全文获取类型
收费全文 | 13142篇 |
免费 | 1637篇 |
国内免费 | 1047篇 |
专业分类
化学 | 2340篇 |
晶体学 | 133篇 |
力学 | 3367篇 |
综合类 | 130篇 |
数学 | 6437篇 |
物理学 | 3419篇 |
出版年
2024年 | 15篇 |
2023年 | 144篇 |
2022年 | 186篇 |
2021年 | 239篇 |
2020年 | 385篇 |
2019年 | 356篇 |
2018年 | 346篇 |
2017年 | 388篇 |
2016年 | 480篇 |
2015年 | 415篇 |
2014年 | 603篇 |
2013年 | 1128篇 |
2012年 | 660篇 |
2011年 | 795篇 |
2010年 | 640篇 |
2009年 | 828篇 |
2008年 | 810篇 |
2007年 | 858篇 |
2006年 | 740篇 |
2005年 | 646篇 |
2004年 | 628篇 |
2003年 | 563篇 |
2002年 | 483篇 |
2001年 | 434篇 |
2000年 | 427篇 |
1999年 | 349篇 |
1998年 | 353篇 |
1997年 | 299篇 |
1996年 | 237篇 |
1995年 | 172篇 |
1994年 | 157篇 |
1993年 | 148篇 |
1992年 | 149篇 |
1991年 | 120篇 |
1990年 | 103篇 |
1989年 | 63篇 |
1988年 | 48篇 |
1987年 | 46篇 |
1986年 | 44篇 |
1985年 | 50篇 |
1984年 | 63篇 |
1983年 | 41篇 |
1982年 | 50篇 |
1981年 | 38篇 |
1980年 | 25篇 |
1979年 | 24篇 |
1978年 | 15篇 |
1976年 | 6篇 |
1973年 | 10篇 |
1957年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 473 毫秒
81.
Sergue A. Nazarov Maria Specovius‐Neugebauer 《Mathematical Methods in the Applied Sciences》2004,27(13):1507-1544
The approximation of solutions to boundary value problems on unbounded domains by those on bounded domains is one of the main applications for artificial boundary conditions. Based on asymptotic analysis, here a new method is presented to construct local artificial boundary conditions for a very general class of elliptic problems where the main asymptotic term is not known explicitly. Existence and uniqueness of approximating solutions are proved together with asymptotically precise error estimates. One class of important examples includes boundary value problems for anisotropic elasticity and piezoelectricity. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
82.
We study the complex Ginzburg–Landau equation with zero Neumann boundary conditions on a finite interval and establish that this boundary problem (with suitably chosen parameters) has countably many stable two-dimensional self-similar tori. The case of periodic boundary conditions is also investigated. 相似文献
83.
A. P. Prishivalko 《Journal of Applied Spectroscopy》1997,64(1):94-100
A method for finding the optimum sizes of pigment particles, their volume concentration, and the paint coating thickness that
provide the covering power and the required coloristic characteristics of reflected light for the minimum flow rate of pigments
is based on using a four-flow approximation of the solution to the equation of radiation transfer in dispersion media and
is extended to coatings of complex composition. The capabilities of the method are demonstrated by examples of coatings of
mixtures of hematite and rutile particles in a binder with n=1.5 for variations of the modal size and the half-width of the
size distribution of the pigment particles.
B. I. Stepanov Institute of Physics, Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated
from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 90–96, January–February, 1997. 相似文献
84.
一类具有非局部反应扩散方程的奇摄动问题 总被引:7,自引:0,他引:7
本文讨论一类具非局部反应扩散方程的奇摄动初始边值问题,利用迭代法及微分不等式,研究了初始边值问题的存在唯一及其渐近性态。 相似文献
85.
Song Jiang 《Mathematische Nachrichten》1998,190(1):169-183
We consider initial boundary value problems for the equations of the one-dimensional motion of a viscous, heat-conducting gas with density-dependent viscosity that decreases (to zero) with decreasing density. We prove that if the viscosity does not decrease to zero too rapidly, then smooth solutions exist globally in time. 相似文献
86.
The Existence of Solutions to Sturm-Liouville Boundary Value Problems with Laplacian-like Operator 总被引:2,自引:0,他引:2
Wei-ping Sun Wei-gao GeDepartment of Applied Mathematics Beijing Institute of Technology Beijing China 《应用数学学报(英文版)》2002,18(2):341-348
Abstract The existence of infinitely many solutions to Sturm-Liouville boundary value problem with aLaplacian-like operator is studied by applying generalized polar coordinates. 相似文献
87.
Tatsien Li 《Mathematical Methods in the Applied Sciences》2006,29(13):1543-1553
By means of a direct and constructive method based on the theory of semi‐global C2 solution, the local exact boundary observability and an implicit duality between the exact boundary controllability and the exact boundary observability are shown for 1‐D quasilinear wave equations with various boundary conditions. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
88.
89.
90.
Yang Zuosheng 《国际流体数值方法杂志》2005,47(12):1423-1430
A complete boundary integral formulation for compressible Navier–Stokes equations with time discretization by operator splitting is developed using the fundamental solutions of the Helmholtz operator equation with different order. The numerical results for wall pressure and wall skin friction of two‐dimensional compressible laminar viscous flow around airfoils are in good agreement with field numerical methods. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献