the electrode/electrolyte interface during degradation of cationic RhB. In the case of anionic dyes, however, it is impossible for the O(2)(*-) and dye cationic radical to coexist at the electrode/electrolyte surface. Experimental results imply both the superoxide anionic radical and the dye cationic radical are essential to the mineralization of the dyes under visible light-induced photocatalytic conditions. 相似文献
6.
7.
A hybrid particle–continuum method is used to study the shear flow confined between two opposing walls, one of which is coated with polymer chains. Molecular dynamics (MD) is used in the particle region near the brush and Navier–Stokes (NS) equations are applied in the remaining region where the continuum assumption holds. The information exchange from the continuum region to the particle region is implemented using the constrained particle dynamics. Both Couette shear flow and oscillatory flow are considered in the present work. The effect of the shear flow on the conformational characteristics of polymer brushes is analyzed. In the overlap region, the velocities obtained from MD simulations are smoothly connected with those from NS equations. Our investigations demonstrate that the hybrid particle–continuum model is valid in exploring the shear behavior of polymer brushes. 相似文献
8.
Chuncheng Wang 《Journal of Difference Equations and Applications》2013,19(7):737-746
In this paper, the discrete Nicholson's blowflies model with delay is considered. First, the stability of the equilibria of the system is investigated by analyzing the characteristic equation and then the existence of fold and Neimark–Sacker bifurcations are verified. Subsequent to that, the direction and stability of the bifurcation are determined by using the normal form theory and center manifold theorem. Finally, some numerical simulations are carried out in order to support the results of mathematical analysis. 相似文献
9.
An Unexpected Fluctuating Reactivity for Odd and Even Carbon Numbers in the TiO2‐Based Photocatalytic Decarboxylation of C2‐C6 Dicarboxylic Acids 下载免费PDF全文
Yiran Sun Dr. Wei Chang Dr. Hongwei Ji Dr. Chuncheng Chen Prof. Wanhong Ma Prof. Jincai Zhao 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(7):1861-1870
The degradation behaviours of five straight‐chain dicarboxylic acids (from ethanedioic acid to hexanedioic acid) were compared in aqueous TiO2‐based photocatalysis. When all other conditions were identical, the degradation rates were found to fluctuate regularly with the parity of the number of carbon atoms. Dicarboxylic acids with an even number of carbon atoms (e‐DAs) always degraded more slowly than those acids with an odd number of carbon atoms (o‐DAs). This unusual fluctuation in the reactivity for the degradation of dicarboxylic acids by TiO2‐based photocatalysis is very closely related to the different pre‐coordination modes of the acids with the photocatalyst. Attenuated total reflection FTIR (ATR‐FTIR) of e‐DAs labelled with 13C showed that both carboxyl groups of the acid coordinate to TiO2 through bidentate chelating forms. In contrast, only one carboxyl group of the o‐DAs coordinated to TiO2 in a bidentate chelating manner, whereas the other formed a monodentate binding linkage. The bidentate chelating form with bilateral symmetric coordination did not favour degradation. Isotope‐labelling experiments were performed with 18O2 to observe the different ways in which incorporated oxygen entered the initial decarboxylated products of e‐ and o‐DAs. For the degradation of butanedioic acid, (45.9±0.5) % of the oxygen in the formed propanedioic acid came from H2O, whereas for pentanedioic acid, (97.4±0.2) % of the oxygen in the formed butanedioic acid came from H2O. Our results demonstrate that in TiO2‐based photocatalysis, the reactivity of active species, such as . OH/hvb+, is far from non‐selective and that the attacks of these active species on organic substrates are significantly affected by the coordination patterns of the substrates on the TiO2 surface. 相似文献
10.
Chuncheng Zou Yuanyuan Han Chuikun Zeng Tony Y. Zhang Jinxing Ye Gonghua Song 《中国化学快报》2020,31(2):377-380
An organocatalytic asymmetric [3+2] cycloaddition of trifluoromethyl-containing azomethine ylides with cyclic 2,4-dienones was developed.The process enables efficient incorporation of CF3 groups into functionalized spiro [pyrro lid in-3,2'-oxindoles] in high yields with good to excellent enantio-and diastereoselectivities. 相似文献