全文获取类型
收费全文 | 8830篇 |
免费 | 267篇 |
国内免费 | 27篇 |
专业分类
化学 | 5879篇 |
晶体学 | 56篇 |
力学 | 279篇 |
综合类 | 1篇 |
数学 | 1187篇 |
物理学 | 1722篇 |
出版年
2023年 | 63篇 |
2022年 | 118篇 |
2021年 | 288篇 |
2020年 | 172篇 |
2019年 | 194篇 |
2018年 | 177篇 |
2017年 | 162篇 |
2016年 | 377篇 |
2015年 | 275篇 |
2014年 | 302篇 |
2013年 | 541篇 |
2012年 | 611篇 |
2011年 | 643篇 |
2010年 | 471篇 |
2009年 | 431篇 |
2008年 | 574篇 |
2007年 | 535篇 |
2006年 | 420篇 |
2005年 | 386篇 |
2004年 | 313篇 |
2003年 | 294篇 |
2002年 | 233篇 |
2001年 | 173篇 |
2000年 | 154篇 |
1999年 | 109篇 |
1998年 | 95篇 |
1997年 | 73篇 |
1996年 | 88篇 |
1995年 | 68篇 |
1994年 | 68篇 |
1993年 | 62篇 |
1992年 | 58篇 |
1991年 | 51篇 |
1990年 | 40篇 |
1989年 | 34篇 |
1988年 | 36篇 |
1987年 | 26篇 |
1986年 | 31篇 |
1985年 | 50篇 |
1984年 | 37篇 |
1983年 | 26篇 |
1982年 | 22篇 |
1981年 | 21篇 |
1980年 | 36篇 |
1979年 | 21篇 |
1978年 | 28篇 |
1976年 | 20篇 |
1975年 | 19篇 |
1974年 | 14篇 |
1973年 | 18篇 |
排序方式: 共有9124条查询结果,搜索用时 593 毫秒
951.
In the context of non-abelian gerbes, we define a cubical version of categorical group 2-bundles with connection over a smooth manifold. We address their two-dimensional parallel transport, study its properties, and construct non-abelian Wilson surface functionals. 相似文献
952.
953.
Bruno?Casella Gareth?O.?RobertsEmail author 《Methodology and Computing in Applied Probability》2011,13(3):449-473
We introduce a novel algorithm (JEA) to simulate exactly from a class of one-dimensional jump-diffusion processes with state-dependent
intensity. The simulation of the continuous component builds on the recent Exact Algorithm (Beskos et al., Bernoulli 12(6):1077–1098,
2006a). The simulation of the jump component instead employs a thinning algorithm with stochastic acceptance probabilities in the
spirit of Glasserman and Merener (Proc R Soc Lond Ser A Math Phys Eng Sci 460(2041):111–127, 2004). In turn JEA allows unbiased Monte Carlo simulation of a wide class of functionals of the process’ trajectory, including
discrete averages, max/min, crossing events, hitting times. Our numerical experiments show that the method outperforms Monte
Carlo methods based on the Euler discretization. 相似文献
954.
This paper is concerned with the existence of solutions of the first‐order fully coupled system with coupled functional boundary conditions. These functional boundary conditions generalize the usual boundary assumptions and may be applied to most of the classical cases. The arguments used are based on the Arzela‐Ascoli theorem and Schauder's fixed‐point theorem. An application to a mathematical model of the thyroid‐pituitary interaction and their homeostatic mechanism is included. 相似文献
955.
956.
This paper deals with a hierarchical control problem for the Kuramoto–Sivashinsky equation following a Stackelberg–Nash strategy. We assume that there is a main control, called the leader, and two secondary controls, called the followers. The leader tries to drive the solution to a prescribed target and the followers intend to be a Nash equilibrium for given functionals. It is known that this problem is equivalent to a null controllability result for an optimality system consisting of three non-linear equations. One of the novelties is a new Carleman estimate for a fourth-order equation with right-hand sides in Sobolev spaces of negative order, which allows to relax some geometric conditions for the observation sets for the followers. 相似文献
957.
João Paulo dos Santos Benedito Leandro 《Journal of Mathematical Analysis and Applications》2019,469(2):882-896
We consider the static vacuum Einstein spacetime when the spatial factor is conformal to a n-dimensional pseudo-Euclidean space. The most general ansatz that reduces the resulting system of partial differential equations to a system of ordinary differential equations is completely described. We obtain the entire set of solutions of the reduced system, where the classical Schwarzschild solution arises as a particular solution. In addition, we show that the Riemannian spatial factors associated to these solutions are foliated by parallel hypersurfaces of constant mean curvature. 相似文献
958.
Potential Analysis - In this paper we present a short proof of the following classification Theorem for g ?harmonic functions in half-spaces. Assume that u is a nonnegative solution to... 相似文献
959.
This paper presents a further analysis of results of airfoil self-noise prediction obtained in the previous work using large eddy simulation and acoustic analogy. The physical mechanisms responsible for airfoil noise generation in the aerodynamic flows analyzed are a combination of turbulent and laminar boundary layers, as well as vortex shedding (VS) originated due to trailing edge bluntness. The primary interest here consists of evaluating the effects of mean flow convection, quadrupole sources and vortex shedding tonal noise on the overall sound pressure level (OASPL) of a NACA0012 airfoil at low and moderate freestream Mach numbers. The overall sound pressure level is the measured quantity which eventually would be the main concern in terms of noise generation for aircraft and wind energy companies, and regulating agencies. The Reynolds number based on the airfoil chord is fixed at Rec=408,000 for all flow configurations studied. The results demonstrate that, for moderate Mach numbers, mean flow effects and quadrupole sources considerably increase OASPL and, therefore, should be taken into account in the acoustic prediction. For a low Mach number flow with vortex shedding, it is observed that OASPL is higher when laminar boundary layer separation is the VS driving mechanism compared to trailing edge bluntness. 相似文献
960.
E. Martínez F. J. Basterrechea F. Beitia F. Castaño M. T. Martínez L. Santos 《光谱学快报》2013,46(8):1007-1017
Franck-Condon factors and R-centroids for the B-X transition of I2 have been calculated from recent molecular parameters. From our radiative lifetimes and others reported in the literature, the validity of several proposed electronic transition moment functions has been checked. Acombination of the Bhale and Koffend functions seems to give the best fitting with the experimental radiative lifetimes. 相似文献