全文获取类型
收费全文 | 14269篇 |
免费 | 361篇 |
国内免费 | 95篇 |
专业分类
化学 | 9990篇 |
晶体学 | 137篇 |
力学 | 321篇 |
数学 | 1863篇 |
物理学 | 2414篇 |
出版年
2023年 | 70篇 |
2022年 | 105篇 |
2021年 | 143篇 |
2020年 | 171篇 |
2019年 | 165篇 |
2018年 | 137篇 |
2017年 | 124篇 |
2016年 | 253篇 |
2015年 | 252篇 |
2014年 | 318篇 |
2013年 | 623篇 |
2012年 | 765篇 |
2011年 | 977篇 |
2010年 | 465篇 |
2009年 | 410篇 |
2008年 | 880篇 |
2007年 | 904篇 |
2006年 | 914篇 |
2005年 | 926篇 |
2004年 | 823篇 |
2003年 | 693篇 |
2002年 | 668篇 |
2001年 | 239篇 |
2000年 | 206篇 |
1999年 | 162篇 |
1998年 | 182篇 |
1997年 | 206篇 |
1996年 | 223篇 |
1995年 | 162篇 |
1994年 | 162篇 |
1993年 | 159篇 |
1992年 | 128篇 |
1991年 | 131篇 |
1990年 | 101篇 |
1989年 | 81篇 |
1988年 | 89篇 |
1987年 | 89篇 |
1986年 | 73篇 |
1985年 | 131篇 |
1984年 | 140篇 |
1983年 | 93篇 |
1982年 | 104篇 |
1981年 | 125篇 |
1980年 | 118篇 |
1979年 | 94篇 |
1978年 | 91篇 |
1977年 | 85篇 |
1976年 | 67篇 |
1975年 | 68篇 |
1973年 | 77篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
83.
Adel Attia Markéta Zukalová Jiří Rathouský Arnošt Zukal Ladislav Kavan 《Journal of Solid State Electrochemistry》2005,9(3):138-145
A mesoporous electrode material whose structure is composed of anatase nanocrystals stabilized by alumina is reported. Powder X-ray diffraction shows the anatase phase only, but micro-Raman spectroscopy shows that the materials have a core-shell morphology with grains of bulk anatase covered by a thin rutile layer on the surface. This structure is unique when compared to analogous materials stabilized by zirconia (PNNL-1). Nitrogen adsorption isotherms demonstrate a monotonous increase in surface area and mesopore volume with increasing Al content. Thin film electrodes from these materials were characterized by lithium insertion electrochemistry. Cyclic voltammograms exhibit significant differences in Li accommodation in Al-free and Al-stabilized materials. 相似文献
84.
Jeffrey T. Culp Franz Frye Mark W. Meisel Daniel R. Talham 《Coordination chemistry reviews》2005,249(23):2642-2648
Studies of metal cyanide thin films prepared directly at interfaces are reviewed. The systems range from monolayers, single-layer analogs of Prussian blue-like networks, to bulk powders prepared as thin films. Monolayer networks are prepared at the air/water interface and transferred to solid supports using Langmuir-Blodgett film methods. Films of bulk materials are prepared directly on solid surfaces using a templated sequential deposition procedure. The magnetic properties of the films have been explored, and in some cases, these monolayers and surface films give rise to new behavior that is only possible because of the fabrication method or thin film architecture. The methods of synthesis can generate oriented samples, even when the materials are poorly crystalline. Furthermore, the interface-assembled networks are inherently anisotropic, leading to phenomena not present in the solid-state analogs, such as anisotropic photomagnetism in a thin film of RbjCok[Fe(CN)6]l·nH2O. 相似文献
85.
Solubility behaviors of binary mixtures of CFCl3 (R-11), CFCl2-CF2Cl (R-113), CHCl3 (R-20), CDCl3 (R-20-d), CHCl2–CF3 (R-123) with room-temperature ionic liquid [bmim][PF6] (1-butyl-3-methylimidazolium hexafluorophosphate) have been investigated using the volumetric and cloud-point methods, since all the systems show liquid–liquid equilibria (LLE). Large immiscibility (LLE) gaps of the perhalogenated compounds (R-11 and R-113) in the ionic liquid have been drastically reduced by the addition of only one hydrogen (or deuterium) in these compounds. The R-123 + [bmim][PF6] binary system belongs to the Type-V fluid behavior. Noticeably large negative values (−2 to −8 cm3 mol−1) of the excess molar volume in the ionic liquid-rich side solution have been observed for all the present systems. Experimental LLE data have been well correlated by the use of the NRTL (non-random two liquid) activity coefficient model. 相似文献
86.
Stols Lucy Kulkarni Gopal Harris Ben G. Donnelly Mark I. 《Applied biochemistry and biotechnology》1997,63(1):153-158
Applied Biochemistry and Biotechnology - The malic enzyme gene ofAscaris suum was cloned into the vector pTRC99a in two forms encoding alternative arnino-termini. The resulting plasmids, pMEAl and... 相似文献
87.
88.
Pathak JA Davis MC Hudson SD Migler KB 《Journal of colloid and interface science》2002,255(2):391-402
We investigate the influence of confinement on the steady state microstructure of emulsions sheared between parallel plates, in a regime where the average droplet dimension is comparable to the gap width between the confining walls. Utilizing droplet velocimetry, we find that the droplets can organize into discrete layers under the influence of shear. The number of layers decreases from two (at relatively higher shear rates) to one (at lower shear rates), as the drops grow slightly larger due to coalescence. We argue that the layering and overall composition profile may be controlled by the interplay of droplet collisions (which can cause separation of droplet centers in the velocity gradient direction), droplet migration toward the centerline (due to wall effects), and droplet packing constraints. We also study the effects of mixture composition on droplet microstructure, and summarize these results in the form of a morphology diagram in the parameter space of mass fraction and shear rate. We find that formation of strings of the suspended phase (reported earlier by our group in flow-visualization studies on confined emulsions) is observed over a broad composition window. We also find a stable (nontransient) morphology wherein the droplets are arranged in highly ordered pearl-necklace chain structures. 相似文献
89.
90.
Mark Pollicott 《Communications in Mathematical Physics》1987,113(1):137-154
For the strong unstable foliation (or horocycle foliation) of an Anosov flow there exists a unique transverse measure called the Margulis measure. In this paper we extend Margulis' results to more general transverse distributions for the foliation. As an application we derive our main result: The non-zero analytic extension to a strip of the Selberg zeta function for compact surfaces of constant negative curvature persists under small perturbations in the metric. There is an equivalent formulation in terms of the Fourier transform of the correlation function. 相似文献