全文获取类型
收费全文 | 218335篇 |
免费 | 18418篇 |
国内免费 | 12300篇 |
专业分类
电工技术 | 34381篇 |
技术理论 | 22篇 |
综合类 | 25026篇 |
化学工业 | 10543篇 |
金属工艺 | 7481篇 |
机械仪表 | 18508篇 |
建筑科学 | 18767篇 |
矿业工程 | 8874篇 |
能源动力 | 8108篇 |
轻工业 | 4692篇 |
水利工程 | 6463篇 |
石油天然气 | 6578篇 |
武器工业 | 4003篇 |
无线电 | 21751篇 |
一般工业技术 | 11275篇 |
冶金工业 | 6701篇 |
原子能技术 | 2293篇 |
自动化技术 | 53587篇 |
出版年
2024年 | 296篇 |
2023年 | 1874篇 |
2022年 | 3616篇 |
2021年 | 4870篇 |
2020年 | 5202篇 |
2019年 | 3789篇 |
2018年 | 3501篇 |
2017年 | 5014篇 |
2016年 | 6046篇 |
2015年 | 7121篇 |
2014年 | 13747篇 |
2013年 | 11620篇 |
2012年 | 16209篇 |
2011年 | 17234篇 |
2010年 | 13057篇 |
2009年 | 13141篇 |
2008年 | 13482篇 |
2007年 | 17245篇 |
2006年 | 15526篇 |
2005年 | 13868篇 |
2004年 | 11365篇 |
2003年 | 10257篇 |
2002年 | 7787篇 |
2001年 | 6510篇 |
2000年 | 5341篇 |
1999年 | 4308篇 |
1998年 | 3201篇 |
1997年 | 2579篇 |
1996年 | 2325篇 |
1995年 | 1999篇 |
1994年 | 1658篇 |
1993年 | 1125篇 |
1992年 | 945篇 |
1991年 | 691篇 |
1990年 | 564篇 |
1989年 | 465篇 |
1988年 | 330篇 |
1987年 | 193篇 |
1986年 | 127篇 |
1985年 | 129篇 |
1984年 | 113篇 |
1983年 | 92篇 |
1982年 | 76篇 |
1981年 | 69篇 |
1980年 | 52篇 |
1979年 | 49篇 |
1978年 | 34篇 |
1977年 | 32篇 |
1976年 | 25篇 |
1959年 | 22篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
We define the emerging research field of applied data science as the knowledge discovery process in which analytic systems are designed and evaluated to improve the daily practices of domain experts. We investigate adaptive analytic systems as a novel research perspective of the three intertwining aspects within the knowledge discovery process in healthcare: domain and data understanding for physician- and patient-centric healthcare, data preprocessing and modelling using natural language processing and (big) data analytic techniques, and model evaluation and knowledge deployment through information infrastructures. We align these knowledge discovery aspects with the design science research steps of problem investigation, treatment design, and treatment validation, respectively. We note that the adaptive component in healthcare system prototypes may translate to data-driven personalisation aspects including personalised medicine. We explore how applied data science for patient-centric healthcare can thus empower physicians and patients to more effectively and efficiently improve healthcare. We propose meta-algorithmic modelling as a solution-oriented design science research framework in alignment with the knowledge discovery process to address the three key dilemmas in the emerging “post-algorithmic era” of data science: depth versus breadth, selection versus configuration, and accuracy versus transparency. 相似文献
62.
63.
Gerardo Valadez Huerta Johanan Álvarez Jordán Michael Dragon Keno Leites Stephan Kabelac 《International Journal of Hydrogen Energy》2018,43(34):16684-16693
Solid oxide fuel cell (SOFC) systems with anode off-gas recirculation (AGR) and diesel pre-reforming are advantageous because they can operate with the current fuel infrastructure. In the SchIBZ-project, the prototype of such a SOFC system for maritime applications has already been commissioned. In this first paper, we model the system devices to conduct an exergy analysis of this real SOFC plant and validate them with experimental values from experiments in laboratory scale. The results of our simulation agree well with the experimental values. The calculations with the validated results may be closer to the real thermodynamic behavior of such system components than previous literature. 相似文献
64.
