全文获取类型
收费全文 | 1585篇 |
免费 | 595篇 |
国内免费 | 95篇 |
专业分类
2275篇 |
出版年
2024年 | 3篇 |
2023年 | 12篇 |
2022年 | 25篇 |
2021年 | 34篇 |
2020年 | 29篇 |
2019年 | 30篇 |
2018年 | 20篇 |
2017年 | 98篇 |
2016年 | 96篇 |
2015年 | 79篇 |
2014年 | 104篇 |
2013年 | 165篇 |
2012年 | 178篇 |
2011年 | 192篇 |
2010年 | 80篇 |
2009年 | 85篇 |
2008年 | 101篇 |
2007年 | 123篇 |
2006年 | 115篇 |
2005年 | 120篇 |
2004年 | 91篇 |
2003年 | 88篇 |
2002年 | 57篇 |
2001年 | 65篇 |
2000年 | 56篇 |
1999年 | 42篇 |
1998年 | 31篇 |
1997年 | 23篇 |
1996年 | 22篇 |
1995年 | 11篇 |
1994年 | 15篇 |
1993年 | 11篇 |
1992年 | 18篇 |
1991年 | 14篇 |
1990年 | 30篇 |
1989年 | 9篇 |
1988年 | 2篇 |
1987年 | 1篇 |
排序方式: 共有2275条查询结果,搜索用时 0 毫秒
141.
142.
143.
144.
145.
146.
Magnetic resonance imaging and other multifunctional diagnostic facilities, which are considered as scarce resources of hospitals, typically provide services to patients with different medical needs. This article examines the admission policies during the appointment management of such facilities. We consider two categories of patients: regular patients who are scheduled in advance through an appointment system and emergency patients with randomly generated demands during the workday that must be served as soon as possible. According to the actual medical needs of patients, regular patients are segmented into multiple classes with different cancelation rates, no‐show probabilities, unit value contributions, and average service times. Management makes admission decisions on whether or not to accept a service request from a regular patient during the booking horizon to improve the overall value that could be generated during the workday. The decisions should be made by considering the cancelation and no‐show behavior of booked patients as well as the emergency patients that would have to be served because any overtime service would lead to higher costs. We studied the optimal admission decision using a continuous‐time discrete‐state dynamic programming model. Identifying an optimal policy for this discrete model is analytically intractable and numerically inefficient because the state is multidimensional and infinite. We propose to study a deterministic counterpart of the problem (i.e., the fluid control problem) and to develop a time‐based fluid policy that is shown to be asymptotically optimal for large‐scale problems. Furthermore, we propose to adopt a mixed fluid policy that is developed based on the information obtained from the fluid control problem. Numerical experiments demonstrate that this improved policy works effectively for small‐scale problems. © 2016 Wiley Periodicals, Inc. Naval Research Logistics 63: 287–304, 2016 相似文献
147.
148.
Andreas Lutsch 《战略研究杂志》2016,39(4):535-558
ABSTRACTRecent nuclear-weapons-related consultation in NATO within the framework of the Defence and Deterrence Posture Review sheds light on historical experiences with nuclear consultation in NATO. In the early years of the Nuclear Planning Group (NPG), which became the main forum for multilateral nuclear consultation in the alliance, developing a nuclear weapons first use doctrine was of particular importance. This process led to the adoption of the Provisional Political Guidelines (PPGs) on the threat to initiate the use of nuclear weapons. With a focus on West Germany as the primary addressee of the NPG, it will be postulated that nuclear consultation functioned and may still be seen as an essential tool to manage the credibility of US extended nuclear deterrence in the framework of NATO. 相似文献
149.
150.