全文获取类型
收费全文 | 16703篇 |
免费 | 2856篇 |
国内免费 | 1478篇 |
专业分类
化学 | 749篇 |
晶体学 | 114篇 |
力学 | 3265篇 |
综合类 | 641篇 |
数学 | 10128篇 |
物理学 | 6140篇 |
出版年
2024年 | 68篇 |
2023年 | 292篇 |
2022年 | 349篇 |
2021年 | 361篇 |
2020年 | 278篇 |
2019年 | 325篇 |
2018年 | 212篇 |
2017年 | 332篇 |
2016年 | 387篇 |
2015年 | 476篇 |
2014年 | 989篇 |
2013年 | 717篇 |
2012年 | 950篇 |
2011年 | 1113篇 |
2010年 | 1089篇 |
2009年 | 1140篇 |
2008年 | 1303篇 |
2007年 | 1020篇 |
2006年 | 851篇 |
2005年 | 894篇 |
2004年 | 858篇 |
2003年 | 963篇 |
2002年 | 732篇 |
2001年 | 813篇 |
2000年 | 686篇 |
1999年 | 534篇 |
1998年 | 519篇 |
1997年 | 465篇 |
1996年 | 394篇 |
1995年 | 397篇 |
1994年 | 287篇 |
1993年 | 250篇 |
1992年 | 288篇 |
1991年 | 247篇 |
1990年 | 217篇 |
1989年 | 157篇 |
1988年 | 25篇 |
1987年 | 27篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 5篇 |
1980年 | 6篇 |
1979年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
本文利用数值模拟研究了浮力对湍流预混V形火焰平均速度场的影响,发现浮力效应主要体现在远场区域,而在火焰刷附近非常有限;利用落塔和 OH-PLIF 方法在正常重力和微重力下观测了火焰皱褶,发现浮力压制火焰皱褶的程度与湍流强度密切相关。分析表明斜压机理是浮力影响火焰皱褶的重要原因。 相似文献
994.
The state 0 of a birth and death process with state space E = {0, 1, 2,....} is a barrier which can be classified into four kinds: reflection, absorption, leaping reflection, quasi-leaping reflection. For the first, second and fourth barriers, the characteristic numbers of different forms have been introduced. In this paper unified characteristic numbers for birth and death processes with barriers were introduced, the related equations were solved and the solutions were expressed by unified characteristic numbers. This paper concerns work solving probability construction problem of birth and death processes with leaping reflection barrier and quasi-leaping reflection barrier. 相似文献
995.
The exact parametric representations of the traveling wave solutions for a nonlinear elastic rod equation are considered. By using the method of planar dynamical systems, in different parameter regions, the phase portraits of the corresponding traveling wave system are given. Exact explicit kink wave solutions, periodic wave solutions and some unbounded wave solutions are obtained. 相似文献
996.
In this paper we apply the (variant) fountain theorems to study the symmetric nonlinear Kirch- hoff nonlocal problems. Under the Ambrosetti-Rabinowitz's 4-superlinearity condition, or no Ambrosetti- Rabinowitz's 4-superlinearity condition, we present two results of existence of infinitely many large energy solutions, respectively. 相似文献
997.
Xin-min Xiang 《应用数学学报(英文版)》2010,26(3):405-414
In this paper, we continue the discussion of [12] to establish the Hermite pseudospectral method with weight ω(x) = 1. As an application, we consider the pseudospectral approximation of the reaction-diffusion equation on the whole line, we prove the existence of the approximate attractor and give the error estimate for the approximate solution. 相似文献
998.
We have developed approximate Riemann solvers for ideal MHD equations based on a relaxation approach in [4], [5]. These lead to entropy consistent solutions with good properties like guaranteed positive density. We describe the extension to higher order and multiple space dimensions. Finally we show our implementation of all this into the astrophysics code FLASH. 相似文献
999.
This paper is devoted to a class of inverse coefficient problems for nonlinear elliptic hemivariational inequalities. The unknown coefficient of elliptic hemivariational inequalities depends on the gradient of the solution and belongs to a set of admissible coefficients. It is shown that the nonlinear elliptic hemivariational inequalities are uniquely solvable for the given class of coefficients. The result of existence of quasisolutions of the inverse problems is obtained. 相似文献
1000.
Strong (Weak) Exact Controllability and Strong (Weak) Exact Observability for Quasilinear Hyperbolic Systems 总被引:3,自引:2,他引:1
Numerical approximations of Cahn-Hilliard phase-field model for the two-phase incompressible flows are considered in this paper.Several efficient and energy stable time discretization schemes for the coupled nonlinear Cahn-Hilliard phase-field system for both the matched density case and the variable density case are constructed,and are shown to satisfy discrete energy laws which are analogous to the continuous energy laws. 相似文献