全文获取类型
收费全文 | 146689篇 |
免费 | 24996篇 |
国内免费 | 28233篇 |
专业分类
化学 | 103022篇 |
晶体学 | 3069篇 |
力学 | 9494篇 |
综合类 | 2409篇 |
数学 | 20126篇 |
物理学 | 61798篇 |
出版年
2024年 | 471篇 |
2023年 | 2476篇 |
2022年 | 5350篇 |
2021年 | 5468篇 |
2020年 | 5660篇 |
2019年 | 5488篇 |
2018年 | 5122篇 |
2017年 | 5469篇 |
2016年 | 6505篇 |
2015年 | 7211篇 |
2014年 | 8815篇 |
2013年 | 11365篇 |
2012年 | 12745篇 |
2011年 | 13225篇 |
2010年 | 10499篇 |
2009年 | 10327篇 |
2008年 | 11160篇 |
2007年 | 9872篇 |
2006年 | 9507篇 |
2005年 | 7930篇 |
2004年 | 6301篇 |
2003年 | 4694篇 |
2002年 | 4489篇 |
2001年 | 4120篇 |
2000年 | 4111篇 |
1999年 | 3229篇 |
1998年 | 2303篇 |
1997年 | 2015篇 |
1996年 | 1983篇 |
1995年 | 1736篇 |
1994年 | 1608篇 |
1993年 | 1378篇 |
1992年 | 1235篇 |
1991年 | 1025篇 |
1990年 | 885篇 |
1989年 | 725篇 |
1988年 | 604篇 |
1987年 | 529篇 |
1986年 | 473篇 |
1985年 | 355篇 |
1984年 | 305篇 |
1983年 | 254篇 |
1982年 | 201篇 |
1981年 | 141篇 |
1980年 | 120篇 |
1979年 | 80篇 |
1978年 | 49篇 |
1977年 | 32篇 |
1976年 | 30篇 |
1975年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
D. Fong J. H. Hamilton A. V. Ramayya J. K. Hwang C. Goodin K. Li J. Kormicki J. O. Rasmussen Y. X. Luo S. C. Wu I. Y. Lee A. V. Daniel G. M. Ter-Akopian G. S. Popeko A. S. Fomichev A. M. Rodin Yu. Ts. Oganessian M. Jandel J. Kliman L. Krupa J. D. Cole M. A. Stoyer R. Donangelo W. C. Ma 《Physics of Atomic Nuclei》2006,69(7):1161-1167
The hot bimodal fission of 252Cf is reexamined with new high-statistics data. We constructed a γ-γ-γ coincidence cube for binary fission and LCP-gated γ-γ matrix for ternary fission. By identifying the secondary fission fragments from their γ-ray transitions, we measured the yields for various fission splits. The normal neutron yield distribution is found to be
Gaussian for Xe-Ru. However, the binary fission split of Ba-Mo is found to exhibit a bimodal neutron distribution with the
“hot mode” corresponding to ≈3.1% of the total yield. In α ternary fission, the first measurements of yields for specific fission splits are presented. The Te-α-Ru and Xe-α-Mo neutron yields fit well with a single mode, but the Ba-α-Zr split shows evidence for an enhanced hot mode with an intensity of ≈13.8% of the normal mode.
The text was submitted by the authors in English. 相似文献
152.
Jiaqiang Wang Hua Fang Ying Li Junjie Li Zhiying Yan 《Journal of molecular catalysis. A, Chemical》2006,250(1-2):75-79
Cobalt-doped mesoporous titania with a crystalline framework synthesized by surfactant templating method presented highly selective (99%) and reasonable conversion rate (49%) of catalytic oxidation of para-chlorotoluene to para-chlorobenzaldehyde in acetic acid using aqueous hydrogen peroxide as oxidant for the first time. Recycling of the catalyst indicates that the catalyst can be used a number of times without losing its activity to a greater extent. By contrast, cobalt-doped mesoporous titania without a crystalline structure and cobalt doped the commercial titania, Degussa P25 prepared by impregnation method with the similar concentration of cobalt were found inactive. The effects of catalyst concentration, reaction time, reaction temperature, and solvents on the performance of the catalyst were also investigated. 相似文献
153.
