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21.
Wide spectral white light emitting diodes have been designed and grown on a sapphire substrate by using a metal-organic chemical vapor deposition system. Three quantum wells with blue-light-emitting, green-light-emitting and red-light-emitting structures were grown according to the design. The surface morphology of the film was observed by using atomic force microscopy. The films were characterized by their photoluminescence measurements. X-ray diffraction θ/2θ scan spectroscopy was carried out on the multi-quantum wells. The secondary fringes of the symmetric ω/2θ X-ray diffraction scan peaks indicate that the thicknesses and the alloy compositions of the individual quantum wells are repeatable throughout the active region. The room temperature photoluminescence spectra of the structures indicate that the white light emission of the multi-quantum wells is obtained. The light spectrum covers 400-700 nm, which is almost the whole visible light spectrum. 相似文献
22.
23.
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
24.
A controlled quantum teleportation scheme of an N-particle unknown state via three-particle W1 states 下载免费PDF全文
In this paper a controlled quantum teleportation scheme of an N-particle unknown state is proposed when N groups of three-particle W1 states are utilized as quantum channels. The quantum information of N-particle unknown state is transmitted from the sender to the recipient under the control of all supervisors. It can be realized with a certain probability. After the sender makes Bell-state measurements and the supervisors perform the computational basis measurements, the recipient will introduce auxiliary particles and carry out unitary transformations depending on classical information from the sender and the supervisors. Finally, the computational basis measurement will be performed by the recipient to confirm whether the teleportation succeeds or not. The successful completion of the scheme relies on all supervisors' cooperation. In addition, the fidelity and security of the scheme are discussed. 相似文献
25.
利用拉曼型的Jaynes-Cummings模型传送两比特的未知原子态 总被引:3,自引:3,他引:3
实现量子态的隐形传送、尤其是多比特量子态的隐形传送在量子信息领域中有非常重要的作用,提出了一种隐形传送两比特未知原子态的方案,在此方案中,用两个两粒子纠缠态代替一个三粒子纠缠态作为量子信道,而且此方案可推广到隐形传送N比特的未知原子态。 相似文献
26.
采用金属有机物化学气相淀积方法在铝酸锂LiAlO2衬底上外延生长m面GaN薄膜.X射线衍射测量的结果表明所得薄膜具有较理想的m面晶体取向,并对其各向异性的应变进行了计算,摇摆曲线的测量发现样品存在明显的面内结构各向异性.采用偏振光致发光研究材料的面内光学各向异性,发现随着偏振角度的改变,发光峰的峰位和强度均有明显变化,并用对称性破缺导致价带子带劈裂的理论对结果进行了解释.
关键词:
m面GaN
结构各向异性
偏振光致发光 相似文献
27.
为了获得1064nm,1319nm,589nm及660nm 4波长激光同时输出,设计了双激光晶体同步声光调Q“T”型复合谐振腔。通过软件模拟与计算,筛选出理想的谐振腔参数,使2波长基频光在大泵浦电流范围内能稳定运转。以KTP晶体和LBO晶体为和频晶体和倍频晶体,在泵浦电流为17A,重复频率为10kHz时,获得了1064nm,1319nm,589nm和660nm 4波长激光输出,最高平均功率分别为150mW,80mW,2.3W和1.7W,同时测得589nm激光和660nm激光的脉冲宽度分别为110ns和130ns。结果表明:使用热稳“T”型复合腔,可以获得4波长激光同时稳定输出。 相似文献
28.
Bin Liu Rong Zhang Zili Xie XiangQian Xiu Liang Li Jieying Kong Huiqiang Yu Pin Han Shulin Gu Yi Shi Zheng YouDou Tang ChenGuang Chen YongHai Wang ZhanGuo 《中国科学G辑(英文版)》2008,51(3):237-242
InN films grown on sapphire at different substrate temperatures from 550°C to 700°C by metalorganic chemical vapor deposition
were investigated. The low-temperature GaN nucleation layer with high-temperature annealing (1100°C) was used as a buffer
for main InN layer growth. X-ray diffraction and Raman scattering measurements reveal that the quality of InN films can be
improved by increasing the growth temperature to 600°C. Further high substrate temperatures may promote the thermal decomposition
of InN films and result in poor crystallinity and surface morphology. The photoluminescence and Hall measurements were employed
to characterize the optical and electrical properties of InN films, which also indicates strong growth temperature dependence.
The InN films grown at temperature of 600°C show not only a high mobility with low carrier concentration, but also a strong
infrared emission band located around 0.7 eV. For a 600 nm thick InN film grown at 600°C, the Hall mobility achieves up to
938 cm2/Vs with electron concentration of 3.9 × 1018 cm−3.
Supported by the National Basic Research Program of China (Grant No. 2006CB6049), the National Natural Science Foundation
of China (Grant Nos. 6039072, 60476030 and 60421003), the Great Fund of the Ministry of Education of China (Grant No. 10416),
the Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20050284004), and the Natural
Science Foundation of Jiangsu Province of China (Grant Nos. BK2005210 and BK2006126) 相似文献
29.
A revised controlled deterministic secure quantum communication protocol using five-photon entangled state is proposed. It amends the security loopholes pointed by Qin et al. in [S.J. Qin, Q.Y. Wen, L.M. Meng, F.C. Zhu, Opt. Commun. 282 (2009) 2656] in the original protocol proposed by Xiu et al. in [X.M. Xiu, L. Dong, Y.J. Gao, F. Chi, Opt. Commun. 282 (2009) 333]. The security loopholes are solved by using order rearrangement of transmission photons and two-step security test. 相似文献
30.
High-Frequency Einstein-Podolsky-Rosen Entanglement via Atomic Memory Effects in Four-Wave Mixing 下载免费PDF全文
Atomic memory effects occur when the atomic relaxation times are comparable to or much longer than the cavlty relaxation times. We show that by using the memory effects, it is possible to obtain high-frequency Einstein- Podolsky-tlosen entanglement between a pair of Stokes and anti-Stokes fields in a four-wave mixing system. The physical origin is traced to the dynamical Stark splittings of dressed states due to the parametrically amplified fields. This mechanism provides an alternative and efficient way for sideband entanglement. 相似文献