全文获取类型
收费全文 | 14614篇 |
免费 | 2319篇 |
国内免费 | 2686篇 |
专业分类
化学 | 10321篇 |
晶体学 | 318篇 |
力学 | 951篇 |
综合类 | 301篇 |
数学 | 1887篇 |
物理学 | 5841篇 |
出版年
2024年 | 69篇 |
2023年 | 301篇 |
2022年 | 537篇 |
2021年 | 558篇 |
2020年 | 569篇 |
2019年 | 565篇 |
2018年 | 495篇 |
2017年 | 549篇 |
2016年 | 640篇 |
2015年 | 714篇 |
2014年 | 830篇 |
2013年 | 1125篇 |
2012年 | 1211篇 |
2011年 | 1271篇 |
2010年 | 1015篇 |
2009年 | 969篇 |
2008年 | 1151篇 |
2007年 | 978篇 |
2006年 | 913篇 |
2005年 | 759篇 |
2004年 | 588篇 |
2003年 | 462篇 |
2002年 | 464篇 |
2001年 | 396篇 |
2000年 | 370篇 |
1999年 | 356篇 |
1998年 | 229篇 |
1997年 | 182篇 |
1996年 | 175篇 |
1995年 | 175篇 |
1994年 | 144篇 |
1993年 | 146篇 |
1992年 | 119篇 |
1991年 | 126篇 |
1990年 | 97篇 |
1989年 | 83篇 |
1988年 | 53篇 |
1987年 | 47篇 |
1986年 | 36篇 |
1985年 | 36篇 |
1984年 | 26篇 |
1983年 | 17篇 |
1982年 | 14篇 |
1981年 | 18篇 |
1980年 | 10篇 |
1979年 | 7篇 |
1978年 | 6篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1957年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
Equilibrium Problems with Applications to Eigenvalue Problems 总被引:5,自引:0,他引:5
In this paper, we consider equilibrium problems and introduce the concept of (S)+ condition for bifunctions. Existence results for equilibrium problems with the (S)+ condition are derived. As special cases, we obtain several existence results for the generalized nonlinear variational inequality studied by Ding and Tarafdar (Ref. 1) and the generalized variational inequality studied by Cubiotti and Yao (Ref. 2). Finally, applications to a class of eigenvalue problems are given. 相似文献
4.
In the ever fusion experiments in SWIP, pellet forming process was carried out through adjusting relative devices by staff member in site, which will make every pellet-forming process slight distinction and will result in pellet difference in shape, size and intensity. In the intervals of HL-2A discharges, staff member have to go site to accomplish the pellet-forming process, this wastes human power and increase the potential danger. So it is necessary to develop a remote control system to perform the pellet-forming process. The control system needs have the features of real-time, reliability and be easy to operate and maintain. 相似文献
5.
Existence, Multiplicity and Infinite Solvability of Positive Solutions for One-Dimensional p-Laplacian 总被引:5,自引:0,他引:5
Qing Liu YAO 《数学学报(英文版)》2005,21(4):691-698
The existence, multiplicity and infinite solvability of positive solutions are established for some two-point boundary value problems of one-dimensional p-Laplacian. In this paper, by multiplicity we mean the existence of m solutions, where m is an arbitrary natural number. 相似文献
6.
YaoKui ChenZhixiang 《分析论及其应用》2003,19(2):115-120
This paper gives the weighted Lp convergence rate estimations of the Gruenwald interpolatory polynomials based on the zeros of Chebyshev polymomials of the first kind,and proves that the order of the estimations is optimal for p≥1. 相似文献
7.
Pyroelectricity and Spontaneous Polarization in [111] Oriented 0.955 Pb(Zn1/3Nb2/3)O3-0.045PbTiO3 Single Crystals 下载免费PDF全文
We report that the measurements of the pyroelectric current of the pre-poled [111]-oriented 0.955 Pb(Zn1/3Nb2/3) O3-0.045 PbTiO3 (PZN-4.5%PT) single crystals can shed some light on the phase transition and spontaneous polarization characters of this material in a similar way to measures of remanent polarization and dielectric properties. The pyroelectric current is measured and the corresponding spontaneous polarization is calculated as a function of temperature with various poling fields added during cooling the sample from 200℃ to room temperature. Critical electric field of 0.061 k V/cm is found to be essential to induce the intermediate ferroelectric orthorhombic phase between the ferroelectric rhombohedral and tetragonal phases. Below the critical field, the polarization increases almost linearly with the increase of poling field. At the critical field, the polarization at 30OC increases abruptly from 14μC/cm^2 for a poling field of O.06kV/cm to 29.5μC/cm^2 for a poling field of 0.061 kV/cm, and afterwards, increases slowly and saturates to 31 μC/cm^2 for poling fields beyond 0.55 kV/cm. 相似文献
8.
Yu‐Hsiang Hu Chuh‐Yung Chen Chen‐Chien Wang Yao‐Hui Huang Shao‐Ping Wang 《Journal of polymer science. Part A, Polymer chemistry》2004,42(19):4976-4993
The bulk polymerization of styrene initiated by ?‐caprolactam (CL) and n‐dodecyl mercaptan (RSH) has been explored. This novel polymerization system shows living characteristics. For example, the molecular weight of the resulting polymers increases with conversion, and the system has the ability to form diblock copolymers and so forth. The polymer chain end contains thiol and lactam structures, which we have investigated with Fourier transform infrared, 1H NMR, and 13C NMR techniques. Electron spin resonance spectra and theoretical calculations by the Hartree–Fock methods have been used to examine the mechanism. The results reveal that the initial polymerization starts from thiol via a chain‐transfer reaction, and the propagation proceeds by the insertion of a monomer between the terminal group and the intermediate structure of lactam. Finally, the polymerization kinetics have been examined. The polymerization rate varies linearly with the concentration of CL and RSH, and this confirms the mechanism. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4976–4993, 2004 相似文献
9.
Yao Ping HOU 《数学学报(英文版)》2005,21(4):955-960
A signed graph is a graph with a sign attached to each edge. This paper extends some fundamental concepts of the Laplacian matrices from graphs to signed graphs. In particular, the relationships between the least Laplacian eigenvalue and the unbalancedness of a signed graph are investigated. 相似文献
10.
Since its discovery in 1946, NMR has become a valuable tool in physics, chemistry, biology, and medicine. With the invention of NMR logging tools that take the medical MRI or laboratory NMR equipment and turn it inside-out, the application of sophisticated laboratory techniques to determine formation properties in situ is now available. The capability has opened a new era in formation evaluation just as the introduction of NMR has revolutionized the other scientific areas. 相似文献