全文获取类型
收费全文 | 231204篇 |
免费 | 1558篇 |
国内免费 | 480篇 |
专业分类
化学 | 105368篇 |
晶体学 | 3618篇 |
力学 | 12132篇 |
综合类 | 5篇 |
数学 | 37235篇 |
物理学 | 74884篇 |
出版年
2018年 | 10139篇 |
2017年 | 11060篇 |
2016年 | 5628篇 |
2015年 | 1947篇 |
2014年 | 1460篇 |
2013年 | 4934篇 |
2012年 | 8049篇 |
2011年 | 17768篇 |
2010年 | 10469篇 |
2009年 | 10348篇 |
2008年 | 15325篇 |
2007年 | 19211篇 |
2006年 | 4277篇 |
2005年 | 11454篇 |
2004年 | 7227篇 |
2003年 | 6803篇 |
2002年 | 4577篇 |
2001年 | 3761篇 |
2000年 | 3020篇 |
1999年 | 2247篇 |
1998年 | 1940篇 |
1997年 | 1908篇 |
1996年 | 2006篇 |
1995年 | 1893篇 |
1994年 | 1653篇 |
1993年 | 1638篇 |
1992年 | 1840篇 |
1991年 | 1841篇 |
1990年 | 1769篇 |
1989年 | 1778篇 |
1988年 | 1785篇 |
1987年 | 1771篇 |
1986年 | 1679篇 |
1985年 | 2245篇 |
1984年 | 2373篇 |
1983年 | 1988篇 |
1982年 | 2306篇 |
1981年 | 2121篇 |
1980年 | 2163篇 |
1979年 | 2171篇 |
1978年 | 2301篇 |
1977年 | 2125篇 |
1976年 | 2187篇 |
1975年 | 2116篇 |
1974年 | 1957篇 |
1973年 | 2206篇 |
1972年 | 1329篇 |
1971年 | 1005篇 |
1968年 | 1157篇 |
1967年 | 1141篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
A theorem on the presentability of a multiple integral as a linear form in 1, ζ(3), ζ(5),..., ζ(2k − 1) over ℚ is proved. This theorem refines the results recently obtained by D. Vasiliev, V. Zudilin, and S. Zlobin.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 11, No. 6, pp. 143–178, 2005. 相似文献
992.
We prove estimates in weighted Hölder norms for a solution to the model linear problem related with the one-phase Stefan problem with a small multiplier ε at time derivative in the heat equation. These estimates are uniform with respect to parameter ε and are significant in justification of passage to the limit in the one-phase Stefan problem as the specific heat tends to zero. Bibliography: 8 titles. 相似文献
993.
O. V. Il’in 《Journal of Mathematical Sciences》2007,141(1):1041-1047
We describe W-geometry of two-dimensional Toda systems associated with the Lie algebra C
n
.
__________
Translated from Fundamental’naya i Prikladnaya Matematika (Fundamental and Applied Mathematics), Vol. 11, No. 1, Geometry,
2005. 相似文献
994.
Z.J. Liu H.H. Long W.C. Ye X.X. Zou Z.L. Qin E.P. Li J.S. Chen 《Journal of magnetism and magnetic materials》2006
In this paper, specific issues related to high-density perpendicular magnetic recording processes, such as transition noise properties and cross-track correlation lengths, were investigated with the help of micromagnetic analysis. The effects of media parameters were taken into consideration, including intergranular exchange coupling, and exchange distribution, irregular grain shapes, magnetization saturation distribution, and anisotropy distribution. The micromagnetic simulation results showed that the effect of anisotropy distribution on transition noise is more significant than magnetization saturation distribution, and it is crucial to reduce this effect to achieve a high signal-to-noise ratio. Additionally, a new method to further estimate the partial erasure threshold was proposed to approximate the partial erasure effects, and the relation between the microtrack jitter and total track jitter was investigated. 相似文献
995.
M.W.C. Dharma-wardana A.H. MacDonald G.C. Aers D.J. Lockwood W.T. Moore R.L.S. Devine 《Superlattices and Microstructures》1987,3(6)
Results of Raman scattering experiments on (a) periodic superlattices made up of GaAs/InxGa1−xAs layers with high indium concentrations, (b) GaAs/Ga1−xAlxAs Fibonacci superlattices, are presented. We discuss the observed peak positions and intensities using the continuum theory of acoustic wave propagation in layered media and the photo-elastic coupling model. 相似文献
996.
Y. Zhang T. M. Benson P. Sewell A. Vukovic D. Zhang W. J. Pan A Loni D. Furniss A. B. Seddon 《Optical and Quantum Electronics》2006,38(1-3):97-110
This paper presents our recent simulation results and novel designs of single mode large cross-section glass-based waveguides for photonic integrated circuits (PICs). Simulations were performed using an in-house Finite Difference (FD) based mode solver and the FD Beam propagation Method (FD-BPM). Our simulation results show that this innovative technology could provide a simplified means to couple optical energy efficiently between optical components in a single chip. This would provide the base for the future large-scale integration of optical components in PICs. The novel idea of using single mode large cross-section glass-based waveguides as an optical integration platform is an evolutionary innovative solution for the monolithic integration of optical components, in which the glass-based structures act both as waveguides and as an optical bench for integration. This allows easy and efficient optical coupling between optical components and optical fibres, removing costly and tedious alignment problems and considerably reducing optical coupling losses in PICs. We expect that the glass-based waveguide PICs technology will enable the emergence of a new generation of compact, reliable, high speed, and multifunctional devices. 相似文献
997.
998.
The 8-mol percentage Y2O3-stabilized Porous Zirconia was prepared using sol–gel method. Zirconium oxalate gel was prepared by the addition of appropriate
amount of oxalic acid solution into the 1 M aqueous solution of zirconium-oxy chloride. A cubic phase zirconia powder was
obtained by calcination and milling of the zirconium oxalate gel. Crystallization temperature was found about 450 °C from
the Differential thermal analysis. The phase analysis by X-ray diffraction shows the presence of cubic phase. Pellets sintered
at 1,350 °C were highly porous, and the electrical conductivity was found with lower value due to the porosity, and the hardness
was about 8.0 GPa.
Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, Dec. 7–9, 2006. 相似文献
999.
In this paper we present several results about local MV-algebras, extending existing results given for MV-chains. The role
of local MV-algebras in sheaf representation and weak boolean product is stressed and the relationship of local MV-algebras
with varieties of MV-algebras is analyzed.
Presented by S. Pulmannova.
Received November 11, 2005; accepted in final form December 20, 2005. 相似文献
1000.
Labour scheduling plays an important and critical role in Sainsburys day to day operations and profitability. The integrated
workforce management solution for Sainsburys is an intelligent solution for the operational deployment of human resources,
integrated business forecasting, generation and calculation of workload and staff scheduling. The workforce management technology
has provided Sainsburys with a fully web-based and centralised system that produces optimised schedules for all employees
satisfying the forecasted demand of work with granularity of fifteen minutes. The system is configured to respect all operational
and business requirements as well as employee contractual constraints. This paper introduces the workforce management solution
system designed, developed and implemented for Sainsburys. We concentrate on two modelling structures, namely the work pattern
model and optimisation model, and briefly discuss the optimisation process. 相似文献