全文获取类型
收费全文 | 4879篇 |
免费 | 463篇 |
国内免费 | 172篇 |
专业分类
电工技术 | 2156篇 |
综合类 | 368篇 |
化学工业 | 229篇 |
金属工艺 | 54篇 |
机械仪表 | 173篇 |
建筑科学 | 282篇 |
矿业工程 | 160篇 |
能源动力 | 307篇 |
轻工业 | 64篇 |
水利工程 | 491篇 |
石油天然气 | 141篇 |
武器工业 | 16篇 |
无线电 | 169篇 |
一般工业技术 | 253篇 |
冶金工业 | 105篇 |
原子能技术 | 21篇 |
自动化技术 | 525篇 |
出版年
2024年 | 20篇 |
2023年 | 68篇 |
2022年 | 105篇 |
2021年 | 141篇 |
2020年 | 139篇 |
2019年 | 146篇 |
2018年 | 99篇 |
2017年 | 132篇 |
2016年 | 141篇 |
2015年 | 217篇 |
2014年 | 357篇 |
2013年 | 290篇 |
2012年 | 452篇 |
2011年 | 415篇 |
2010年 | 294篇 |
2009年 | 324篇 |
2008年 | 244篇 |
2007年 | 322篇 |
2006年 | 238篇 |
2005年 | 240篇 |
2004年 | 214篇 |
2003年 | 162篇 |
2002年 | 138篇 |
2001年 | 126篇 |
2000年 | 104篇 |
1999年 | 67篇 |
1998年 | 48篇 |
1997年 | 63篇 |
1996年 | 36篇 |
1995年 | 35篇 |
1994年 | 21篇 |
1993年 | 16篇 |
1992年 | 18篇 |
1991年 | 11篇 |
1990年 | 15篇 |
1989年 | 9篇 |
1988年 | 12篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 7篇 |
1984年 | 8篇 |
1983年 | 2篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1973年 | 1篇 |
1963年 | 1篇 |
1962年 | 1篇 |
1961年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有5514条查询结果,搜索用时 31 毫秒
1.
Yan He Kangren Kong Zhengxi Guo Weifeng Fang Zaiqiang Ma Haihua Pan Ruikang Tang Zhaoming Liu 《Advanced functional materials》2021,31(26):2101291
Sensitivity and multi-directional motivation are major two factors for developing optimized humidity-response materials, which are promising for sensing, energy production, etc. Organic functional groups are commonly used as the water sensitive units through hydrogen bond interactions with water molecules in actuators. The multi-coordination ability of inorganic ions implies that the inorganic ionic compounds are potentially superior water sensitive units. However, the particle forms of inorganic ionic compounds produced by classical nucleation limit the number of exposed ions to interact with water. Recent progress on the inorganic ionic oligomers has broken through the limitation of classical nucleation, and realized the molecular-scaled incorporation of inorganic ionic compounds into an organic matrix. Here, the incorporation of hydrophilic calcium carbonate ionic oligomers into hydrophobic poly(vinylidene fluoride) (PVDF) is demonstrated. The ultra-small calcium carbonate oligomers within a PVDF film endow it with an ultra-sensitive, reversible, and bidirectional response. The motivation ability is superior to other bidirectional humidity-actuators at present, which realizes self-motivation on an ice surface, converting the chemical potential energy of the humidity gradient from ice to kinetic energy. 相似文献
2.
High dimensionality in real-world multi-reservoir systems greatly hinders the application and popularity of evolutionary algorithms, especially for systems with heterogeneous units. An efficient hierarchical optimization framework is presented for search space reduction, determining the best water distributions, not only between cascade reservoirs, but also among different types of hydropower units. The framework is applied to the Three Gorges Project (TGP) system and the results demonstrate that the difficulties of multi-reservoir optimization caused by high dimensionality can be effectively solved by the proposed hierarchical method. For the day studied, power output could be increased by 6.79 GWh using an optimal decision with the same amount of water actually used; while the same amount of power could be generated with 2.59 × 107 m3 less water compared to the historical policy. The methodology proposed is general in that it can be used for other reservoir systems and other types of heterogeneous unit generators. 相似文献
3.
Crashworthiness simulation system is one of the key computer-aided engineering (CAE) tools for the automobile industry and implies two potential conflicting requirements: accuracy and efficiency. A parallel crashworthiness simulation system based on graphics processing unit (GPU) architecture and the explicit finite element (FE) method is developed in this work. Implementation details with compute unified device architecture (CUDA) are considered. The entire parallel simulation system involves a parallel hierarchy-territory contact-searching algorithm (HITA) and a parallel penalty contact force calculation algorithm. Three basic GPU-based parallel strategies are suggested to meet the natural parallelism of the explicit FE algorithm. Two free GPU-based numerical calculation libraries, cuBLAS and Thrust, are introduced to decrease the difficulty of programming. Furthermore, a mixed array and a thread map to element strategy are proposed to improve the performance of the test pairs searching. The outer loop of the nested loop through the mixed array is unrolled to realize parallel searching. An efficient storage strategy based on data sorting is presented to realize data transfer between different hierarchies with coalesced access during the contact pairs searching. A thread map to element pattern is implemented to calculate the penetrations and the penetration forces; a double float atomic operation is used to scatter contact forces. The simulation results of the three different models based on the Intel Core i7-930 and the NVIDIA GeForce GTX 580 demonstrate the precision and efficiency of this developed parallel crashworthiness simulation system. 相似文献
4.
The objective of this paper is to review and document the mine fleet management systems’ models and algorithms. The purpose is to understand the algorithms behind the fleet management systems and the proposed academic solutions in this area to identify any gaps in the current literature and to open up opportunities to establish research questions that need to be addressed in an integrated simulation and optimisation operational planning research framework. In this paper, we review industrial fleet management systems and the main academic algorithms behind such systems. The fleet management systems are divided into three subsequently related problems to review: shortest path, production optimisation and real-time dispatching. Finally, the limitations of current algorithms for fleet management systems are documented in terms of mining practice feasibility and optimality of the solution on large-scale problems. The results of this literature review enable us to evaluate the logical links between major components of an integrated simulation and optimisation operational planning framework with current theory of fleet management systems. 相似文献
5.
通过分析石化装置施工过程中常见的现象,分析产生由这些现象加重腐蚀的原因和机理, 指出应加强施工过程中的控制,而达到预期的防腐蚀效果,消除腐蚀隐患。 相似文献
6.
7.
8.
文章介绍了几种缝纫设备输送动力装置的送布原理,认为应针对不同的面料特性及经制工艺要求,选用合适的设备输送系统。 相似文献
9.
一种新型智能光纤传感器的研制与应用 总被引:5,自引:2,他引:3
光纤传感技术是一种新型的传感技术,目前已受到国内外广泛重视而得到高速发展。光纤液位变送器具有高精度、高可靠性,不受电磁干扰等优点,特别是在防爆要求非常高的油气集输领域,它的无电检测、光信号传输完全消除了不安全的因素,为易燃易爆场所提供了安全可靠的检测仪器。 相似文献
10.
金沙江防洪(库容)规划的探讨 总被引:1,自引:0,他引:1
在分析长江灾害洪水特征的基础上,全面深入地研究了全沙江水库的防洪库客、防洪目标、防洪特点和调度原则,并对防洪库容的作用进行了估算和分析。从多方面比较了虎跳峡高坝方案与低坝方案,结果表明:高坝方案的效益明显高于低坝方案,而两者所需付出的代价相差不大。 相似文献