全文获取类型
收费全文 | 369篇 |
免费 | 14篇 |
国内免费 | 6篇 |
专业分类
化学 | 267篇 |
晶体学 | 1篇 |
力学 | 16篇 |
数学 | 44篇 |
物理学 | 61篇 |
出版年
2023年 | 2篇 |
2022年 | 3篇 |
2021年 | 8篇 |
2020年 | 13篇 |
2019年 | 16篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 18篇 |
2015年 | 18篇 |
2014年 | 18篇 |
2013年 | 40篇 |
2012年 | 28篇 |
2011年 | 29篇 |
2010年 | 33篇 |
2009年 | 28篇 |
2008年 | 22篇 |
2007年 | 21篇 |
2006年 | 13篇 |
2005年 | 12篇 |
2004年 | 9篇 |
2003年 | 5篇 |
2002年 | 4篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1986年 | 3篇 |
1985年 | 1篇 |
1981年 | 1篇 |
1979年 | 2篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有389条查询结果,搜索用时 15 毫秒
91.
92.
93.
94.
95.
96.
97.
A high-order immersed boundary method is devised for the compressible Navier-Stokes equations by employing high-order summation-by-parts difference operators. The immersed boundaries are treated as sharp interfaces by enforcing the solid wall boundary conditions via flow variables at ghost points. Two different interpolation schemes are tested to compute values at the ghost points and a hybrid treatment is used. The first method provides the bilinearly interpolated flow variables at the image points of the corresponding ghost points and the second method applies the boundary condition at the immersed boundary by using the weighted least squares method with high-order polynomials. The approach is verified and validated for compressible flow past a circular cylinder at moderate Reynolds numbers. The tonal sound generated by vortex shedding from a circular cylinder is also investigated. In order to demonstrate the capability of the solver to handle complex geometries in practical cases, flow in a cross-section of a human upper airway is simulated. 相似文献
98.
Behdin Vahedi-Nouri Parviz Fattahi Mohammad Rohaninejad Reza Tavakkoli-Moghaddam 《Applied Mathematical Modelling》2013
This paper considers a single machine scheduling problem with the learning effect and multiple availability constraints that minimizes the total completion time. To solve this problem, a new binary integer programming model is presented, and a branch-and-bound algorithm is also developed for solving the given problem optimally. Since the problem is strongly NP-hard, to find the near-optimal solution for large-sized problems within a reasonable time, two meta-heuristics; namely, genetic algorithm and simulated annealing are developed. Finally, the computational results are provided to compare the result of the binary integer programming, branch-and-bound algorithm, genetic algorithm and simulated annealing. Then, the efficiency of the proposed algorithms is discussed. 相似文献
99.
Donya Rahmani Reza Ramezanian Parviz Fattahi Mahdi Heydari 《Applied Mathematical Modelling》2013,37(20-21):8957-8971
Production planning (PP) is one of the most important issues carried out in manufacturing environments which seeks efficient planning, scheduling and coordination of all production activities that optimizes the company’s objectives. In this paper, we studied a two-stage real world capacitated production system with lead time and setup decisions in which some parameters such as production costs and customer demand are uncertain. A robust optimization model is developed to formulate the problem in which minimization of the total costs including the setup costs, production costs, labor costs, inventory costs, and workforce changing costs is considered as performance measure. The robust approach is used to reduce the effects of fluctuations of the uncertain parameters with regards to all the possible future scenarios. A mixed-integer programming (MIP) model is developed to formulate the related robust production planning problem. In fact the robust proposed model is presented to generate an initial robust schedule. The performance of this schedule could be improved against of any possible occurrences of uncertain parameters. A case from an Iran refrigerator factory is studied and the characteristics of factory and its products are discussed. The computational results display the robustness and effectiveness of the model and highlight the importance of using robust optimization approach in generating more robust production plans in the uncertain environments. The tradeoff between solution robustness and model robustness is also analyzed. 相似文献
100.
We establish new iterative methods of local order fourteen to approximate the simple roots of nonlinear equations. The considered
three-step eighth-order construction can be viewed as a variant of Newton’s method in which the concept of Hermite interpolation
is used at the third step to reduce the number of evaluations. This scheme includes three evaluations of the function and
one evaluation of the first derivative per iteration, hence its efficiency index is 1.6817. Next, the obtained approximation
for the derivative of the Newton’s iteration quotient is again taken into consideration to furnish novel fourteenth-order
techniques consuming four function and one first derivative evaluations per iteration. In providing such new fourteenth-order
methods, we also take a special heed to the computational burden. The contributed four-step methods have 1.6952 as their efficiency
index. Finally, various numerical examples are given to illustrate the accuracy of the developed techniques. 相似文献