全文获取类型
收费全文 | 518篇 |
免费 | 139篇 |
国内免费 | 20篇 |
专业分类
化学 | 31篇 |
力学 | 14篇 |
综合类 | 14篇 |
数学 | 425篇 |
物理学 | 193篇 |
出版年
2023年 | 12篇 |
2022年 | 25篇 |
2021年 | 35篇 |
2020年 | 27篇 |
2019年 | 22篇 |
2018年 | 17篇 |
2017年 | 26篇 |
2016年 | 30篇 |
2015年 | 16篇 |
2014年 | 50篇 |
2013年 | 25篇 |
2012年 | 32篇 |
2011年 | 42篇 |
2010年 | 48篇 |
2009年 | 37篇 |
2008年 | 37篇 |
2007年 | 38篇 |
2006年 | 40篇 |
2005年 | 17篇 |
2004年 | 8篇 |
2003年 | 17篇 |
2002年 | 14篇 |
2001年 | 12篇 |
2000年 | 10篇 |
1999年 | 3篇 |
1998年 | 14篇 |
1997年 | 5篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
排序方式: 共有677条查询结果,搜索用时 15 毫秒
31.
We prove a uniqueness theorem for two non-constant meromorphic functions sharing three values which improves a recent result of T.C. Alzahary. As a consequence of our main result we also improve a theorem of G. Brosch. 相似文献
32.
申红艳 《数学的实践与认识》2016,(22):22-31
建立了由单手机广告主、手机广告代理商和移动运营商构成的三级广告产业链之间的基于协作的收益共享契约模型,分析了在以移动运营商为主导的手机广告链中,移动运营商的努力动机受收益共享和努力成本补偿参数的影响.采用量化分析和模拟仿真结合的方法,得出契约参数只有在满足一定条件下,移动运营商所做出的最优努力水平投入决策,将使得整个手机产业链收益最大化,实现多方共赢. 相似文献
33.
Natalia Osipova 《Operations Research Letters》2008,36(3):372-376
We study the Processor Sharing queueing model with a hyper-exponential service time distribution and Poisson batch arrival process. In the case of the hyper-exponential service time distribution we find an analytical expression for the expected conditional response time function and obtain an alternative proof of its concavity with respect to the service time. 相似文献
34.
An experimentally feasible scheme for implementing quantum secret sharing via cavity quantum electrodynamics (QED) is proposed. The scheme requires the large detuning of the cavity field from the atomic transition, the cavity is only virtually excited, thus the requirement on the quality factor of the cavity is greatly loosened. 相似文献
35.
基于分时原理的多相流体比例分配方法 总被引:1,自引:0,他引:1
提出了从“时间”上对多相流进行分配的新思路,分析了分时分配的基本原理,并设计了具体的实现方式。在空气-水实验回路上对分时分配装置进行了实验研究和验证。分时分配的基本原理就是通过“分时”的方法,使整个分配器“空间”内的多相流都能按照给定的时间份额周期性地交替流向对应的支路,从而保证各支路内的多相流具有高度一致的相含量和确定的流量比例。实验研究证明,分时分配法具有切实的可行性,分流比等于分时比且与流量和流体的物性无关,仅取决于分配器的几何参数。 相似文献
36.
We discuss a case study of an industrial production-marketing coordination problem involving component commonality. For the product line considered, the strategic goal of the company is to move from the current low volume market to a high volume market. The marketing department believes that this can be achieved by substantially lowering the end products’ prices. However, this requires a product redesign to lower production costs in order to maintain profit margins. The redesign decision involves grouping end products into families. All products within one family use the same version of some components. This paper fits in the stream of recent literature on component commonality where the focus has shifted from inventory cost savings to production and development cost savings. Further, we consider both costs and revenues, leading to a profit maximization approach. The price elasticity of demand determines the relationship between the price level and number of units sold. Consequently, we integrate information from different functional areas such as production, marketing and accounting. We formulate the problem as a net-present-value investment decision. We propose a mixed integer nonlinear optimization model to find the optimal commonality decision. The recommendation based on our analysis has been implemented in the company. In addition, the application allows us to experimentally validate some claims made in the literature and obtain managerial insights into the trade-offs. 相似文献
37.
Reference-frame-independent quantum key distribution of wavelength division multiplexing with multiple quantum channels
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Zhongqi Sun 《中国物理 B》2021,30(11):110303-110303
Reference-frame-independent quantum key distribution (RFI-QKD) can allow a quantum key distribution system to obtain the ideal key rate and transmission distance without reference system calibration, which has attracted much attention. Here, we propose an RFI-QKD protocol based on wavelength division multiplexing (WDM) considering finite-key analysis and crosstalk. The finite-key bound for RFI-QKD with decoy states is derived under the crosstalk of WDM. The resulting secret key rate of RFI-QKD, which is more rigorous, is obtained. Simulation results reveal that the secret key rate of RFI-QKD based on WDM is affected by the multiplexing channel number, as well as crosstalk between adjacent channels. 相似文献
38.
This paper is devoted to studying the relationship between meromorphic functions f(z) and g(z) when their differential polynomials satisfy sharing condition weaker than sharing one value IM. 相似文献
39.
A high contrast and capacity efficient visual cryptography scheme for the encryption of multiple secret images 总被引:1,自引:0,他引:1
The visual secret sharing for multiple secrets (VSSM) allows for the encryption of a greater number of secret images into a given image area. Previous researches on VSSM schemes incur a very serious pixel expansion that will damage capable of increasing the capacity of secret image encryption. Moreover, the most of VSSM schemes will decrease the contrast of recover images while the amount of secret image encryption increases. These drawbacks limit applicability of the existing VSSM schemes. In this paper, we propose a highly efficient encryption algorithm to cope with this problem. The proposed algorithm adopts a novel hybrid encryption approach that includes a VC-based encryption and a camouflaging process. The experimental results demonstrate that the proposed approach not only can increase the capacity efficient for VSSM schemes, but also maintains an excellent level of contrast in the recovered secret images. 相似文献
40.
In this article, we propose a three-party quantum secret sharing protocol with four-state Grover algorithm. The protocol has several advantages. It uses only four initial states which simplifies its experimental implementation. It has a higher encoding capacity, each two-qubit state provides two bits of information. We have experimentally demonstrated the protocol in a nuclear magnetic resonance quantum information processor successfully. 相似文献