全文获取类型
| 收费全文 | 32801篇 |
| 免费 | 2264篇 |
| 国内免费 | 713篇 |
专业分类
| 电工技术 | 1597篇 |
| 技术理论 | 3篇 |
| 综合类 | 1746篇 |
| 化学工业 | 5435篇 |
| 金属工艺 | 2022篇 |
| 机械仪表 | 2140篇 |
| 建筑科学 | 2420篇 |
| 矿业工程 | 1016篇 |
| 能源动力 | 895篇 |
| 轻工业 | 1908篇 |
| 水利工程 | 554篇 |
| 石油天然气 | 2111篇 |
| 武器工业 | 221篇 |
| 无线电 | 3568篇 |
| 一般工业技术 | 4103篇 |
| 冶金工业 | 1658篇 |
| 原子能技术 | 428篇 |
| 自动化技术 | 3953篇 |
出版年
| 2025年 | 54篇 |
| 2024年 | 805篇 |
| 2023年 | 716篇 |
| 2022年 | 978篇 |
| 2021年 | 1397篇 |
| 2020年 | 1293篇 |
| 2019年 | 998篇 |
| 2018年 | 1045篇 |
| 2017年 | 1042篇 |
| 2016年 | 1036篇 |
| 2015年 | 1240篇 |
| 2014年 | 1523篇 |
| 2013年 | 1814篇 |
| 2012年 | 1903篇 |
| 2011年 | 1928篇 |
| 2010年 | 1735篇 |
| 2009年 | 1699篇 |
| 2008年 | 1574篇 |
| 2007年 | 1564篇 |
| 2006年 | 1654篇 |
| 2005年 | 1372篇 |
| 2004年 | 880篇 |
| 2003年 | 839篇 |
| 2002年 | 750篇 |
| 2001年 | 619篇 |
| 2000年 | 667篇 |
| 1999年 | 808篇 |
| 1998年 | 697篇 |
| 1997年 | 629篇 |
| 1996年 | 555篇 |
| 1995年 | 458篇 |
| 1994年 | 354篇 |
| 1993年 | 267篇 |
| 1992年 | 200篇 |
| 1991年 | 162篇 |
| 1990年 | 117篇 |
| 1989年 | 104篇 |
| 1988年 | 82篇 |
| 1987年 | 55篇 |
| 1986年 | 49篇 |
| 1985年 | 24篇 |
| 1984年 | 25篇 |
| 1983年 | 17篇 |
| 1982年 | 21篇 |
| 1981年 | 13篇 |
| 1980年 | 8篇 |
| 1966年 | 1篇 |
| 1964年 | 1篇 |
| 1954年 | 1篇 |
| 1953年 | 4篇 |
排序方式： 共有10000条查询结果，搜索用时 0 毫秒
991.
Bin Cao Hao Xu Lei Zhang Muhammad Imran Oluwakayode Onireti Paulo Valente Klaine 《Digital Communications & Networks》2020,6(3):261-269
The sixth-generation (6G) network must provide better performance than previous generations to meet the requirements of emerging services and applications, such as multi-gigabit transmission rate, higher reliability, and sub-1 ms latency and ubiquitous connection for the Internet of Everything (IoE). However, with the scarcity of spectrum resources, efficient resource management and sharing are crucial to achieving all these ambitious requirements. One possible technology to achieve all this is the blockchain. Because of its inherent properties, the blockchain has recently gained an important position, which is of great significance to the 6G network and other networks. In particular, the integration of the blockchain in 6G will enable the network to monitor and manage resource utilization and sharing efficiently. Hence, in this paper, we discuss the potentials of the blockchain for resource management and sharing in 6G using multiple application scenarios, namely, Internet of things, device-to-device communications, network slicing, and inter-domain blockchain ecosystems. 相似文献
992.
