全文获取类型
收费全文 | 6266篇 |
免费 | 651篇 |
国内免费 | 583篇 |
专业分类
化学 | 1470篇 |
晶体学 | 15篇 |
力学 | 402篇 |
综合类 | 82篇 |
数学 | 2844篇 |
物理学 | 2687篇 |
出版年
2024年 | 11篇 |
2023年 | 55篇 |
2022年 | 111篇 |
2021年 | 119篇 |
2020年 | 113篇 |
2019年 | 153篇 |
2018年 | 139篇 |
2017年 | 199篇 |
2016年 | 197篇 |
2015年 | 205篇 |
2014年 | 286篇 |
2013年 | 485篇 |
2012年 | 300篇 |
2011年 | 326篇 |
2010年 | 243篇 |
2009年 | 358篇 |
2008年 | 404篇 |
2007年 | 421篇 |
2006年 | 316篇 |
2005年 | 307篇 |
2004年 | 303篇 |
2003年 | 287篇 |
2002年 | 282篇 |
2001年 | 194篇 |
2000年 | 215篇 |
1999年 | 172篇 |
1998年 | 165篇 |
1997年 | 165篇 |
1996年 | 112篇 |
1995年 | 96篇 |
1994年 | 83篇 |
1993年 | 65篇 |
1992年 | 59篇 |
1991年 | 52篇 |
1990年 | 53篇 |
1989年 | 43篇 |
1988年 | 38篇 |
1987年 | 45篇 |
1986年 | 31篇 |
1985年 | 48篇 |
1984年 | 32篇 |
1983年 | 12篇 |
1982年 | 37篇 |
1981年 | 39篇 |
1980年 | 20篇 |
1979年 | 21篇 |
1978年 | 17篇 |
1977年 | 20篇 |
1976年 | 16篇 |
1973年 | 8篇 |
排序方式: 共有7500条查询结果,搜索用时 15 毫秒
101.
The wavelet and harmonic filtering method suggested by Zalevsky and Ouzieli is introduced in this paper and adopted in our volume holographic image recognition system. This composite filter combines several scaled versions of the cascaded wavelet and harmonic filter, obtaining high discrimination ability and wide dynamic range of rotation and scale deformations. Optical experiments are conducted to demonstrate the validity and practicability of the algorithm. To the best of our knowledge, this is the first report of using this algorithm in a volume holographic system. Moreover, the separate correlation approach proposed in this paper greatly simplifies the manufacturing process and reduces the cost of the system. 相似文献
102.
C. Andreoiu D. Rudolph I. Ragnarsson C. Fahlander R.A.E. Austin M.P. Carpenter R.M. Clark J. Ekman R.V.F. Janssens T.L. Khoo F.G. Kondev T. Lauritsen T. Rodinger D.G. Sarantites D. Seweryniak T. Steinhardt C.E. Svensson O. Thelen J.C. Waddington 《The European Physical Journal A - Hadrons and Nuclei》2002,14(3):317-348
High-spin states in 59Cu were populated using the fusion-evaporation reaction 28Si + 40Ca at a beam energy of 122 MeV. The Gammasphere Ge-detector array in conjunction with the 4π charged-particle detector array
Microball allowed for the detection of γ-rays in coincidence with evaporated light particles. The resulting extensive high-spin
decay scheme of 59Cu is presented, which comprises more than 320 γ-ray transitions connecting about 150 excited states. Their spins and parities
have been assigned via directional correlations of γ-rays emitted from oriented states. Average quadrupole moments of rotational
bands have been determined from the analysis of residual Doppler shifts. Shell model calculations in the fp shell are invoked to study some of the low-spin states, while the experimental characteristics of the rotational bands are
analyzed in the configuration-dependent cranked Nilsson-Strutinsky (CNS) approach.
Received: 15 February 2002 / Accepted: 23 April 2002 相似文献
103.
Maxim Braverman Valentin Silantyev 《Transactions of the American Mathematical Society》2006,358(8):3329-3361
We extend the Novikov Morse-type inequalities for closed 1-forms in 2 directions. First, we consider manifolds with boundary. Second, we allow a very degenerate structure of the critical set of the form, assuming only that the form is non-degenerated in the sense of Kirwan. In particular, we obtain a generalization of a result of Floer about the usual Morse inequalities on a manifold with boundary. We also obtain an equivariant version of our inequalities.
Our proof is based on an application of the Witten deformation technique. The main novelty here is that we consider the neighborhood of the critical set as a manifold with a cylindrical end. This leads to a considerable simplification of the local analysis. In particular, we obtain a new analytic proof of the Morse-Bott inequalities on a closed manifold.
104.
We present a new approach, requiring the solution of a SemiDefinite Program, for decomposing the Hessian of a nonseparable mixed-integer quadratic problem to permit using perspective cuts to improve its continuous relaxation bound. The new method favorably compares with a previously proposed one requiring a minimum eigenvalue computation. 相似文献
105.
106.
107.
Marcinkiewicz–Zygmund inequalities 总被引:1,自引:1,他引:0
We study a generalization of the classical Marcinkiewicz–Zygmund inequalities. We relate this problem to the sampling sequences in the Paley–Wiener space and by using this analogy we give sharp necessary and sufficient computable conditions for a family of points to satisfy the Marcinkiewicz–Zygmund inequalities. 相似文献
108.
关于Gerber不等式的一个猜想 总被引:4,自引:1,他引:3
本文证明了陈计-单墫关于Gerber不等式的一个猜想,作为其应用,导出了单形内一点到顶点的距离与到面的距离的两个不等式. 相似文献
109.
Summary Complete Active-Space Self-Consistent-Field (CAS-SCF) calculations for cubic N8 are presented. We studied the N8↔4N2 reaction inD
4h
symmetry and found its energy release and activation barrier with three different atomic basis sets. The energy release for
this reaction is predicted to be around 526 kcal/mol, while the energy barrier to dissociation is estimated about 159 kcal/mol.
These results are in substantial agreement with previousab initio estimates.
The authors of this paper have agreed to not receive the proofs for correction. 相似文献
110.
本文用数字散斑相关方法测量了五种不同幂硬化指数韧性金属材料(铝和铜),双边裂纹尖端细观区域内应变场.对所得结果用韧性损伤模型进行了分析.在此法中以金属自然表面结构为散斑场,不同加载状态的散斑场进行比较,得到相对变形与应变.图象之间相关性 C 是变形参数或是位移及其导数的泛函.使其相关性 C 取最大值的试凑变形即为其真实变形场.这一方法在细观测量中应用得到满意的结果. 相似文献