全文获取类型
收费全文 | 13068篇 |
免费 | 1002篇 |
国内免费 | 518篇 |
专业分类
电工技术 | 668篇 |
综合类 | 682篇 |
化学工业 | 2237篇 |
金属工艺 | 685篇 |
机械仪表 | 827篇 |
建筑科学 | 885篇 |
矿业工程 | 332篇 |
能源动力 | 411篇 |
轻工业 | 764篇 |
水利工程 | 178篇 |
石油天然气 | 855篇 |
武器工业 | 72篇 |
无线电 | 1834篇 |
一般工业技术 | 1699篇 |
冶金工业 | 642篇 |
原子能技术 | 90篇 |
自动化技术 | 1727篇 |
出版年
2024年 | 34篇 |
2023年 | 216篇 |
2022年 | 299篇 |
2021年 | 509篇 |
2020年 | 330篇 |
2019年 | 299篇 |
2018年 | 339篇 |
2017年 | 381篇 |
2016年 | 354篇 |
2015年 | 488篇 |
2014年 | 666篇 |
2013年 | 809篇 |
2012年 | 778篇 |
2011年 | 930篇 |
2010年 | 782篇 |
2009年 | 716篇 |
2008年 | 769篇 |
2007年 | 692篇 |
2006年 | 753篇 |
2005年 | 666篇 |
2004年 | 426篇 |
2003年 | 363篇 |
2002年 | 299篇 |
2001年 | 279篇 |
2000年 | 276篇 |
1999年 | 396篇 |
1998年 | 354篇 |
1997年 | 269篇 |
1996年 | 256篇 |
1995年 | 182篇 |
1994年 | 174篇 |
1993年 | 112篇 |
1992年 | 98篇 |
1991年 | 68篇 |
1990年 | 57篇 |
1989年 | 35篇 |
1988年 | 28篇 |
1987年 | 8篇 |
1986年 | 22篇 |
1985年 | 4篇 |
1984年 | 10篇 |
1983年 | 7篇 |
1982年 | 16篇 |
1981年 | 9篇 |
1980年 | 8篇 |
1979年 | 5篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 3篇 |
1974年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
942.
943.
Zhi Li Shun-Li Shang Jianyun Shen Po-Hsien Liao Zi-Kui Liu Timothy J. Anderson 《Journal of Phase Equilibria and Diffusion》2018,39(6):870-881
The substitution of Ag for Cu in CuInxGa1?xSe2-based photovoltaic absorber layers can be used to adjust the bandgap energy to better optimize the overall cell efficiency. Based on available thermochemical, equilibrium, and structural data, the Ag-Se system has been assessed and modeled. Given the order-disorder structure transition Ag2Se, the 2- and 3-sublattice models were used to represent the low- and high-temperature phases of the intermetallic compound respectively. Density functional theory based first-principles calculations were used to calculate the Gibbs energy of formation of the end-member compounds. A set of modeling parameters was obtained by the CALculation of PHAse Diagram approach and reasonable agreement was obtained between the experimental thermodynamic properties of the stable phases and the phase relationships in the Ag-Se system. 相似文献
944.
Radiation dosimeters based on in situ oxygen plasma post-treated diamond thin films were fabricated in a simple sandwich configuration.
Effects of deposition process, methane concentration, and in situ oxygen plasma post-treatment on the sensitivity of the devices
to X-ray irradiation were investigated. X-ray response demonstrates that the cyclic deposition process could improve response
sensitivity. The increase in methane concentration in the deposition gas mixture will worsen the irradiation response of the
devices mainly resulted from the change of the orientation and purity of the films. X-ray photoelectron spectroscopy, photoluminescence,
and Raman measurements suggest that in situ oxygen plasma post-treatment can effectively etch non-diamond phases and passivate
the silicon-vacancy and nitrogen-vacancy defects of the diamond films, resulting in an increase in the sensitivity of the
device by a factor of about 2. Time-dependent response to X-ray indicates that the extended period to achieve photocurrent
signals stability for the devices is a limitation for promising applications in radiation dosimetry. 相似文献
945.
In project management, a project can be represented as a network in two ways; namely, activity-on-arc (AoA) and activity-on-node (AoN). Two recent papers have shown that ant colony optimization (ACO) could find critical path(s) in projects represented as AoA networks. This paper points out that the number and placement of logical dummy activities associated with AoA-based networks can pose serious problems. To get around the problems, an ACO technique based on AoN networks is then proposed. For comparison, the two existing AoA-based ACO algorithms were reproduced and modified into AoN-based algorithms. Moreover, the proposed ACO algorithm was applied to AoA networks as well. All six algorithms were tested with several benchmark problems. The test results strongly indicate that AoN-based ACO algorithms are more effective and efficient in finding critical paths than AoA-based algorithms. 相似文献
946.
Hong-Tzer Yang Chiung-Chou Liao 《Power Delivery, IEEE Transactions on》2001,16(3):353-360
By means of the wavelet transform (WT), a power quality (PQ) monitoring system could easily and correctly detect and localize the disturbances in the power systems. However, the signal under investigation is often corrupted by noises, especially the ones with overlapping high-frequency spectrum of the transient signals. The performance of the WT in detecting the disturbance would be greatly degraded, due to the difficulty of distinguishing the noises and the disturbances. To enhance the capability of the WT-based PQ monitoring system, this paper proposes a de-noising approach to detection of transient disturbances in a noisy environment. In the proposed de-noising approach, a threshold of eliminating the influences of noises is determined adaptively according to the background noises. The abilities of the WT in detecting and localizing the disturbances can hence be restored. To test the effectiveness of the developed de-noising scheme, employed were diverse data obtained from the EMTP/ATP programs for the main transient disturbances in the power systems as well as from actual field tests. Using the approach proposed in this paper, remarkable efficiency of monitoring the PQ problems and high tolerance to the noises are approved 相似文献
947.
Chun-da Liao Jui-che Tsai 《Industrial Electronics, IEEE Transactions on》2009,56(4):1057-1065
Due to the advancement of microoptoelectromechanical systems and microelectromechanical systems (MEMS) technologies, novel display architectures have emerged. One of the most successful and well-known examples is the Digital Micromirror Device from Texas Instruments, a 2-D array of bistable MEMS mirrors, which function as spatial light modulators for the projection display. This concept of employing an array of modulators is also seen in the grating light valve and the interferometric modulator display, where the modulation mechanism is based on optical diffraction and interference, respectively. Along with this trend comes the laser scanning display, which requires a single scanning device with a large scan angle and a high scan frequency. A special example in this category is the retinal scanning display, which is a head-up wearable module that laser-scans the image directly onto the retina. MEMS technologies are also found in other display-related research, such as stereoscopic (3-D) displays and plastic thin-film displays. 相似文献
948.
Rigid polyurethane foams were fabricated with five kinds of liquefied sugarcane bagasse polyols (LBP). The foams derived from
sugarcane bagasse were investigated by thermogravimetric analysis (TGA), and the thermal degradation data were analyzed using
the Coast-Redfern method and Ozawa method to obtain the reaction order and activation energy. The results indicate that the
sugarcane bagasse-foams exhibit an excellent heat-resistant property, whereas their pyrolysis procedures are quite complicated.
The reaction as first order only takes place from 250 to 400 °C, and the pyrolysis activation energies vary from 20 to 140
kJ/mol during the whole pyrolysis process. 相似文献
949.
950.
分析了KNX系统与其他系统的区别,指出标准化和互联化给市场带来的便捷和竞争力,并简要介绍了KNX的网络、配置、通讯介质的架构。 相似文献