Jienan Chen Siyu Chen Siyu Luo Qi Wang Bin Cao Xiaoqian Li 《Digital Communications & Networks》2020,6(4):433-443
Unmanned Aerial Vehicle (UAV) has emerged as a promising technology for the support of human activities, such as target tracking, disaster rescue, and surveillance. However, these tasks require a large computation load of image or video processing, which imposes enormous pressure on the UAV computation platform. To solve this issue, in this work, we propose an intelligent Task Offloading Algorithm (iTOA) for UAV edge computing network. Compared with existing methods, iTOA is able to perceive the network’s environment intelligently to decide the offloading action based on deep Monte Calor Tree Search (MCTS), the core algorithm of Alpha Go. MCTS will simulate the offloading decision trajectories to acquire the best decision by maximizing the reward, such as lowest latency or power consumption. To accelerate the search convergence of MCTS, we also proposed a splitting Deep Neural Network (sDNN) to supply the prior probability for MCTS. The sDNN is trained by a self-supervised learning manager. Here, the training data set is obtained from iTOA itself as its own teacher. Compared with game theory and greedy search-based methods, the proposed iTOA improves service latency performance by 33% and 60%, respectively. 相似文献
993.
Houyi Cheng Jingle Chen Shouzhong Peng Boyu Zhang Zilu Wang Daoqian Zhu Kewen Shi Sylvain Eimer Xinran Wang Zongxia Guo Yong Xu Danrong Xiong Kaihua Cao Weisheng Zhao 《Advanced Electronic Materials》2020,6(8)
A strong perpendicular magnetic anisotropy (PMA) and a high thermal stability are essential for long‐term stable storage of data in PMA‐based magnetic tunnel junctions (p‐MTJs). This work investigates the magnetic anisotropy of the MgO/CoFeB/X/CoFeB/MgO double‐interface free layer stacks, where X represents the spacer material. After annealing at 350 °C for an hour, interfacial magnetic anisotropy (Ki) as high as 4.06 mJ m−2 is obtained in the MgO/CoFeB/Mo (0.4 nm)/CoFeB/MgO stacks, much higher than those for Ta‐ and W‐based films. Experimental and first‐principle calculation results demonstrate that bulk PMA plays a great role in the Mo‐based structure, which is often negligible in Ta‐ and W‐based structures. Moreover, a strong PMA is achieved after annealing at 500 °C, which is attributed to the weak interdiffusion and good uniformity as shown in high‐resolution transmission electron microscopy and energy‐dispersive X‐ray spectroscopy results. These findings help to understand the origin of strong PMA in Mo‐based structures and show the promising prospect of using this structure for high‐packing‐density p‐MTJs and other spintronic device applications down to 10 nm scale. 相似文献
994.
Shirui Pu Jia Fu Yutian Liao Lurong Ge Yihao Zhou Songlin Zhang Shenlong Zhao Xiaowei Liu Xuejiao Hu Kang Liu Jun Chen 《Advanced materials (Deerfield Beach, Fla.)》2020,32(17):1907307
High temperature brings adverse impacts on the energy efficiency, and even destroys a semiconductor device. Here, a novel and cost-effective strategy is proposed to boost the energy efficiency of semiconductor devices by using the self-adaptive evaporative cooling of a lithium- and bromine-enriched polyacrylamide hydrogel. Water inside the hydrogel can quickly evaporate to dissipate the waste heat generated by the nugatory carrier transport in the P-N junction. In dormancy, the hydrogel harvests water molecules from the surrounding air to regenerate itself. The hydrogel is demonstrated to low down the operating temperature of a commercial polycrystalline silicon solar cell by 17 °C under one sun condition and enhances its efficiency from 14.5% to 15.5%. It is also capable of increasing the maximum power of a simulated chip by 45% at a fixed operating temperature. The hydrogel is expected to be widely adopted in current semiconductor industry to improve its energy efficiency. 相似文献
995.
