全文获取类型
收费全文 | 61920篇 |
免费 | 5027篇 |
国内免费 | 4703篇 |
专业分类
化学 | 38984篇 |
晶体学 | 732篇 |
力学 | 3391篇 |
综合类 | 376篇 |
数学 | 5963篇 |
物理学 | 22204篇 |
出版年
2025年 | 101篇 |
2024年 | 809篇 |
2023年 | 1444篇 |
2022年 | 2329篇 |
2021年 | 2663篇 |
2020年 | 2922篇 |
2019年 | 2777篇 |
2018年 | 1913篇 |
2017年 | 1851篇 |
2016年 | 2744篇 |
2015年 | 2755篇 |
2014年 | 3255篇 |
2013年 | 4040篇 |
2012年 | 4908篇 |
2011年 | 4845篇 |
2010年 | 3360篇 |
2009年 | 3149篇 |
2008年 | 3386篇 |
2007年 | 2984篇 |
2006年 | 2673篇 |
2005年 | 2299篇 |
2004年 | 1785篇 |
2003年 | 1403篇 |
2002年 | 1294篇 |
2001年 | 1049篇 |
2000年 | 910篇 |
1999年 | 1054篇 |
1998年 | 873篇 |
1997年 | 807篇 |
1996年 | 807篇 |
1995年 | 727篇 |
1994年 | 617篇 |
1993年 | 524篇 |
1992年 | 431篇 |
1991年 | 404篇 |
1990年 | 341篇 |
1989年 | 259篇 |
1988年 | 182篇 |
1987年 | 168篇 |
1986年 | 143篇 |
1985年 | 144篇 |
1984年 | 86篇 |
1983年 | 92篇 |
1982年 | 56篇 |
1981年 | 39篇 |
1980年 | 34篇 |
1976年 | 21篇 |
1975年 | 22篇 |
1973年 | 19篇 |
1972年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Min-Sung Kang Chang-Ho Hong Jino Heo Jong-In Lim Hyung-Jin Yang 《International Journal of Theoretical Physics》2014,53(6):1862-1866
This comment explains that the quantum signature scheme proposed by Ming-Xing Luo et al. (in Int. J. Theor. Phys. 51:2134, 2012) cannot satisfy the signature requirements. The comment presents methods of possible attacks by forgers, while also demonstrating that it is difficult to proceed by the normal protocol because of some errors in the formula of the scheme. 相似文献
92.
By introducing four potential functions, the governing equations of plane problems in 1D orthorhombic quasicrystals with piezoelectric effect are composed of four second-order partial differential equations, in which the quasi-harmonic functions are the essential unknowns. The general solution of these equations is further established, and all expressions are expressed in terms of the potential functions. As an application of the general solution, the closed-form solutions are obtained for wedge problems or half-plane problems of 1D orthorhombic piezoelectric quasicrystals. 相似文献
93.
The ratio of K(S)K(S) (K(L)K(L)) and K(L)K(L) production rates is calculated by considering K(0) - K(0) oscillation in J/psi --> K(0)K(0) decay. The theoretical uncertainty due to strong interaction in J/psi decay is completely canceled in the ratio; therefore, the absolute branching fractions of the CP-violating processes of J/psi --> K(S)K(S) and K(L)K(L) can be cleanly and model-independently determined in the case that J/psi K(S)K(L) decay is precisely measured. In the future tau-charm factory, the expected CP violating process of J/psi --> K(S)K(S) should be reached. It is important to measure J/psi to K(S)K(S) and K(S)K(L) decays simultaneously, so that many systematic errors will be canceled. More precise measurements are suggested to examine the predicted isospin relation in J/psi --> KK decays. All results can be extended to decays of other vector quarkonia, phi, psi(2S), and gamma(1S), etc. 相似文献
94.
We experimentally evaluate and correct the non-equivalence between electrical and radiative heating of solar irradiance absolute radiometer to compensate the systematic error of radiant power measurement at ambient pressure. A relative difference of the order of 0.08%-0.27% between electrical and radiative heating sensitivities is shown, and the resulting non-equivalence correction factor is calculated. The radiant power measurement equation is modified using the non-equivalence correction factor, a systematic deviation of 0.19% of radiant power measurement is hence eliminated. 相似文献
95.
