全文获取类型
收费全文 | 11915篇 |
免费 | 1884篇 |
国内免费 | 1055篇 |
专业分类
化学 | 8411篇 |
晶体学 | 133篇 |
力学 | 593篇 |
综合类 | 54篇 |
数学 | 1427篇 |
物理学 | 4236篇 |
出版年
2024年 | 33篇 |
2023年 | 199篇 |
2022年 | 364篇 |
2021年 | 379篇 |
2020年 | 441篇 |
2019年 | 425篇 |
2018年 | 376篇 |
2017年 | 349篇 |
2016年 | 519篇 |
2015年 | 573篇 |
2014年 | 631篇 |
2013年 | 939篇 |
2012年 | 1070篇 |
2011年 | 1050篇 |
2010年 | 712篇 |
2009年 | 666篇 |
2008年 | 778篇 |
2007年 | 665篇 |
2006年 | 623篇 |
2005年 | 532篇 |
2004年 | 449篇 |
2003年 | 377篇 |
2002年 | 342篇 |
2001年 | 278篇 |
2000年 | 197篇 |
1999年 | 199篇 |
1998年 | 191篇 |
1997年 | 189篇 |
1996年 | 195篇 |
1995年 | 141篇 |
1994年 | 150篇 |
1993年 | 121篇 |
1992年 | 78篇 |
1991年 | 76篇 |
1990年 | 69篇 |
1989年 | 67篇 |
1988年 | 42篇 |
1987年 | 29篇 |
1986年 | 51篇 |
1985年 | 38篇 |
1984年 | 34篇 |
1983年 | 21篇 |
1982年 | 16篇 |
1981年 | 14篇 |
1980年 | 16篇 |
1979年 | 12篇 |
1978年 | 22篇 |
1977年 | 13篇 |
1976年 | 13篇 |
1974年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
991.
We determine the free energy of micelle formation for model surfactants in a Lennard-Jones solvent by employing a hybrid semi-grand Monte Carlo simulation scheme in combination with umbrella sampling and configurational bias techniques. Comparing the results to theoretical prediction, we obtain good agreement for large micellar sizes. We also study the effect of changing the surfactant headgroup size and tail length on the critical micelle concentration. The values of and the trends in the calculated critical micelle concentrations do agree with experimental observation for nonionic surfactants. The results open up the way for the calculation of critical micelle concentrations using realistic atomic force fields. 相似文献
992.
Fernández CE Mancera M Holler E Bou JJ Galbis JA Muñoz-Guerra S 《Macromolecular bioscience》2005,5(2):172-176
Low-molecular-weight poly(alpha-methyl beta,L-malate) made of approximately 25-30 units was prepared from microbial poly(beta,L-malic acid) by treatment with diazomethane. The thermal characterization of the polymalate methyl ester was carried out and its crystalline structure was preliminary examined. Its ability to crystallize both from solution and from the melt was comparatively evaluated. 相似文献
993.
Huang JY Chen S Jo SH Wang Z Han DX Chen G Dresselhaus MS Ren ZF 《Physical review letters》2005,94(23):236802
We report the atomic-scale imaging with concurrent transport measurements of the breakdown of individual multiwall carbon nanotubes inside a transmission electron microscope equipped with a piezomanipulator. We found unexpectedly three distinct breakdown sequences: namely, from the outermost wall inward, from the innermost wall outward, and alternatively between the innermost and the outmost walls. Remarkably, a significant amount of current drop was observed when an innermost wall is broken, proving unambiguously that every wall is conducting. Moreover, the breakdown of each wall in any sequence initiates in the middle of the nanotube, not at the contact, proving that the transport is not ballistic. 相似文献
994.
López-Urías F Muñoz-Sandoval E Reyes-Reyes M Romero AH Terrones M Morán-López JL 《Physical review letters》2005,94(21):216102
We report a novel magnetic phenomenon consisting of the formation of helical spin configurations during the magnetization of densely packed ferromagnetic nanowires encapsulated inside carbon nanotubes. We studied the hysteresis loops when the magnetic fields are applied parallel and perpendicular to the nanotubes axes. We also performed theoretical calculations on aligned nanowire arrays that clearly indicate the creation of helical spin vortices in the hysteresis loops. The latter are caused by the presence of strong dipolar interactions among neighboring wires. 相似文献
995.
Efficient and accurate integration of stochastic (partial) differential equations with multiplicative noise can be obtained through a split-step scheme, which separates the integration of the deterministic part from that of the stochastic part, the latter being performed by sampling exactly the solution of the associated Fokker-Planck equation. We demonstrate the computational power of this method by applying it to the most absorbing phase transitions for which Langevin equations have been proposed. This provides precise estimates of the associated scaling exponents, clarifying the classification of these nonequilibrium problems, and confirms or refutes some existing theories. 相似文献
996.
We apply the nonperturbative renormalization group method to a class of out-of-equilibrium phase transitions (usually called "parity-conserving" or, more properly, "generalized voter" class) which is out of the reach of perturbative approaches. We show the existence of a genuinely nonperturbative fixed point, i.e., a critical point that does not seem to be Gaussian in any dimension. 相似文献
997.
Zúñiga-Pérez J Muñoz-Sanjosé V Palacios-Lidón E Colchero J 《Physical review letters》2005,95(22):226105
The surface electrical properties of ZnO thin films grown along the nonpolar [1120] direction have been investigated by Kelvin probe microscopy on a nanometer scale. Two different charge domains, with a 75 meV work function difference, coexist within the ZnO surface, which is covered by rhombohedral pyramids whose sidewalls are shown to be {1011}-type planes. The presence and relative orientation of the two kinds of charge domains are explained in terms of the atomic arrangement at the {1011} polar surfaces. 相似文献
998.
We report here "strain glass," a new glassy phenomenon in ferroelastic-martensitic system of Ni-rich intermetallic Ti(50-x)Ni(50+x) (x > 1), where local strain is frozen in disordered configuration below a critical temperature Tg. The ac elastic modulus shows a minimum at Tg, which exhibits logarithmic frequency dependence following Vogel-Fulcher relationship, and the corresponding internal friction shows a frequency-dependent peak located at a lower temperature. In situ high-resolution transmission electron microscopy observations reveal uncorrelated nanoclusters of martensiticlike phase, randomly frozen in the otherwise untransformed parentlike matrix. Being parallel to spin glass and relaxor, strain glass may shed new light on the fundamental physics of glass and lead to the discovery of novel properties. 相似文献
999.
Tip-enhanced Raman spectroscopy (TERS) is based on the optical excitation of localized surface plasmons in the tip-substrate cavity, which provides a large but local field enhancement near the tip apex. We report on TERS with smooth single crystalline surfaces as substrates. The adsorbates were CN- ions at Au(111) and malachite green isothiocyanate (MGITC) molecules at Au(111) and Pt(110) using either Au or Ir tips. The data analysis yields Raman enhancements of about 4 x 10(5) for CN- and up to 10(6) for MGITC at Au(111) with a Au tip, probing an area of less than 100 nm radius. 相似文献
1000.