Yi Cao Yu Sheng Kevin William Edmonds Yang Ji Houzhi Zheng Kaiyou Wang 《Advanced materials (Deerfield Beach, Fla.)》2020,32(16):1907929
Current-induced magnetization switching by spin–orbit torque (SOT) holds considerable promise for next generation ultralow-power memory and logic applications. In most cases, generation of spin–orbit torques has relied on an external injection of out-of-plane spin currents into the magnetic layer, while an external magnetic field along the electric current direction is generally required for realizing deterministic switching by SOT. Here, deterministic current-induced SOT full magnetization switching by lateral spin–orbit torque in zero external magnetic field is reported. The Pt/Co/Pt magnetic structure is locally annealed by a laser track along the in-plane current direction, resulting in a lateral Pt gradient within the ferromagnetic layer, as confirmed by microstructure and chemical composition analysis. In zero magnetic field, the direction of the deterministic current-induced magnetization switching depends on the location of the laser track, but shows no dependence on the net polarization of external out-of-plane spin currents. From the behavior under external magnetic fields, two independent mechanisms giving rise to SOT are identified, i.e., the lateral Pt–Co asymmetry as well as out-of-plane injected spin currents, where the polarization and the magnitude of the SOT in the former case depends on the relative location and the laser power of the annealing track. 相似文献
996.
Dongmei Xi Ming Xiao Jianfang Cao Luyang Zhao Ning Xu Saran Long Jiangli Fan Kun Shao Wen Sun Xuehai Yan Xiaojun Peng 《Advanced materials (Deerfield Beach, Fla.)》2020,32(11):1907855
Traditional photothermal therapy requires high-intensity laser excitation for cancer treatments due to the low photothermal conversion efficiency (PCE) of photothermal agents (PTAs). PTAs with ultra-high PCEs can decrease the required excited light intensity, which allows safe and efficient therapy in deep tissues. In this work, a PTA is synthesized with high PCE of 88.3% based on a BODIPY scaffold, by introducing a CF3 “barrier-free” rotor on the meso-position (tfm-BDP). In both the ground and excited state, the CF3 moiety in tfm-BDP has no energy barrier to rotation, allowing it to efficiently dissipate absorbed (NIR) photons as heat. Importantly, the barrier-free rotation of CF3 can be maintained after encapsulating tfm-BDP into polymeric nanoparticles (NPs). Thus, laser irradiation with safe intensity (0.3 W cm−2, 808 nm) can lead to complete tumor ablation in tumor-bearing mice after intravenous injection of tfm-BDP NPs. This strategy of “barrier-free rotation” provides a new platform for future design of PTT agents for clinical cancer treatment. 相似文献
997.
Yameng Ren Yiming Cao Dan Zhang Shaik Mohammed Zakeeruddin Anders Hagfeldt Peng Wang Michael Grätzel 《Advanced materials (Deerfield Beach, Fla.)》2020,32(17):2000193
Semitransparent dye-sensitized solar cells (DSCs) are appealing as aesthetically pleasing and colorful see-through photovoltaics. Green semitransparent DSCs have been presented, but the best ones rely on green zinc porphyrin photosensitizers and high volatile electrolytes. For potential outdoor applications, the zinc porphyrin DSCs employing ionic liquid electrolytes merely reached a power conversion efficiency (PCE) of 6.3% even with opaque mesoporous TiO2 films. Herein, the new green DSC is realized by using a blue organic photosensitizer in conjunction with an orange ionic-liquid-based electrolyte, presenting a simple and an effective path for color tuning of photovoltaics. The new approach allows for broadly modulating the color from spring green to cyan by tuning the contributions of the light absorption by the dye-sensitized TiO2 film and the electrolyte layer. The new semitransparent DSCs with spring green to cyan colors have PCEs ranging from 6.7% to 8.1% and show stability for 1000 h under accelerated ageing test at 80 °C, superior to the zinc porphyrin DSCs. The findings pave a new way to achieve efficient and stable colorful solar cells. 相似文献
998.
