全文获取类型
收费全文 | 349篇 |
免费 | 153篇 |
国内免费 | 25篇 |
出版年
2024年 | 2篇 |
2022年 | 4篇 |
2021年 | 14篇 |
2020年 | 8篇 |
2019年 | 6篇 |
2018年 | 7篇 |
2017年 | 21篇 |
2016年 | 30篇 |
2015年 | 13篇 |
2014年 | 25篇 |
2013年 | 43篇 |
2012年 | 23篇 |
2011年 | 28篇 |
2010年 | 18篇 |
2009年 | 32篇 |
2008年 | 36篇 |
2007年 | 26篇 |
2006年 | 18篇 |
2005年 | 27篇 |
2004年 | 16篇 |
2003年 | 18篇 |
2002年 | 20篇 |
2001年 | 13篇 |
2000年 | 7篇 |
1999年 | 11篇 |
1998年 | 12篇 |
1997年 | 6篇 |
1996年 | 4篇 |
1995年 | 3篇 |
1994年 | 6篇 |
1993年 | 5篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 17篇 |
1989年 | 2篇 |
排序方式: 共有527条查询结果,搜索用时 46 毫秒
161.
The drivers of HIV/AIDS in the South African Police Service (SAPS) and impact of the disease on this workforce are neglected areas of research. Existing evidence suggests that while the occupational risk for contracting HIV is low, there are factors associated with the profession that, if left unmanaged, place police officers at risk of contracting HIV. This study's two aims are to identify the potential pathways of HIV infection within policing services and determine the probable impact of HIV/AIDS on SAPS. Through a systematic literature review on HIV/AIDS within police services, and by analysing selected SAPS human resource data, the causal pathways and impact of HIV/AIDS on police services are explored. The study finds that police officers (particularly male officers) are likely to be highly susceptible to HIV infection as a result of risky sexual behaviours born out of occupational characteristics such as high levels of stress, difficult working conditions, living away from home and interactions with sex workers. The problem is exacerbated by the ‘macho’ culture that often prevails among police officers. HIV/AIDS interventions within SAPS must focus on sustained behaviour change. Further, HIV programmes must equip officers with the knowledge and awareness to avoid engaging in high-risk sexual practices that may compromise their health and the effectiveness of the policing service. 相似文献
162.
Martin Rupiah 《African Security Review》2013,22(4):51-59
In May 2012, Zambia's Inspector-General of Police announced a crackdown on sex workers. This commentary discusses the rationale behind this proposed crackdown and the problems associated with such a policy response. 相似文献
163.
164.
165.
在传统的含储能单元分布式供电系统中,一般都需要多个单向直流变换器和双向直流变换器才能实现其功能。提出一种新的双输入多通道直流变换器,它的功能等效于一个单向直流变换器和一个双向直流变换器。分析了双输入多通道直流变换器的工作原理,给出了变换器的稳态关系式以及能量管理方法,并运用Saber软件进行仿真,验证了理论分析的正确性。该直流变换器除具有双输入Buck直流变换器的优点外,还能实现可再生能源向储电输入源充电。 相似文献
166.
In this article, a distribution system is studied where the sum of transportation and inventory costs is to be minimized. The inventory holding cost is assumed to be the same for all retailers. A fixed partition (FP) periodic policy is proposed with tight asymptotic worst‐case performance of 3/2 with respect to the best possible policy. This bound cannot be improved in the class of FP periodic policies. In partition‐based PB policies, the retailers are first partitioned into sets and then the sets are grouped in such a way that sets of retailers within a group are served together at selected times. A PB periodic, policy is presented with tight worst‐case asymptotic performance of with respect to the best possible policy. This latter performance improves the worst‐case asymptotic performance of of the previously best known policy for this problem. We also show that the proposed PB periodic policy has the best worst‐case asymptotic performance within the class of PB policies. Finally, practical heuristics inspired by the analyzed policies are designed and tested. The asymptotic worst–case performances of the heuristics are shown to be the same of those of the analyzed policies. Computational results show that the heuristics suggested are less than 6.4% on average from a lower bound on the optimal cost when 50 or more retailers are involved. © 2013 Wiley Periodicals, Inc. Naval Research Logistics 00: 000–000, 2013 相似文献
167.
Ordered flow shop models have appeared in the literature since the mid‐1970s and proportionate flow shop models have appeared since the early 1980s. We provide a detailed review of these models along with some analysis and potential topics for future research. © 2012 Wiley Periodicals, Inc. Naval Research Logistics, 2013 相似文献
168.
169.
Sean Mirski 《战略研究杂志》2013,36(3):385-421
The mounting challenge posed by China's military modernization has highlighted the need for the United States to analyze its ability to execute a naval blockade. A blockade strategy is viable, but it would be limited to a narrow context: the United States would have to be engaged in a protracted conflict over vital interests, and it would need the support of key regional powers. The United States would also need to implement a mix between a close and distant blockade in order to avoid imperiling the conflict's strategic context. If enacted, a blockade could exact a ruinous cost on the Chinese economy and state. 相似文献
170.
数据粒度是海量空间数据并行计算的重要问题之一。通过对不同性质的并行算法的对比分析,提出空间数据粒度模型,量化地反映并行地形分析中数据划分的规模,建立并行数据粒度评价模型。通过研究集群环境下不同算法的数据并行数据粒度问题,提出基于并行数据粒度评价模型的优化数据粒度调度算法。通过计算每一次并行计算的时间与数据粒度效率,从而实现对计算数据粒度动态更新以追求更高的加速比。经过实验验证,该算法较之传统算法,可提供更高的任务执行效率并具有更好的可移植性。 相似文献