Yang Li Zhen-Hua Ye Chun Lin Xiao-Ning Hu Rui-Jun Ding Li He 《Optical and Quantum Electronics》2013,45(7):641-648
Current–voltage characteristics of HgCdTe photodiodes in the forward bias region have been modeled considering mechanisms including drift-diffusion current, recombination current, metal-semiconductor contact and constant series resistance. Moreover, a fitting method based on the genetic algorithm has been developed to obtain values of related physical parameters from the measured dynamic resistance–voltage curves. Fitting results of $n^+$ -on- $p$ planar devices with different cutoff wavelengths are presented to illustrate the model and method, which are available and promising in acquiring device parameter values and evaluating the electrode contact quality. 相似文献
96.
HE LiPing LIU Shuang DAI JunBeijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Lü HuiBin JIN KuiJuan YANG GuoZhen 《中国科学:物理学 力学 天文学(英文版)》2014,57(4):615-618
Selected Mouse IgG of 1 mg/mL as target was fabricated on microarray for 500 sample dots.Label-free and real-time reaction dynamic processes were detected between the microarrays with Goat Anti-mouse IgG of 0.02 mg/mL using the obliqueincidence reflectivity difference(OIRD)method.We obtained the reaction results and the reaction dynamic curves of 500 protein dots.In addition,we also used label-free detection of protein microarrays of 10080 sample dots,including BSA and different concentrations of Mouse IgG and Rabbit IgG,by OIRD.The obtained reaction results between the protein microarray with 1 mg/mL Goat Anti-mouse IgG and 1 mg/mL Goat Anti-rabbit IgG are reported herein.Experimental results show that OIRD can be not only label-free high-throughput detection method for biological microarrays but also label-free real-time detection in the interaction processes of biomolecules. 相似文献
97.
Ma Jianglei Yang Hong-Sheng Lu Zhong-zuo 《International Journal of Infrared and Millimeter Waves》1993,14(1):129-134
Circular-rectangular groove guide is a new type of structure we have presented for coupling between circular groove guide and rectangular groove guide. In this paper, as the continuity of our previous work, the characteristic equation of circular-rectangular groove guide has been solved and the numerical results have been given and discussed.The Project Supported by National Natural Science Foundation of P. R. China 相似文献
98.
Jing R Guang Y Huidan Z Guorong C Tanaka K Fujita K Murai S Tsujiie Y 《Optics letters》2006,31(23):3492-3494
Second-harmonic generation in 60GeS(2)-20Ga(2)S(3)-20KBr chalcohalide glass was investigated by the thermal poling method. A large second-order nonlinear susceptibility, as high as 7.0 pm/V, was obtained in a poled sample by Maker fringe analysis. We believe this to be the first time that a clear second-harmonic wave was observed in chalcohalide glasses containing large amount of alkali ions (6.25 at. %). Such observation is of great potential use in all optical waveguide devices. 相似文献
99.
Q. Yang S. Lin L. Xu F. Yang Y. Yang L. Pan C. Sun Y. Li G. Sun Z. Jiang 《Applied physics. B, Lasers and optics》2005,80(8):953-955
The observations of three-photon-induced frequency-upconversion fluorescence and the highly directional stimulated visible emission in two dyes, 4-[p-(dicyanoethylamino) styryl]-N-methylpyridinium iodide (abbreviated as CEASP) and the complex of CEASP and Ce(NO3) (abbreviated as CEASP-Ce), are reported. The photographs of the forward amplified spontaneous emissions spots, pumped by an optical parametric oscillator idler with a pulse width of 8 ns and a wavelength of 1.3 μ m, are shown. The upconversion fluorescence produced both in dimethyl formamide solution and 2-hydroxyethyl methacrylate (HEMA) polymer spans from green to red, with a cubic dependence on the pump light intensity. The experimental results imply that the existence of the lanthanide ion Ce3 + sensitizes the nonlinear absorption and emission. 相似文献
100.
Fan?YangEmail author Guowu?Yang Yujie?Hao 《International Journal of Theoretical Physics》2016,55(7):3414-3427
The most crucial issue of quantum cryptography protocols is its security. There exists many ways to attack the quantum communication process. In this paper, we present a model checking method for modeling the eavesdropping in quantum information protocols. So when the security properties of a certain protocol are needed to be verified, we can directly use the models which are already built. Here we adopt the probabilistic model checking tool—PRISM to model these attack methods. The verification results show that the detection rate of eavesdropping is approximately close to 1 when enough photons are transmitted. 相似文献