全文获取类型
收费全文 | 2211篇 |
免费 | 276篇 |
国内免费 | 222篇 |
专业分类
化学 | 106篇 |
晶体学 | 6篇 |
力学 | 220篇 |
综合类 | 55篇 |
数学 | 1824篇 |
物理学 | 498篇 |
出版年
2024年 | 2篇 |
2023年 | 28篇 |
2022年 | 28篇 |
2021年 | 44篇 |
2020年 | 54篇 |
2019年 | 48篇 |
2018年 | 65篇 |
2017年 | 62篇 |
2016年 | 74篇 |
2015年 | 51篇 |
2014年 | 94篇 |
2013年 | 158篇 |
2012年 | 89篇 |
2011年 | 132篇 |
2010年 | 103篇 |
2009年 | 128篇 |
2008年 | 159篇 |
2007年 | 154篇 |
2006年 | 142篇 |
2005年 | 120篇 |
2004年 | 85篇 |
2003年 | 120篇 |
2002年 | 118篇 |
2001年 | 75篇 |
2000年 | 78篇 |
1999年 | 74篇 |
1998年 | 68篇 |
1997年 | 57篇 |
1996年 | 48篇 |
1995年 | 36篇 |
1994年 | 33篇 |
1993年 | 26篇 |
1992年 | 20篇 |
1991年 | 15篇 |
1990年 | 25篇 |
1989年 | 12篇 |
1988年 | 5篇 |
1987年 | 6篇 |
1986年 | 9篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 2篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1978年 | 11篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1975年 | 3篇 |
排序方式: 共有2709条查询结果,搜索用时 234 毫秒
61.
62.
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
63.
In this paper, the issue of multi-degree reduction of Bézier curves with C1 and G2-continuity at the end points of the curve is considered. An iterative method, which is the first of this type, is derived. It is shown that this algorithm converges and can be applied iteratively to get the required accuracy. Some examples and figures are given to demonstrate the efficiency of this method. 相似文献
64.
杨奇祥 《数学物理学报(B辑英文版)》2011,(4):1517-1534
If we use Littlewood-Paley decomposition, there is no pseudo-orthogonality for Ho¨rmander symbol operators OpS m 0 , 0 , which is different to the case S m ρ,δ (0 ≤δ < ρ≤ 1). In this paper, we use a special numerical algorithm based on wavelets to study the L p continuity of non infinite smooth operators OpS m 0 , 0 ; in fact, we apply first special wavelets to symbol to get special basic operators, then we regroup all the special basic operators at given scale and prove that such scale operator’s continuity decreases very fast, we sum such scale operators and a symbol operator can be approached by very good compact operators. By correlation of basic operators, we get very exact pseudo-orthogonality and also L 2 → L 2 continuity for scale operators. By considering the influence region of scale operator, we get H 1 (= F 0 , 2 1 ) → L 1 continuity and L ∞→ BMO continuity. By interpolation theorem, we get also L p (= F 0 , 2 p ) → L p continuity for 1 < p < ∞ . Our results are sharp for F 0 , 2 p → L p continuity when 1 ≤ p ≤ 2, that is to say, we find out the exact order of derivations for which the symbols can ensure the resulting operators to be bounded on these spaces. 相似文献
65.
TOPSIS is one of the well-known methods for multiple attribute decision making (MADM). In this paper, we extend the TOPSIS method to solve multiple attribute group decision making (MAGDM) problems in interval-valued intuitionistic fuzzy environment in which all the preference information provided by the decision-makers is presented as interval-valued intuitionistic fuzzy decision matrices where each of the elements is characterized by interval-valued intuitionistic fuzzy number (IVIFNs), and the information about attribute weights is partially known. First, we use the interval-valued intuitionistic fuzzy hybrid geometric (IIFHG) operator to aggregate all individual interval-valued intuitionistic fuzzy decision matrices provided by the decision-makers into the collective interval-valued intuitionistic fuzzy decision matrix, and then we use the score function to calculate the score of each attribute value and construct the score matrix of the collective interval-valued intuitionistic fuzzy decision matrix. From the score matrix and the given attribute weight information, we establish an optimization model to determine the weights of attributes, and construct the weighted collective interval-valued intuitionistic fuzzy decision matrix, and then determine the interval-valued intuitionistic positive-ideal solution and interval-valued intuitionistic negative-ideal solution. Based on different distance definitions, we calculate the relative closeness of each alternative to the interval-valued intuitionistic positive-ideal solution and rank the alternatives according to the relative closeness to the interval-valued intuitionistic positive-ideal solution and select the most desirable one(s). Finally, an example is used to illustrate the applicability of the proposed approach. 相似文献
66.
In this paper, we establish the Hölder continuity of solution mappings to parametric vector quasiequilibrium problems in metric spaces under the case that solution mappings are set-valued. Our main assumptions are weaker than those in the literature, and the results extend and improve the recent ones. Furthermore, as an application of Hölder continuity, we derive upper bounds for the distance between an approximate solution and a solution set of a vector quasiequilibrium problem with fixed parameters. 相似文献
67.
为了实现在连续性空间中的离散分段问题,采用解决离散性问题的方法虚拟构造连续性集合,将连续性问题映射为分段的离散问题,根据集合中元素的离散特性实现连续性模型的分段求解.通过数据结构的设计与压缩路径的算法证实,模型的映射能够解决实际问题的分段求解. 相似文献
68.
69.
混合分数布朗运动下亚式期权定价 总被引:2,自引:0,他引:2
运用混合分数布朗运动的Ito公式,将几何平均亚式期权定价化成一个偏微分方程求解问题,通过偏微分方程求解获得了几何平均型亚式看涨期权的定价公式. 相似文献
70.
研究每个忙期中第一个顾客被拒绝服务的M/M/1排队模型的主算子在左半复平面中的特征值,证明对一切θ∈(0,1),(2√λμ-λ—μ)θ是该主算子的几何重数为1的特征值. 相似文献