全文获取类型
收费全文 | 304篇 |
免费 | 3篇 |
国内免费 | 5篇 |
专业分类
化学 | 130篇 |
晶体学 | 2篇 |
力学 | 19篇 |
数学 | 58篇 |
物理学 | 103篇 |
出版年
2020年 | 2篇 |
2019年 | 2篇 |
2017年 | 2篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 3篇 |
2013年 | 11篇 |
2012年 | 11篇 |
2011年 | 23篇 |
2010年 | 10篇 |
2009年 | 12篇 |
2008年 | 11篇 |
2007年 | 23篇 |
2006年 | 20篇 |
2005年 | 11篇 |
2004年 | 12篇 |
2003年 | 11篇 |
2002年 | 11篇 |
2001年 | 8篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 8篇 |
1997年 | 3篇 |
1996年 | 8篇 |
1995年 | 8篇 |
1994年 | 2篇 |
1993年 | 8篇 |
1992年 | 8篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1986年 | 3篇 |
1984年 | 3篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 4篇 |
1980年 | 3篇 |
1979年 | 3篇 |
1978年 | 7篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1970年 | 2篇 |
1967年 | 2篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1922年 | 2篇 |
1916年 | 1篇 |
1914年 | 1篇 |
排序方式: 共有312条查询结果,搜索用时 15 毫秒
51.
We present a bulk ship scheduling problem that is a combined multi-ship pickup and delivery problem with time windows (m-PDPTW) and multi-allocation problem. In contrast to other ship scheduling problems found in the literature, each ship in the fleet is equipped with a flexible cargo hold that can be partitioned into several smaller holds in a given number of ways. Therefore, multiple products can be carried simultaneously by the same ship. The scheduling of the ships constitutes the m-PDPTW, while the partition of the ships' flexible cargo holds and the allocation of cargoes to the smaller holds make the multi-allocation problem. A set partitioning approach consisting of two phases is proposed for the combined ship scheduling and allocation problem. In the first phase, a number of candidate schedules (including allocation of cargoes to the ships' cargo holds) is generated for each ship. In the second phase, we minimise transportation costs by solving a set partitioning problem where the columns are the candidate schedules generated in phase one. The computational results show that the proposed approach works, and optimal solutions are obtained on several cases of a real ship planning problem. 相似文献
52.
Hanne Dalgas Christiansen 《BIT Numerical Mathematics》1988,28(3):671-677
Sums of independent, identically distributed (iid) binomial variates have binomial distributions; yet it is possible to construct a sequence of binomial distributions over {0, 1} for variatesX
1,X
2, ... such that all partial sumsY
i =X
1 + ... +X
i have uniform distributions. The price to pay is to give up the iid condition. Requiring the property of only one sum does not alleviate the situation much.It is also possible to generate on a computerm × n-matrices, of 0–1 binomial variates with uniformly distributed row and column sums of all major submatrices, but only for smallm andn. Even a three-dimensional 2 × 2 × 2 array can have a similar property.Other target distributions than the rectangular are possible, but cumbersome. An example with smaller variance is given.The results were needed for simulating the performance of some Operations Research algorithms.Dedicated to Peter Naur on the occasion of his 60th birthday 相似文献
53.
For the driven, damped space-independent double sine-Gordon equation threshold curves for horseshoe chaos of the Smale type are derived by the Melnikov technique. Different qualitative behaviour of the solutions is found in different regions of parameter space. 相似文献
54.
Stetter M. Felsner P. Christiansen J. Frank K. Gortler A. Hintz G. Mehr T. Stark R. Tkotz R. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1995,23(3):283-293
The intention of this paper is to give an overview of recent experiments explaining the development and transition of the discharge phases in a pseudospark. The reported experiments include single gap pseudospark discharges in ultra-high-vacuum systems with hydrogen as working gas, as well as multigap pseudospark discharges in argon. Temporally and spatially resolved framing photography, spectrometry, raster electron microscopy and time resolved electrical measurements are presented. The experiments comprise a current range of some hundreds of amps to 60 kA. The results are used to specify the four characteristic phases of the pseudospark: Townsend-, hollow cathode-, high current- and metal vapor arc phase 相似文献
55.
Numerical analysis of a class of nonlinear duality problems is presented. One side of the duality is to minimize a sum of Euclidean norms subject to linear equality constraints (the constrained MSN problem). The other side is to maximize a linear objective function subject to homogeneous linear equality constraints and quadratic inequalities. Large sparse problems of this form result from the discretization of infinite dimensional duality problems in plastic collapse analysis.The solution method is based on the l
1 penalty function approach to the constrained MSN problem. This can be formulated as an unconstrained MSN problem for which the first author has recently published an efficient Newton barrier method, and for which new methods are still being developed.Numerical results are presented for plastic collapse problems with up to 180000 variables, 90000 terms in the sum of norms and 90000 linear constraints. The obtained accuracy is of order 10-8 measured in feasibility and duality gap. 相似文献
56.
57.
Walter C. Ermler Yoon S. Lee Phillip A. Christiansen Kenneth S. Pitzer 《Chemical physics letters》1981,81(1):70-74
The first ab initio procedure for the treatment of spin-orbit coupling in molecules based on the use of relativistic effective potentials derived from Dirac-Fock atomic wavefunctions is presented. A rigorous definition for the spin-orbit operator is given and its use in molecular calculations discussed. 相似文献
58.
59.
K. A. Gonchar L. A. Golovan’ V. Yu. Timoshenko V. A. Sivakov S. Christiansen 《Bulletin of the Russian Academy of Sciences: Physics》2010,74(12):1712-1714
The effect of light localization in photoluminescence (PL) and Raman scattering (RS) in silicon nanowires with diameter of
100 nm was investigated. The optical excitation was done by CW radiation of a YAG:Nd laser at 1.064 μm. The PL an RS intensities
were found to increase strongly for the samples with Si nanowires in comparison with corresponding values of c-Si substrate.
The effect is explained by an increase of the lifetime of photons in silicon nanowire structures. 相似文献
60.