全文获取类型
收费全文 | 13532篇 |
免费 | 1111篇 |
国内免费 | 805篇 |
专业分类
化学 | 2509篇 |
晶体学 | 143篇 |
力学 | 736篇 |
综合类 | 51篇 |
数学 | 314篇 |
物理学 | 11695篇 |
出版年
2024年 | 10篇 |
2023年 | 94篇 |
2022年 | 174篇 |
2021年 | 151篇 |
2020年 | 202篇 |
2019年 | 189篇 |
2018年 | 218篇 |
2017年 | 408篇 |
2016年 | 496篇 |
2015年 | 457篇 |
2014年 | 1023篇 |
2013年 | 836篇 |
2012年 | 687篇 |
2011年 | 1170篇 |
2010年 | 801篇 |
2009年 | 949篇 |
2008年 | 962篇 |
2007年 | 1041篇 |
2006年 | 803篇 |
2005年 | 623篇 |
2004年 | 551篇 |
2003年 | 506篇 |
2002年 | 444篇 |
2001年 | 452篇 |
2000年 | 347篇 |
1999年 | 326篇 |
1998年 | 301篇 |
1997年 | 212篇 |
1996年 | 185篇 |
1995年 | 137篇 |
1994年 | 93篇 |
1993年 | 101篇 |
1992年 | 67篇 |
1991年 | 67篇 |
1990年 | 65篇 |
1989年 | 46篇 |
1988年 | 45篇 |
1987年 | 46篇 |
1986年 | 20篇 |
1985年 | 31篇 |
1984年 | 31篇 |
1983年 | 17篇 |
1982年 | 16篇 |
1981年 | 8篇 |
1980年 | 8篇 |
1979年 | 6篇 |
1978年 | 4篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 558 毫秒
991.
Ivan S. Maksymov 《Physics letters. A》2011,375(5):918-921
We propose a hybrid resonance architecture in which a plasmonic element is coupled to a silicon-on-insulator photonic crystal nanobeam cavity operating at telecom wavelengths. It benefits from the combined characteristics of the photonic cavity and the plasmonic element, and exploits the unique properties of Fano resonances resulting from interactions between the continuum and the localized cavity states. As confirmed through 3D time-domain simulations, a strong cavity mode damping by the plasmonic element offers mechanisms of controlling a probe signal propagating in the nanobeam. It makes possible to create optical switching devices and logic gates relying on any optical nonlinear effect. 相似文献
992.
差分比热实验方法是测量两个样品的比热差,具有高达万分之一的比热测量分辨率,适合测量相变时微小的比热变化及宽温区的电子比热.文章介绍了高分辨连续升温差分比热实验的测量原理和测量方法,并以铜氧化物高温超导体Y0.8Ca0.2Ba2Cu3O6+x为例,介绍了差分比热实验手段在宽温区电子比热的获得、正常态赝能隙及超导凝聚能研究等方面的应用. 相似文献
993.
We present an approach to faithfully teleport an unknown quantum state of entangled particles in a multi-particle system involving multi spatially remote agents via probabilistic channels. In our scheme, the integrity of an entangled multi-particle state can be maintained even when the construction of a faithful channel fails. Furthermore, in a quantum teleportation network, there are generally multi spatially remote agents which play the role of relay nodes between a sender and a distant receiver. Hence, we propose two schemes for directly and indirectly constructing a faithful channel between the sender and the distant receiver with the assistance of relay agents, respectively. Our results show that the required auxiliary particle resources, local operations and classical communications are considerably reduced for the present purpose. 相似文献
994.
In this paper we develop a theoretical model for the magnetically induced optical anisotropy in dense magnetic colloids made of spherical and un-aggregated magnetic monodomain nanoparticles. Both dipole-field and dipole-dipole magnetic and electric interactions between the magnetic monodomain particles are taken into account in the Hamiltonian of the system. Using the pair correlation function in a colloidal suspension of magnetic nanoparticles developed by Ivanov and Kuznetsova (2001) [11], the complex dielectric constant of a magnetic colloid is modeled as a function of the light polarization direction, the magnetic field intensity and magnetic particle concentration and diameter. The two main features of the model are that, on the one hand, it predicts the possibility of magnetically induced optical anisotropy in dense magnetic colloids made of spherical and un-aggregated monodomain nanoparticles, and on the other hand, unlike the existing models for diluted samples, it predicts a non-linear dependence of dichroism and birefringence on magnetic particle concentration. 相似文献
995.
Target detection is one of the key technology of precision chemical application.Previously the digital coding modulation technique was commonly used to emit and receive the optical signal in the target detection systems previously in China.It was difficult to adjust the output power,and the anti-interference ability was weak in these systems.In order to resolve these problems,the target detection method based on analog sine-wave modulation was studied.The spectral detecting system was set up in the aspects ... 相似文献
996.
997.
《Communications in Nonlinear Science & Numerical Simulation》2014,19(11):3969-3987
By means of symbolic computation and Darboux transformation, analytically and numerically investigated in this paper is a two-coupled Sasa–Satsuma system, which can describe the pulse propagation in birefringent fibers, so as to increase the bit rate in optical fibers, or achieve wavelength-division multiplexing. Analytical bright N-soliton solution of the system is firstly derived. Based on the bright one- and two-soliton solutions, numerical simulation and figure illustration are carried out on through the multi-parametric management, i.e., different choices among eight parameters in the two-soliton solutions. The interaction mechanisms for the bright two-solitons are revealed in three aspects: Separating evolution behaviors, elastic collision behaviors and inelastic collision behaviors. There exist three different cases for the inelastic collision for the two-soliton, which reflect correspondingly different energy transfer mechanisms (by intensity redistribution) between the two components: Manakov-typed collision; a near-elastic collision and another completely inelastic collision between the two components; and four single-solitons in two components undergo shape changes (inelastic and elastic) due to intensity redistribution, where one single-soliton keeps invariant and the other three single-solitons change during the collision. The collision mechanisms may be viewed as the two-solitons interact in a waveguide supporting propagation of two nonlinear waves simultaneously. In general, partial suppression (enhancement) of intensity between the components is dependent on the values of the soliton parameters. 相似文献
998.
In this paper, we consider the partially nonlinear errors-in-variables models when the non- parametric component is measured with additive error. The profile nonlinear least squares estimator of unknown parameter and the estimator of nonparametric component are constructed, and their asymptotic properties are derived under general assumptions. Finite sample performances of the proposed statistical inference procedures are illustrated by Monte Carlo simulation studies. 相似文献
999.
基于TGARCH-t的混合Copula投资组合风险测度研究 总被引:1,自引:0,他引:1
在分析了现有Copula函数在测度投资组合风险不足的情况下,首先充分考虑资产波动的时变性、杠杆效应等特征,选择了TGARCH-t模型进行边缘分布建模.接着引入混合Copula模型来描述投资组合的复杂相关结构,同时利用构造的主对角线距离统计量等方法验证了混合Copula模型的优势.最后通过VaR的蒙特卡洛模拟结果看到,这种方法能更为精确的测度投资组合风险值. 相似文献
1000.
研究偏序集上的测度拓扑以及与其它内蕴拓扑间的关系,利用测度拓扑刻画了偏序集的连续性.构造了反例说明存在完全分配格,其上的测度拓扑不是连续格从而不是局部紧拓扑. 相似文献