全文获取类型
收费全文 | 1786篇 |
免费 | 129篇 |
国内免费 | 173篇 |
专业分类
化学 | 138篇 |
力学 | 37篇 |
综合类 | 11篇 |
数学 | 1766篇 |
物理学 | 136篇 |
出版年
2024年 | 2篇 |
2023年 | 29篇 |
2022年 | 28篇 |
2021年 | 29篇 |
2020年 | 25篇 |
2019年 | 46篇 |
2018年 | 34篇 |
2017年 | 42篇 |
2016年 | 46篇 |
2015年 | 28篇 |
2014年 | 81篇 |
2013年 | 183篇 |
2012年 | 64篇 |
2011年 | 111篇 |
2010年 | 79篇 |
2009年 | 148篇 |
2008年 | 135篇 |
2007年 | 159篇 |
2006年 | 121篇 |
2005年 | 99篇 |
2004年 | 95篇 |
2003年 | 96篇 |
2002年 | 63篇 |
2001年 | 54篇 |
2000年 | 52篇 |
1999年 | 31篇 |
1998年 | 43篇 |
1997年 | 35篇 |
1996年 | 34篇 |
1995年 | 9篇 |
1994年 | 22篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 2篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 5篇 |
1987年 | 3篇 |
1986年 | 5篇 |
1985年 | 2篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1979年 | 6篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 3篇 |
1973年 | 1篇 |
1970年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有2088条查询结果,搜索用时 38 毫秒
21.
For any Sturm-Liouville problem with a separable boundary condition and whose leading coefficient function changes sign (exactly once), we first give a geometric characterization of its eigenvalues λn using the eigenvalues of some corresponding problems with a definite leading coefficient function. Consequences of this characterization include simple proofs of the existence of the λn's, their Prüfer angle characterization, and a way for determining their indices from the zeros of their eigenfunctions. Then, interlacing relations among the λn's and the eigenvalues of the corresponding problems are obtained. Using these relations, a simple proof of asymptotic formulas for the λn's is given. 相似文献
22.
考虑一类p-Laplacian算子型泛函微分方程的奇异边值问题,利用锥不动点定理,得到了其正解及多个正解存在的充分条件. 相似文献
23.
Henrik Stetkær 《Journal of Functional Analysis》2007,252(1):1-33
We extend results on square integrable representations of a locally compact group to subrepresentations of a representations induced from a character of a closed subgroup. We do so working in the framework of quotient representations of ∗-algebras. 相似文献
24.
By means of the Leggett-Williams fixed-point theorem, criteria are developed for the existence of at least three positive solutions to the one-dimensional p-Laplacian boundary value problem, ((y′))′ + g(t)f(t,y) = 0, y(0) - B0(y′(0)) = 0, y(1) + B1(y′(1)) = 0, where (v) |v|p−2v, p > 1. 相似文献
25.
Zhao Yang YIN 《数学学报(英文版)》2006,22(3):819-826
Sufficient conditions for the existence of positive solutions to a class of quasilinear elliptic equations in two-dimensional exterior domains are given. 相似文献
26.
The bunching system of the ATLAS positive ion injector (PII) has been improved by relocating the harmonic buncher to a point
significantly closer to the second stage sine-wave buncher and the injector LINAC. The longitudinal optics design has also
been modified and now employs a virtual waist from the harmonic buncher feeding the second stage sine-wave buncher. This geometry
improves the handling of space charge for high-current beams, significantly increases the capture fraction into the primary
rf bucket and reduces the capture fraction of the unwanted parasitic rf bucket. Total capture and transport through the PII
has been demonstrated as high as 80% of the injected dc beam while the population of the parasitic, unwanted rf bucket is
typically less than 3% of the total transported beam. To remove this small residual parasitic component a new traveling-wave
transmission-line chopper has been developed reducing both transverse and longitudinal emittance growth from the chopping
process. This work was supported by the U.S. Department of Energy under contract W-31-109-ENG-38. 相似文献
27.
28.
本文在环形域上证明了带有奇异性的半线性椭圆方程边值问题(1)、(2·)在C~2(Ω)∩C~0(Ω)中正解的存在性,且这个解是径向对称的,解关于R_0(R_1)的连续单调性.还给出了解有熄灭现象的充分必要条件. 相似文献
29.
In this paper, we are concerned with the existence of positive periodic solution to a class of two-species ratio-dependent predator–prey diffusion model with time delay. By using the continuation theorem of coincidence degree theory, we transform this problem into a problem of calculating the topological degree of a continuous mapping, and then some sufficient conditions of the existence of positive periodic solution is established for the system. 相似文献
30.
G. Sreenivasulu Reddy J. Hanumanthachari T. Vasanthi 《Southeast Asian Bulletin of Mathematics》2003,26(2):331-335
This paper is mainly dealt with the structure of totally ordered rings (t.o. rings) whose positive cones are finitely generated as multiplicative right ideals.AMS Subject Classification (1991): 16W80, 13J25 相似文献