全文获取类型
收费全文 | 271195篇 |
免费 | 25406篇 |
国内免费 | 17507篇 |
专业分类
电工技术 | 38574篇 |
技术理论 | 31篇 |
综合类 | 30793篇 |
化学工业 | 11312篇 |
金属工艺 | 8180篇 |
机械仪表 | 21944篇 |
建筑科学 | 20611篇 |
矿业工程 | 10218篇 |
能源动力 | 8776篇 |
轻工业 | 5337篇 |
水利工程 | 7617篇 |
石油天然气 | 9491篇 |
武器工业 | 4616篇 |
无线电 | 30275篇 |
一般工业技术 | 13976篇 |
冶金工业 | 7676篇 |
原子能技术 | 3017篇 |
自动化技术 | 81664篇 |
出版年
2024年 | 414篇 |
2023年 | 2591篇 |
2022年 | 5101篇 |
2021年 | 6744篇 |
2020年 | 7217篇 |
2019年 | 5356篇 |
2018年 | 4912篇 |
2017年 | 6778篇 |
2016年 | 8013篇 |
2015年 | 9430篇 |
2014年 | 17427篇 |
2013年 | 14921篇 |
2012年 | 20225篇 |
2011年 | 21462篇 |
2010年 | 16423篇 |
2009年 | 16337篇 |
2008年 | 17153篇 |
2007年 | 21341篇 |
2006年 | 18953篇 |
2005年 | 17038篇 |
2004年 | 14070篇 |
2003年 | 12533篇 |
2002年 | 9524篇 |
2001年 | 7837篇 |
2000年 | 6449篇 |
1999年 | 5137篇 |
1998年 | 3850篇 |
1997年 | 3139篇 |
1996年 | 2755篇 |
1995年 | 2406篇 |
1994年 | 1989篇 |
1993年 | 1353篇 |
1992年 | 1094篇 |
1991年 | 841篇 |
1990年 | 678篇 |
1989年 | 562篇 |
1988年 | 405篇 |
1987年 | 249篇 |
1986年 | 174篇 |
1985年 | 210篇 |
1984年 | 158篇 |
1983年 | 162篇 |
1982年 | 131篇 |
1981年 | 99篇 |
1980年 | 72篇 |
1979年 | 76篇 |
1978年 | 45篇 |
1977年 | 48篇 |
1976年 | 33篇 |
1959年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
针对目标估计过程需要大量人工参与、自动化程度低的问题,提出了基于数据质量评价的目标估计方法。利用目标数据质量评价方法,对不同传感器得到的目标数据质量进行科学、有效的测度和评价,并根据质量得分动态调整各数据源在目标估计过程中所占的权重,从而减少人工干预,提高目标估计效能。仿真试验结果证明了该方法的有效性。 相似文献
2.
3.
4.
《International Journal of Hydrogen Energy》2022,47(62):26435-26457
In this study, some locations with different climates, off-grid zero energy buildings with hydrogen energy storage systems are designed, and transient analysis is conducted. These considered buildings supply their electricity consumption without using the electrical grid and PV panels or wind turbines. Also, they supply thermal comfort to occupants by using a vapor compression chiller and humidifier. Domestic hot water of occupants is supplied using solar collectors. For analyzing building's performance and objectives achievement, TRNSYS software is used. Also, for evaluating occupant thermal comfort, the Fanger model is used. The considered building is a one-story building with a 150 m2 area. Four occupants are considered. Both of them are seated at rest, and another is seated with light working such as typing. Using the Fanger model equation and MATLAB software, the thermal comfort of occupants is determined. For domestic hot water consumption, verified profiles that vary during 24 h of the day are considered. Achieved results show that for humid and cold cities, PV panels with an area of 73 and 76 m2 can be supplied the required electricity of considered building with four occupants and battery state of charge is higher than 50% and 10%, respectively. Moreover, with a suitable air conditioner system, the predicted percentage of dissatisfied (PPD) can be lower than 12% and 8% for humid and cold cities. Therefore, the building can be converted to a zero-energy building using its rooftop area. 相似文献
5.
