全文获取类型
收费全文 | 6847篇 |
免费 | 216篇 |
国内免费 | 55篇 |
专业分类
化学 | 4283篇 |
晶体学 | 50篇 |
力学 | 107篇 |
数学 | 1311篇 |
物理学 | 1367篇 |
出版年
2024年 | 8篇 |
2023年 | 31篇 |
2022年 | 143篇 |
2021年 | 179篇 |
2020年 | 129篇 |
2019年 | 191篇 |
2018年 | 205篇 |
2017年 | 173篇 |
2016年 | 253篇 |
2015年 | 216篇 |
2014年 | 216篇 |
2013年 | 481篇 |
2012年 | 430篇 |
2011年 | 534篇 |
2010年 | 373篇 |
2009年 | 307篇 |
2008年 | 439篇 |
2007年 | 405篇 |
2006年 | 367篇 |
2005年 | 354篇 |
2004年 | 304篇 |
2003年 | 245篇 |
2002年 | 199篇 |
2001年 | 88篇 |
2000年 | 86篇 |
1999年 | 99篇 |
1998年 | 77篇 |
1997年 | 55篇 |
1996年 | 86篇 |
1995年 | 49篇 |
1994年 | 46篇 |
1993年 | 51篇 |
1992年 | 41篇 |
1991年 | 29篇 |
1990年 | 14篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 10篇 |
1986年 | 12篇 |
1985年 | 15篇 |
1984年 | 13篇 |
1983年 | 18篇 |
1982年 | 14篇 |
1981年 | 13篇 |
1979年 | 8篇 |
1978年 | 11篇 |
1977年 | 12篇 |
1976年 | 6篇 |
1975年 | 11篇 |
1973年 | 5篇 |
排序方式: 共有7118条查询结果,搜索用时 15 毫秒
21.
The coherent inelastic processes of the type a → b, which may take place in the interaction of hadrons and γ quanta with nuclei at very high energies (the nucleus remains the same), are theoretically investigated. Analytical formulas for the effective cross-section σcoh(a→b) are obtained. 相似文献
22.
Vladimir Kozlov 《Journal of Functional Analysis》2004,217(2):448-488
We develop an asymptotic theory of nonlinear operator differential equations of an arbitrary order in Banach spaces. The nonlinear part of the equation is written in a divergent form. It is shown that the main term in an asymptotic representation of solutions at infinity satisfies a finite-dimensional dynamical system perturbed by a small nonlocal operator. 相似文献
23.
24.
25.
Tatiana B. Mikenas Vladimir A. Zakharov Lyudmila G. Echevskaya Mikhail A. Matsko 《Journal of polymer science. Part A, Polymer chemistry》2007,45(22):5057-5066
The effects of polymerization temperature, polymerization time, ethylene and hydrogen concentration, and effect of comonomers (hexene‐1, propylene) on the activity of supported catalyst of composition LFeCl2/MgCl2‐Al(i‐Bu)3 (L = 2,6‐bis[1‐(2,6‐dimethylphenylimino)ethyl] pyridyl) and polymer characteristics (molecular weight (MW), molecular‐weight distribution (MWD), molecular structure) have been studied. Effective activation energy of ethylene polymerization over LFeCl2/MgCl2‐Al(i‐Bu)3 has a value typical of supported Ziegler–Natta catalysts (11.9 kcal/mol). The polymerization reaction is of the first order with respect to monomer at the ethylene concentration >0.2 mol/L. Addition of small amounts of hydrogen (9–17%) significantly increases the activity; however, further increase in hydrogen concentration decreases the activity. The IRS and DSC analysis of PE indicates that catalyst LFeCl2/MgCl2‐Al(i‐Bu)3 has a very low copolymerizing ability toward propylene and hexene‐1. MW and MWD of PE produced over these catalysts depend on the polymerization time, ethylene and hexene‐1 concentration. The activation effect of hydrogen and other kinetic features of ethylene polymerization over supported catalysts based on the Fe (II) complexes are discussed. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5057–5066, 2007 相似文献
26.
Victor V. Dodonov Margarita A. Man’ko Vladimir I. Man’ko Apostol Vourdas 《Journal of Russian Laser Research》2007,28(5):404-428
A brief review of the history of ten workshops/conferences on “Squeezed States and Uncertainty Relations” and main achievements
in the related fields of quantum physics for the period from 1991 to 2007 are presented. 相似文献
27.
28.
We study the chiral behavior of the nucleon and Δ-isobar masses within a manifestly covariant chiral effective-field theory, consistent with the analyticity principle. We compute the πN and πΔ one-loop contributions to the mass and field-normalization constant, and find that they can be described in terms of universal relativistic loop functions, multiplied by appropriate spin, isospin and coupling constants. We show that these manifestly relativistic one-loop corrections, when properly renormalized, obey the chiral power-counting and vanish in the chiral limit. The results including only the πN-loop corrections compare favorably with the lattice QCD data for the pion-mass dependence of the nucleon and Δ masses, while inclusion of the πΔ loops tends to spoil this agreement. 相似文献
29.
Characterization of spherical particles using high-order neural networks and scanning flow cytometry
Vladimir V. Berdnik Alexander Shvalov Valeri Maltsev Valery A. Loiko 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,102(1):62-72
We retrieve the radius R, real n and imaginary k parts of the refractive index of homogeneous spherical particles using angular distribution of the light-scattering intensity. To solve the inverse light-scattering problem we use a high-order neural-network technique. The effect of network parameters on optimization is examined. The technique is evaluated for noise-corrupted input data at 0.6 μm<R<10.6 μm, 1.02<n<1.38, and 0<k<0.03. The errors of retrieval for nonabsorbing particles do not exceed 0.05 μm for radius and 0.015 for refractive index. The experimental verification is fulfilled by experimental data retrieved by means of a scanning flow cytometer. The light-scattering profiles of polystyrene beads and spherized red blood cells are processed with the high-order neural networks and a non-linear regression at Mie theory. The parameters retrieved by the high-order neural networks correlate well with the parameters retrieved by the least-square method. 相似文献