Kaiying Cao Bing Xu Yi He Qingyun Xu 《International Transactions in Operational Research》2020,27(5):2270-2293
Carbon tax policy is widely adopted by many countries to curb carbon emissions. In the context of carbon tax policy, firms have more incentive to improve carbon reduction levels by reducing their carbon tax costs. However, firms need to bear carbon reduction costs that may cause shortage of capital. Thus, firms may face problems of financial constraints, which may demotivate firms to produce greener products. To address the decision‐making challenges of firms in the contexts of carbon tax policy and financial constraints, we consider a supply chain with a manufacturer who produces green products and a retailer who sells these products. Our study develops five models to investigate the two firms’ optimal wholesale price, carbon reduction level and ordering quantity, according to the manufacturer and retailer with or without financial constraints. Our goal in this study is to explore how carbon tax policy and banks’ interest rates affect the profits of the two firms, supply chain and consumer surplus. Certain managerial insights are obtained as follows. We demonstrate that carbon tax policy and banks’ interest rates demotivate the manufacturer to produce greener products and demotivate the retailer to order more products. If the interest rate to the manufacturer (retailer) is relatively low, then the manufacturer with financial constraint benefits (harms) the consumers compared with the retailer with financial constraint. Importantly, our analysis suggests that carbon tax policy harms the firms but benefits consumers, and the government in some conditions should reduce unit carbon tax. 相似文献
999.
Kaiying Cao Yuqiu Xu Jiajia Cao Bing Xu Jia Wang 《International Transactions in Operational Research》2020,27(6):2878-2898
Considering consumers are increasingly shopping online nowadays and the online sales market is dominated by e‐commerce giants, traditional retailers need to choose whether to enter e‐commerce platforms. Moreover, traditional retailers need to determine whether to offer offline return services considering online return services are very popular. To address these challenges, we explore a retailer's optimal offline return strategy and channel choice of whether or not to enter a platform in the contexts of symmetric information and asymmetric information, respectively. We present conditions for the retailer to share information. Interestingly, we find that the retailer in some conditions has no motivation to improve customer satisfaction rate of offline store. Most important, we find that the retailer's channel choice depends on the magnitude of the annual service fee that is affected by offline return strategy and asymmetric information, and the offline return strategy depends on the magnitude of the average residual value of returned products. 相似文献
1000.
Wei Zhang Yonggang Sun Huiqiu Deng Jianming Ma Yi Zeng Zhiqiang Zhu Zhisheng Lv Huarong Xia Xiang Ge Shengkai Cao Yao Xiao Shibo Xi Yonghua Du Anmin Cao Xiaodong Chen 《Advanced materials (Deerfield Beach, Fla.)》2020,32(19):2000496
High-energy Li-rich layered cathode materials (≈900 Wh kg−1) suffer from severe capacity and voltage decay during cycling, which is associated with layered-to-spinel phase transition and oxygen redox reaction. Current efforts mainly focus on surface modification to suppress this unwanted structural transformation. However, the true challenge probably originates from the continuous oxygen release upon charging. Here, the usage of dielectric polarization in surface coating to suppress the oxygen evolution of Li-rich material is reported, using Mg2TiO4 as a proof-of-concept material. The creation of a reverse electric field in surface layers effectively restrains the outward migration of bulk oxygen anions. Meanwhile, high oxygen-affinity elements of Mg and Ti well stabilize the surface oxygen of Li-rich material via enhancing the energy barrier for oxygen release reaction, verified by density functional theory simulation. Benefited from these, the modified Li-rich electrode exhibits an impressive cyclability with a high capacity retention of ≈81% even after 700 cycles at 2 C (≈0.5 A g−1), far superior to ≈44% of the unmodified counterpart. In addition, Mg2TiO4 coating greatly mitigates the voltage decay of Li-rich material with the degradation rate reduced by ≈65%. This work proposes new insights into manipulating surface chemistry of electrode materials to control oxygen activity for high-energy-density rechargeable batteries. 相似文献