全文获取类型
收费全文 | 16773篇 |
免费 | 1111篇 |
国内免费 | 996篇 |
专业分类
化学 | 519篇 |
晶体学 | 3篇 |
力学 | 1652篇 |
综合类 | 211篇 |
数学 | 15003篇 |
物理学 | 1492篇 |
出版年
2024年 | 34篇 |
2023年 | 169篇 |
2022年 | 201篇 |
2021年 | 233篇 |
2020年 | 353篇 |
2019年 | 376篇 |
2018年 | 434篇 |
2017年 | 446篇 |
2016年 | 448篇 |
2015年 | 324篇 |
2014年 | 732篇 |
2013年 | 1380篇 |
2012年 | 733篇 |
2011年 | 904篇 |
2010年 | 818篇 |
2009年 | 1099篇 |
2008年 | 1126篇 |
2007年 | 1179篇 |
2006年 | 1025篇 |
2005年 | 800篇 |
2004年 | 696篇 |
2003年 | 744篇 |
2002年 | 665篇 |
2001年 | 502篇 |
2000年 | 504篇 |
1999年 | 457篇 |
1998年 | 408篇 |
1997年 | 375篇 |
1996年 | 287篇 |
1995年 | 250篇 |
1994年 | 170篇 |
1993年 | 145篇 |
1992年 | 143篇 |
1991年 | 123篇 |
1990年 | 86篇 |
1989年 | 49篇 |
1988年 | 56篇 |
1987年 | 49篇 |
1986年 | 45篇 |
1985年 | 59篇 |
1984年 | 58篇 |
1983年 | 33篇 |
1982年 | 30篇 |
1981年 | 32篇 |
1980年 | 22篇 |
1979年 | 23篇 |
1978年 | 14篇 |
1977年 | 19篇 |
1976年 | 10篇 |
1936年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Bjorn Fritzell 《Journal of voice》1992,6(2)
Inverse filtering is a noninvasive method of producing a glottogram thought to reflect the vibratory motions of the vocal fold. The flow glottogram provides information related to the type of phonation, the sound pressure level, the regularity of vocal fold vibrations, and to the presence or absence of vocal fold closure. Limited data, speech samples, filter tuning, and lack of unanimity on waveform display and interpretation have contributed to slow application of the techniques to the clinical population. The author argues the technique has utility in both diagnosis and treatment 相似文献
92.
In this paper, we provide numerical means to compute the quasi-stationary (QS) distributions inM/GI/1/K queues with state-dependent arrivals andGI/M/1/K queues with state-dependent services. These queues are described as finite quasi-birth-death processes by approximating the general distributions in terms of phase-type distributions. Then, we reduce the problem of obtaining the QS distribution to determining the Perron-Frobenius eigenvalue of some Hessenberg matrix. Based on these arguments, we develop a numerical algorithm to compute the QS distributions. The doubly-limiting conditional distribution is also obtained by following this approach. Since the results obtained are free of phase-type representations, they are applicable for general distributions. Finally, numerical examples are given to demonstrate the power of our method. 相似文献
93.
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
94.
Neil S. TrudingerXu-Jia Wang 《Journal of Functional Analysis》2002,193(1):1-23
In this paper, we continue previous investigations into the theory of Hessian measures. We extend our weak continuity result to the case of mixed k-Hessian measures associated with k-tuples of k-convex functions, on domains in Euclidean n-space, k=1,2,…,n. Applications are given to capacity, quasicontinuity, and the Dirichlet problem, with inhomogeneous terms, continuous with respect to capacity or combinations of Dirac measures. 相似文献
95.
图G(V,E)的一个k-正常全染色f叫做一个k-点强全染色当且仅当对任意v∈V(G), N[v]中的元素被染不同色,其中N[v]={u|uv∈V(G)}∪{v}.χTvs(G)=min{k|存在图G的k- 点强全染色}叫做图G的点强全色数.对3-连通平面图G(V,E),如果删去面fo边界上的所有点后的图为一个树图,则G(V,E)叫做一个Halin-图.本文确定了最大度不小于6的Halin- 图和一些特殊图的的点强全色数XTvs(G),并提出了如下猜想:设G(V,E)为每一连通分支的阶不小于6的图,则χTvs(G)≤△(G) 2,其中△(G)为图G(V,E)的最大度. 相似文献
96.
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
97.
We investigate the existence and stability of solutions for higher-order two-point boundary value problems in case the differential
operator is not necessarily positive definite, i.e. with superlinear nonlinearities. We write an abstract realization of the
Dirichlet problem and provide abstract existence and stability results which are further applied to concrete problems. 相似文献
98.
Giovanni Cupini Marcello Guidorzi Cristina Marcelli 《Journal of Differential Equations》2007,243(2):329-348
Classical one-dimensional, autonomous Lagrange problems are considered. In absence of any smoothness, convexity or coercivity condition on the energy density, we prove a DuBois-Reymond type necessary condition, expressed as a differential inclusion involving the subdifferential of convex analysis. As a consequence, a non-existence result is obtained. 相似文献
99.
We study problems of interpolation of positive linear operators in couples of ordered Banach spaces. From this viewpoint, we study couples of noncommutative spaces L 1, L ∞ associated with weights and traces on von Neumann algebras. 相似文献
100.