全文获取类型
收费全文 | 503144篇 |
免费 | 5246篇 |
国内免费 | 1657篇 |
专业分类
化学 | 253147篇 |
晶体学 | 8241篇 |
力学 | 23965篇 |
综合类 | 8篇 |
数学 | 60656篇 |
物理学 | 164030篇 |
出版年
2021年 | 4182篇 |
2020年 | 4554篇 |
2019年 | 5162篇 |
2018年 | 6962篇 |
2017年 | 7114篇 |
2016年 | 9965篇 |
2015年 | 5839篇 |
2014年 | 9730篇 |
2013年 | 23406篇 |
2012年 | 17622篇 |
2011年 | 21507篇 |
2010年 | 15663篇 |
2009年 | 15563篇 |
2008年 | 19458篇 |
2007年 | 19403篇 |
2006年 | 18076篇 |
2005年 | 15975篇 |
2004年 | 14864篇 |
2003年 | 13146篇 |
2002年 | 13107篇 |
2001年 | 15338篇 |
2000年 | 11585篇 |
1999年 | 9099篇 |
1998年 | 7616篇 |
1997年 | 7381篇 |
1996年 | 7010篇 |
1995年 | 6225篇 |
1994年 | 6129篇 |
1993年 | 6088篇 |
1992年 | 6562篇 |
1991年 | 6850篇 |
1990年 | 6516篇 |
1989年 | 6370篇 |
1988年 | 6192篇 |
1987年 | 6215篇 |
1986年 | 5817篇 |
1985年 | 7670篇 |
1984年 | 7902篇 |
1983年 | 6427篇 |
1982年 | 6678篇 |
1981年 | 6397篇 |
1980年 | 6203篇 |
1979年 | 6569篇 |
1978年 | 6609篇 |
1977年 | 6586篇 |
1976年 | 6667篇 |
1975年 | 6193篇 |
1974年 | 6166篇 |
1973年 | 6256篇 |
1972年 | 4422篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
W Y Hung S Kucherenko N J Samsatli N Shah 《The Journal of the Operational Research Society》2004,55(8):801-813
In this paper, we present a new modelling approach for realistic supply chain simulation. The model provides an experimental environment for informed comparison between different supply chain policies. A basic simulation model for a generic node, from which a supply chain network can be built, has been developed using an object-oriented approach. This generic model allows the incorporation of the information and physical systems and decision-making policies used by each node. The object-oriented approach gives the flexibility in specifying the supply chain configuration and operation decisions, and policies. Stochastic simulations are achieved by applying Latin Supercube Sampling to the uncertain variables in descending order of importance, which reduces the number of simulations required. We also present a case study to show that the model is applicable to a real-life situation for dynamic stochastic studies. 相似文献
992.
993.
Malmquist indexes can be used to estimate technical change over time. The index generally represents the average effect of technical change on all outputs in a multi-output firm. However, changes in technology do not necessarily affect all outputs involved in the analysis equally. In this paper, a method for estimating the effect of technical change on each of the different outputs is proposed. This estimation is done by a modification of quasi-Malmquist indexes. An artificial data set has been used to validate the method proposed in this paper. 相似文献
994.
Tracing is a method of assigning flows in an electricity network to particular generators and loads, assuming perfect mixing at each node. It can be used to assign costs to transmission users. We show that the resulting allocation is equal to the Shapley value of an equivalent co-operative game. 相似文献
995.
996.
The essential self-adjointness on a natural domain of the sharp-time Wick powers of the relativistic free field in two space-time dimension is proven. Other results on Wick powers are reviewed and discussed. 相似文献
997.
D. P. Zhelobenko 《Acta Appl Math》2004,81(1):347-354
A special class of associative algebras is introduced and studied. A criteria of semisimplicity for suitable category of modules is obtained. 相似文献
998.
D. P. Zhelobenko 《Acta Appl Math》2004,81(1):355-383
An algebraic approach to harmonic analysis on reductive Lie groups is proposed. The case of complex semisimple Lie groups is considered in details. Some problems for real reductive Lie groups are discussed. 相似文献
999.
1000.
Using the result by D. Gessler, we show that any invariant variational bivector (resp., variational 2-form) on an evolution equation with nondegenerate right-hand side is Hamiltonian (resp., symplectic). 相似文献