全文获取类型
收费全文 | 19930篇 |
免费 | 2579篇 |
国内免费 | 1814篇 |
专业分类
电工技术 | 3264篇 |
技术理论 | 4篇 |
综合类 | 2871篇 |
化学工业 | 1025篇 |
金属工艺 | 488篇 |
机械仪表 | 1134篇 |
建筑科学 | 2717篇 |
矿业工程 | 675篇 |
能源动力 | 894篇 |
轻工业 | 686篇 |
水利工程 | 632篇 |
石油天然气 | 628篇 |
武器工业 | 335篇 |
无线电 | 1640篇 |
一般工业技术 | 1621篇 |
冶金工业 | 674篇 |
原子能技术 | 106篇 |
自动化技术 | 4929篇 |
出版年
2024年 | 177篇 |
2023年 | 429篇 |
2022年 | 673篇 |
2021年 | 861篇 |
2020年 | 868篇 |
2019年 | 672篇 |
2018年 | 620篇 |
2017年 | 780篇 |
2016年 | 829篇 |
2015年 | 934篇 |
2014年 | 1565篇 |
2013年 | 1297篇 |
2012年 | 1629篇 |
2011年 | 1579篇 |
2010年 | 1298篇 |
2009年 | 1263篇 |
2008年 | 1218篇 |
2007年 | 1309篇 |
2006年 | 1259篇 |
2005年 | 1014篇 |
2004年 | 826篇 |
2003年 | 677篇 |
2002年 | 540篇 |
2001年 | 437篇 |
2000年 | 382篇 |
1999年 | 243篇 |
1998年 | 175篇 |
1997年 | 142篇 |
1996年 | 129篇 |
1995年 | 105篇 |
1994年 | 94篇 |
1993年 | 55篇 |
1992年 | 53篇 |
1991年 | 35篇 |
1990年 | 35篇 |
1989年 | 30篇 |
1988年 | 13篇 |
1987年 | 13篇 |
1986年 | 6篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 5篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1977年 | 4篇 |
1975年 | 3篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1964年 | 2篇 |
1962年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Against the background of smart manufacturing and Industry 4.0, how to achieve real-time scheduling has become a problem to be solved. In this regard, automatic design for shop scheduling based on hyper-heuristics has been widely studied, and a number of reviews and scheduling algorithms have been presented. Few studies, however, have specifically discussed the technical points involved in algorithm development. This study, therefore, constructs a general framework for automatic design for shop scheduling strategies based on hyper-heuristics, and various state-of-the-art technical points in the development process are summarized. First, we summarize the existing types of shop scheduling strategies and classify them using a new classification method. Second, we summarize an automatic design algorithm for shop scheduling. Then, we investigate surrogate-assisted methods that are popular in the current algorithm field. Finally, current problems and challenges are discussed, and potential directions for future research are proposed. 相似文献
2.
3.
《International Journal of Hydrogen Energy》2020,45(38):19720-19732
The need to reduce PEMFC systems cost as well as to increase their durability is crucial for their integration in various applications and especially for transport applications. A new simplified architecture of the anode circuit called Alternating Fuel Feeding (AFF) offers to reduce the development costs. Requiring a new stack concept, it combines the simplicity of Dead-End Anode (DEA) with the operation advantages of the hydrogen recirculation. The three architectures (DEA, recirculation and AFF) are compared in terms of performance on a 5-kW test bench in automotive conditions, through a sensitivity analysis. A gain of 17% on the system efficiency is observed when switching from DEA to AFF. Moreover, similar performances are obtained both for AFF and for recirculation after an accurate optimization of the AFF tuning parameters. Based on DoE data, a gain of 25% on the weight of the anodic line has been identified compared to pulsed ejector architecture and 43% with the classic recirculation architecture with blower only (Miraï). 相似文献
4.
本文对运营商信息安全集中管控架构演进和信息安全管控策略面临的问题进行了深入分析,提出了信息安全集中管控架构的演进方向建议及对信息安全监控策略工作优化的若干意见。 相似文献
5.
