全文获取类型
收费全文 | 137324篇 |
免费 | 13825篇 |
国内免费 | 8488篇 |
专业分类
电工技术 | 10200篇 |
技术理论 | 6篇 |
综合类 | 10869篇 |
化学工业 | 20079篇 |
金属工艺 | 8560篇 |
机械仪表 | 9376篇 |
建筑科学 | 11023篇 |
矿业工程 | 4322篇 |
能源动力 | 4172篇 |
轻工业 | 9397篇 |
水利工程 | 3314篇 |
石油天然气 | 7037篇 |
武器工业 | 1650篇 |
无线电 | 16693篇 |
一般工业技术 | 14741篇 |
冶金工业 | 5398篇 |
原子能技术 | 1913篇 |
自动化技术 | 20887篇 |
出版年
2024年 | 462篇 |
2023年 | 1996篇 |
2022年 | 3819篇 |
2021年 | 5723篇 |
2020年 | 4243篇 |
2019年 | 3419篇 |
2018年 | 3821篇 |
2017年 | 4295篇 |
2016年 | 3911篇 |
2015年 | 5783篇 |
2014年 | 7435篇 |
2013年 | 8546篇 |
2012年 | 10130篇 |
2011年 | 11092篇 |
2010年 | 10279篇 |
2009年 | 9532篇 |
2008年 | 9742篇 |
2007年 | 9252篇 |
2006年 | 8697篇 |
2005年 | 7059篇 |
2004年 | 5079篇 |
2003年 | 4164篇 |
2002年 | 4047篇 |
2001年 | 3451篇 |
2000年 | 2876篇 |
1999年 | 2425篇 |
1998年 | 1621篇 |
1997年 | 1334篇 |
1996年 | 1154篇 |
1995年 | 961篇 |
1994年 | 773篇 |
1993年 | 555篇 |
1992年 | 427篇 |
1991年 | 329篇 |
1990年 | 242篇 |
1989年 | 208篇 |
1988年 | 145篇 |
1987年 | 103篇 |
1986年 | 96篇 |
1985年 | 55篇 |
1984年 | 47篇 |
1983年 | 53篇 |
1982年 | 38篇 |
1981年 | 40篇 |
1980年 | 34篇 |
1979年 | 20篇 |
1978年 | 15篇 |
1977年 | 19篇 |
1959年 | 19篇 |
1951年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Wan Huan Wang Hui Scotney Bryan Liu Jun Ng Wing W. Y. 《Multimedia Tools and Applications》2020,79(39-40):29327-29352
Multimedia Tools and Applications - In many real-world classification problems there exist multiple subclasses (or clusters) within a class; in other words, the underlying data distribution is... 相似文献
93.
Creating the brain and interacting with the brain: an integrated approach to understanding the brain
In the past two decades, brain science and robotics have made gigantic advances in their own fields, and their interactions have generated several interdisciplinary research fields. First, in the ‘understanding the brain by creating the brain’ approach, computational neuroscience models have been applied to many robotics problems. Second, such brain-motivated fields as cognitive robotics and developmental robotics have emerged as interdisciplinary areas among robotics, neuroscience and cognitive science with special emphasis on humanoid robots. Third, in brain–machine interface research, a brain and a robot are mutually connected within a closed loop. In this paper, we review the theoretical backgrounds of these three interdisciplinary fields and their recent progress. Then, we introduce recent efforts to reintegrate these research fields into a coherent perspective and propose a new direction that integrates brain science and robotics where the decoding of information from the brain, robot control based on the decoded information and multimodal feedback to the brain from the robot are carried out in real time and in a closed loop. 相似文献
94.
95.
As accessing computing resources from the remote cloud inherently incurs high end-to-end (E2E) delay for mobile users, cloudlets, which are deployed at the edge of a network, can potentially mitigate this problem. Although some research works focus on allocating workloads among cloudlets, the cloudlet placement aiming to minimize the deployment cost (i.e., consisting of both the cloudlet cost and average E2E delay cost) has not been addressed effectively so far. The locations and number of cloudlets have a crucial impact on both the cloudlet cost in the network and average E2E delay of users. Therefore, in this paper, we propose the Cost Aware cloudlet PlAcement in moBiLe Edge computing (CAPABLE) strategy, where both the cloudlet cost and average E2E delay are considered in the cloudlet placement. To solve this problem, a Lagrangian heuristic algorithm is developed to achieve the suboptimal solution. After cloudlets are placed in the network, we also design a workload allocation scheme to minimize the E2E delay between users and their cloudlets by considering the user mobility. The performance of CAPABLE has been validated by extensive simulations. 相似文献
96.
Yejun Wu Bowen Yan Juan Zhou Huizhang Lian Xiaojun Yu Jianxin Zhao Hao Zhang Wei Chen Daming Fan 《Journal of food science》2020,85(10):3282-3292
97.
Hechun Cao Hui Zheng Lining Fan Zifeng Cheng Jianwei Zhou Qiong Wu Peng Zheng Liang Zheng Yang Zhang 《International Journal of Applied Ceramic Technology》2020,17(2):813-822
In this study, yttrium iron garnet co-doped with Zn and Zr atoms with a chemical formula Y3ZnxZrxFe(5−2x)O12 (x = 0.0-0.3) has been successfully prepared by the solid-state reaction method. The effects of doping concentration on the microstructure, crystal structure, magnetic properties, and dielectric properties of Y3ZnxZrxFe(5−2x)O12 were investigated. The microstructure analysis indicates that co-doping of YIG with Zn and Zr can effectively reduce the grain size of the ceramic. The crystal structure results reveal that the doping concentration of Zn–Zr has substantial influence on the lattice parameters of YIG, such as, increases the lattice constant, crystal cell size, and interplanar spacing. However, the second phase of ZrO2 appears once x ≥ 0.15. Additionally, the dielectric properties of YIG ferrite can be regulated using this Zn–Zr co-doping method. Zn–Zr co-doping can improve the dielectric stability and reduce the dielectric loss at high temperature. The magnetization measurement shows that the saturation magnetization is stabilized at x < 0.15, and the magnetic loss is decreased with the increase in the doping concentration. Overall, the findings show that the ceramic with x = 0.1 exhibits better properties included high saturation magnetization (24.607 emu/g), low magnetic loss (0.0025 @ 1 MHz), and relatively low dielectric loss (496 @ 400°C). 相似文献
98.
99.
Qiang Wang Lei Shen Tong Xue Gao Cheng Cheng Zhi Huang Hong Jin Fan Yuan Ping Feng 《Advanced functional materials》2021,31(2):2002187
The {100} facet of single-crystalline TiO2(B) is an ideal platform for inserting Li ions, but it is hard to be obtained due to its high surface energy. Here, the single-crystalline TiO2(B) nanobelts from H2Ti3O7 with nearly 70% {100} facets exposed are synthesized, which significantly enhances Li-storage capacity. The first-principle calculations demonstrate an ab in-plane 2D diffusion through the exposed {100} facets. As a consequence, the nanobelts can significantly accommodate Li ions in LiTiO2 formula with specific capacity up to 335 mAh g−1, which is in good agreement with the electrochemical characterizations. Coating with conductive and protective poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate), the cut-off discharge voltage is as low as 0.5 V, leading to a capacity of 160.7 mAh g−1 after 1500 cycles with a retention rate of 66% at 1C. This work provides a practical strategy to increase the Li-ion capacity and cycle stability by tailoring the crystal orientation and nanostructures. 相似文献
100.
Natural Computing - The fiber stretching process plays the key role in the process of fiber production and its effects is measured by the stretching ratio. The stretching ratio is determined by the... 相似文献