全文获取类型
收费全文 | 20598篇 |
免费 | 6971篇 |
国内免费 | 6980篇 |
专业分类
化学 | 8862篇 |
晶体学 | 270篇 |
力学 | 3320篇 |
综合类 | 730篇 |
数学 | 5869篇 |
物理学 | 15498篇 |
出版年
2024年 | 191篇 |
2023年 | 601篇 |
2022年 | 792篇 |
2021年 | 742篇 |
2020年 | 623篇 |
2019年 | 658篇 |
2018年 | 467篇 |
2017年 | 635篇 |
2016年 | 715篇 |
2015年 | 801篇 |
2014年 | 1741篇 |
2013年 | 1311篇 |
2012年 | 1292篇 |
2011年 | 1509篇 |
2010年 | 1622篇 |
2009年 | 1687篇 |
2008年 | 1906篇 |
2007年 | 1642篇 |
2006年 | 1642篇 |
2005年 | 1411篇 |
2004年 | 1526篇 |
2003年 | 1378篇 |
2002年 | 1270篇 |
2001年 | 1088篇 |
2000年 | 918篇 |
1999年 | 813篇 |
1998年 | 694篇 |
1997年 | 680篇 |
1996年 | 688篇 |
1995年 | 656篇 |
1994年 | 571篇 |
1993年 | 421篇 |
1992年 | 445篇 |
1991年 | 381篇 |
1990年 | 392篇 |
1989年 | 343篇 |
1988年 | 97篇 |
1987年 | 68篇 |
1986年 | 52篇 |
1985年 | 27篇 |
1984年 | 9篇 |
1983年 | 20篇 |
1982年 | 19篇 |
1980年 | 2篇 |
1959年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
241.
现代热力学的完整分类系统--非平衡非耗散热力学新领域 总被引:1,自引:0,他引:1
在同一体系中同时有多个不可逆过程时,不可逆过程之间会有相互影响,原来的非自发过程有可能在其他自发过程的影响下得以进行,这种现象就称为热力学耦合或反应耦合,长期以来,经典热力学把热力学第二定律的等式作为平衡体系的充分必要条件,其中隐含了一个前提性的假定,即经典热力学的对象只限于非耦合的体系,摈弃这一隐含的前提性假定以后,热力学自身就发展成为一个现代热力学的完整学术体系,适用于任何宏观体系(包括极其复杂的生命体系),现代热力学的完整学术体系中包含了一个崭新的非平衡非耗散热力学新领域,由于该领域属于热力学第二定律的等式部分,因此可以定量计算,并得到一系列理论计算的非平衡相图,与文献上报道的激尖低压金刚石合成等的大量实验数据相符。 相似文献
242.
The validity condition of the brick-wall model is analysed in nonstationary space-time.It is shown that the model holds only in thin regions,only by using tortoise coordinates near the event horizon of a slowly varying(quasistationary)black hole.The reason for the use of tortoise cooridnates is that the stationary state solutions of quantum field equations in other coordinates do not exist for any region in nonstationary space-time.Meanwhile,the quantum corrections to the entropy of the Vaidya-Bonner black hole due to the spin fields are calculated in terms of the brick-wall model. 相似文献
243.
An effcient multiparty quantum secret sharing scheme is proposed with Greenberger-Horne-Zeilinger (GHZ) states following some ideas in quantum dense coding. The agents take the single-photon measurements on the photons received for eavesdropping check and exploit the four local unitary operations Ⅰ, σx, σx and iσy to code their message. This scheme has the advantage of high capacity as each GHZ state can carry two bits of information. The parties do not need to announce the measuring bases for almost all the photons, which will reduce the classical information exchanged largely. The intrinsic efficiency for qubits and the total effciency both approach the maximal values. 相似文献
244.
Wengu Chen Yixin Lai 《分析论及其应用》2006,22(2):195-200
Let μ be a Borel measure on Rd which may be non doubling. The only condition that μ must satisfy is μ(Q) ≤ col(Q)n for any cube Q () Rd with sides parallel to the coordinate axes and for some fixed n with 0 < n ≤ d. The purpose of this paper is to obtain a boundedness property of fractional integrals in Hardy spaces H1 (μ). 相似文献
245.
Quantum Key Distribution Using Four-Qubit W State 总被引:3,自引:0,他引:3
CAO Hai-Jing SONG He-Shan 《理论物理通讯》2006,46(1):65-68
A new theoretical quantum key distribution scheme based on entanglement swapping is proposed, where four-qubit symmetric W state functions as quantum channel. It is shown that two legitimate users can secretly share a series of key bits by using Bell-state measurements and classical communication. 相似文献
246.
By utilizing a fixed point theorem on cone,some new results on the existence of positive periodic solutions for nonautonomous differential equations with delay are derived. 相似文献
247.
Wei-nan E Ping-bing Ming 《应用数学学报(英文版)》2007,23(4):529-550
We study continuum and atomistic models for the elastodynamics of crystalline solids at zerotemperature.We establish sharp criterion for the regime of validity of the nonlinear elastic wave equationsderived from the well-known Cauchy-Born rule. 相似文献
248.
Quantum gravity can modify the usual energy-momentum dispersion relation. We provide evidence for the argument that the modified dispersion relation is constrained by the black hole thermodynamics, for consistency of quantum gravity. 相似文献
249.
The mutual interaction of three different defects in photonic crystals is studied theoretically. A theoretical model based on the classical wave analogue of the tight-binding (TB) picture is applied to the structure. We obtain analytic expressions for the eigenfrequencies and eigenmodes, from which the transmissions at resonance are derived. Based on this, a new type of the photonic quantum-well structure is investigated and its possible application is discussed. The TB predictions are compared with the transfer matrix method simulation results. 相似文献
250.
We investigate the new spinor field realizations of the W3 algebra, making use of the fact that the W3 algebra can be linearized by the addition of a spin-1 current. We then use these new realizations to build the nilpotent Becchi-Rouet-Stora-Tyutin charges of the spinor non-critical W3 string. 相似文献