全文获取类型
收费全文 | 113331篇 |
免费 | 5793篇 |
国内免费 | 3995篇 |
专业分类
化学 | 48978篇 |
晶体学 | 1125篇 |
力学 | 8764篇 |
综合类 | 241篇 |
数学 | 35818篇 |
物理学 | 28193篇 |
出版年
2024年 | 111篇 |
2023年 | 759篇 |
2022年 | 1224篇 |
2021年 | 1400篇 |
2020年 | 1443篇 |
2019年 | 1330篇 |
2018年 | 11298篇 |
2017年 | 11064篇 |
2016年 | 7511篇 |
2015年 | 2445篇 |
2014年 | 2280篇 |
2013年 | 2870篇 |
2012年 | 6936篇 |
2011年 | 13425篇 |
2010年 | 7659篇 |
2009年 | 7948篇 |
2008年 | 8666篇 |
2007年 | 10568篇 |
2006年 | 2034篇 |
2005年 | 2805篇 |
2004年 | 2783篇 |
2003年 | 2918篇 |
2002年 | 1880篇 |
2001年 | 975篇 |
2000年 | 973篇 |
1999年 | 978篇 |
1998年 | 880篇 |
1997年 | 777篇 |
1996年 | 898篇 |
1995年 | 714篇 |
1994年 | 623篇 |
1993年 | 562篇 |
1992年 | 501篇 |
1991年 | 426篇 |
1990年 | 373篇 |
1989年 | 294篇 |
1988年 | 274篇 |
1987年 | 255篇 |
1986年 | 198篇 |
1985年 | 202篇 |
1984年 | 177篇 |
1983年 | 152篇 |
1982年 | 121篇 |
1981年 | 97篇 |
1980年 | 95篇 |
1979年 | 77篇 |
1978年 | 60篇 |
1976年 | 43篇 |
1975年 | 47篇 |
1914年 | 45篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
111.
112.
Tao Jin Feng-Xian Jiang Xiao-Li Li Fang Wang Xiao-Hua Shen Rui-Qiang Zhang Hai-Shun Wu 《Applied Surface Science》2006,253(5):2708-2712
CoPt/Ag and [C/CoPt]n/Ag thin films have been prepared onto the glass substrates by magnetron sputtering. We investigated the evolution of texture and magnetic properties of CoPt/Ag and [C/CoPt]n/Ag films. The results show that C-doping plays an important role in improving (0 0 1) texture, improving the order parameter S, reducing the intergrain interactions, and making the magnetization reversal mechanism more close to Stoner-Wolfarth rotational mechanism. The growth mechanism of (0 0 1) texture also seems to be related strongly to the films thickness. Our results show that the highly (0 0 1)-oriented films with ordered fct phase have a significant potential for the perpendicular media of extremely high-density recording. 相似文献
113.
Elizabeth Wulcan 《Arkiv f?r Matematik》2007,45(1):157-178
With a given holomorphic section of a Hermitian vector bundle, one can associate a residue current by means of Cauchy–Fantappiè–Leray
type formulas. In this paper we define products of such residue currents. We prove that, in the case of a complete intersection,
the product of the residue currents of a tuple of sections coincides with the residue current of the direct sum of the sections. 相似文献
114.
Liang-gen Hu 《应用数学学报(英文版)》2007,23(2):281-288
In this paper,we will establish several strong convergence theorems for the approximation ofcommon fixed points of r-strictly asymptotically pseudocontractive mappings in uniformly convex Banachspaces using the modiied implicit iteration sequence with errors,and prove the necessary and sufficient conditionsfor the convergence of the sequence.Our results generalize,extend and improve the recent work,in thistopic. 相似文献
115.
Daniel Maerten 《Annals of Global Analysis and Geometry》2007,32(4):391-414
We prove a Penrose-like inequality for the mass of a large class of constant mean curvature (CMC) asymptotically flat n-dimensional spin manifolds which satisfy the dominant energy condition and have a future converging, or past converging compact
and connected boundary of non-positive mean curvature and of positive Yamabe invariant. We prove that for every n ≥ 3 the mass is bounded from below by an expression involving the norm of the linear momentum, the volume of the boundary,
dimensionless geometric constants and some normalized Sobolev ratio. 相似文献
116.
In cricket, a rain-affected pitch can make batting more difficult than normal. Several other conditions such as poor light or an initially lively pitch, may also result in difficulties for the batsmen. In this note, we refer to all of them as ‘sticky wickets’. On sticky wickets, lower order batsmen are often sent into ‘hold the fort’ until conditions improve. In this paper, a stochastic dynamic programming model is used to examine the appropriateness of this policy. The model suggests that the tactic is often optimal when the sticky wicket persists until the end of the day's play, but not often when the sticky wicket is transitory. In some circumstances, it is worthwhile, on a normal wicket near the end of the day, to send in a lower order batsman to hold the fort (a night watchman): when the wicket is sticky, this tactic is even more worthwhile. 相似文献
117.
118.
Investigation of remelting and cladding processing with laminar plasma jets on several metals has been conducted looking for possible development of a new surface modification technique. The remelting tests illustrated that the new method could evidently improve the material microstructure and properties of cast iron. The cladding was done with Al2O3 ceramic powder on stainless steel. The energy dispersive spectra (EDS) analysis was used to determine the distribution of the major cladding element in the plasma-processed layers, for which the microstructure observations and hardness measurements were also performed. 相似文献
119.
The influence of the electron-LO-phonon coupling on energy spectrum of the low-lying states ofan exciton inparabolic quantum dots is investigated as a function of dot size. Calculations are made by using the method of few-bodyphysics within the effective-mass approximation. A considerable decrease of the energy in the stronger confinement rangeis found for the low-lying states of an exciton in quantum dots, which results from the confinement of electron-phononcoupling. 相似文献
120.
Ying Zhang Gang Hu Shigang Chen H.A. Cerdeira 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,27(3):381-384
A method of controlling global stochasticity in Hamiltonian systems by applying nonlinear perturbation is proposed. With the
well-known standard map we demonstrate that this control method can convert global stochasticity into regular motion in a
wide chaotic region for arbitrary initial condition, in which the control signal remains very weak after a few kicks. The
system in which chaos has been controlled approximates to the original Hamiltonian system, and this approach appears robust
against small external noise. The mechanism underlying this high control efficiency is intuitively explained.
Received 15 January 2002 Published online 6 June 2002 相似文献