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971.
In this paper, we firstly propose a new simple method to calculate entanglement swapping of χ-type entangled states, and then present a novel quantum steganography protocol with large payload. The new protocol adopts entanglement swapping to build up the hidden channel within quantum secure direct communication with χ-type entangled states for securely transmitting secret messages. Comparing with the previous quantum steganographies, the capacity of the hidden channel is much higher, which is increased to eight bits. Meanwhile, due to the quantum uncertainty theorem and the no-cloning theorem its imperceptibility is proved to be great in the analysis, and its security is also analyzed in detail, which is proved that intercept-resend attack, measurement-resend attack, ancilla attack, man-in-the-middle attack or even Dos(Denial of Service) attack couldn't threaten it. As a result, the protocol can be applied in various fields of quantum communication. 相似文献
972.
Tzonelih Hwang Song-Kong Chong Yi-Ping Luo Tong-Xuan Wei 《Optics Communications》2011,284(12):3144-3148
Recently, Chong et al. [Opt. Comm. 284, (2011) 893-895] pointed out that a dishonest party in Yang and Wen's arbitrated quantum signature scheme [Opt. Comm. 283, (2010) 3198-3201] is able to reveal the other party's secret key without being detected by using the Trojan-horse attacks. However, the solution to avoid the attack still remains open. This work further points out that in Yang and Wen's scheme, the arbitrator is unable to arbitrate the dispute between two users. Consequently, a user can deny that he/she has signed or verified a signature without performing a Trojan-horse attack. A solution is proposed to solve this problem as well as the open problem mentioned earlier. 相似文献
973.
Fangfang Luo Geng Lin Haiyi Sun Li Liu Qingxi Chen Jianrong Qiu Zhizhan Xu 《Optics Communications》2011,284(19):4592-4595
Permanent microscale bubbles with varied size and number density are induced in borosilicate glasses by adjusting the focusing depth (FD) of a tightly focused femtosecond laser. With continuously increasing of the focusing depth, the average size of generated bubbles experiences an increase-decrease process. However, the number density of generated bubbles experiences an opposite changing process compared to the change of the size. The possible mechanism for the bubble generation and changing with the focusing depth has been discussed. 相似文献
974.
We report a new type of black silicon: flexible black silicon. A silicon-on-insulator (SOI) wafer is irradiated by automatically scanning a femtosecond laser and then split by etching out the SOI silica middle layer. Large-area, uniform micro spikes on the surface of a very thin flexible silicon layer are obtained. The black silicon shows good flexibility and optical properties. The absorption spectrum of the flexible black silicon is as high as 97% in the visible and insensitive to the change of the incident angle of the light, which makes it a potential good candidate as an absorber for the solar-thermo generator. 相似文献
975.
A numerical wave optics approach for simulating multiplex super Gaussian beam combination in high-power laser facility is presented. The approach involves the application of a sequence of random phase screens and von Karman turbulence phase to an initial beam field and the summation of the intensity results. The analytical and numerical calculation results have been given to illustrate the properties of the resulting far-field pattern after coherent, incoherent and spatially coherent combination, and some of that are compared with experimental results. The approach can be used for modeling and evaluating applications such as high-power laser shooting that might utilize different beams combining approach. 相似文献
976.
We report a simple fabricating approach to control the mode couplings in long-period fiber gratings (LPFGs) through side exposing fiber to long-pulse-10.6-μm laser from a cheap, internally modulated CO2 tube. By tuning focused-spot size on fibers, not only circularly symmetric mode coupling but also asymmetric mode couplings can be effectively achieved. Simulation of mode profiles in grating cross-section with Finite Element Method (FEM), and LPFG-cladding etching experiment with hydrofluoric acid (HF), support our explanation that asymmetric mode coupling in LPFGs depends on local refractive-index (RI) change within an azimuthally thin cladding layer, resulted from large-spot method induced deep melt flow on fiber surface during CO2 laser irradiation. 相似文献
977.
In this paper, we use a two-photon technique to record data points on bisazobenzene-containing films. The recording data points are evidently polarization dependent. It is found that the recording data points can be erased by the linearly polarized light whose polarization direction is perpendicular to that of the recording beam and then, in the same region, new data can be rewritten after erasing. In addition, the recorded data can also be erased completely by the circularly polarized light. Compared with linearly polarized beam, the circularly polarized light is a better choice for erasure as no main orientation is regained after erasing rather than reorientation. 相似文献
978.
A set of recursion equations was developed for the design of an optical interleaver based on retardant crystals and a third-order optical interleaver with maximally flat passband was designed accordingly. The fabrication tolerance for the retardant crystals was simulated based on crosstalk consideration. Given crosstalk requirement of −25 dB, the tolerance for the crystal thickness and axis orientation was obtained as 0.91 μm and 0.51°, respectively. 相似文献
979.
以CuSO4/sub>为前驱体,HCl为添加剂,采用电化学沉积方法,在室温条件下制得了μm级、面心立方结构分形铜的枝状晶体,研究了铜离子浓度、硫酸浓度、电流密度、沉积时间、氯离子浓度等实验参数对分形枝状铜晶体尺寸、结构的影响。结果表明:硫酸的浓度对铜沉积物结构无明显影响;随着Cu2+/sup>浓度的不断增大,铜沉积物的分形效果越来越明显;增大电流密度(0.4~1.6 A·cm-2/sup>),铜沉积物由致密向多分枝的开放型转变;延长沉积时间(大于等于5 min),可获得含大量次级分枝铜的晶体;适当增加盐酸用量(0.05~0.20 mol/L),铜沉积物枝晶尺寸显著减小。最后讨论了分形枝晶铜在碱性条件下氧化甲醇的电化学性能。 相似文献
980.