全文获取类型
收费全文 | 205篇 |
免费 | 4篇 |
专业分类
化学 | 18篇 |
力学 | 5篇 |
综合类 | 7篇 |
数学 | 152篇 |
物理学 | 27篇 |
出版年
2023年 | 2篇 |
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 1篇 |
2018年 | 2篇 |
2017年 | 6篇 |
2016年 | 2篇 |
2015年 | 3篇 |
2014年 | 12篇 |
2013年 | 17篇 |
2012年 | 11篇 |
2011年 | 14篇 |
2010年 | 7篇 |
2009年 | 9篇 |
2008年 | 20篇 |
2007年 | 16篇 |
2006年 | 8篇 |
2005年 | 6篇 |
2004年 | 10篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 3篇 |
1988年 | 3篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 2篇 |
1980年 | 2篇 |
1978年 | 1篇 |
排序方式: 共有209条查询结果,搜索用时 31 毫秒
51.
Hani I. Mesak Abdullahel Bari Michael S. Luehlfing Fei Han 《European Journal of Operational Research》2015
Using a market share attraction structure of advertising competition and following a supermodular game approach, this article demonstrates for an asymmetric oligopoly, the directional impact of changes in model parameters on the marketing controlled variables of all rivals (advertising budgets) and the operations controlled variables of all rivals (ordered quantities). Importantly, the various changes are examined analytically, empirically and numerically in both non-dominated and dominated asymmetric oligopolies. 相似文献
52.
Andrey A. Krasovskii Alexander M. Tarasyev 《Applied mathematics and computation》2010,217(3):1125-1134
The problem of regulation of logistic growth trends is examined in the framework of control theory for problems with infinite horizon. The problem statement is related to microeconomic models of dynamic optimization of a company’s indicator of functionality development. Various control regimes of functionality development are studied for identification of plausible production trends. Optimal control problem is posed to optimize the utility function of logarithmic consumption index of the system entropy type. Solution of the problem is constructed in analysis of the Hamiltonian system and its algebraic properties. Based on this analysis nonlinear stabilizers are elaborated which lead the system to the steady state with the same growth rates as the optimal control regime. The model is tested on the real time series of dynamic trends of functionality development for two generations of mobile phones in Japan. 相似文献
53.
模糊需求下的库存风险及最优库存决策 总被引:1,自引:0,他引:1
分析了在模糊需求下,按经典库存模型中的经济订货批量和订货周期所导致的库存风险损失。推导了模糊需求下的经济风险函数。给出了风险函数在模糊需求分布下的重心决策方法,在此基础上得到了模糊需求下经济批量的修正公式,为模糊库存风险分析的研究提供了一种方法。 相似文献
54.
55.
在经济增长因素贡献率测算中 ,常用的方法有时存在比较大的误差 .本文利用柯布 -道格拉斯生产函数 ,导出经济增长因素贡献率测算新的模型 ,从理论上给出了其精确的表达形式 ,并对我国实际情况进行了测算 . 相似文献
56.
Potential of membrane distillation in seawater desalination: Thermal efficiency,sensitivity study and cost estimation 总被引:1,自引:0,他引:1
Sulaiman Al-Obaidani Efrem Curcio Francesca Macedonio Gianluca Di Profio Hilal Al-Hinai Enrico Drioli 《Journal of membrane science》2008
In this work, an extensive analysis on direct contact membrane distillation (DCMD) performance was developed to estimate the mass flux and the heat efficiency, considering transport phenomena, membrane structural properties and most sensitive process parameters, with the aim to provide optimization guidelines for materials and methods. The results showed that an increase of the temperature gradient resulted in the enhancement of both transmembrane flux and thermal efficiency. The investigation of the effects of membrane properties confirmed that better DCMD performance was achieved when using polymeric membranes characterized by low thermal conductivity (flux and thermal efficiency declined by 26% and 50%, respectively, when increasing thermal conductivity from 0.1 to 0.5 W/m K), and high porosity. An optimal thickness value (around 0.7 mm) was identified when operating at low temperature gradient (<5 °C). However, at higher temperature gradient (>10 °C), increasing the membrane thickness from 0.25 to 1.55 mm resulted in a flux decay of about 70% without a significant improvement in thermal efficiency. 相似文献
57.
本文研究具有可分解性质的区间冯·纽曼经济系统模型均衡解的存在性,并推导出两个重要而实用的判别定理,为研究不确定性经济系统模型提供了新工具. 相似文献
58.
Miguel Constantino 《Operations Research Letters》2007,35(5):645-650
In this paper we apply a discretization reformulation technique to the classical economic lot sizing problem. This reformulation yields the same LP bounds as the original model. We show, however, that by reducing adequately the coefficients of some variables, one obtains an enhanced reformulation whose LP relaxation solution is integer. 相似文献
59.
There are two key tools for the control of production processes — Statistical Process Control (SPC) and Maintenance Management (MM), which are traditionally separated (both in science and in business practice), even though their goals overlap a great deal. Their common goal is to achieve optimal product quality, little downtime and cost reduction by controlling variances in the process. Since single or separated parallel applications may not be fully effective, this paper discusses the integration of statistical process control and maintenance, and provides an integrated model of Control Chart (CC) and MM. A mathematical model is given to analyze the cost of the integrated model and the grid-search approach is used to find the optimal values of policy variables (n,h,L,k) that minimize hourly cost. Finally, a numerical experiment is conducted to investigate the effects of cost parameters on the solution of the design. 相似文献
60.
A control model is presented which studies optimal spending for the fight against terrorism. Under the assumptions that economic damages are larger the greater the number of terrorists and that the success of counter terror operations depends on public opinion, it is demonstrated that a so-called DNSS threshold may exist, separating the basin of attraction of optimal paths. 相似文献