全文获取类型
收费全文 | 1092篇 |
免费 | 157篇 |
国内免费 | 195篇 |
专业分类
化学 | 381篇 |
晶体学 | 17篇 |
力学 | 11篇 |
综合类 | 5篇 |
数学 | 387篇 |
物理学 | 643篇 |
出版年
2023年 | 2篇 |
2022年 | 8篇 |
2021年 | 14篇 |
2020年 | 7篇 |
2019年 | 10篇 |
2018年 | 6篇 |
2017年 | 8篇 |
2016年 | 12篇 |
2015年 | 28篇 |
2014年 | 72篇 |
2013年 | 120篇 |
2012年 | 166篇 |
2011年 | 166篇 |
2010年 | 121篇 |
2009年 | 118篇 |
2008年 | 109篇 |
2007年 | 114篇 |
2006年 | 94篇 |
2005年 | 40篇 |
2004年 | 35篇 |
2003年 | 30篇 |
2002年 | 38篇 |
2001年 | 30篇 |
2000年 | 23篇 |
1999年 | 12篇 |
1998年 | 11篇 |
1997年 | 9篇 |
1996年 | 7篇 |
1995年 | 8篇 |
1994年 | 8篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 4篇 |
排序方式: 共有1444条查询结果,搜索用时 15 毫秒
81.
We propose a scheme for implementing the Grover search algorithm
with two superconducting quantum interference devices (SQUIDs) in a
cavity. Our scheme only requires single resonant interaction of the
SQUID-cavity system and the required interaction time is very short.
The simplicity of the process and the reduction of the interaction
time are important for restraining decoherence. 相似文献
82.
TIAN Yupeng YU Wentao FANG Qi WU Jieying JIANG Minhua WANG Hezhou ZHENG Xiguang 《高等学校化学研究》2002,18(2):211-215
The title compound, trans-4-[ p-( N-ethyl-N-(hydroxyethyl ) amino) styryl ]-N-methylpyridiniumtetraphenylborate (abbreviated as ESMT, C46H49N4OB) crystallizes in a space group P1- with a= 0. 983 23 (15)nm, b=1.410 73(16) nm, c=1.54 21(12) nm, a=95.252(13)°, β=91.959(17)°, γ= 107.421(12)°, Z=2, F(000)=712, μ= 0.1 mm-1 Mo Ka radiation, R=0. 093 8. The result shows that the cation of themolecule almost lies in one plane, the hydroxyethyl group is perpendicular to the plane, the anion takes a slightdistorted tetrahedral geometry. Also the thermal stability, two-photon fluorescence, two-photon pumped lasingproperty for the title compound were studied. 相似文献
83.
YUAN Hao LIU Yin-Min ZHANG Wen ZHANG Zhan-Jun 《理论物理通讯》2008,49(1):103-106
Security of the quantum secure direct communication protocol (i.e., the C-S QSDC protocol) recently proposed by Cao and Song [Chin. Phys. Lett. 23 (2006) 290] is analyzed in the case of considerable quantum channel noise. The eavesdropping scheme is presented, which reveals that the C-S QSDC protocol is not secure if the quantum bit error rate (QBER) caused by quantum channel noise is higher than 4.17%. Our eavesdropping scheme induces about 4.17% QBER for those check qubits. However, such QBER can be hidden in the counterpart induced by the noisy quantum channel if the eavesdropper Eve replaces the original noisy channel by an ideal one. Furthermore, if the QBER induced by quantum channel noise is lower than 4.17%, then in the eavesdropping scheme Eve still can eavesdrop part of the secret messages by safely attacking a fraction of the transmitted qubits. Finally, an improvement on the C-S QSDC protocol is put forward. 相似文献
84.
ZHANG Wen-Hai DAI Jie-Lin YE Liu 《理论物理通讯》2008,49(6):1473-1476
We propose an experimentally feasible scheme to implement the optimal asymmetric economical 1→2 phase-covariant quantum cloning in two dimensions based on the cavity QED technique. The protocol is very simple and only two atoms are required. Our scheme is insensitive to the cavity field states and cavity decay. During the processes, the cavity is only virtually excited and it thus greatly prolongs the efficient decoherent time. Therefore, it may be realized in experiment. 相似文献
85.
WU Dao-Hua DONG Ping YANG Ming CAO Zhuo-Liang 《理论物理通讯》2008,49(4):877-880
We propose a scheme for controlled entanglement swapping of continuous variable, where an EPR pair shared by two parties (Alice and Debbie) and a GHZ entangled state shared by three parties (Alice, Bob and Claire) are required. One optical beams of the EPR state will be entangled with the output mode displaced by Bob with the help of Claire. It is shown that the entanglement swapping can occur controlled by the third party (Claire) 相似文献
86.
We propose a scheme to implement the optimal symmetric 1→2 universal quantum telecloning through cavity-assisted interaction. In our scheme, an arbitrary single atomic state can be
telecloned to two single atomic states. And three atoms are trapped
in three spatially separated cavities respectively. With a particular
multiparticle entangled state acting as a quantum information
channel and the trapped single atom acting as a quantum network node
for its long-lived internal state, quantum information can be
telecloned among nodes and can stored in the nodes. 相似文献
87.
We propose a scheme for generating multi-ion graph states using
many trapped ions in thermal motion. Our generation scheme is
insensitive to external state since the interaction between ions
and laser fields does not involve the external degree of freedom.
The scheme can be well realized within the current experimental technique. 相似文献
88.
用直流溅射法制备了6个不同厚度的超薄Ag膜。结合超薄Ag膜的结构特点,采用了Drude模型联合Lorentz Oscillator模型的解谱方法,得到1~6号样品的厚度分别为4.0,6.2,12.5,26.2,30.0和40.6 nm。从拟合结果的消光系数k图谱中发现,在1号到4号样品中分别于430,450,560和570 nm处出现了表面等离子体共振峰(SPR),随膜厚的增加共振峰宽化且峰位红移。最后,利用SPR理论计算出不同厚度Ag薄膜等离子体共振峰出现的位置,并和实验结果进行了比较。 相似文献
89.
两种新颖的咔唑乙酰化衍生物的合成、表征、光谱性质与量子化学研究 总被引:1,自引:0,他引:1
采用Friedel-Crafts亲电取代反应,合成了两种新颖的咔唑乙酰化衍生物[9-己基-3-乙酰基咔唑(3-acetyl-9-n-hexylcarbazole)(AHCZ)和9-己基-3,6-二乙酰基咔唑(3, 6-diacetyl-9-n-hexylcarbazole)(DHCZ)]。通过元素分析、红外光谱、核磁共振谱、有机质谱等方法进行了结构表征。测定了这两种衍生物的紫外-可见光谱,并与咔唑(CZ)及9-己基咔唑(HCZ)进行了比较。AHCZ和DHCZ的吸收强度比CZ和HCZ有明显增强,归因于AHCZ和DHCZ具有大的π共轭体系。采用密度泛函理论(density functional theory, DFT),在B3LYP/6-31G*水平上对两种化合物基态结构进行优化,用含时密度泛函理论(TDDFT)在相同水平上计算了AHCZ和DHCZ的电子吸收光谱,并比较了理论计算结果与实验值。 相似文献
90.
WANG Xian-Ping DONG Ping YANG Ming CAO Zhuo-Liang 《理论物理通讯》2008,50(9):640-642
We propose a scheme for generating multi-ion graph states using many trapped ions in thermal motion. Our generation scheme is insensitive to external state since the interaction between ions and laser fields does not involve the external degree of freedom. The scheme can be well realized within the current experimental technique. 相似文献