全文获取类型
收费全文 | 115篇 |
免费 | 37篇 |
国内免费 | 2篇 |
专业分类
化学 | 20篇 |
力学 | 4篇 |
综合类 | 24篇 |
数学 | 88篇 |
物理学 | 18篇 |
出版年
2023年 | 1篇 |
2022年 | 11篇 |
2021年 | 13篇 |
2020年 | 10篇 |
2019年 | 12篇 |
2018年 | 3篇 |
2017年 | 4篇 |
2016年 | 9篇 |
2015年 | 4篇 |
2014年 | 7篇 |
2013年 | 12篇 |
2012年 | 7篇 |
2011年 | 4篇 |
2010年 | 6篇 |
2009年 | 3篇 |
2008年 | 11篇 |
2007年 | 6篇 |
2006年 | 4篇 |
2005年 | 2篇 |
2004年 | 6篇 |
2003年 | 6篇 |
2002年 | 1篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1998年 | 2篇 |
1997年 | 2篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
排序方式: 共有154条查询结果,搜索用时 125 毫秒
151.
通过构建两个供应商和两个电商平台之间的博弈模型,探讨竞争性供应商选择电商平台销售模式的互动机理。研究发现:(1)竞争性供应商在电商平台销售模式选择上存在互动机理。(2)在短期均衡中,当佣金费率较高或较低时,供应商的销售模式选择不受竞争对手影响;当佣金费率适中时,供应商的销售模式选择将采取跟随策略,与竞争对手的选择保持一致。(3)在长期均衡中,当佣金费率较低时,两个供应商均会选择代销模式;当佣金费率较高时,两个供应商均会选择转销模式;当供应商自身的佣金费率较高(较低),竞争对手的佣金费率较低(较高)时,供应自身选择转销(代销)模式,竞争对手会选择代销(转销)模式。 相似文献
152.
研究了信息不对称下电子商务交易平台对在线卖方提高产品质量的激励问题.在线卖方提高产品质量需要付出质量成本,电子商务交易平台监督卖方产品质量需要付出监督成本.当作为理性人的卖方和交易平台提供商考虑自身利益最大化时,导致电子商务中的产品质量不高.将在线卖方在交易平台处的广告费用与其提供的产品质量相联系,证明了通过建立广告费用价格折扣与产品合格率正向相关的契约可以激励在线卖方提高产品质量,并且证明了该契约对在线卖方和电子商务交易平台是双赢的. 相似文献
153.
154.
The microbiome emits informative signals of biological organization and environmental pressure that aid ecosystem monitoring and prediction. Are the many signals reducible to a habitat-specific portfolio that characterizes ecosystem health? Does an optimally structured microbiome imply a resilient microbiome? To answer these questions, we applied our novel Eco-Evo Mandala to bacterioplankton data from four habitats within the Great Barrier Reef, to explore how patterns in community structure, function and genetics signal habitat-specific organization and departures from theoretical optimality. The Mandala revealed communities departing from optimality in habitat-specific ways, mostly along structural and functional traits related to bacterioplankton abundance and interaction distributions (reflected by and as power law and exponential distribution parameters), which are not linearly associated with each other. River and reef communities were similar in their relatively low abundance and interaction disorganization (low and ) due to their protective structured habitats. On the contrary, lagoon and estuarine inshore reefs appeared the most disorganized due to the ocean temperature and biogeochemical stress. Phylogenetic distances (D) were minimally informative in characterizing bacterioplankton organization. However, dominant populations, such as Proteobacteria, Bacteroidetes, and Cyanobacteria, were largely responsible for community patterns, being generalists with a large functional gene repertoire (high D) that increases resilience. The relative balance of these populations was found to be habitat-specific and likely related to systemic environmental stress. The position on the Mandala along the three fundamental traits, as well as fluctuations in this ecological state, conveys information about the microbiome’s health (and likely ecosystem health considering bacteria-based multitrophic dependencies) as divergence from the expected relative optimality. The Eco-Evo Mandala emphasizes how habitat and the microbiome’s interaction network topology are first- and second-order factors for ecosystem health evaluation over taxonomic species richness. Unhealthy microbiome communities and unbalanced microbes are identified not by macroecological indicators but by mapping their impact on the collective proportion and distribution of interactions, which regulates the microbiome’s ecosystem function. 相似文献