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991.
铕掺杂BaPbO3的EXAFS研究 总被引:3,自引:0,他引:3
采用扩展X射线吸收精细结构方法,研究了铕掺杂BaPbO3多晶粉末中Eu,Pb两种原子的近邻结构。Eu的掺杂,导致八面体中金属Pg,Eu的配位数降低。 相似文献
992.
Daren Guan Xizhang Yi Shiliang Ding Benhui Yang 《International journal of quantum chemistry》1997,63(5):981-989
The Lie algebraic approach of Alhassid and Levine [Phys. Rev. A 18 , 89 (1978)] is applied to the molecule–surface scattering. Specially, the diffractionally and rotationally inelastic scattering of a diatomic molecule from a solid surface is dealt with. Within the framework of the close-coupling method, we construct a Hamiltonian for the scattering system and use it to generate a dynamical algebra h6. By solving equations of motion for the group parameters, the scattering wave functions near the surface are obtained. Computed transition probabilities of diffractively and rotationally inelastic scattering of H2 from LiF(001) surface with the use of Lie algebraic method are seen to agree well with the coupled-channel calculations. The Lie algebraic method thus appears to have a wide range of validity for describing the dynamics of gas–surface scattering. © 1997 John Wiley & Sons, Inc. Int J Quant Chem 63: 981–989, 1997 相似文献
993.
Ming-Wu Ding Wen-Jing Xiao Shui-Ming Lu Wen-Fang Huang De-Qing Shi Tian-Jie Wu 《Heteroatom Chemistry》1997,8(2):191-197
ω-Azolylalkenes 3, 4, and 5 were synthesized by N-alkylation of C-alkylation of ω-bromoalkenes 2, which were obtained either by phase transfer Wittig reactions of ω-bromoalkylphosphonium salts 1 with aldehydes or by Wittig reactions of ω-hydroxyalkylphosphonium salts 6 with aldehydes and subsequent bromination. ω-Azolylalkenes 3 were also directly prepared by the Wittig reaction of ω-azolylalkyltriphenylphosphonium salts 8 with aromatic aldehydes. The stereochemistry of these Wittig reactions was studied. © 1997 John Wiley & Sons, Inc. 相似文献
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995.
Qiding Mi Lianxun Gao Leiming Li Yu Ma Xing Zhang Mengxian Ding 《Journal of polymer science. Part A, Polymer chemistry》1997,35(15):3287-3297
A series of new optically active aromatic polyimides containing axially dissymmetric 1,1′-binaphthalene-2,2-diyl units were prepared from optically pure (R)-(+)- or(S)-(−)-2,2′-bis(3,4-dicarboxyphenoxy)-1,1′-binaphthalene dianhydrides and various aromatic diamines via a conventional two-step procedure that included ring-opening polycondensation and chemical cyclodehydration. The optically pure isomer of dianhydride was prepared by a nucleophilic substitution of optically pure (R)-(+)- or(S)-(−)-1,1′-bi-2-naphthol with 4-nitrophthalonitrile in aprotic polar solvent and subsequent hydrolysis of the resultant tetranitrile derivatives, followed by the dehydration of the corresponding tetracarboxylic acids to obtain the dianhydrides. These polymers were readily soluble in common organic solvents such as N,N-dimethylacetamide, N-methyl-2-pyrrolidone, and m-cresol, etc., and have glass transition temperatures of 251–296°C, and 5% weight loss occurs not lower than 480°C. The specific rotations of the optically active polyimides ranged from +196° to +263°, and the optical stability and chiroptical properties of them were also studied. © 1997 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 35: 3287–3297, 1997 相似文献
996.
Allan S. Hoffman Patrick S. Stayton Tsuyoshi Shimoboji Guohua Chen Zhongli Ding Ashutosh Chilkoti Cindi Long Morikazu Miura Jingping Chen Taegwan Park Nobuo Monji Carol-Ann Cole J. Milton Harris K. Nakamae 《Macromolecular Symposia》1997,118(1):553-562
Intelligent polymers exhibit sharp, reversible phase changes in response to small changes in environmental conditions. For example, a small temperature change can cause a sharp precipitation or gelation of a smart polymer solution. Conjugation of these unusual polymers to biomolecules such as enzymes, ligands, lipids, and drugs can lead to many new and exciting applications in medicine and biotechnology. (1–4) This presentation reviews the principles, methodolgies and applications of these “smart” polymer-biomolecule systems, with special focus on temperature-sensitive polymer-protein conjugates. 相似文献
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Xiaolei Cai Meili Liu Yipeng Ji Guodong Ding Long Zhang 《Journal of Dispersion Science and Technology》2017,38(10):1435-1447
Huge amounts of produced water are generated in offshore oil production. The Compact Flotation Unit (CFU) is an excellent pretreatment technology of produced water with high separation efficiency, low residence, and small split ratio. The Computational Fluid Dynamics-population balance model (CFD-PBM) method is used in the present work to study the oil–water separation characteristics in the self-developed Beijing Institute of Petrochemical Technology Compact Flotation Unit (BIPTCFU) at both micro-scale and macro-scale, which would help us gain more insights into the mechanism and the influence of flow field on the oil–water separation process such as the oil droplets’ diameter distribution and separation efficiency. The effects of the inlet diameter, the height of the preliminary separation zone, and the width of the annular space on the oil–water separation characteristics of CFU were discussed systematically. It is illustrated that the appropriate increase of inlet velocity, decrease of annular gap width, and increase of the height in the preliminary separation zone can effectively promote the collision and coalescence process of oil droplets. However, the overlarge height of the preliminary separation zone and the too narrow width of the annular space will both have a significant negative effect on the migration and separation of oil and water and lead to the decrease of separation efficiency. 相似文献