全文获取类型
收费全文 | 2741篇 |
免费 | 271篇 |
国内免费 | 127篇 |
专业分类
电工技术 | 301篇 |
综合类 | 276篇 |
化学工业 | 444篇 |
金属工艺 | 133篇 |
机械仪表 | 128篇 |
建筑科学 | 121篇 |
矿业工程 | 36篇 |
能源动力 | 400篇 |
轻工业 | 67篇 |
水利工程 | 25篇 |
石油天然气 | 66篇 |
武器工业 | 29篇 |
无线电 | 326篇 |
一般工业技术 | 498篇 |
冶金工业 | 104篇 |
原子能技术 | 55篇 |
自动化技术 | 130篇 |
出版年
2024年 | 4篇 |
2023年 | 32篇 |
2022年 | 46篇 |
2021年 | 81篇 |
2020年 | 104篇 |
2019年 | 98篇 |
2018年 | 61篇 |
2017年 | 82篇 |
2016年 | 104篇 |
2015年 | 117篇 |
2014年 | 130篇 |
2013年 | 214篇 |
2012年 | 165篇 |
2011年 | 203篇 |
2010年 | 127篇 |
2009年 | 134篇 |
2008年 | 153篇 |
2007年 | 160篇 |
2006年 | 162篇 |
2005年 | 117篇 |
2004年 | 110篇 |
2003年 | 106篇 |
2002年 | 94篇 |
2001年 | 61篇 |
2000年 | 66篇 |
1999年 | 64篇 |
1998年 | 56篇 |
1997年 | 55篇 |
1996年 | 35篇 |
1995年 | 31篇 |
1994年 | 28篇 |
1993年 | 36篇 |
1992年 | 16篇 |
1991年 | 18篇 |
1990年 | 9篇 |
1989年 | 9篇 |
1988年 | 10篇 |
1987年 | 9篇 |
1986年 | 2篇 |
1985年 | 5篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 2篇 |
1979年 | 6篇 |
1976年 | 1篇 |
1972年 | 1篇 |
1959年 | 1篇 |
1955年 | 1篇 |
1951年 | 1篇 |
排序方式: 共有3139条查询结果,搜索用时 375 毫秒
1.
《Ceramics International》2020,46(13):21196-21201
In this work, TiO2/ZrO2 bilayer thin film was prepared on fluorine doped tin oxide (FTO)/glass substrates by using a simple and low-cost chemical solution deposition method. Reproducible bipolar resistive switching (RS) characteristics in Au/TiO2/ZrO2/FTO/glass devices are reported in this work. TiO2/ZrO2 bilayer thin films prepared in this work shows reversible bipolar resistive switching and unidirectional conduction performances under applying voltage and these special performances of TiO2/ZrO2 bilayer thin films was first reported. Obvious resistive switching performance can be observed after setting a compliance current, the ratio of high/low resistance reached about 100 at a read voltage of +0.1V and −0.1V and the RS properties showed no obvious degradation after 100 successive cycles tests. The resistive switching characteristics of Au/TiO2/ZrO2/FTO/glass device can be explained by electron trapping/detrapping related with the vacancy oxygen defects in TiO2/ZrO2 bilayer thin film layer. According to slope fitting, the main conduction mechanisms of the sample are Ohmic and Space charge limited current mechanism. 相似文献
2.
The performance of surface ionic conduction single chamber fuel cell (SIC‐SCFC) prepared by the sol gel method was studied on electric characteristics due to the differences of the operating temperature and humidity, the electrode distance and electrolyte film depth, and multiple cells with the series and parallel connections. The SIC–SCFC was arranged the both anode of Pt and cathode of Au on the boehmite electrolyte. The open circuit voltage (OCV) of single cell achieved a maximum of 530mV in the dry gas mixtures of O2/H2=50% in room temperature operation, and but it became decrease as over 60%. The OCV was maintained the constant value between operating temperatures of 30°C to 80°C, and but it was decreased sharply at over 90°C because a humidity on the cell became lower as increasing operating temperature. Then, the cell property was improved to 120°C by adding to the humidity of 70% using a humidifier. The electrode distance and the electrolyte film depth of SIC‐SCFC found to be contributed to the reductions of the cell resistance and the surface roughness on the electrode, respectively. Moreover, the power property of SIC‐SCFC was significantly improved by cell stacks comprised of the series or parallel connection of a cell. 相似文献
3.
