全文获取类型
收费全文 | 56683篇 |
免费 | 6512篇 |
国内免费 | 3825篇 |
专业分类
电工技术 | 5182篇 |
技术理论 | 2篇 |
综合类 | 5261篇 |
化学工业 | 7549篇 |
金属工艺 | 3721篇 |
机械仪表 | 3990篇 |
建筑科学 | 4474篇 |
矿业工程 | 2261篇 |
能源动力 | 1722篇 |
轻工业 | 4791篇 |
水利工程 | 1742篇 |
石油天然气 | 2609篇 |
武器工业 | 914篇 |
无线电 | 6335篇 |
一般工业技术 | 5465篇 |
冶金工业 | 2259篇 |
原子能技术 | 879篇 |
自动化技术 | 7864篇 |
出版年
2024年 | 306篇 |
2023年 | 901篇 |
2022年 | 2056篇 |
2021年 | 2807篇 |
2020年 | 2030篇 |
2019年 | 1462篇 |
2018年 | 1656篇 |
2017年 | 2061篇 |
2016年 | 1757篇 |
2015年 | 2699篇 |
2014年 | 3373篇 |
2013年 | 3833篇 |
2012年 | 4674篇 |
2011年 | 4759篇 |
2010年 | 4402篇 |
2009年 | 4310篇 |
2008年 | 4240篇 |
2007年 | 4195篇 |
2006年 | 3573篇 |
2005年 | 2897篇 |
2004年 | 2032篇 |
2003年 | 1384篇 |
2002年 | 1281篇 |
2001年 | 1115篇 |
2000年 | 946篇 |
1999年 | 619篇 |
1998年 | 340篇 |
1997年 | 297篇 |
1996年 | 231篇 |
1995年 | 174篇 |
1994年 | 136篇 |
1993年 | 114篇 |
1992年 | 75篇 |
1991年 | 66篇 |
1990年 | 43篇 |
1989年 | 36篇 |
1988年 | 22篇 |
1987年 | 18篇 |
1986年 | 13篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 15篇 |
1980年 | 14篇 |
1979年 | 9篇 |
1974年 | 1篇 |
1967年 | 1篇 |
1959年 | 12篇 |
1951年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
82.
分析大学课程时间表问题的特征,结合已有蚁群算法的求解策略,构建了新的问题求解模型,提出了一种基于蚁群算法和改进过程的求解算法,并在不同规模的问题实例上进行实验。结果表明,算法在目标函数解的质量上有明显改进。 相似文献
83.
Jialiang Sun Qiang Tian Haiyan Hu 《Structural and Multidisciplinary Optimization》2017,55(4):1159-1177
A topology optimization methodology is proposed for the flexible multibody system undergoing both large overall motion and large deformation. The system of concern is modeled via the absolute nodal coordinate formulation. The equivalent static load method is employed to transform the topology optimization of the nonlinear dynamic response of the system into a static one, and evaluated to adapt to the absolute nodal coordinate formulation by splitting the elastic deformations of the flexible components from the overall motions of those components. During the static topology optimization, the material interface is implicitly described as the zero level set of a higher-dimensional scalar function. Then, the semi-implicit level set method with the additive operator splitting algorithm is employed to solve the corresponding Hamilton-Jacobi partial differential equation. In addition, the expert evaluation method of weights based on the grey theory is utilized to define the objective function, and a modified augmented Lagrange multiplier method is proposed to treat the inequality volume constraint so as to avoid the oscillation and drift of the volume. Finally, two numerical examples are provided to validate the proposed methodology. 相似文献
84.
从ARM7中断处理机制入手,分析了ARM7+μC/OS-Ⅱ平台下的中断处理过程,提出了一套基于中断优先级的ARM中断优化方法。试验证明,此方法在不更改操作系统代码的情况下可以实现中断嵌套功能,有效提高了系统的实时性能,在工程应用中具有一定的实用价值。 相似文献
85.
86.
87.
改进遗传算法搜索性能的研究 总被引:1,自引:0,他引:1
本文针对改进遗传算法的搜索性能,提出了一种新的变异算子-自适应多位变异算子,它根据每一代的每一个体在当代中的优劣程度,自适应地控制其发生变异的位数。适应度差的个体变异的位数多,一方面使差的模式生存机会少,另一方面增加了种群的多样性,同时也扩大了搜索范围。我们用模式定理证明了该算子的有效性,并且我们作的仿真实验也同样表明该算子能大大改进遗传算法的搜索性能。 相似文献
88.
To deal with the planarization problem widely used in many applications including routing very-large-scale integration (VLSI) circuits, this paper points out that only when its vertices are arranged in some specific order in a line can a planar graph be embedded on a line without any cross connections or cross edges. Energy function is proposed to meet the need of embedding a graph on a single line and route it correctly. A Hopfield network is designed according to the proposed energy function for such embedding and routing. The advantage of the proposed method is that it not only can detect if a graph is a planar one or not, but also can embed a planar graph or the maximal planar subgraph of a non-planar graph on a single line. In addition, simulated annealing is employed for helping the network to escape from local minima during the running of the Hopfield network. Experiments of the proposed method and its comparison with some existent conventional methods were performed and the results indicate that the proposed method is of great feasibility and effectiveness especially for the planarization problem of large graphs. 相似文献
89.
A new criterion of delay-dependent asymptotic stability for Hopfield neural networks with time delay. 总被引:1,自引:0,他引:1
Shaoshuai Mou Huijun Gao James Lam Wenyi Qiang 《Neural Networks, IEEE Transactions on》2008,19(3):532-535
In this brief, the problem of global asymptotic stability for delayed Hopfield neural networks (HNNs) is investigated. A new criterion of asymptotic stability is derived by introducing a new kind of Lyapunov-Krasovskii functional and is formulated in terms of a linear matrix inequality (LMI), which can be readily solved via standard software. This new criterion based on a delay fractioning approach proves to be much less conservative and the conservatism could be notably reduced by thinning the delay fractioning. An example is provided to show the effectiveness and the advantage of the proposed result. 相似文献