全文获取类型
收费全文 | 1882篇 |
免费 | 24篇 |
国内免费 | 8篇 |
专业分类
化学 | 1021篇 |
晶体学 | 16篇 |
力学 | 65篇 |
数学 | 253篇 |
物理学 | 559篇 |
出版年
2018年 | 18篇 |
2016年 | 20篇 |
2015年 | 23篇 |
2014年 | 22篇 |
2013年 | 70篇 |
2012年 | 53篇 |
2011年 | 46篇 |
2010年 | 31篇 |
2009年 | 35篇 |
2008年 | 36篇 |
2007年 | 54篇 |
2006年 | 53篇 |
2005年 | 64篇 |
2004年 | 44篇 |
2003年 | 37篇 |
2002年 | 39篇 |
2001年 | 48篇 |
2000年 | 49篇 |
1999年 | 43篇 |
1998年 | 34篇 |
1997年 | 33篇 |
1996年 | 24篇 |
1995年 | 34篇 |
1994年 | 37篇 |
1993年 | 28篇 |
1992年 | 25篇 |
1991年 | 33篇 |
1990年 | 23篇 |
1989年 | 32篇 |
1988年 | 21篇 |
1987年 | 30篇 |
1986年 | 29篇 |
1985年 | 30篇 |
1984年 | 35篇 |
1983年 | 24篇 |
1982年 | 28篇 |
1980年 | 18篇 |
1979年 | 30篇 |
1978年 | 23篇 |
1977年 | 25篇 |
1976年 | 20篇 |
1975年 | 28篇 |
1974年 | 19篇 |
1973年 | 24篇 |
1972年 | 22篇 |
1970年 | 21篇 |
1968年 | 31篇 |
1967年 | 56篇 |
1966年 | 61篇 |
1965年 | 19篇 |
排序方式: 共有1914条查询结果,搜索用时 0 毫秒
81.
Sheida Esmail Tehrani Long Quang Nguyen Giulia Garelli Bettina M. Jensen Tautgirdas Ruzgas Jenny Emnéus Stephan Sylvest Keller 《Electroanalysis》2021,33(12):2516-2528
A highly sensitive amperometric Prussian blue-based hydrogen peroxide sensor was developed using 3D pyrolytic carbon microelectrodes. A 3D printed multielectrode electrochemical cell enabled simultaneous highly reproducible Prussian blue modification on multiple carbon electrodes. The effect of oxygen plasma pre-treatment and deposition time on Prussian blue electrodeposition was studied. The amperometric response of 2D and 3D sensors to the addition of hydrogen peroxide in μM and sub-μM concentrations in phosphate buffer was investigated. A high sensitivity comparable to flow injection systems and a detection limit of 0.16 μM was demonstrated with 3D pyrolytic carbon microelectrodes at stirred batch condition 相似文献
82.
Charlotte Kielar Siqi Zhu Guido Grundmeier Adrian Keller 《Angewandte Chemie (International ed. in English)》2020,59(34):14336-14341
High‐speed atomic force microscopy (HS‐AFM) is widely employed in the investigation of dynamic biomolecular processes at a single‐molecule level. However, it remains an open and somewhat controversial question, how these processes are affected by the rapidly scanned AFM tip. While tip effects are commonly believed to be of minor importance in strongly binding systems, weaker interactions may significantly be disturbed. Herein, we quantitatively assess the role of tip effects in a strongly binding system using a DNA origami‐based single‐molecule assay. Despite its femtomolar dissociation constant, we find that HS‐AFM imaging can disrupt monodentate binding of streptavidin (SAv) to biotin (Bt) even under gentle scanning conditions. To a lesser extent, this is also observed for the much stronger bidentate SAv–Bt complex. The presented DNA origami‐based assay can be universally employed to quantify tip effects in strongly and weakly binding systems and to optimize the experimental settings for their reliable HS‐AFM imaging. 相似文献
83.
84.
85.
86.
M.B. Zölfl Th. Maier Th. Pruschke J. Keller 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(1):47-53
We study one-particle spectra and the electronic band-structure of a CuO
2
-plane within the three-band Hubbard model. The Dynamical Mean-Field Theory (DMFT) is used to solve the many particle problem.
The calculations show that the optical gap is given by excitations from the lower Hubbard band into the so called Zhang-Rice singlet band. The optical gap turns out to be considerably smaller than the bare charge transfer energy () for a typical set of parameters, which is in agreement with experiment. We also investigate the dependence of the shape
of the Fermi surface on the different hopping parameters t
CuO and t
OO. A value t
OO
/
t
CuO
>0 leads to a Fermi surface surrounding the M point.
Received 21 September 1998 and Received in final form 8 June 1999 相似文献
87.
A new formulation of the elastic coherent tunneling current has been developed. Electron transport is described by quasifree electrons in the metals and by an effective one-particle barrier in the insulator. This phenomenological theory needs three parameters to characterize the barrier (barrier height φ, tunneling length s and an asymmetric parameter Vb). Four independent quantities containing these three parameters have been experimentally determined to check the consistency of this theory and an excellent agreement has been found. Finally, the theory is extended to a trapezoidal barrier explaining the experimental results obtained on AlIAl diodes. 相似文献
88.
We report the observation of Absorption Line Narrowing (A.L.N.) in a Doppler-broadened three-level system of neon under interaction with two quasi-resonant single-mode lasers. The resonance signals are obtained with the laser beams propagating either in the same direction or in opposite direction. The resonance width is found to be smaller in the latter case. The isotopic shifts 22Ne-20Ne of the lines λ = 1.15μ, λ = 6096 Å and λ = 5945 Å have been measured using the A.L.N. method. 相似文献
89.
Let HD d (p, q) denote the minimal size of a transversal that can always be guaranteed for a family of compact convex sets in Rd which satisfy the (p, q)-property (p ≥ q ≥ d + 1). In a celebrated proof of the Hadwiger–Debrunner conjecture, Alon and Kleitman proved that HD d (p, q) exists for all p ≥ q ≥ d + 1. Specifically, they prove that \(H{D_d}(p,d + 1)is\tilde O({p^{{d^2} + d}})\).We present several improved bounds: (i) For any \(q \geqslant d + 1,H{D_d}(p,d) = \tilde O({p^{d(\frac{{q - 1}}{{q - d}})}})\). (ii) For q ≥ log p, \(H{D_d}(p,q) = \tilde O(p + {(p/q)^d})\). (iii) For every ? > 0 there exists a p0 = p0(?) such that for every p ≥ p0 and for every \(q \geqslant {p^{\frac{{d - 1}}{d} + \in }}\) we have p ? q + 1 ≤ HD d (p, q) ≤ p ? q + 2. The latter is the first near tight estimate of HD d (p, q) for an extended range of values of (p, q) since the 1957 Hadwiger–Debrunner theorem.We also prove a (p, 2)-theorem for families in R2 with union complexity below a specific quadratic bound. 相似文献
90.
J. Tripathi J.M. Keller K. Das S. Tripathi T. Shripathi 《Journal of Physics and Chemistry of Solids》2012,73(8):1026-1033
Contribution of Rhodamine B doping on the structural and optical properties of PVA is investigated here. With increasing doping wt%, Raman spectra show the disappearance of main PVA peaks revealing a decrease in crystallinity and breaking of bonds, which also results in modified surface morphology as seen from corresponding SEM measurements. Optical absorption measurements show the possibility of both direct and indirect transitions, also indicating strong modifications in optical properties as a result of doping fluorescent dye in the polymer host. 相似文献