全文获取类型
收费全文 | 1613篇 |
免费 | 85篇 |
国内免费 | 25篇 |
专业分类
化学 | 1018篇 |
晶体学 | 4篇 |
力学 | 87篇 |
数学 | 257篇 |
物理学 | 357篇 |
出版年
2024年 | 4篇 |
2023年 | 13篇 |
2022年 | 55篇 |
2021年 | 42篇 |
2020年 | 78篇 |
2019年 | 53篇 |
2018年 | 56篇 |
2017年 | 46篇 |
2016年 | 102篇 |
2015年 | 82篇 |
2014年 | 101篇 |
2013年 | 134篇 |
2012年 | 142篇 |
2011年 | 152篇 |
2010年 | 105篇 |
2009年 | 70篇 |
2008年 | 62篇 |
2007年 | 76篇 |
2006年 | 73篇 |
2005年 | 45篇 |
2004年 | 50篇 |
2003年 | 37篇 |
2002年 | 36篇 |
2001年 | 20篇 |
2000年 | 8篇 |
1999年 | 3篇 |
1998年 | 6篇 |
1997年 | 5篇 |
1996年 | 10篇 |
1995年 | 2篇 |
1994年 | 5篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 4篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 4篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1974年 | 5篇 |
1969年 | 1篇 |
1965年 | 1篇 |
1964年 | 1篇 |
1963年 | 1篇 |
1930年 | 1篇 |
1925年 | 1篇 |
排序方式: 共有1723条查询结果,搜索用时 15 毫秒
81.
Isolated singularities of polyharmonic inequalities 总被引:1,自引:0,他引:1
Marius Ghergu Amir Moradifam Steven D. Taliaferro 《Journal of Functional Analysis》2011,261(3):660-680
We study nonnegative classical solutions u of the polyharmonic inequality
82.
Payment data is one of the most valuable assets that retail banks can leverage as the major competitive advantage with respect to new entrants such as Fintech companies or giant internet companies. In marketing, the value behind data relates to the power of encoding customer preferences: the better you know your customer, the better your marketing strategy. In this paper, we present a B2B2C lead generation application based on payment transaction data within the online banking system. In this approach, the bank is an intermediary between its private customers and merchants. The bank uses its competence in Machine Learning driven marketing to build a lead generation application that helps merchants run data driven campaigns through the banking channels to reach retail customers. The bank’s retail customers trade the utility hidden in its payment transaction data for special offers and discounts offered by merchants. During the entire process banks protects the privacy of the retail customer. 相似文献
83.
Gas sensing is one of the most promising applications for graphene. Using molecular dynamics simulation method, adsorption isotherm of xenon (Xe) gas on defected and perfect graphene is studied in order to investigate sensing properties of graphene for Xe gas. In this method, first generation of Brenner many-body potential is used to simulate the interaction of carbon–carbon (C) atoms in graphene, and Lennard–Jones two-body potential is used to simulate interaction of Xe–Xe and Xe–C atoms. In the simulated systems, adsorption coverage, radial distribution function, heat of adsorption, binding energy and specific heat capacity at constant volume are calculated for several temperatures between 90 K and 130 K, and various pressures. It was found that both of the defected and perfect graphene could be introduced as very good candidates for adsorption of Xe gas. 相似文献
84.
85.
Maliheh Khatibi Moghaddam Amir Reza Attari Mir Mojtaba Mirsalehi 《Photonics and Nanostructures》2010,8(1):47-53
We investigate a photonic crystal (PC) waveguide coupler which is formed by two closely spaced linear waveguides in a two-dimensional triangular lattice of air holes. Our study shows that shifting one row of the air holes between the waveguides affects the dispersion curves of the guided modes and if the triangular lattice of air holes between the waveguides is replaced by a rectangular lattice, this modification results in an ultra-short coupling structure with coupling length less than 3a, where a is the lattice constant. Also, we investigate the effect of changing the radii of air holes that are adjacent to or between the waveguides on the coupling length and show that increasing the radius of air holes between the waveguides decreases the coupling length. We analyze the output spectrum of an ultra-short channel drop filter designed based on this structure. 相似文献
86.
87.
88.
Dganit Amitai Amir Averbuch Moshe Israeli Samuel Itzikowitz 《Numerical Algorithms》1996,12(1):159-192
In achieving significant speed-up on parallel machines, a major obstacle is the overhead associated with synchronizing the concurrent processes. This paper presents high-orderparallel asynchronous schemes, which are schemes that are specifically designed to minimize the associated synchronization overhead of a parallel machine in solving parabolic PDEs. They are asynchronous in the sense that each processor is allowed to advance at its own speed. Thus, these schemes are suitable for single (or multi) user shared memory or (message passing) MIMD multiprocessors. Our approach is demonstrated for the solution of the multidimensional heat equation, of which we present a spatial second-order Parametric Asynchronous Finite-Difference (PAFD) scheme. The well-known synchronous schemes are obtained as its special cases. This is a generalization and expansion of the results in [5] and [7]. The consistency, stability and convergence of this scheme are investigated in detail. Numerical tests show that although PAFD provides the desired order of accuracy, its efficiency is inadequate when performed on each grid point.In an alternative approach that uses domain decomposition, the problem domain is divided among the processors. Each processor computes its subdomain mostly independently, while the PAFD scheme provides the solutions at the subdomains' boundaries. We use high-order finite-difference implicit scheme within each subdomain and determine the values at subdomains' boundaries by the PAFD scheme. Moreover, in order to allow larger time-step, we use remote neighbors' values rather than those of the immediate neighbors. Numerical tests show that this approach provides high efficiency and in the case which uses remote neighbors' values an almost linear speedup is achieved. Schemes similar to the PAFD can be developed for other types of equations [3].This research was supported by the fund for promotion of research at the Technion. 相似文献
89.
Light is shown to exhibit critical and tricritical behavior in passively mode-locked lasers with externally injected pulses. It is a first and unique example of critical phenomena in a one-dimensional many-body light-mode system. The phase diagrams consist of regimes with continuous wave, driven parapulses, spontaneous pulses via mode condensation, and heterogeneous pulses, separated by phase transition lines that terminate with critical or tricritical points. Enhanced non-Gaussian fluctuations and collective dynamics are present at the critical and tricritical points, showing a mode system analog of the critical opalescence phenomenon. The critical exponents are calculated and shown to comply with the mean field theory, which is rigorous in the light system. 相似文献
90.
We study the magneto-optic (MO) Faraday rotation in a two-dimensional square-lattice photonic crystal with a central MO defect layer in the optical wavelength range. We show that when a TM plane wave is incident upon a photonic crystal, an enhancement of Faraday rotation takes place in a region where a resonance peak appears in the photonic bandgap. In this region the mode conversion is high. 相似文献