《International Journal of Hydrogen Energy》2019,44(2):587-593
A solid-state photoelectrochemical (SSPEC) cell is an attractive approach for solar water splitting, especially when it comes to monolithic device design. In a SSPEC cell the electrodes distance is minimized, while the use of polymer-based membranes alleviates the need for liquid electrolytes, and at the same time they can separate the anode from the cathode. In this work, we have made and tested, firstly, a SSPEC cell with a Pt/C electrocatalyst as the cathode electrode, under purely gaseous conditions. The anode was supplied with air of 80% relative humidity (RH) and the cathode with argon. Secondly, we replaced the Pt/C cathode with a photocathode consisting of 2D photocatalytic g-C3N4, which was placed in tandem with the photoanode (tandem-SSPEC). The tandem configuration showed a three-fold enhancement in the obtained photovoltage and a steady-state photocurrent density. The mechanism of operation is discussed in view of recent advances in surface proton conduction in absorbed water layers. The presented SSPEC cell is based on earth-abundant materials and provides a way towards systems of artificial photosynthesis, especially for areas where water sources are scarce and electrical grid infrastructure is limited or nonexistent. The only requirements to make hydrogen are humidity and sunlight. 相似文献
4.
Baizhan Li Chenqiu Du Hong Liu Wei Yu Jie Zheng Meilan Tan Zhenxing Jin Wenjie Li Jing Wu Lu Chen Runming Yao 《Indoor air》2019,29(2):308-319
The extensive research interests in environmental temperature can be linked to human productivity / performance as well as comfort and health; while the mechanisms of physiological indices responding to temperature variations remain incompletely understood. This study adopted a physiological sensory nerve conduction velocity (SCV) as a temperature‐sensitive biomarker to explore the thermoregulatory mechanisms of human responding to annual temperatures. The measurements of subjects’ SCV (over 600 samples) were conducted in a naturally ventilated environment over all four seasons. The results showed a positive correlation between SCV and annual temperatures and a Boltzmann model was adopted to depict the S‐shaped trend of SCV with operative temperatures from 5°C to 40°C. The SCV increased linearly with operative temperatures from 14.28°C to 20.5°C and responded sensitively for 10.19°C‐24.59°C, while tended to be stable beyond that. The subjects’ thermal sensations were linearly related to SCV, elaborating the relation between human physiological regulations and subjective thermal perception variations. The findings reveal the body SCV regulatory characteristics in different operative temperature intervals, thereby giving a deeper insight into human autonomic thermoregulation and benefiting for built environment designs, meantime minimizing the temperature‐invoked risks to human health and well‐being. 相似文献
5.
6.
针对辽河油田应用泡沫夹克管道的情况,从泡沫夹克管的制作和敷设施工直到设计等环节,结合泡沫夹克管防腐保温的机理,并从理论与实践相结合角度出发,提出导致泡沫夹克管腐蚀损坏的最主要原因是管道保温层漏水,进而提出了在设计和施工过程中提高泡沫夹克管质量的措施。 相似文献
7.
8.
D.J. Bekers S.J.L. van Eijndhoven A.A.F. van de Ven 《Journal of Engineering Mathematics》2004,49(4):373-390
A long thin conducting stripline embedded in a dielectric and centered between two large conducting plates, i.e., the stripline environment, is considered. The stripline is modeled as infinitely long, infinitely thin, and perfectly conducting by first considering a stripline of finite length, thickness, and conductivity in a dielectric layer. Starting from Maxwell's equations and assuming that the current on the stripline is a propagating wave in length direction, asymptotic expressions for the fields inside and in the neighbourhood of the stripline are deduced. These expressions are used to model the stripline in the stripline environment, which leads to a boundary-value problem for the electric potential. This problem is solved by two different approaches, leading to integral equations for the current and for an auxiliary function describing the electric potential. A relation between the current and the auxiliary function is deduced, which is used to obtain asymptotic expressions for current and impedance. Results are compared with a numerical solution of the integral equation for the current and with results in literature. 相似文献
9.
新型保温材料—炭化稻壳在连铸生产中的应用效果 总被引:3,自引:0,他引:3
对新型保温材料──炭化稻壳的理化指标及其保温性能进行了阐述。在连铸生产中采用炭化稻壳做保温剂可取得显著的经济效益,是理想的保温材料。 相似文献
10.
A remarkable nonlinearity has been observed for electric transport in K-TCNQ (potassium tetracyanoquinodimethane) quasi-one-dimensional
conductor. The negative differential resistance region appears afterV
m (turn over voltage), beyond which voltage goes down with increase of current. A possible mechanism is discussed in terms
of dynamics of charged solitons and domain walls in one-dimensional molecular stacks of these types of crystals. 相似文献