全文获取类型
收费全文 | 809篇 |
免费 | 66篇 |
国内免费 | 11篇 |
专业分类
化学 | 23篇 |
力学 | 46篇 |
综合类 | 33篇 |
数学 | 670篇 |
物理学 | 114篇 |
出版年
2024年 | 2篇 |
2023年 | 11篇 |
2022年 | 22篇 |
2021年 | 21篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 19篇 |
2017年 | 27篇 |
2016年 | 31篇 |
2015年 | 21篇 |
2014年 | 66篇 |
2013年 | 55篇 |
2012年 | 44篇 |
2011年 | 39篇 |
2010年 | 47篇 |
2009年 | 65篇 |
2008年 | 54篇 |
2007年 | 65篇 |
2006年 | 25篇 |
2005年 | 26篇 |
2004年 | 15篇 |
2003年 | 18篇 |
2002年 | 18篇 |
2001年 | 16篇 |
2000年 | 21篇 |
1999年 | 13篇 |
1998年 | 8篇 |
1997年 | 7篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1994年 | 6篇 |
1993年 | 4篇 |
1992年 | 7篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 2篇 |
1988年 | 11篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 17篇 |
1984年 | 7篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 4篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1970年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有886条查询结果,搜索用时 15 毫秒
1.
This paper deals with mathematical human resource planning; more specifically, it suggests a new model for a manpower‐planning system. In general, we study a k‐classed hierarchical system where the workforce demand at each time period is satisfied through internal mobility and recruitment. The motivation for this work is based on various European Union incentives, which promote regional or local government assistance programs that could be exploited by firms not only for hiring and training newcomers, but also to improve the skills and knowledge of their existing personnel. In this respect, in our augmented mobility model we establish a new ‘training/standby’ class, which serves as a manpower inventory position for potential recruits. This class, which may very well be internal or external to the system, is incorporated into the framework of a non‐homogeneous Markov chain model. Furthermore, cost objectives are employed using the goal‐programming approach, under different operating assumptions, in order to minimize the operational cost in the presence of system's constraints and regulations. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
2.
Various problems associated with optimal path planning for mobile observers such as mobile robots equipped with cameras to obtain maximum visual coverage of a surface in the three-dimensional Euclidean space are considered. The existence of solutions to these problems is discussed first. Then, optimality conditions are derived by considering local path perturbations. Numerical algorithms for solving the corresponding approximate problems are proposed. Detailed solutions to the optimal path planning problems for a few examples are given. 相似文献
3.
4.
W. Brüggemann K. Fischer H. Jahnke 《Journal of Mathematical Modelling and Algorithms》2003,2(2):153-169
In Part I of this study, we suggest to identify an operations research (OR) problem with the equivalence class of models describing the problem and enhance the standard computer-science theory of computational complexity to be applicable to this situation of an often model-based OR context. The Discrete Lot-sizing and Scheduling Problem (DLSP) is analysed here in detail to demonstrate the difficulties which can arise if these aspects are neglected and to illustrate the new theoretical concept. In addition, a new minimal model is introduced for the DLSP which makes this problem eventually amenable to a rigorous analysis of its computational complexity. 相似文献
5.
重离子治疗计划系统的构想 总被引:2,自引:1,他引:1
对重离子柬治癌的优势进行简要的回顾,并着重介绍了用于重离子放射治疗的治疗计划系统。治疗计划系统是一套软件系统,不同的硬件设施应有与其相匹配的软件系统,即治疗计划系统。在此基础上,针对兰州重离子加速器的特点提出一些关于治疗计划系统方面的构想。After a brief review concerning the advantages of heavy ions in radiotherapy, more interests are concentrated on treatment planning system (TPS) for heavy ion radiotherapy. Compared to the hardware devices such as accelerator and beam delivery system, the TPS is a set of software system, and different therapy facilities require their corresponding TPSs. Based on the specialities of the Heavy Ion Research Facility in Lanzhou (HIIRFL), some suggestions on the TPS for tumor therapy at HIRFL finally are given. 相似文献
6.
We study dynamic self-reconfiguration of modular metamorphic systems. We guarantee the feasibility of motion planning in a
rectangular model consisting of square modules that are allowed to slide along or rotate about one another. That is, we show
that any two connected configurations of the same number of modules can be transformed into each other by a sequence of moves
so that all intermediate configurations are connected. This settles a conjecture formulated in [6]. 相似文献
7.
宁波城市设计的若干思考与建议 总被引:1,自引:0,他引:1
张柳燕 《宁波大学学报(理工版)》2004,17(2):166-169
通过探讨城市设计概念的形成过程和历史积淀,阐明其在城市建设中的意义,并运用城市设计的理论与分析方法,针对目前宁波城市大规模的规划、设计、改造现象,提出若干思考与建议. 相似文献
8.
This paper describes a methodology for allocating resources in hospitals. The methodology uses two linear goal-programming models. One model sets case mix and volume for physicians, while holding service costs fixed; the other translates case mix decisions into a commensurate set of practice changes for physicians. The models allow decision makers to set case mix and case costs in such a way that the institution is able to break even, while preserving physician income and minimizing disturbance to practice. The models also permit investigation of trade-offs between case mix and physician practice parameters. Results are presented from a decision-making scenario facing the surgical division of Toronto's Mount Sinai Hospital after the announcement of a 3-year, 18% reduction in funding. 相似文献
9.
航空公司在给定的运力和机队配置条件下,如何适应航线需求的不断变化而合理地分配运力,使航空公司的经营效益最大化是我国航空经营管理的一个重大课题.根据航班效益分析,在一定的经营时间,航行班次的条件下,建立一个航线贡献最大化的含有随机变量的动态规划模型.求解方法是先用M ON TE C ARLO方法计算机仿真把模型转化为非线性的整数规划.再用动态规划中资源分配算法求出模型的最优解,编排最优各航线规划. 相似文献
10.