全文获取类型
收费全文 | 11710篇 |
免费 | 1868篇 |
国内免费 | 1097篇 |
专业分类
化学 | 3777篇 |
晶体学 | 138篇 |
力学 | 427篇 |
综合类 | 116篇 |
数学 | 2601篇 |
物理学 | 7616篇 |
出版年
2023年 | 92篇 |
2022年 | 114篇 |
2021年 | 167篇 |
2020年 | 248篇 |
2019年 | 250篇 |
2018年 | 291篇 |
2017年 | 369篇 |
2016年 | 437篇 |
2015年 | 374篇 |
2014年 | 540篇 |
2013年 | 964篇 |
2012年 | 666篇 |
2011年 | 801篇 |
2010年 | 590篇 |
2009年 | 783篇 |
2008年 | 840篇 |
2007年 | 920篇 |
2006年 | 776篇 |
2005年 | 674篇 |
2004年 | 610篇 |
2003年 | 519篇 |
2002年 | 528篇 |
2001年 | 449篇 |
2000年 | 416篇 |
1999年 | 334篇 |
1998年 | 272篇 |
1997年 | 177篇 |
1996年 | 228篇 |
1995年 | 183篇 |
1994年 | 145篇 |
1993年 | 113篇 |
1992年 | 119篇 |
1991年 | 91篇 |
1990年 | 68篇 |
1989年 | 53篇 |
1988年 | 73篇 |
1987年 | 55篇 |
1986年 | 39篇 |
1985年 | 51篇 |
1984年 | 45篇 |
1983年 | 24篇 |
1982年 | 34篇 |
1981年 | 33篇 |
1980年 | 16篇 |
1979年 | 17篇 |
1978年 | 19篇 |
1977年 | 12篇 |
1976年 | 16篇 |
1974年 | 9篇 |
1973年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
1.
Measurement of integrated luminosities at BESIII for data samples at center-of-mass energies between 4.0 and 4.6 GeV 下载免费PDF全文
《中国物理C(英文版)》2022,46(11):113002-113002-11
The integrated luminosities of data samples collected in the BESIII experiment in 2016–2017 at center-of-mass energies between 4.19 and 4.28 GeV are measured with a precision better than 1% by analyzing large-angle Bhabha scattering events. The integrated luminosities of old datasets collected in 2010–2014 are updated by considering corrections related to detector performance, offsetting the effect of newly discovered readout errors in the electromagnetic calorimeter, which can haphazardly occur. 相似文献
2.
Here we propose and analyze a mathematical model that aims to describe the marble sulphation process occurring in a given material. The model accounts for rugosity as well as for damaging effects. This model is characterized by some technical difficulties that seem hard to overcome from a theoretical viewpoint. Therefore, we introduce some physically reasonable modifications in order to establish the existence of a suitable notion of solution on a given time interval. Numerical simulations are presented and discussed, also in view of further research. 相似文献
3.
Dev Raj Alok Kumar Rohit Kumar Singh Abhishek Singh Bhadouria A.S.K. Sinha Deepak Dwivedi 《Current Opinion in Electrochemistry》2022
As the application of electrocatalyst continues to expand, envisaging the hidden mechanisms occurring at various length scale affecting the catalytic efficiency became important. To enhance the stability of electrocatalyst and reduce the cost, it is of paramount importance to reveal the active site's dynamics (using in situ techniques for getting the real-time information) which directly affect the reactions such as oxygen evolution reaction, hydrogen evolution reaction, and so on. Since such reactions are crucial for many engineering and scientific applications, in situ characterization techniques are required, which could capture such reactions happening at a different length and time scale. This article analyzes the recent progress made in the field of electrocatalyst's characterization using in situ neutron techniques. The article also paves the future path and has delineated the future challenges involved in multiscale correlative techniques (e.g., neutron techniques in the combination of synchrotron or microscopic techniques) used for getting the multiscale (atomic to micrometer range) mechanistic information about the electrocatalyst's working and degradation. 相似文献
4.
In this work, we present and analyze a mathematical model for tumor growth incorporating ECM erosion, interstitial flow, and the effect of vascular flow and nutrient transport. The model is of phase-field or diffused-interface type in which multiple phases of cell species and other constituents are separated by smooth evolving interfaces. The model involves a mesoscale version of Darcy’s law to capture the flow mechanism in the tissue matrix. Modeling flow and transport processes in the vasculature supplying the healthy and cancerous tissue, one-dimensional (1D) equations are considered. Since the models governing the transport and flow processes are defined together with cell species models on a three-dimensional (3D) domain, we obtain a 3D–1D coupled model. 相似文献
5.
L. G. Kuz'mina I. I. Konstantinov A. V. Churakov 《Molecular Crystals and Liquid Crystals》2018,664(1):95-100
4-methoxyphenyl-4′-n-nonyloxybenzoate have been investigated by single crystal X-ray structural analysis. Crystal packing of the compounds does not represent a precursor of the mesophse although the typical for liquid crystal compounds separation of crystal packing on aromatic and aliphatic areas is observed here. Possible reason for monotropic properties are discussed. 相似文献
6.
Bilender P. Allahverdiev 《Mathematical Methods in the Applied Sciences》2019,42(1):229-236
In this study, maximal dissipative second‐order dynamic operators on semi‐infinite time scale are studied in the Hilbert space , that the extensions of a minimal symmetric operator in limit‐point case. We construct a self‐adjoint dilation of the dissipative operator together with its incoming and outgoing spectral representations so that we can determine the scattering function of the dilation as stated in the scheme of Lax‐Phillips. Moreover, we construct a functional model of the dissipative operator and identify its characteristic function in terms of the Weyl‐Titchmarsh function of a self‐adjoint second‐order dynamic operator. Finally, we prove the theorems on completeness of the system of root functions of the dissipative and accumulative dynamic operators. 相似文献
7.
8.
Eduard Feireisl 《偏微分方程通讯》2019,44(3):271-278
We show the weak–strong uniqueness property for the compressible Navier–Stokes system with general non-monotone pressure law. A weak solution coincides with the strong solution emanating from the same initial data as long as the latter solution exists. 相似文献
9.
原子系综中的Duan-Lukin-Cirac-Zoller(DLCZ)过程是产生光与原子(量子界面)量子关联和纠缠的重要手段.当一束写光与原子发生作用时,将会产生斯托克斯(Stokes)光子的自发拉曼散射,并同时产生一个自旋波(spin-wave)存储在原子系综中,上述过程即为DLCZ量子记忆产生过程.这一过程被广泛地研究.本文将87Rb原子系综放入驻波腔,并使Stokes光子与光学腔共振,我们观察到有腔且锁定的情况下Stokes光子产生概率比无腔时增大了8.7倍.在此条件下研究了Stokes光子产生概率和写光功率的关系,Stokes光子产生概率随写光功率线性增大. 相似文献
10.
《Mendeleev Communications》2022,32(6):742-744
A solution of a histone-like protein from Spiroplasma melliferum (HUSpm) was examined by small-angle X-ray scattering (SAXS). The experimental SAXS curve was compared with those calculated for the HUSpm structures from the PDB databank obtained by both X-ray diffraction analysis and nuclear magnetic resonance spectroscopy. The model of the HUSpm structure in solution, which best agrees with the experimental SAXS data, has a shorter distance between the centers of mass of the HUSpm monomers compared to the crystal structure, indicating that the HUSpm monomers can be located closer to each other in solution than in the crystalline state. 相似文献