全文获取类型
收费全文 | 4356篇 |
免费 | 157篇 |
国内免费 | 62篇 |
专业分类
化学 | 2661篇 |
晶体学 | 16篇 |
力学 | 163篇 |
数学 | 806篇 |
物理学 | 929篇 |
出版年
2023年 | 25篇 |
2022年 | 50篇 |
2021年 | 123篇 |
2020年 | 109篇 |
2019年 | 125篇 |
2018年 | 123篇 |
2017年 | 104篇 |
2016年 | 173篇 |
2015年 | 134篇 |
2014年 | 154篇 |
2013年 | 288篇 |
2012年 | 313篇 |
2011年 | 326篇 |
2010年 | 204篇 |
2009年 | 177篇 |
2008年 | 286篇 |
2007年 | 234篇 |
2006年 | 279篇 |
2005年 | 261篇 |
2004年 | 203篇 |
2003年 | 154篇 |
2002年 | 139篇 |
2001年 | 79篇 |
2000年 | 53篇 |
1999年 | 53篇 |
1998年 | 39篇 |
1997年 | 32篇 |
1996年 | 31篇 |
1995年 | 33篇 |
1994年 | 32篇 |
1993年 | 14篇 |
1992年 | 24篇 |
1991年 | 27篇 |
1990年 | 12篇 |
1989年 | 6篇 |
1988年 | 9篇 |
1985年 | 13篇 |
1984年 | 15篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 11篇 |
1980年 | 8篇 |
1979年 | 8篇 |
1978年 | 5篇 |
1977年 | 8篇 |
1976年 | 9篇 |
1975年 | 8篇 |
1974年 | 11篇 |
1973年 | 5篇 |
1971年 | 6篇 |
排序方式: 共有4575条查询结果,搜索用时 31 毫秒
11.
12.
In the present paper, the notion of norm series with respect to the norm residue symbol is generalized to high-dimensional local fields. Necessary and sufficient conditions for the existence of norm series are obtained. Bibliography: 12 titles.__________Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 305, 2003, pp. 60–83. 相似文献
13.
We show that for a random choice of the parameters, the subset sum pseudorandom number generator produces a sequence of uniformly and independently distributed pseudorandom numbers. The result can be useful for both cryptographic and quasi-Monte Carlo applications and relies on bounds of exponential sums.
14.
We obtain asymptotic formulas for all the moments of certain arithmetic functions with linear recurrence sequences. We also apply our results to obtain asymptotic formulas for some mean values related to average orders of elements in finite fields. 相似文献
15.
16.
Ronald H. Nickel Igor Mikolic-Torreira Jon W. Tolle 《Computational Optimization and Applications》2006,35(1):109-126
Deployed US Navy aircraft carriers must stock a large number of spare parts to support the various types of aircraft embarked
on the ship. The sparing policy determines the spares that will be stocked on the ship to keep the embarked aircraft ready
to fly. Given a fleet of ten or more aircraft carriers and a cost of approximately 50 million dollars per carrier plus the
cost of spares maintained in warehouses in the United States, the sparing problem constitutes a significant portion of the
Navy’s resources. The objective of this work is to find a minimum-cost sparing policy that meets the readiness requirements
of the embarked aircraft. This is a very large, nonlinear, integer optimization problem. The cost function is piecewise linear
and convex while the constraint mapping is highly nonlinear. The distinguishing characteristics of this problem from an optimization
viewpoint are that a large number of decision variables are required to be integer and that the nonlinear constraint functions
are essentially “black box” functions; that is, they are very difficult (and expensive) to evaluate and their derivatives
are not available. Moreover, they are not convex. Integer programming problems with a large number of variables are difficult
to solve in general and most successful approaches to solving nonlinear integer problems have involved linear approximation
and relaxation techniques that, because of the complexity of the constraint functions, are inappropriate for attacking this
problem. We instead employ a pattern search method to each iteration of an interior point-type algorithm to solve the relaxed
version of the problem. From the solution found by the pattern search on each interior point iteration, we begin another pattern
search on the integer lattice to find a good integer solution. The best integer solution found across all interations is returned
as the optimal solution. The pattern searches are distributed across a local area network of non-dedicated, heterogeneous
computers in an office environment, thus, drastically reducing the time required to find the solution. 相似文献
17.
Oleg S. Ugolnikov Igor A. Maslov 《Journal of Quantitative Spectroscopy & Radiative Transfer》2006,102(3):499-512
The work is devoted to the analysis of the surface photometric observations of two total lunar eclipses in 2004. The lunar surface relative brightness distribution inside the umbra was used to retrieve the vertical distribution of aerosol extinction of the solar radiation expanding by a tangent path and its dependence on the location at the limb of the Earth. The upper altitude of troposphere aerosol layer was estimated for different latitude zones. The correlation between additional aerosol extinction in the upper troposphere and cyclones was investigated. 相似文献
18.
19.
20.
Igor V. Bliznets Grigory G. Aleksandrov Sergey M. Lukyanov 《Tetrahedron letters》2004,45(49):9127-9130
2-Methyl-3-cyanopyridines were converted into the corresponding 2-azidomethyl derivatives, which then underwent an intramolecular cycloaddition reaction. A novel heterocyclic system containing a 3-(tetrazol-5-yl)pyridine unit was obtained in this way. 相似文献