全文获取类型
收费全文 | 6641篇 |
免费 | 623篇 |
国内免费 | 236篇 |
专业分类
电工技术 | 409篇 |
技术理论 | 1篇 |
综合类 | 407篇 |
化学工业 | 1216篇 |
金属工艺 | 452篇 |
机械仪表 | 419篇 |
建筑科学 | 480篇 |
矿业工程 | 247篇 |
能源动力 | 182篇 |
轻工业 | 334篇 |
水利工程 | 134篇 |
石油天然气 | 455篇 |
武器工业 | 39篇 |
无线电 | 663篇 |
一般工业技术 | 927篇 |
冶金工业 | 361篇 |
原子能技术 | 70篇 |
自动化技术 | 704篇 |
出版年
2024年 | 31篇 |
2023年 | 123篇 |
2022年 | 230篇 |
2021年 | 310篇 |
2020年 | 257篇 |
2019年 | 193篇 |
2018年 | 246篇 |
2017年 | 219篇 |
2016年 | 211篇 |
2015年 | 295篇 |
2014年 | 349篇 |
2013年 | 425篇 |
2012年 | 444篇 |
2011年 | 457篇 |
2010年 | 403篇 |
2009年 | 381篇 |
2008年 | 365篇 |
2007年 | 361篇 |
2006年 | 314篇 |
2005年 | 240篇 |
2004年 | 179篇 |
2003年 | 146篇 |
2002年 | 123篇 |
2001年 | 134篇 |
2000年 | 148篇 |
1999年 | 178篇 |
1998年 | 142篇 |
1997年 | 123篇 |
1996年 | 125篇 |
1995年 | 93篇 |
1994年 | 74篇 |
1993年 | 46篇 |
1992年 | 45篇 |
1991年 | 29篇 |
1990年 | 20篇 |
1989年 | 11篇 |
1988年 | 9篇 |
1987年 | 5篇 |
1986年 | 7篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1965年 | 1篇 |
排序方式: 共有7500条查询结果,搜索用时 9 毫秒
1.
2.
Zenan Yu Julian Moore Jean Calderon Lei Zhai Jayan Thomas 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(39):5289-5295
Cable‐shaped supercapacitors (SCs) have recently aroused significant attention due to their attractive properties such as small size, lightweight, and bendability. Current cable‐shaped SCs have symmetric device configuration. However, if an asymmetric design is used in cable‐shaped supercapacitors, they would become more attractive due to broader cell operation voltages, which results in higher energy densities. Here, a novel coil‐type asymmetric supercapacitor electrical cable (CASEC) is reported with enhanced cell operation voltage and extraordinary mechanical‐electrochemical stability. The CASECs show excellent charge–discharge profiles, extraordinary rate capability (95.4%), high energy density (0.85 mWh cm−3), remarkable flexibility and bendability, and superior bending cycle stability (≈93.0% after 4000 cycles at different bending states). In addition, the CASECs not only exhibit the capability to store energy but also to transmit electricity simultaneously and independently. The integrated electrical conduction and storage capability of CASECS offer many potential applications in solar energy storage and electronic gadgets. 相似文献
3.
Multibody System Dynamics - This paper represents an explicit analytical solution for attitude dynamics of spacecraft combination during on-orbit refueling. Due to the fuel transfer from the... 相似文献
4.
Xueliang Wang Huiqin Yin Wenguan Liu Guojun Yu Jian He Zhongfeng Tang Long Yan 《工业材料与腐蚀》2020,71(6):931-937
Understanding the corrosion of molten ZnCl2 on metal surfaces is significant for the corrosion protection of metals, sustainable use of molten salts, preparation of ZnO coatings, and so on. In this paper, surfaces of pure Ni, Cr, and Fe corroded by molten ZnCl2 were investigated. The results show that Ni suffered very slight corrosion, while Cr experienced more serious corrosion than Ni, but lighter corrosion than Fe. The morphology of the corrosion of Cr and Fe, respectively, presented pitting and intergranular corrosion characteristics. Furthermore, nanostructured ZnO coatings were obtained on the surfaces of Ni and Fe, but not on the surface of Cr. The ZnO coating on the Ni surface was doped with a small amount of Zn5(OH)8Cl2, and the ZnO coating on the Fe surface was doped with ZnFe2O4 and Zn2OCl2. The coatings on the Ni and Fe surfaces had an average thickness of 1.5 and 50 μm, respectively. 相似文献
5.
6.
The smoke suppression of rigid polyurethane foam (RPUF) modified by melamine was investigated based on three sections: the condensed phase, the carbon layer, and the gas phase. In the condensed phase, the results of thermogravimetry, X‐ray photoelectron spectroscopy (XPS) N1S spectrum, and Fourier transform infrared spectroscopy indicated that melamine could suppress the degradation of RPUF by reacting with the aromatic hydrocarbons. It also reduced the smoke generation because the volatilizable aromatic hydrocarbons were the principal smoke precursors in a fire. In the carbon layer, the decrease from 38.50% to 24.76% of the inner layer oxygen content identified by XPS full‐spectrum and C1S spectrum indicated that melamine could prevent oxygen from transferring into the inner foam by the formation of an enhanced surface carbon layer, and the enhanced carbon layer could also block the release of smoke precursors. In the gas phase, the content of total aromatic hydrocarbons declined to 59.12% according to pyrolysis gaseous chromatography mass spectroscopy and indicated that melamine could reduce the smoke precursors. The results of smoke density chamber and cone calorimeter tests revealed that the addition of the melamine could decrease the smoke density of burning RPUF. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
7.
L. Vu‐Quoc V. Srinivas Y. Zhai 《International journal for numerical methods in engineering》2003,58(3):397-461
We establish a systematic methodology to design and analyse electromagnetic components such as advanced multilayer ceramic capacitors (MLCCs) using the finite element (FE) method. We employ a coupled formulation to compute the interaction between the electric and magnetic fields. Unlike a linear distribution of current assumed in the circuit model, an accurate electrostatic solution to model the entire advanced MLCCs (4 × 4 × 27 = 432 cells) is presented. The FE solution is used to compute the lumped parameters for a range of frequencies. These lumped parameters are then used to compute the parasitic elements of the MLCCs. We introduce two algorithms to efficiently analyse the behaviour of a capacitor with changing frequency. The lower frequency (much below the self‐resonant frequency of the capacitor) algorithm separates the effect of the electric and magnetic fields and reduces the computational effort required to solve the FE problem, whereas, the high‐frequency algorithm couples the effect between the electric and the magnetic fields. We use these algorithms in conjunction with a new multiple scale technique to effectively determine the small values of R, L and C in MLCCs. The formulation, the implementation, and the numerical results demonstrate the efficacy of the present FE formulation and establish a systematic methodology to design and analyse advanced electromagnetic components. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
8.
ImprovingWearResistanceoftheNibaseThermalSprayWeldingCoatingUsingRareEarthsZhaiGuangjie(翟光杰)(InstituteofPhysics,AcademicaSi... 相似文献
9.
10.