A functional equation of nonlinear iterates is discussed on the circle S1 for its continuous solutions and differentiable solutions. By lifting to R, the existence, uniqueness and stability of those solutions are obtained. Techniques of continuation are used to guarantee the preservation of continuity and differentiability in lifting. 相似文献
154.
Baoqiang Li Dechang Jia Yu Zhou Qiaoling Hu Wei Cai 《Journal of magnetism and magnetic materials》2006
Chitosan/magnetite nanocomposite was synthesized induced by magnetic field via in situ hybridization in ambient condition. Results of XRD patterns and TEM micrographs indicated that magnetite particles with 10–20 nm were dispersed in chitosan homogeneously. An interesting result is that magnetite nanoparticles were assembled to form chain-like structures under the influence of the external magnetic field, which mimics the magnetite chains inside of magnetotatic bacteria. The saturated magnetization (Ms) of nano-magnetite in chitosan was 50.54 emu/g, which is as high as 54% of bulk magnetite. The remanence (Mr) and coercivity (Hc) were 4 emu/g and14.8 Oe, respectively, which indicated that magnetite nanoparticles were superparamagnetic. The key of route is that a pre-precipitated chitosan hydrogel membrane, used as chemical reactor, which controlled the precipitation of chitosan precipitation and in situ transformation of magnetite from the precursor simultaneously in the magnetic field environment. 相似文献
155.
Entangled states based on two coherent states 3π/2 out of phase with each other, i.e. |α〉 and e^iФ|-iα〉, as well as on a special state with a relative phase Ф = |α|^2, are constructed. By analysing the amount of entanglement it is evident that entangled states based on this special state can be used as an excellent resource for quantum teleportation. It is also revealed that these entangled states possess some nonclassical features. 相似文献
156.
基于SPA的双枝模糊决策分析 总被引:3,自引:0,他引:3
将集对理论(SPA)与双枝模糊决策理论相结合,用集对分析的方法研究进行双枝模糊决策的方法,分别对双枝模糊决策因素域和双枝模糊决策的上枝、下枝和双枝进行了集对分析,给出了用SPA进行双枝模糊决策的性质,同时讨论了双枝模糊决策的动态分析方法,以及双枝模糊决策度强弱态势预测的方法,从而为双枝模糊决策理论的研究提供了新的视角和方法,为双枝模糊决策的应用提供了更方便的工具和更强的理论支持。 相似文献
157.
E. Liénard G. Ban J. Blieck D. Durand F. Duval X. Fléchard M. Herbane M. Labalme Y. Lemière F. Mauger A. Méry O. Naviliat-Cuncic D. Rodríguez J. C. Thomas 《Hyperfine Interactions》2006,172(1-3):29-33
We report on the status of the LPCTrap experiment, devoted to measure the β–ν angular correlation in the pure Gamow–Teller
decay of 6He. This measurement is motivated by the search for the presence of tensor type contributions to the weak interaction. The
6He ions are confined in a novel transparent Paul trap. The β particles and the recoil ions are detected in coincidence to
deduce the angular correlation parameter. The commissioning run performed in 2005 has given the proof of principle of this
experiment. Up to 105 coincidences were recorded during a second run in 2006. 相似文献
158.
李明融 《数学物理学报(B辑英文版)》2007,27(4):703-734
In this article the author works with the ordinary differential equation u" = |u|^p for some p 〉 0 and obtains some interesting phenomena concerning blow-up, blow-up rate, life-span, stability, instability, zeros and critical points of solutions to this equation. 相似文献
159.
160.
Based on solving the couple mode equation numerically, the characterization of the signal power on the gate power was analyzed. And the relationship of the tolerance of the grating period and the bulk temperature on the interaction length was analyzed. 相似文献