全文获取类型
收费全文 | 4165篇 |
免费 | 670篇 |
国内免费 | 494篇 |
专业分类
化学 | 3266篇 |
晶体学 | 65篇 |
力学 | 94篇 |
综合类 | 23篇 |
数学 | 12篇 |
物理学 | 1869篇 |
出版年
2024年 | 9篇 |
2023年 | 29篇 |
2022年 | 99篇 |
2021年 | 99篇 |
2020年 | 153篇 |
2019年 | 131篇 |
2018年 | 103篇 |
2017年 | 154篇 |
2016年 | 158篇 |
2015年 | 162篇 |
2014年 | 189篇 |
2013年 | 406篇 |
2012年 | 241篇 |
2011年 | 263篇 |
2010年 | 204篇 |
2009年 | 249篇 |
2008年 | 280篇 |
2007年 | 284篇 |
2006年 | 271篇 |
2005年 | 218篇 |
2004年 | 202篇 |
2003年 | 187篇 |
2002年 | 144篇 |
2001年 | 172篇 |
2000年 | 114篇 |
1999年 | 133篇 |
1998年 | 105篇 |
1997年 | 80篇 |
1996年 | 77篇 |
1995年 | 68篇 |
1994年 | 49篇 |
1993年 | 41篇 |
1992年 | 41篇 |
1991年 | 27篇 |
1990年 | 23篇 |
1989年 | 24篇 |
1988年 | 16篇 |
1987年 | 16篇 |
1986年 | 14篇 |
1985年 | 9篇 |
1984年 | 11篇 |
1983年 | 10篇 |
1982年 | 9篇 |
1981年 | 9篇 |
1980年 | 11篇 |
1979年 | 7篇 |
1978年 | 4篇 |
1976年 | 5篇 |
1974年 | 3篇 |
1973年 | 5篇 |
排序方式: 共有5329条查询结果,搜索用时 31 毫秒
991.
An effective teleportation scheme for an unknown ionic internal state
via trapped ions is proposed without joint Bell-state measurement
(BSM). In the constructed quantum channel process, we make use of
entanglement swapping to avoid decrease in entanglement during
the distributing of particles. Thus our scheme provides new prospects
for quantum teleportation in a longer distance. The distinct
advantage of our scheme is insensitive to the heating of vibrational
mode. Furthermore, our scheme has no any individual optical access,
and the successful probability also can reach 1. 相似文献
992.
In the system with two two-level ions confined in a linear trap,
this paper presents a simple scheme to realize the quantum phase
gate (QPG) and the swap gate beyond the Lamb--Dicke (LD) limit.
These two-qubit quantum logic gates only involve the internal states
of two trapped ions. The scheme does not use the vibrational mode as
the data bus and only requires a single resonant interaction of the
ions with the lasers. Neither the LD approximation nor the auxiliary
atomic level is needed in the proposed scheme. Thus the scheme is
simple and the interaction time is very short, which is important in
view of decoherence. The experimental feasibility for achieving this
scheme is also discussed. 相似文献
993.
Controlling optical responses through local dielectric resonance in nanometre metallic clusters 下载免费PDF全文
Optical responses in dilute composites are controlled through the
local dielectric resonance of metallic clusters. We consider two
located metallic clusters close to each other with admittances
\varepsilon1 and \varepsilon2. Through varying the
difference admittance ratio \eta [ = (\varepsilon2- \varepsilon
0) / (\varepsilon1- \varepsilon0)], we find that their
optical responses are determined by the local resonance. There is a
blueshift of absorption peaks with the increase of \eta.
Simultaneously, it is known that the absorption peaks will be
redshifted by enlarging the cluster size. By adjusting the
nano-metallic cluster geometry, size and admittances, we can control
the positions and intensities of absorption peaks effectively. We
have also deduced the effective linear optical responses of
three-component composites \varepsilone= \varepsilon0
\bigl(1 + \sumn=1^{ns} [(\gamman2+ \eta \gamman2)/({\varepsilon0(s - sn))]} \bigr), and the sum
rule of cross sections: \sumn=1^{ns} {(\gamman2+
\eta \gamman2 ) = Nh1+ Nh2, where Nh1and
Nh2 are the numbers of \varepsilon1 and \varepsilon2
bonds along the electric field, respectively. These results may be
beneficial to the study of surface plasmon resonances on a nanometre
scale. 相似文献
994.
We propose a scheme for the preparation of one-dimensional and
two-dimensional cluster states by using hot trapped ions. The scheme
is based on the interaction between two ions and bichromatic
radiation. The vibrational mode in our protocol is only virtually
excited so that the system is insensitive to the thermal field. In
addition, we only use two levels of ions as qubits and the
successful probability may achieve 100%. 相似文献
995.
Minghui Yu Fang He Yanli Tang Shu Wang Yuliang Li Daoben Zhu 《Macromolecular rapid communications》2007,28(12):1333-1338
A new non-ionic water-soluble polyfluorene that contains two benzo-18-crown-6 side chains per repeat unit (PFDC) is synthesized and characterized. Upon addition of Pb2+ ions to a solution of PFDC, the PFDC fluorescence is strongly quenched. The minor interference from other metal ions, especial from Cu2+ and Hg2+ions, clearly shows that the PFDC can be used to detect Pb2+ ions with high selectivity. The fluorescence quenching of PFDC in solution originates from the multivalent coordination of the crown-ether moieties to Pb2+ ions followed by precipitation. In comparison to ionic conjugated polymers, the pH of the medium shows less effect on the binding of non-ionic PFDC to Pb2+ ions.
996.
荧光光谱法研究锌(Ⅱ)存在下诺氟沙星与牛血清白蛋白的结合作用 总被引:3,自引:0,他引:3
在模拟生理条件下,用荧光光谱法研究了诺氟沙星对牛血清白蛋白以及锌(Ⅱ)对诺氟沙星和牛血清白蛋白荧光光谱特性的影响。实验结果表明,诺氟沙星和锌(Ⅱ)都可以使牛血清白蛋白的荧光强度发生猝灭。根据荧光猝灭双倒数图计算诺氟沙星和牛血清白蛋白之间的结合常数为6.80×105,结合位点数为1.21。由此可见,诺氟沙星和牛血清白蛋白之间有很强的结合作用,这为诺氟沙星在体内被蛋白质储存和转运提供了条件。并且在锌(Ⅱ)存在下,诺氟沙星与牛血清白蛋白的结合作用有所增强。荧光猝灭双倒数图计算的结果表明,诺氟沙星和牛血清白蛋白之间的结合常数和结合位点数均随锌(Ⅱ)浓度的增大而增大。通过对锌(Ⅱ)、诺氟沙星和牛血清白蛋白的结合反应的研究,进一步探讨了诺氟沙星、锌(Ⅱ)在生物体内与蛋白质相互作用的机理。 相似文献
997.
近年来,表面等离子共振(SPR)现象、由于在金属纳米材料研究以及在作为灵敏检测不同化学和生化物种信号的报告器方面有着特殊的应用价值,因而受到广泛的关注.本文较详细的介绍了表面等离子共振现象的形成机制,特别对如何利用本方法作为一种新型的物种检测报告器的有关问题做了较系统的讨论. 相似文献
998.
999.
1000.
The random matrices theory is applied to a study of the heat capacity of small metallic grains. The numerical calculations indicate that the level distribution and the difference between the particles respectively with an even and an odd numbers of electrons are important for the heat capacity of the small metallic grains at a low temperature and the level correlation mainly affects the heat capacity at a high temperature. 相似文献