全文获取类型
收费全文 | 68799篇 |
免费 | 12609篇 |
国内免费 | 19258篇 |
专业分类
化学 | 51358篇 |
晶体学 | 2262篇 |
力学 | 4539篇 |
综合类 | 1978篇 |
数学 | 9740篇 |
物理学 | 30789篇 |
出版年
2024年 | 194篇 |
2023年 | 851篇 |
2022年 | 2324篇 |
2021年 | 2418篇 |
2020年 | 2474篇 |
2019年 | 2639篇 |
2018年 | 2308篇 |
2017年 | 2926篇 |
2016年 | 2740篇 |
2015年 | 3556篇 |
2014年 | 4208篇 |
2013年 | 5586篇 |
2012年 | 5956篇 |
2011年 | 6236篇 |
2010年 | 5704篇 |
2009年 | 5631篇 |
2008年 | 6349篇 |
2007年 | 5576篇 |
2006年 | 5467篇 |
2005年 | 4673篇 |
2004年 | 3772篇 |
2003年 | 2687篇 |
2002年 | 2796篇 |
2001年 | 2584篇 |
2000年 | 2651篇 |
1999年 | 1627篇 |
1998年 | 911篇 |
1997年 | 701篇 |
1996年 | 654篇 |
1995年 | 575篇 |
1994年 | 567篇 |
1993年 | 512篇 |
1992年 | 392篇 |
1991年 | 366篇 |
1990年 | 312篇 |
1989年 | 254篇 |
1988年 | 265篇 |
1987年 | 199篇 |
1986年 | 173篇 |
1985年 | 138篇 |
1984年 | 136篇 |
1983年 | 118篇 |
1982年 | 74篇 |
1981年 | 71篇 |
1980年 | 62篇 |
1979年 | 62篇 |
1978年 | 26篇 |
1977年 | 18篇 |
1965年 | 24篇 |
1959年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
71.
72.
In this note, we study convergence rates in the law of large numbers for independent and identically distributed random variables under sublinear expectations. We obtain a strong L^p-convergence version and a strongly quasi sure convergence version of the law of large numbers. 相似文献
73.
Ying Zhang Gang Hu Shigang Chen H.A. Cerdeira 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(3):381-384
A method of controlling global stochasticity in Hamiltonian systems by applying nonlinear perturbation is proposed. With the
well-known standard map we demonstrate that this control method can convert global stochasticity into regular motion in a
wide chaotic region for arbitrary initial condition, in which the control signal remains very weak after a few kicks. The
system in which chaos has been controlled approximates to the original Hamiltonian system, and this approach appears robust
against small external noise. The mechanism underlying this high control efficiency is intuitively explained.
Received 15 January 2002 Published online 6 June 2002 相似文献
74.
75.
ZHANG Lin-bo LIU Xiao-hua JIANG Yuan GUO Ping SHA Li-jin LI Yu 《高等学校化学研究》2006,22(2):139-144
After establishing hemi-Parkinsonian rat models, the relationships between neuron death and the expression of several proteins, such as c-Fos, GFAP, GDNF, NF-κB and some cytokines were determined. Therapeutics experiments with notoginsenoside-Rg1 were carried out. The research results show that the expressions of GFAP, NF-Kκ and c-Fos will obviously increase in the lesion side of the striatum and the expression of GDNF will decrease, which implies that the signal transduction pathway may participate in the apoptosis in neurons. The levels of some cytokines such as TNF-α, IL-1β in the striatum of PD rat models increased compared to those of normal rats. The results of the therapeutics experiments show that notoginsenoside-Rg1 may repress the immune inflammation response and regulate the immune function through the neuro-immune molecular network. Therefore, notoginsenoside-Rg1 can be used as an effective drug for anti-oxidation and anti-inflammation, and can be used in the therapy of Parkinson's disease(PD). 相似文献
76.
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
77.
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
78.
高固体分羟基丙烯酸树脂的合成 总被引:1,自引:0,他引:1
以过氧化二苯甲酰(BPO)/过氧化二异丙苯(DCP)(质量比为2:3)为复合引发剂,二甲苯为溶剂,选用适量含羟基单体和分子量调节剂,以减缓树脂合成聚合反应中的自动加速现象,合成了分子量为3000-4000,多分散性指数d〈2的高固体分羟基丙烯酸树脂.该树脂与缩二脲多异氰酸酯(HDI)的配漆实验证明,所得漆膜鲜映性好、丰满度高、色泽好、雾影值低、综合性能较好. 相似文献
79.
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
80.
This study presents a compact optical configuration that can generate a multiplex dot-matrix hologram with complex interlaced images for anti-counterfeiting applications on valuable paper. Varying the orientation of the interference plane can enable the multiplex hologram to be recorded without changing the interference angle of two laser beams. With its simple asymmetric optical setup, a multiplex hologram with many interlaced images can be efficiently fabricated, increasing the cost of imitation. Experimental details of the asymmetric optical setup are also described. 相似文献