《International Journal of Hydrogen Energy》2022,47(67):29172-29183
To improve the safety of wet dust removal systems for processing magnesium-based alloys, a new method is proposed for preventing hydrogen generation. In this paper, hydrogen generation by Mg–Zn alloy dust was inhibited with six common metal corrosion inhibitors. The results showed that sodium dodecylbenzene sulfonate was the best hydrogen inhibitor, while CeCl3 enhanced hydrogen precipitation. The film-forming stability of sodium dodecylbenzene sulfonate was tested with different contents, temperatures, Cl? concentrations and perturbation rates. The results showed that this inhibitor formed stable protective films on the surfaces of Mg–Zn alloy particles, and adsorption followed the Langmuir adsorption model. 相似文献
6.
《International Journal of Hydrogen Energy》2022,47(94):39931-39942
A dual-coolant integrated experimental facility named DRAGON-V has been developed at the Institute of Nuclear Energy Safety Technology, Hefei Institute of Physical Science, Chinese Academy of Sciences, for the key technology research and performance evaluation of candidate liquid lithium-lead (PbLi) blanket of hydrogen fusion reactors. The loop is composed of a material test sub-loop and thermal-hydraulic test sub-loop, the design parameters are PbLi inventory 20 tons, PbLi temperature up to 550 °C, the maximum PbLi flow rate up to 40 kg/s. A novel cold trap system is designed to remove the suspended and crystalized impurities in PbLi fluid with three cooling zones and cross row arrangement of rod bundle filter elements. The paper describes the loop itself and its major components, initial loop testing, flow and measurement diagnostics and current experiments. The obtained test results of the loop and its components have demonstrated that the new facility is fully functioning and ready for experimental studies of material corrosion with/without a magnetic field, magnetohydrodynamic (MHD) effect, purification, heat and mass transfer phenomena in PbLi flows and can also be used in mock-up testing in conditions relevant to fusion applications. 相似文献
7.
In the present work, the heating performance of a new system combined with a new modified baseboard radiator and fan coil is investigated. Using longitudinal fins with special geometry and also forced airflow at the end of the system causes that at the lower inlet water temperature compared with the conventional models, higher heat output rate be obtained. The heat output rate of the new modified system is obtained by experimental metrology based on the European Standard No. EN-442. Temperature and velocity distribution in the room space is done by simulation of the modified system in the Flovent software. Computational fluid dynamics (CFD) results are validated against experimental results and there is a good agreement between them. Also, the energy consumption of the system during the winter season is calculated in TRANSYS software. Experimental results show that the heat output rate of a new modified heating system with inlet water temperature in the range of 45–55°C is on average 4.17 times higher compared with the conventional model. CFD simulation also showed that the combined system provides good thermal comfort conditions. Energy consumption of the new system reduced about 13% compared with conventional models. 相似文献
8.
In the present paper, therapeutic treatment of infected tumorous cells has been studied through mathematical modeling and simulation of heat transfer in tissues by using a nonlinear dual-phase lag bioheat transfer model with Dirichlet boundary condition. The components of volumetric heat source in this model such as blood perfusion and metabolism are assumed experimentally validated temperature-dependent function, which gives more accurate temperature distribution in tissues through this model. We have used the finite difference and RK (4, 5) techniques of numerical methods to solve the proposed problem and obtained the exact solution in a particular case. After comparison, we got a good agreement between them. We have used dimensionless quantities throughout this paper. The effect of relaxation and thermalization time with respect to dimensionless temperature distribution has been analyzed in the treatment process. 相似文献
9.
针对目前气象数据存储所面临的海量扩张、高并发读写、结构化和非结构化数据并存以及长时间序列和大数据集检索效率低下等问题,提出了以Hadoop开源框架为基础的气象数据分布式存储方案。通过对气象数据自身属性和特点进行分析,得出了气象数据在经过充分优化的基础上,在分布式存储框架中具有很强的适应性和规模化应用的潜力;并在HBase数据库中的Row Key设计和小文件合并策略方面做了创新。最后针对气象数据中广泛存在的结构化和非结构化这两种主要数据类型,以自动气象站数据和雷达产品数据为具体实例,给出了详细的设计思路和实现方法。 相似文献
10.