全文获取类型
收费全文 | 362篇 |
免费 | 19篇 |
专业分类
化学 | 238篇 |
晶体学 | 3篇 |
力学 | 3篇 |
数学 | 74篇 |
物理学 | 63篇 |
出版年
2024年 | 2篇 |
2023年 | 4篇 |
2022年 | 9篇 |
2021年 | 17篇 |
2020年 | 9篇 |
2019年 | 16篇 |
2018年 | 9篇 |
2017年 | 19篇 |
2016年 | 19篇 |
2015年 | 17篇 |
2014年 | 14篇 |
2013年 | 31篇 |
2012年 | 23篇 |
2011年 | 29篇 |
2010年 | 22篇 |
2009年 | 17篇 |
2008年 | 18篇 |
2007年 | 15篇 |
2006年 | 21篇 |
2005年 | 9篇 |
2004年 | 4篇 |
2003年 | 6篇 |
2002年 | 4篇 |
2001年 | 5篇 |
2000年 | 5篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1989年 | 2篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 1篇 |
排序方式: 共有381条查询结果,搜索用时 31 毫秒
111.
Fiona Byrne Adriele Prina-Mello Bashir M. Mohamed Yurii K. Gun’ko Yuri Volkov 《Journal of magnetism and magnetic materials》2009,321(10):1341-1345
Nickel nanowires, 20 μm long and 200 nm in diameter, were fabricated by electrodeposition into alumina templates, and characterised by superconducting quantum interference device (SQUID) magnetometer, X-ray diffraction and scanning electron microscopy. Biocompatibility studies of nickel nanowires with differentiated THP-1 cell line-derived macrophages were carried out. From a multiparametric assay, using high content analysis (HCA), the critical time points and concentrations of nickel nanowires on THP-1 cellular response were identified. The nanowires displayed little or no toxic effects on THP-1 cells over short incubation times (10 h), and at low concentrations (<100 nanowires per cell). Our findings indicate the potential suitability of these wires for biological and clinical applications. 相似文献
112.
113.
114.
S. Bashir R. W. McCabe C. Boxall M. S. Leaver D. Mobbs 《Journal of nanoparticle research》2009,11(3):701-706
Forced hydrolysis of Fe(III) ions in acidic media was performed under controlled synthetic conditions to produce α- and β-FeOOH
iron oxides. The forced hydrolysis synthesis was carried out, separately, in an aqueous medium and the lamellar lyotropic
liquid crystalline phase of a commercial non-ionic surfactant/water system. The FT-IR analyses confirmed formation of α- and
β-FeOOH iron oxides in the aqueous and the surfactant media with slight formation of ferrihydrite and haematite. TEM micrographs
have shown that particles formed in the lamellar lyotropic phase are smaller than those produced in the aqueous medium with
their smallest size dimension being constrained in the nanometre scale with a size ranging between 5 and 100 nm. Particles
produced in the nanoscale size appeared to have different optical properties compared to their counterparts produced in the
microscale size. 相似文献
115.
A detailed study of the elution behaviour, apparent molecular characteristics and hydrodynamic properties of amylopectin-type fraction (isolated from normal corn starch) in aqueous media employing asymmetrical flow field-flow fractionation (AF4) was undertaken by systematically varying the channel flow (Fch), cross flow (Fcr) and Fcr/Fch ratios. Distributions of apparent molar masses and radii of gyration, mass recoveries and hydrodynamic radii decreased as a function of increasing Fcr at a fixed Fch, due to the increase in the retention of amylopectin-type fraction in the AF4 channel. Increased retention of the amylopectin-type fraction in the AF4 channel was also observed at low Fch and high Fcr/Fch ratios. Large amylopectin-type molecules/particles (possibly aggregates) eluted at high Fch, low Fcr and low Fcr/Fch ratios. 相似文献
116.
117.
In this paper, we study the dynamics of a stochastic Susceptible-Infective-Removed-Infective (SIRI) epidemic model with relapse. By constructing a suitable stochastic Lyapunov function, we establish sufficient conditions for the existence of an ergodic stationary distribution to the model. Moreover, sufficient conditions for extinction of the disease are also obtained. 相似文献
118.
Abstract A class of non-mesogenic molecules, which as mixtures exhibit monotropic nematic phases, is described. 相似文献
119.
A new homologous series of thermotropic liquid crystalline poly (azomethine‐ether)s based on dibenzylidene derivatives were synthesized by solution polycondensation of various diformyl‐α,ω-diphenoxyalkanes, I–VIII with 2,6‐bis(m‐aminobenzylidene)‐4‐phenylcyclohexanone X, and characterized by 1H‐NMR, IR and elemental analyses. The inherent viscosities of the polymers were in the range 0.29–0.58 dI/g. All the poly (azomethine‐ether)s were insoluble in common organic solvents but dissolved completely in concentrated H2SO4 and methanesulphonic acid. The mesomorphic properties were studied as a function of the diphenoxyalkane space length. Analysis by DSC and optical polarized microscopy demonstrated that the poly (azomethine‐ether)s from nematic mesophases over wide temperature ranges. 相似文献
120.
Pareek A Borodin S Bashir A Ankah GN Keil P Eckstein GA Rohwerder M Stratmann M Gründer Y Renner FU 《Journal of the American Chemical Society》2011,133(45):18264-18271
Dealloying is widely utilized but is a dangerous corrosion process as well. Here we report an atomistic picture of the initial stages of electrochemical dealloying of the model system Cu(3)Au (111). We illuminate the structural and chemical changes during the early stages of dissolution up to the critical potential, using a unique combination of advanced surface-analytical tools. Scanning tunneling microscopy images indicate an interlayer exchange of topmost surface atoms during initial dealloying, while scanning Auger-electron microscopy data clearly reveal that the surface is fully covered by a continuous Au-rich layer at an early stage. Initiating below this first layer a transformation from stacking-reversed toward substrate-oriented Au surface structures is observed close to the critical potential. We further use the observed structural transitions as a reference process to evaluate the mechanistic changes induced by a thiol-based model-inhibition layer applied to suppress surface diffusion. The initial ultrathin Au layer is stabilized with the intermediate island morphology completely suppressed, along an anodic shift of the breakdown potential. Thiol-modification induces a peculiar surface microstructure in the form of microcracks exhibiting a nanoporous core. On the basis of the presented atomic-scale observations, an interlayer exchange mechanism next to pure surface diffusion becomes obvious which may be controlling the layer thickness and its later change in orientation. 相似文献