首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   270139篇
  免费   33308篇
  国内免费   22610篇
化学   169582篇
晶体学   3238篇
力学   16949篇
综合类   1421篇
数学   34615篇
物理学   100252篇
  2023年   3750篇
  2022年   7196篇
  2021年   7774篇
  2020年   8601篇
  2019年   8607篇
  2018年   8555篇
  2017年   8108篇
  2016年   11469篇
  2015年   10185篇
  2014年   13078篇
  2013年   17469篇
  2012年   20021篇
  2011年   20943篇
  2010年   14980篇
  2009年   14640篇
  2008年   15415篇
  2007年   14138篇
  2006年   13069篇
  2005年   11202篇
  2004年   9015篇
  2003年   7449篇
  2002年   7165篇
  2001年   6210篇
  2000年   5271篇
  1999年   5163篇
  1998年   4649篇
  1997年   4233篇
  1996年   4320篇
  1995年   3631篇
  1994年   3547篇
  1993年   3029篇
  1992年   2811篇
  1991年   2669篇
  1990年   2362篇
  1989年   2000篇
  1988年   1679篇
  1987年   1562篇
  1986年   1505篇
  1985年   1424篇
  1984年   1292篇
  1983年   1096篇
  1982年   1040篇
  1981年   876篇
  1979年   867篇
  1978年   867篇
  1977年   851篇
  1976年   977篇
  1975年   867篇
  1974年   897篇
  1973年   895篇
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
51.
Sun  Qinqin  Wang  Xiuye  Yang  Guolai  Chen  Ye-Hwa  Ma  Fai 《Nonlinear dynamics》2022,109(3):1629-1650
Nonlinear Dynamics - This paper proposes an optimal parameter design of control scheme for mechanical systems by adopting the Stackelberg game theory. The goal of the control is to drive the...  相似文献   
52.
Wang  Xigui  Ruan  Jiafu  Wang  Yongmei  Ji  Shue  An  Siyuan 《Meccanica》2021,56(2):303-316
Meccanica - In gear pair actual alternating meshing process, the comprehensive errors of the transmission system and the thermal elastic deformation of the teeth body cause the gears in the meshing...  相似文献   
53.
Annals of the Institute of Statistical Mathematics - In this paper, a model averaging approach is developed for the linear regression models with response missing at random. It is shown that the...  相似文献   
54.
Xu  Mengtao  Li  Changyou  Sun  Yang  Yang  Tianzhi  Zhang  Hongzhuang  Liu  Zhendong  Liu  Haiyang  Li  Zhenyuan  Zhang  Yimin 《Nonlinear dynamics》2021,105(4):3061-3092
Nonlinear Dynamics - Investigation of the dynamic characteristics of linear guideway is essential for enhancing structural performance of machine tools. However, few mechanical models are...  相似文献   
55.
56.
Journal of Fourier Analysis and Applications - We develop a theory of Sobolev orthogonal polynomials on the Sierpiński gasket ( $$SG$$ ), which is a fractal set that can be viewed as a limit...  相似文献   
57.
Acridone as a new kind of visible light photocatalyst has been developed to catalyze metal free atom transfer radical polymerization (ATRP). The photocatalyst possess low excited state potential as can undergo an oxidative quenching pathway to initiate ATRP of vinyl monomers. Kinetic study and light on/off reaction demonstrate the “living”/controlled nature of the polymerization by light. Block copolymers can be achieved by using PMMA as macroinitiator to reinitiate polymerization of other vinyl monomers, which shows highly preserved Br chain-end functionality in the synthesized polymers. Moreover, the polymerization can be conducted under air atmosphere as most photocatalysts need anaerobic condition, which may give inspiration of further application of this kind of photocatalyst.  相似文献   
58.
The chiral phase transition and equation of state are studied within a novel self-consistent mean-field approximation of the two-flavor Nambu-Jona-Lasinio model. In this newly developed model, modifications to the chemical μ and chiral chemical \begin{document}$\mu_5$\end{document} potentials are naturally included by introducing vector and axial-vector channels from Fierz-transformed Lagrangian to the standard Lagrangian. In the proper-time scheme, the chiral phase transition is a crossover in the \begin{document}$T-\mu$\end{document} plane. However, when \begin{document}$\mu_5$\end{document} is incorporated, our study demonstrates that a first order phase transition may emerge. Furthermore, the chiral imbalance will soften the equation of state of quark matter. The mass-radius relationship and tidal deformability of quark stars are calculated. The maximum mass and radius decrease as \begin{document}$\mu_5$\end{document} increases. Our study also indicates that the vector and axial-vector channels exhibit an opposite influence on the equation of state.  相似文献   
59.
Herein, we successfully construct the 3D biocompatible graphene through crosslinking 2D graphene nanosheet onto carbon fiber paper with poly(diallyldimethylammonium chloride) (PDDA) as anode of the alcohol biofuel cell. Compared with the bioanode without 3D graphene, the current density and output power of PDDA-graphene-ADH bioanode is increased by 23 % and 41 % at a high concentration of ethanol at pH 8.9, suggesting the stabilization role of graphene in enzyme loading. The study provides us a deep analysis on structures and performances of the bioanode incl. electrochemistry, X-ray photoelectron spectra, and atomic force microscopy images, which is significant to develop the new methods to construct 3D porous electrodes in energy conversion device.  相似文献   
60.
Cao  Xiangyang  Zhang  Chenghui  Zhao  Daduan  Li  Yan 《Nonlinear dynamics》2022,107(4):3557-3572
Nonlinear Dynamics - This paper investigates the guaranteed cost positive consensus for linear multi-agent systems (MASs) with multiple time-varying delays and switching topologies. First,...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号