全文获取类型
收费全文 | 17836篇 |
免费 | 4012篇 |
国内免费 | 1724篇 |
专业分类
化学 | 5643篇 |
晶体学 | 185篇 |
力学 | 1391篇 |
综合类 | 166篇 |
数学 | 2137篇 |
物理学 | 14050篇 |
出版年
2024年 | 54篇 |
2023年 | 197篇 |
2022年 | 567篇 |
2021年 | 655篇 |
2020年 | 740篇 |
2019年 | 613篇 |
2018年 | 581篇 |
2017年 | 750篇 |
2016年 | 877篇 |
2015年 | 819篇 |
2014年 | 1302篇 |
2013年 | 1429篇 |
2012年 | 1218篇 |
2011年 | 1295篇 |
2010年 | 1158篇 |
2009年 | 1190篇 |
2008年 | 1175篇 |
2007年 | 1118篇 |
2006年 | 998篇 |
2005年 | 885篇 |
2004年 | 853篇 |
2003年 | 714篇 |
2002年 | 641篇 |
2001年 | 512篇 |
2000年 | 517篇 |
1999年 | 440篇 |
1998年 | 379篇 |
1997年 | 311篇 |
1996年 | 276篇 |
1995年 | 186篇 |
1994年 | 168篇 |
1993年 | 126篇 |
1992年 | 115篇 |
1991年 | 96篇 |
1990年 | 98篇 |
1989年 | 98篇 |
1988年 | 71篇 |
1987年 | 59篇 |
1986年 | 58篇 |
1985年 | 46篇 |
1984年 | 38篇 |
1983年 | 14篇 |
1982年 | 32篇 |
1981年 | 20篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1978年 | 13篇 |
1977年 | 8篇 |
1976年 | 7篇 |
1975年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
21.
A. N. Logunov 《Journal of Russian Laser Research》2004,25(4):331-348
A physical multidimensional local model of the propagation process of a laser pulse in air having no analogy to famous models in laser physics is constructed. It is based on the representations of classical wave mechanics characteristic of the theory of scalar wave fields. 相似文献
22.
K. Dayananda R. Dhamodharan K. Vijayakumaran T. Rajamannar 《Journal of polymer science. Part A, Polymer chemistry》2004,42(21):5413-5423
A monolayer of covalently anchored, novel, binaphthyl ketone is used as a surface‐confined photochemical radical generator (PRG) for anchoring a variety of polymers to silicon surfaces. The precursor PRG is synthesized by the application of a facile and novel method for the oxidation of sterically hindered benzylic hydrocarbons to carbonyl compounds. Oxidation was carried out with a stoichiometric amount of potassium peroxydisulfate, in the presence of a catalytic amount of copper sulfate in an acetonitrile/water mixture. The PRG synthesized is characterized by 1H NMR, UV, and Fourier transform infrared (FTIR). The covalently attached monolayers are characterized by X‐ray photoelectron spectroscopy, ellipsometry, and water contact angle measurements. The method developed is applicable to the preparation of a monolayer of a variety of polymers on a wide range of substrates carrying surface hydroxyl groups. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5413–5423, 2004 相似文献
23.
According to a multiphase mixture theory, we have mathematically developed a multiphysical model with chemoelectromechanical coupling considerations, termed the multieffect‐coupling electric‐stimulus (MECe) model, to simulate the responsive behavior of electric‐sensitive hydrogels immersed in a bath solution under an externally applied electric field. For solutions of the MECe model consisting of coupled nonlinear partial differential governing equations, a meshless Hermite–Cloud method with a hierarchical iteration technique has been used for a one‐dimensional steady‐state analysis of a hydrogel strip. The computed results are compared with the experimental data, and there is very good agreement. Simulations within the domains of both hydrogels and surrounding solutions also present distributions of the ionic concentrations and electric potential as well as the hydrogel displacement. The effects of various physical parameters on the response behavior of electric‐stimulus responsive hydrogels are discussed in detail. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1514–1531, 2004 相似文献
24.
通过对非饱和土非线性本构方程和场方程的线性化,推导出了非饱和土的线性本构方程和场方程,把线性方程表示为与Biot饱和多孔介质方程相似的形式;证明了Darcy定律对非饱和土的适用性;说明了Biot饱和多孔介质方程是这些线性方程的特征。所有这些都表明用混合理论处理非饱和土本构问题的正确性。 相似文献
25.
The electromagnetic (EM) energy flow near single spheres is investigated by applying Mie theory. From the patterns of the energy flow, the absorption and the scattering of light can be understood in the microscopic point of view. In the absorption profiles of metallic particles, most absorbed energy is consumed on the surface of the particles, which indicates that the resonance of surface plasmon is different from that of the bulk plasmon. Two mechanisms to enhanced local EM field are also distinguished. One is the surface plasmon resonance, and another one is the intensified energy flow. 相似文献
26.
27.
28.
29.
30.
I.IntroductionWhenastructurcvibratcs,itsvibratingsurfacewillmakesurroundingmediummovetogethcrwithit.Ifthernotionissofastthatthcmediumroundthestructureproduccaloca1contractionandcxpansionandthcypropagatefaraway,thesoundradiationisformed.Itispossiblctodcscribeanalytica11ytheradiationfic1dofsimplyandregularlyshapcdsourcessuchaspointsoundsourccs,spherica1soundsourccsandinflnite1engthllnearsoundsourccs,butitisa1mostimpossib1ctosolvetheradiationfiledbyanyanalyt-ica1methodforsourcesofvcrycomplicateds… 相似文献