Self-adaptive surface measurements that can reduce data redundancy and improve time efficiency are in high demand in many fields of science and technology. For this purpose, a system implemented with Gaussian process (GP) adaptive sampling is developed. The non-parametric GP model is applied to reconstruct the topography and guide the subsequent sampling position, which is determined from the inference uncertainty estimation. A criterion is proposed to terminate the GP adaptive measurement automatically without any prior model or data of the topography. Experiments on typical surfaces validate the intelligence, adaptability, and high accuracy of the GP method along with the stabilization of the automatic iteration termination. Compared with traditional raster sampling, data redundancy is reduced and the time efficiency is improved without sacrificing the surface reconstruction accuracy. The proposed method can be implemented in other systems with similar measurement principles, thus benefitting surface characterizations. 相似文献
6.
我国的军工科研所成立于上世纪,它以军工项目的科研、预研为主,为我国的国防军工提供研发产品。伴随着我国经济实力的增强和科技军事力量的增长,军工科研院所也转变了原有的工业专属性质,走上了军民两用、寓军于民的道路,并在时代的进步中成为了我国先进装备制造业的重要科研力量和科技创新支柱。凸现军事工业“高、精、尖”的特点,以项目管理的优化为具体策略进行军工科研开发工作。 相似文献
7.
8.
This paper proposes the application of Covariance Matrix Adaptation Evolution Strategy (CMA-ES) in fixed structure H∞ loop shaping controller design. Integral Time Absolute Error (ITAE) performance requirement is incorporated as a constraint with an objective of maximization of stability margin in the fixed structure H∞ loop shaping controller design problem. Pneumatic servo system, separating tower process and F18 fighter aircraft system are considered as test systems. The CMA-ES designed fixed structure H∞ loop-shaping controller is compared with the traditional H∞ loop shaping controller, non-smooth optimization and Heuristic Kalman Algorithm (HKA) based fixed structure H∞ loop shaping controllers in terms of stability margin. 20% perturbation in the nominal plant is used to validate the robustness of the CMA-ES designed H∞ loop shaping controller. The effect of Finite Word Length (FWL) is considered to show the implementation difficulties of controller in digital processors. Simulation results demonstrated that CMA-ES based fixed structure H∞ loop shaping controller is suitable for real time implementation with good robust stability and performance. 相似文献
9.
《International Journal of Project Management》2020,38(7):429-440
Agile practices become increasingly popular for projects and project portfolios offering firms a higher flexibility to adapt to dynamic environments. This study investigates the antecedents and consequences of agile practices' relevance for strategy formulation in project portfolio management processes. Building on complex adaptive systems theory, we hypothesize a positive relationship between agile capabilities and emerging strategy initiatives and eventually portfolio success. Agile capabilities refer to both the project portfolio organization's intensity of and competence in applying agile practices. Using a sample of 135 portfolios and multiple informants for each portfolio, the results support entrepreneurial orientation and voice behavior as antecedents for agile capabilities. Furthermore, the findings support an agile portfolio's positive relationship with emergence recognition and overall portfolio success. The findings contribute to the literature by identifying two significant antecedents of agile capabilities as well as empirically demonstrating the positive relationship between agile portfolios and emerging strategy recognition. For practitioners, the study encourages the application of agile practices by stressing the general positive influence of agile capabilities and underlines entrepreneurial orientation and voice behavior as important methods of empowerment for agile portfolio processes. 相似文献
10.
Central force optimization (CFO) is an efficient and powerful population-based intelligence algorithm for optimization problems. CFO is deterministic in nature, unlike the most widely used metaheuristics. CFO, however, is not completely free from the problems of premature convergence. One way to overcome local optimality is to utilize the multi-start strategy. By combining the respective advantages of CFO and the multi-start strategy, a multi-start central force optimization (MCFO) algorithm is proposed in this paper. The performance of the MCFO approach is evaluated on a comprehensive set of benchmark functions. The experimental results demonstrate that MCFO not only saves the computational cost, but also performs better than some state-of-the-art CFO algorithms. MCFO is also compared with representative evolutionary algorithms. The results show that MCFO is highly competitive, achieving promising performance. 相似文献