全文获取类型
收费全文 | 101223篇 |
免费 | 16681篇 |
国内免费 | 11777篇 |
专业分类
化学 | 71596篇 |
晶体学 | 1137篇 |
力学 | 5751篇 |
综合类 | 667篇 |
数学 | 12627篇 |
物理学 | 37903篇 |
出版年
2024年 | 243篇 |
2023年 | 2001篇 |
2022年 | 2905篇 |
2021年 | 3526篇 |
2020年 | 4111篇 |
2019年 | 3877篇 |
2018年 | 3570篇 |
2017年 | 3209篇 |
2016年 | 4846篇 |
2015年 | 4679篇 |
2014年 | 5795篇 |
2013年 | 7539篇 |
2012年 | 9107篇 |
2011年 | 9474篇 |
2010年 | 6625篇 |
2009年 | 6366篇 |
2008年 | 6686篇 |
2007年 | 5971篇 |
2006年 | 5588篇 |
2005年 | 4664篇 |
2004年 | 3651篇 |
2003年 | 2929篇 |
2002年 | 2664篇 |
2001年 | 2226篇 |
2000年 | 1943篇 |
1999年 | 2052篇 |
1998年 | 1740篇 |
1997年 | 1561篇 |
1996年 | 1555篇 |
1995年 | 1369篇 |
1994年 | 1239篇 |
1993年 | 1003篇 |
1992年 | 902篇 |
1991年 | 777篇 |
1990年 | 652篇 |
1989年 | 503篇 |
1988年 | 376篇 |
1987年 | 338篇 |
1986年 | 334篇 |
1985年 | 262篇 |
1984年 | 188篇 |
1983年 | 153篇 |
1982年 | 125篇 |
1981年 | 78篇 |
1980年 | 59篇 |
1979年 | 24篇 |
1978年 | 22篇 |
1976年 | 22篇 |
1975年 | 22篇 |
1957年 | 26篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
202.
203.
Soliton interaction under the influence of higher-order effects 总被引:6,自引:0,他引:6
In this paper, we present exact N-soliton solution by employing simple, straightforward Darboux transformation based on the Lax pair for Hirota equation, a higher-order nonlinear Schrödinger (HNLS) equation. As examples, one- and two-soliton solutions in explicit forms are given and their properties are also analyzed. A bound solution without interaction will be theoretically predicted if one can adjust frequency shift for each soliton appropriately. Further, we obtain the approximate eigenvalues by employing two-soliton solution and discuss analytically the interaction between neighboring solitons under the influence of the higher-order effects. It is shown that the combined effects of the higher-order effects can restrain the interaction between neighboring solitons to some extent. The results are proved by directly solving HNLS equation numerically. 相似文献
204.
205.
Existence and Uniqueness of Endemic States for the Age-structured MSEIR Epidemic Model 总被引:1,自引:0,他引:1
Geni Gupur 《应用数学学报(英文版)》2002,18(3):441-454
The existence and uniqueness of positive steady states for the age-structured MSEIR epidemic model with age-dependent transmission coefficient is considered. Threshold results for the existence of endemic states are established; under certain conditions, uniqueness is also shown. 相似文献
206.
A convective flow CO laser composed of polytetrafluoroethylene discharge tubes, nickel–chromium steel components, a cupric heat exchanger and other components is described. Operating in liquid nitrogen condition, output power of 60 W has been obtained from a non-selective cavity. 相似文献
207.
C.-G. Duan L.-H. Song L.-J. Huo G.-L. Li 《The European Physical Journal C - Particles and Fields》2003,29(4):557-561
The energy loss effect in nuclear matter, which is a nuclear effect apart from the nuclear effect on the parton distribution as in deep-inelastic scattering process, can be measured best by the nuclear dependence of the high energy nuclear Drell-Yan process. By means of the nuclear parton distribution studied only with lepton deep-inelastic scattering experimental data, the measured Drell-Yan production cross sections for 800 GeV proton incident on a variety of nuclear targets are analyzed within the Glauber framework which takes into account the energy loss of the beam proton. It is shown that the theoretical results with considering the energy loss effect are in good agreement with the FNAL E866 data.Arrival of the final proofs: 24 June 2003 相似文献
208.
Yun-Zhi Tang Shao-Song Qian Xi-Sen Wang Hong Zhao Xue-Feng Huang Yong-Hua Li Xing-Cai Jiao Ren-Gen Xiong Prof. Dr. 《无机化学与普通化学杂志》2004,630(11):1623-1626
The in situ hydrolysis of phthalyl-γ-glutaminyl-histidine with Cd(ClO4)2·6H2O in the presence of water and methanol affords a novel two-dimensional cadmium coordination polymer, a new phase, anhydrous cadmium(II) phthalate, ( 1 ). The structure was determined by single crystal X-ray diffraction. Crystal data: P21/c, a = 13.8168(14), b = 7.0351(7), c = 8.2054(8) Å, β = 105.540(2)°, V = 768.43(13) Å3, Z = 4, R1 = 0.0380, wR2 = 0.1111. 相似文献
209.
By further generalizing the skew-symmetric triangular splitting iteration method studied by Krukier, Chikina and Belokon (Applied Numerical Mathematics, 41 (2002), pp. 89–105), in this paper, we present a new iteration scheme, called the modified skew-Hermitian triangular splitting iteration method, for solving the strongly non-Hermitian systems of linear equations with positive definite coefficient matrices. We discuss the convergence property and the optimal parameters of this new method in depth. Moreover, when it is applied to precondition the Krylov subspace methods like GMRES, the preconditioning property of the modified skew-Hermitian triangular splitting iteration is analyzed in detail. Numerical results show that, as both solver and preconditioner, the modified skew-Hermitian triangular splitting iteration method is very effective for solving large sparse positive definite systems of linear equations of strong skew-Hermitian parts. 相似文献
210.
A sample of 1233 events is used to study the general characteristics of {}^{16}O-Em interactions at 4.5 A GeV/c. Multiplicity and angular distributions of slow particles and correlations among them are discussed. The present data are compared with the corresponding results from the interactions of other projectiles at the same energy and also the same projectile at different energies. The results indicate that black particle production is independent of the energy and mass of the projectile, but for grey particles it is dependent on the mass of projectile. 相似文献