全文获取类型
收费全文 | 144761篇 |
免费 | 10159篇 |
国内免费 | 6973篇 |
专业分类
化学 | 69463篇 |
晶体学 | 1408篇 |
力学 | 10994篇 |
综合类 | 515篇 |
数学 | 39617篇 |
物理学 | 39896篇 |
出版年
2024年 | 228篇 |
2023年 | 1399篇 |
2022年 | 2280篇 |
2021年 | 2468篇 |
2020年 | 2522篇 |
2019年 | 2423篇 |
2018年 | 12056篇 |
2017年 | 11671篇 |
2016年 | 8701篇 |
2015年 | 3868篇 |
2014年 | 3922篇 |
2013年 | 5132篇 |
2012年 | 9486篇 |
2011年 | 16059篇 |
2010年 | 9439篇 |
2009年 | 9753篇 |
2008年 | 10502篇 |
2007年 | 12239篇 |
2006年 | 3757篇 |
2005年 | 4337篇 |
2004年 | 3942篇 |
2003年 | 3791篇 |
2002年 | 2657篇 |
2001年 | 1752篇 |
2000年 | 1699篇 |
1999年 | 1709篇 |
1998年 | 1518篇 |
1997年 | 1309篇 |
1996年 | 1417篇 |
1995年 | 1183篇 |
1994年 | 1081篇 |
1993年 | 957篇 |
1992年 | 820篇 |
1991年 | 726篇 |
1990年 | 603篇 |
1989年 | 538篇 |
1988年 | 424篇 |
1987年 | 406篇 |
1986年 | 354篇 |
1985年 | 346篇 |
1984年 | 244篇 |
1983年 | 212篇 |
1982年 | 186篇 |
1981年 | 150篇 |
1980年 | 128篇 |
1979年 | 93篇 |
1978年 | 90篇 |
1977年 | 70篇 |
1975年 | 73篇 |
1973年 | 82篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Maxim V. Pavlov 《Communications in Mathematical Physics》2007,272(2):469-505
The algebro-geometric approach for integrability of semi-Hamiltonian hydrodynamic type systems is presented. The class of
symmetric hydrodynamic type systems is defined and the calculation of the associated Riemann surfaces is greatly simplified for this
class. Many interesting and physically motivated examples are investigated. 相似文献
82.
Chii-Wann Lin Kuo-Ping Chen Ming-Chii Su Chih-Kung Lee Chih-Chung Yang 《Optical and Quantum Electronics》2005,37(13-15):1423-1437
We have reported a novel design of surface plasmon resonance (SPR) device, which uses alternating dielectric layers to enhance the SPR signal quality and modulate its resonant position. Admittance loci method of thin film design has been used in the design of such a device. The use of biomolecular thin film, such as DNAs or Porteins, in this design can result in resonant condition of wavelength changes as well. Bio-plasmonics is proposed for the research and development of novel devices, which use biomolecules as a part of the plasmon oscillation system to actively interact with nano/micro structure. 相似文献
83.
Kwang-Hua W. Chu 《International Journal of Theoretical Physics》2007,46(12):3230-3233
The modified Gross–Pitaevskii equation was derived and solved to obtain the 1D solution in the zero-energy limit. This stationary
solution could account for the dominated contributions due to the kinetic effect as well as the chemical potential in inhomogeneous
Bose gases. 相似文献
84.
Masaharu Asano Jinhua Chen Yasunari Maekawa Takahiro Sakamura Hitoshi Kubota Masaru Yoshida 《Journal of polymer science. Part A, Polymer chemistry》2007,45(13):2624-2637
A novel process comprising the UV‐induced photografting of styrene into poly(tetrafluoroethylene) (PTFE) films and subsequent sulfonation has been developed for preparing proton‐conducting membranes. Although under UV irradiation the initial radicals were mainly generated on the surface of the PTFE films by the action of photosensitizers such as xanthone and benzoyl peroxide, the graft chains were readily propagated into the PTFE films. The sulfonation of the grafted films was performed in a chlorosulfonic acid solution. Fourier transform infrared and scanning electron microscopy were used to characterize the grafted and sulfonated membranes. With a view to use in fuel cells, the proton conductivity, water uptake, and mechanical properties of the prepared membranes were measured. Even through the degree of grafting was lower than 10%, the proton conductivity in the thickness direction of the newly prepared membranes could reach a value similar to that of a Nafion membrane. In comparison with γ‐ray radiation grafting, UV‐induced photografting is very simple and safe and is less damaging to the membranes because significant degradation of the PTFE main chains can be avoided. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2624–2637, 2007 相似文献
85.
Djamel Meraghni Abdelhakim Necir 《Methodology and Computing in Applied Probability》2007,9(4):557-572
The characteristic exponent α of a Lévy-stable law S
α
(σ, β, μ) was thoroughly studied as the extreme value index of a heavy tailed distribution. For 1 < α < 2, Peng (Statist. Probab. Lett. 52: 255–264, 2001) has proposed, via the extreme value approach, an asymptotically normal estimator for the location parameter μ. In this paper, we derive by the same approach, an estimator for the scale parameter σ and we discuss its limiting behavior.
相似文献
86.
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
87.
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
88.
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
89.
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
90.