全文获取类型
收费全文 | 70405篇 |
免费 | 9880篇 |
国内免费 | 6673篇 |
专业分类
化学 | 47038篇 |
晶体学 | 659篇 |
力学 | 4661篇 |
综合类 | 515篇 |
数学 | 8449篇 |
物理学 | 25636篇 |
出版年
2024年 | 228篇 |
2023年 | 1399篇 |
2022年 | 2281篇 |
2021年 | 2477篇 |
2020年 | 2525篇 |
2019年 | 2423篇 |
2018年 | 2190篇 |
2017年 | 1941篇 |
2016年 | 2967篇 |
2015年 | 3080篇 |
2014年 | 3657篇 |
2013年 | 4849篇 |
2012年 | 5898篇 |
2011年 | 6016篇 |
2010年 | 4083篇 |
2009年 | 4022篇 |
2008年 | 4195篇 |
2007年 | 3792篇 |
2006年 | 3573篇 |
2005年 | 3095篇 |
2004年 | 2480篇 |
2003年 | 1896篇 |
2002年 | 1682篇 |
2001年 | 1520篇 |
2000年 | 1418篇 |
1999年 | 1563篇 |
1998年 | 1330篇 |
1997年 | 1169篇 |
1996年 | 1228篇 |
1995年 | 1071篇 |
1994年 | 1007篇 |
1993年 | 865篇 |
1992年 | 768篇 |
1991年 | 664篇 |
1990年 | 555篇 |
1989年 | 481篇 |
1988年 | 366篇 |
1987年 | 350篇 |
1986年 | 297篇 |
1985年 | 300篇 |
1984年 | 202篇 |
1983年 | 176篇 |
1982年 | 145篇 |
1981年 | 112篇 |
1980年 | 82篇 |
1978年 | 56篇 |
1977年 | 52篇 |
1976年 | 50篇 |
1975年 | 57篇 |
1973年 | 57篇 |
排序方式: 共有10000条查询结果,搜索用时 13 毫秒
981.
描述了简并V型三能级原子与单模相干态光场的Raman相互作用,获得了处于激发态单态的原子与相干态光场相互作用的结果.利用探测原子与光场的相互作用将原子和光场制备成最大缠结态,并注入待测原子,通过原子与腔模构成的Bell基矢演化,对腔场进行选择性探测,获得探测原子相互作用后可能的量子状态,然后对待测原子与腔场进行联合探测,接着对探测原子的量子状态实施幺正变换,就将探测原子制备到待测原子的初始量子态上,从而实现未知原子态的隐形传送. 相似文献
982.
983.
984.
985.
孔径旋转频闪散斑照相法测量物体的固有频率 总被引:1,自引:1,他引:1
提出了一种测量物体固有频率的新方法--孔径旋转频闪散斑照相法。该方法能方便地测量振动物体的固有频率,具有精度高、全场显示、条纹可见度好等优点,给出了理论分析和实验结果。 相似文献
986.
The laser-induced fluorescence excitation spectrum of the A2Σ-X2Π3/2 transition of CuO in the 540-620nm region has been studied, where the CuO molecule was produced by using the technique of dc discharge reaction under a supersonic condition. We have recorded and rotationally analysed the 0-0, 1-0, 2-0 and 3-0 bands. The rotational constants of the upper state A2Σ- were determined and vibrational constants improved. In addition, the lifetime measurement for the A2Σ- state was carried out under the collision-free condition, and the lifetimes obtained are 469±2, 456±2, 488±3 and 490±4ns for v'=0, v'=1, v'=2 and v'=3 levels, respectively. 相似文献
987.
We propose a scheme for the implementation of nonlocal quantum swap operation on two spatially separated entangled pairs and we show that the operation can swap two qubits of these entangled pairs.We discuss the resources of the entangled qubits and classical communication bits required for the optimal implementation of the nonlocal quantum swap operation.We also put forward a scheme for probabilistic implementation of nonlocal swap operation via a nonmaximally entangled quantum channel.The probability of a successful nonlocal swap operation is obtained by introducing a collective unitary transformation. 相似文献
988.
The exact solutions of the rate equations of the n-polymer stochastic aggregation involving two types of clusters, active and passive for the kernel \dprnk=1s(ik)(s(ik)=ik) and \dsumnk=1s(ik)(s(ik)=ik), are obtained. The large-mass behaviours of the final mass distribution of the active and passive clusters have scaling-like forms, although the models exhibit different properties. Respectively, they have different decay exponents γ=\dfrac{2n+1}{2(n-1)} and γ=q+\dfrac{2n+1}{2(n-1)} for \dprnk=1}s(ik)(s(ik)=ik) and γ=\dfrac 3{2(n-1)} and γ=q+\dfrac 3{2(n-1)} for \dsumnk=1}s(ik)(s(ik)=ik), which include exponents of two-polymer stochastic aggregation. We also find that gelation is suppressed for kernel \dprnk=1s(ik)(s(ik)=ik) which is different from the deterministic aggregation. 相似文献
989.
A chaotic synchronized system of two coupled skew tent maps is discussed in this paper. The locally and globally riddled basins of the chaotic synchronized attractor are studied. It is found that there is a novel phenomenon in the local-global riddling bifurcation of the attractive basin of the chaotic synchronized attractor in some specific coupling intervals. The coupling parameter corresponding to the locally riddled basin has a single value which is embedded in the coupling parameter interval corresponding to the globally riddled basin, just like a breakpoint. Also, there is no relation between this phenomenon and the form of the chaotic synchronized attractor. This phenomenon is found analytically. We also try to explain it in a physical sense. It may be that the chaotic synchronized attractor is in the critical state, as it is infinitely close to the boundary of its attractive basin. We conjecture that this isolated critical value phenomenon will be common in a system with a chaotic attractor in the critical state, in spite of the system being discrete or differential. 相似文献
990.
An open plus nonlinear closed loop control law is presented for chaotic oscillations described by a set of nonautonomous second-order ordinary differential equations.It is proven that the basins of entrainment are global when the right-hand sides of the equations are given by arbitrary polynomical functions.The forece Duffing oscillator and the forced van der Pol oscillator are treated as numerical examples to demonstrate the applications of the method. 相似文献