全文获取类型
收费全文 | 768篇 |
免费 | 77篇 |
国内免费 | 14篇 |
专业分类
化学 | 15篇 |
晶体学 | 1篇 |
力学 | 11篇 |
综合类 | 15篇 |
数学 | 754篇 |
物理学 | 63篇 |
出版年
2023年 | 3篇 |
2022年 | 33篇 |
2021年 | 25篇 |
2020年 | 18篇 |
2019年 | 18篇 |
2018年 | 15篇 |
2017年 | 23篇 |
2016年 | 37篇 |
2015年 | 16篇 |
2014年 | 29篇 |
2013年 | 88篇 |
2012年 | 52篇 |
2011年 | 53篇 |
2010年 | 59篇 |
2009年 | 52篇 |
2008年 | 57篇 |
2007年 | 52篇 |
2006年 | 38篇 |
2005年 | 39篇 |
2004年 | 29篇 |
2003年 | 26篇 |
2002年 | 25篇 |
2001年 | 15篇 |
2000年 | 15篇 |
1999年 | 12篇 |
1998年 | 9篇 |
1997年 | 2篇 |
1996年 | 4篇 |
1995年 | 2篇 |
1994年 | 3篇 |
1993年 | 1篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 1篇 |
1985年 | 3篇 |
1982年 | 1篇 |
排序方式: 共有859条查询结果,搜索用时 281 毫秒
71.
针对股票内在价值评判方法中指标权重设定的主观性缺陷,提出在利用熵权确定各指标权重的基础上,运用模糊综合评价方法对股票会计信息的综合指标进行模糊处理,为投资者投资股票提供一种新的参考;并通过"一带一路"概念股中的五支工程基建行业类股票进行模拟实证分析,证明将会计信息进行相关量化处理,能够为投资者提供较为客观的选择,同时基于熵权的模糊综合评价模型在股票内在价值评价中具有可行性. 相似文献
72.
Efficient pricing of discrete Asian options 总被引:2,自引:0,他引:2
Asian options are popular path-dependent financial derivatives. This paper uses lattices to price fixed-strike European-style Asian options that are discretely monitored. The algorithm proposed can also be applied to floating-strike Asian options as well because fixed-strike and floating-strike Asian options are related through an equation. The discretely monitored version is usually found in practice instead of the continuously monitored version usually encountered in the literature. This paper presents the first provably quadratic-time convergent lattice algorithm for pricing fixed-strike European-style discretely monitored Asian options. It is the most efficient lattice algorithm with convergence guarantees. The algorithm relies on the Lagrange multipliers to choose the number of states for each node of the lattice. Extensive numerical experiments and comparisons with many existing numerical methods confirm the performance claims and the competitiveness of our algorithm. This result places fixed-strike European-style discretely monitored Asian options in the same complexity class as vanilla options. 相似文献
73.
Shib Sankar Sana 《Applied mathematics and computation》2011,218(7):3277-3288
The paper deals with an inventory model to determine the retailer’s optimal order quantity for similar products. It is assumed that the amount of display space is limited and the demand of the products depends on the display stock level where more stock of one product makes a negative impression of the another product. Besides it, the demand rate is also dependent on selling price and salesmen’s initiatives. Also, the replenishment rate depends on the level of stock of the items. The objective of the model is to maximize the profit function, including the effect of inflation and time value of money by Pontryagin’s Maximal Principles. The stability analysis of the concerned dynamical system has been done analytically. 相似文献
74.
Bivariate Fréchet (BF) copulas characterize dependence as a mixture of three simple structures: comonotonicity, independence and countermonotonicity. They are easily interpretable but have limitations when used as approximations to general dependence structures. To improve the approximation property of the BF copulas and keep the advantage of easy interpretation, we develop a new copula approximation scheme by using BF copulas locally and patching the local pieces together. Error bounds and a probabilistic interpretation of this approximation scheme are developed. The new approximation scheme is compared with several existing copula approximations, including shuffle of min, checkmin, checkerboard and Bernstein approximations and exhibits better performance, especially in characterizing the local dependence. The utility of the new approximation scheme in insurance and finance is illustrated in the computation of the rainbow option prices and stop-loss premiums. 相似文献
75.
Nergiz KasimbeyliTugba Sarac Refail Kasimbeyli 《Journal of Computational and Applied Mathematics》2011,235(16):4663-4674
This paper considers a one-dimensional cutting stock and assortment problem. One of the main difficulties in formulating and solving these kinds of problems is the use of the set of cutting patterns as a parameter set in the mathematical model. Since the total number of cutting patterns to be generated may be very huge, both the generation and the use of such a set lead to computational difficulties in solution process. The purpose of this paper is therefore to develop a mathematical model without the use of cutting patterns as model parameters. We propose a new, two-objective linear integer programming model in the form of simultaneous minimization of two contradicting objectives related to the total trim loss amount and the total number of different lengths of stock rolls to be maintained as inventory, in order to fulfill a given set of cutting orders. The model does not require pre-specification of cutting patterns. We suggest a special heuristic algorithm for solving the presented model. The superiority of both the mathematical model and the solution approach is demonstrated on test problems. 相似文献
76.
On the explicit evaluation of the Geometric Asian options in stochastic volatility models with jumps 总被引:1,自引:0,他引:1
Friedrich Hubalek 《Journal of Computational and Applied Mathematics》2011,235(11):3355-3365
In the present paper we provide a semiexplicit valuation formula for Geometric Asian options, with fixed and floating strike under continuous monitoring, when the underlying stock price process exhibits both stochastic volatility and jumps. More precisely, we shall work in the Barndorff-Nielsen and Shephard (BNS) model framework. We shall provide some numerical illustrations of the results obtained. 相似文献
77.
Most decision making research in real options focuses on revenue uncertainty assuming discount rates remain constant. However, for many decisions revenue or cost streams are relatively static and investment is driven by interest rate uncertainty, for example the decision to invest in durable machinery and equipment. Using interest rate models from Cox et al. (1985b), we generalize the work of Ingersoll and Ross (1992) in two ways. Firstly, we include real options on perpetuities (in addition to zero coupon cash flows). Secondly, we incorporate abandonment or disinvestment as well as investment options, and thus model interest rate hysteresis (parallel to revenue uncertainty in Dixit (1989a)). Under stochastic interest rates, economic hysteresis is found to be significant, even for small sunk costs. 相似文献
78.
79.
主要探讨不确定环境下用模糊集理论处理亚式期权的定价问题.运用梯形模糊数来表示标的资产价格、无风险利率、红利率和波动率,建立了亚式期权的加权可能性均值模糊定价模型,得到连续几何和算术亚式期权的模糊价格公式.最后通过数值例子表明:亚式期权的加权可能性均值模糊定价模型具有很大的灵活性,更符合现实的不确定情况,具有较强的实用价值. 相似文献
80.
城市社区共享资源维护的个体异质性效应研究 总被引:1,自引:0,他引:1
城市社区共享资源经历日晒雨淋或人为频繁使用而逐渐耗损,为了"保值增值",必然出现对其维护捐赠的可持续性问题.在多人跨期均衡模型和数学赋值的随机模拟基础上,对个体偏好异质性等参数影响捐赠投入的机理进行了探讨,认为:差异程度与城市社区共享资源维护的捐赠投入正相关;且初始存量较大或耗损速率较慢时,异质性的作用更加显著. 相似文献