AbstractIn recent years, to prevent accidents and disaster are desired by implementing maintenance and management of facilities, such as conducting periodic inspections with appropriate frequency at plants. However, because the dangerous materials such as flammable gas and explosives is used in a plant, and there are many dangerous places in a plant such as high-temperature environment and high places and narrow spaces, it is desirable to use a remote-controlled robot for safety work and short inspections. Against this background, the Disaster Robotics Category-Plant Disaster Prevention Challenge was held in Japan at the World Robot Summit 2018. Our team was ranked 3rd in this competition, because our strategy of ‘inspection and investigation in cooperation with UGV and UAV’ was effective. In this paper, the competition contents of World Robot Summit 2018 and the robot inspection system that we are studying are explained. And what kind of strategy was challenged and result for these given competition tasks by using our robot system are introduced. And the lessons learned such as advantages and issues in UGV and UAV collaboration work at this competition are described for evaluate a robot investigation system for disaster response and inspection work at plants. 相似文献
65.
66.
基于微电子机械系统(MEMS)工艺,提出一种多层圆片堆叠的THz硅微波导结构及其制作方法。为了验证该结构在制作THz无源器件中的优势,基于6层圆片堆叠的硅微波导结构,设计了一种中心频率365 GHz、带宽80 GHz的功率分配/合成结构,并对其进行了仿真。研究了制作该结构的工艺流程,攻克了工艺过程中的关键技术,包括硅深槽刻蚀技术和多层热压键合技术,并给出了工艺结果。最终实现了多层圆片堆叠功率分配/合成结构的工艺制作和测试。测试结果表明,尽管样品的插入损耗较仿真值增加3 dB左右,考虑到加工误差和夹具损耗等情况,样品主要技术指标与设计值较为一致。 相似文献
67.
This paper proposes an adaptive super-twisting decoupled terminal sliding mode control technique for a class of fourth-order systems. The adaptive-tuning law eliminates the requirement of the knowledge about the upper bounds of external perturbations. Using the proposed control procedure, the state variables of cart-pole system are converged to decoupled terminal sliding surfaces and their equilibrium points in the finite time. Moreover, via the super-twisting algorithm, the chattering phenomenon is avoided without affecting the control performance. The numerical results demonstrate the high stabilization accuracy and lower performance indices values of the suggested method over the other ones. The simulation results on the cart-pole system as well as experimental validations demonstrate that the proposed control technique exhibits a reasonable performance in comparison with the other methods. 相似文献
68.
Water hyacinth was the chosen alternative biomass for H2 production in this study. A batch and a continuous pilot plant systems are proposed. A batch system of 500?ml capacity was developed first for finding an appropriate biomass ratio which was found to be 2.5%wt. Results from the batch system was used to construct a kinetic model of water hyacinth hydrolysis. The same biomass and water ratio was used in the continuous system. Besides water hyacinth, glucose and cellulose?+?lignin biomasses were tested. During processing, temperature, pressure, and electric consumption of the system were recorded. The quality and quantity of gas products were analyzed by gas chromatography (GC). The water hyacinth biomass attained the highest rate of H2 production (providing energy of 11.43?kWh/mole of glucose). Comparing the batch and continuous pilot systems, the continuous system achieved 2.7 times more H2 mole% than the batch system did. 相似文献
69.
通过对磷酸二铵生产造粒特性分析,高压中速磨粉机原理分析,结合实践生产中的工艺需求,利用高压中速磨粉系统将颗粒状不合格品磨成细粉后添加进系统重新喷浆造粒,提高返料添加量,减少不合格品的产生,腾空仓库有限货位,以获取更大的经济价值。 相似文献
70.
This paper elucidates Common Mode Voltage (CMV) reduction in transformerless 3-phase 3-level Coupled Inductor Neutral Point (CI-NPC) Clamped Inverter with Hybrid Energy System. The three dimensional Space Vector Pulse Width Modulation (3D-SVPWM) with Nearest State Vector (NSV) is implemented to reduce the CMV by proper selection of medium, large and small vectors in 3D cubic space region. This NSV scheme in addition to CMV reduction, reduces the capacitor voltage balancing issues and minimizes switching losses. The proposed control provides full utilization of dc link voltage with reduced harmonics. This 3-level CI-NPC inverter is energized by hybrid energy source which includes photovoltaic system and wind energy system. The results obtained for the proposed scheme through simulation and experimental setup is compared with the conventional 2D-SVPWM and 3D-SVPWM scheme. From the compared results it is evident that the proposed scheme reduces CMV to a larger extent than 2D and 3D-SVPWM control. The simulation and experimental results are verified using matlab-simulink and FPGA-Spartan-6 controller respectively. 相似文献