全文获取类型
收费全文 | 5838篇 |
免费 | 483篇 |
国内免费 | 302篇 |
专业分类
化学 | 1530篇 |
晶体学 | 10篇 |
力学 | 605篇 |
综合类 | 96篇 |
数学 | 2570篇 |
物理学 | 1812篇 |
出版年
2023年 | 68篇 |
2022年 | 127篇 |
2021年 | 146篇 |
2020年 | 143篇 |
2019年 | 174篇 |
2018年 | 138篇 |
2017年 | 207篇 |
2016年 | 235篇 |
2015年 | 158篇 |
2014年 | 268篇 |
2013年 | 347篇 |
2012年 | 341篇 |
2011年 | 277篇 |
2010年 | 228篇 |
2009年 | 340篇 |
2008年 | 341篇 |
2007年 | 332篇 |
2006年 | 305篇 |
2005年 | 227篇 |
2004年 | 223篇 |
2003年 | 237篇 |
2002年 | 365篇 |
2001年 | 177篇 |
2000年 | 173篇 |
1999年 | 133篇 |
1998年 | 132篇 |
1997年 | 103篇 |
1996年 | 87篇 |
1995年 | 82篇 |
1994年 | 75篇 |
1993年 | 54篇 |
1992年 | 49篇 |
1991年 | 52篇 |
1990年 | 39篇 |
1989年 | 38篇 |
1988年 | 25篇 |
1987年 | 20篇 |
1986年 | 21篇 |
1985年 | 20篇 |
1984年 | 18篇 |
1983年 | 7篇 |
1982年 | 12篇 |
1981年 | 9篇 |
1980年 | 10篇 |
1979年 | 9篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 5篇 |
1975年 | 9篇 |
1974年 | 5篇 |
排序方式: 共有6623条查询结果,搜索用时 15 毫秒
21.
22.
DING Ning FANG Jian-Hui 《理论物理通讯》2006,46(2):265-268
In this paper the Lie symmetry and conserved quantities for nonholonomic Vacco dynamical systems are studied. The determining equation of the Lie symmetry for the system is given. The general Hojman conserved quantity and the Lutzky conserved quantity deduced from the symmetry are obtained. 相似文献
23.
本文研究了未知分布的逼近问题,利用随机加权法,给出了有Edgeworth展式的一类(未知)分布的模拟分布,证明了在一定条件下,模拟分布与未知分布的逼近精度达到O(n^-1√lnlnn),称之为随机加权逼近的重对数律。 相似文献
24.
Andreas Spillner 《Mathematical Logic Quarterly》2006,52(1):29-36
We study the problem of tiling a polyomino P with as few squares as possible such that every square in the tiling has a non‐empty intersection with the boundary of P . Our main result is an algorithm which given a simply connected polyomino P computes such a tiling of P . We indicate how one can improve the running time of this algorithm for the more restricted row‐column‐convex polyominoes. Finally we show that a related decision problem is in NP for rectangular polyominoes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
25.
本利用矩阵给出了几类数列的通项公式的求法,把数列通项公式的求法转化为矩阵幂的计算,思路简单、计算简便,并能判别其敛散性。 相似文献
26.
27.
G. Pizzella 《Il Nuovo Cimento C》1992,15(6):931-941
Summary A review of the correlations between gravitational-wave detectors and particle detectors during SN1987A is given. The correlation
between the Maryland and Rome g.w. detectors with the Mont Blanc neutrino detector is illustrated. This correlation extends
during a period of one or two hours centred at 2∶45 UT of 23 February 1987, with the ?neutrino? signals delayed by (1.1±0.5)
s and with a probability of the order of 10−5 to be accidental. Using the data obtained with the Kamiokande and IMB detectors, with the same statistical choices and procedures
for the data analysis used previously, the above result is confirmed with a probability of the order of 10−3 or 10−4 that the additional correlation be accidental.
Paper presented at the V Cosmic Physics National Conference, S. Miniato, November 27–30, 1990. 相似文献
28.
Summary We report on the development of an adaptive optimum filter for processing the data of a resonant bar gravitational-wave detector.
This filter, based on the matched-filter theory, is adaptive in the sense that the function it realizes is derived from the
actual noise spectrum of the data being analysed (instead from an idealized model of the noise). Its implementation is mostly
based on frequency domain techniques. We also report on the application of the new filter to the data of the cryogenic antenna
Explorer of the Rome group, with particular reference to the comparison between its performance and that of an otpimum filter
with fixed values of the parameters. 相似文献
29.
We introducegeneral starvation and consider cyclic networks withgeneral blocking and starvation (GBS). The mechanism of general blocking allows the server to process a limited number of jobs when the buffer downstream is full, and that of general starvation allows the server to perform a limited number of services in anticipation of jobs that are yet to arrive. The two main goals of this paper are to investigate how the throughput of cyclic GBS networks is affected by varying (1) the total number of jobsJ, and (2) the buffer allocationk=(k1..., km) subject to a fixed total buffer capacityK=k
1 +... + km. In particular, we obtain sufficient conditions for the throughput to be symmetric inJ and to be maximized whenJ=K/2. We also show that the equal buffer allocation is optimal under the two regimes of light or heavy usage. In order to establish these results, we obtain several intermediate structural properties of the throughput, using duality, reversibility, and concavity, which are of independent interest.Research supported in part by NSF Grant No. ECS-8919818. 相似文献
30.
Li Changjun; Li Zheng; Evans David J.; Zhang Tie 《IMA Journal of Numerical Analysis》2003,23(4):581-592
Golub et al. (2001, BIT, 41, 7185) gave a generalizedsuccessive over-relaxation method for the augmented systems.In this paper, the connection between the SOR-like method andthe preconditioned conjugate gradient (PCG) method for the augmentedsystems is investigated. It is shown that the PCG method isat least as accurate (fast) as the SOR-like method. Numericalexamples demonstrate that the PCG method is much faster thanthe SOR-like method. 相似文献