全文获取类型
收费全文 | 87710篇 |
免费 | 2173篇 |
国内免费 | 1919篇 |
专业分类
化学 | 31825篇 |
晶体学 | 926篇 |
力学 | 7330篇 |
综合类 | 94篇 |
数学 | 33165篇 |
物理学 | 18462篇 |
出版年
2024年 | 73篇 |
2023年 | 184篇 |
2022年 | 333篇 |
2021年 | 417篇 |
2020年 | 433篇 |
2019年 | 449篇 |
2018年 | 10717篇 |
2017年 | 10513篇 |
2016年 | 6537篇 |
2015年 | 1434篇 |
2014年 | 910篇 |
2013年 | 1071篇 |
2012年 | 4640篇 |
2011年 | 11311篇 |
2010年 | 6304篇 |
2009年 | 6667篇 |
2008年 | 7247篇 |
2007年 | 9274篇 |
2006年 | 715篇 |
2005年 | 1770篇 |
2004年 | 1945篇 |
2003年 | 2352篇 |
2002年 | 1505篇 |
2001年 | 662篇 |
2000年 | 548篇 |
1999年 | 371篇 |
1998年 | 376篇 |
1997年 | 274篇 |
1996年 | 308篇 |
1995年 | 221篇 |
1994年 | 158篇 |
1993年 | 159篇 |
1992年 | 107篇 |
1991年 | 120篇 |
1990年 | 85篇 |
1989年 | 86篇 |
1988年 | 80篇 |
1987年 | 73篇 |
1986年 | 69篇 |
1985年 | 55篇 |
1984年 | 56篇 |
1983年 | 47篇 |
1982年 | 46篇 |
1981年 | 51篇 |
1980年 | 53篇 |
1979年 | 51篇 |
1914年 | 45篇 |
1912年 | 40篇 |
1909年 | 41篇 |
1908年 | 40篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
P. G. Siddheshwar R. K. Vanishree Anthony Christy Melson 《Transport in Porous Media》2012,92(2):277-288
The effects of temperature-dependent viscosity, gravity modulation and thermo-mechanical anisotropies on heat transport in a low-porosity medium are studied using the Ginzburg–Landau model. The effect of gravity modulation is to decrease the Nusselt number, Nu and variable viscosity leads to increase in Nu. The thermo-mechanical anisotropies have opposite effect on Nu with thermal anisotropy decreasing the heat transport. 相似文献
82.
Antonio Strozzi 《Journal of Elasticity》2012,108(1):119-123
The solution of cylindrical problems is addressed. A series solution is considered of the biharmonic equation, in which the series terms of the stress function Φ are expressions based upon Legendre polynomials and logarithmically singular functions. An explicit form of a polynomial supplementing each logarithmically singular part of the series solution is obtained. 相似文献
83.
We consider the flow of a viscous incompressible fluid in a pipe when the boundary is a deformable shell of Naghdi type. We prove that the corresponding system of partial differential equations has a solution when the deformation of the shell is smooth and small enough. We propose an algorithm that uncouples the unknowns and prove its convergence. 相似文献
84.
We apply the recently improved version of the 0–1 test for chaos to real experimental time series of laser droplet generation process. In particular two marginal regimes of dripping are considered: spontaneous and forced dripping. The outcomes of the test reveal that both spontaneous and forced dripping time series can be characterized as chaotic, which coincides with the previous analysis based on nonlinear time series analysis. 相似文献
85.
GaAs:Cr探测器中子辐照改性研究 总被引:3,自引:0,他引:3
介绍了一种新型脉冲辐射探测器以及提高其性能的一种方法,并报告了探测器性能与中子积分通量关系的实验结果。 相似文献
86.
本文描述了用膜吸收法测量激光等离子体辐射温度空间分布的原理和方法给出了柱形缝靶轴向辐射温度随空间位置变化的特征,对测量结果进行了分析讨论。 相似文献
87.
Krishna S Kumar 《Pramana》1993,41(1):45-53
We report on two sensitive tests of lepton universality carried out by the 4 LEP experiments at the Z0 pole. From measurements of the τ polarization in e+ e?→τ + τ ?, the ratios of the vector and axial vector coupling constants of the electron and the tau lepton to the weak neutral current are obtained to beg v e /g a e =0.066±0.015 andg V τ /g A τ =0.070±0.009 respectively. From measurement of the τ lifetime and the τ leptonic branching ratios, the ratio of the coupling constants describing weak leptonic decays of the τ and the μ is measured to beG τ /G μ =0.996±0.008. 相似文献
88.
A review is given of the StandardSU(5) supergravity model. This model has passed an important check regarding unification of the electro-weak and the strong couplings using high precision LEP data. It is shown that for a significant domain of the parameter space the model also satisfies constraints on the SUSY spectrum from CDF and LEP, as well as proton stability and cosmological relic density constraints. 相似文献
89.
Ignattos Antoniadis 《Pramana》2004,62(2):163-176
The recent understanding of string theory opens the possibility that the string scale can be as low as a few TeV. The apparent
weakness of gravitational interactions can then be accounted by the existence of large internal dimensions, in the sub-millimeter
region. Furthermore, our world must be confined to live on a brane transverse to these large dimensions, with which it interacts
only gravitationally. In my lecture, I describe briefly this scenario which gives a new theoretical framework for solving
the gauge hierarchy problem and the unification of all interactions. I also discuss a minimal embedding of the standard model,
gauge coupling unification and proton stability.
On leave from: Centre de Physique Théorique, Ecole Polytechnique, 91128 Palaiseau, Cedex, France. 相似文献
90.
JIANG Wei-na YANG Shi-long LU Wen XU Li TANG Ying XUE Hua-yu GAO Bu-hong DU Li-ting SUN Hai-jun MA Meng-tao XU Hai-jun CAO Fu-liang 《光谱学与光谱分析》2018,38(8):2650-2656
制备了一种基于天然产物槲皮素接枝硅包银核壳结构的纳米荧光传感器(Ag@SiO2@Qc),对铜离子具有好的选择性和灵敏性。Ag@SiO2@Qc与Cu2+离子结合后,荧光发射强度发生猝灭,并且可通过荧光滴定光谱得到了荧光滴定曲线:y = -32.864x+587.59(R2=0.998),其线性范围分别为:3×10-7~4.8×10-6 mol·L-1,最低检测限为1.0×10-7 mol·L-1。并且将Ag@SiO2@Qc应用于环境中水样的检测结果的准确度好,精密度高,而且更加环保、方便、快捷,具有很大发展潜力与应用价值。 相似文献