全文获取类型
收费全文 | 1591篇 |
免费 | 80篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 24篇 |
化学工业 | 365篇 |
金属工艺 | 31篇 |
机械仪表 | 45篇 |
建筑科学 | 24篇 |
矿业工程 | 6篇 |
能源动力 | 134篇 |
轻工业 | 139篇 |
水利工程 | 44篇 |
石油天然气 | 4篇 |
无线电 | 172篇 |
一般工业技术 | 256篇 |
冶金工业 | 79篇 |
原子能技术 | 9篇 |
自动化技术 | 342篇 |
出版年
2024年 | 5篇 |
2023年 | 42篇 |
2022年 | 65篇 |
2021年 | 63篇 |
2020年 | 50篇 |
2019年 | 67篇 |
2018年 | 85篇 |
2017年 | 58篇 |
2016年 | 71篇 |
2015年 | 49篇 |
2014年 | 68篇 |
2013年 | 122篇 |
2012年 | 67篇 |
2011年 | 107篇 |
2010年 | 72篇 |
2009年 | 88篇 |
2008年 | 60篇 |
2007年 | 70篇 |
2006年 | 52篇 |
2005年 | 41篇 |
2004年 | 33篇 |
2003年 | 36篇 |
2002年 | 26篇 |
2001年 | 16篇 |
2000年 | 17篇 |
1999年 | 15篇 |
1998年 | 20篇 |
1997年 | 26篇 |
1996年 | 16篇 |
1995年 | 19篇 |
1994年 | 11篇 |
1993年 | 7篇 |
1992年 | 16篇 |
1991年 | 13篇 |
1990年 | 12篇 |
1989年 | 11篇 |
1988年 | 13篇 |
1987年 | 7篇 |
1986年 | 6篇 |
1985年 | 6篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 6篇 |
1977年 | 4篇 |
1976年 | 4篇 |
1972年 | 3篇 |
1969年 | 1篇 |
排序方式: 共有1674条查询结果,搜索用时 15 毫秒
71.
72.
73.
Fast pyrolysis of the crushed Delonix regia seed was carried out in a semi-batch reactor at a temperature ranging from 400 to 650°C with an objective to produce bio-oil. The effect of temperature to obtain an optimum condition for maximum bio-oil yield and the composition of pyrolysis product were investigated. The maximum bio-oil yield was found to be 48?wt% at pyrolysis temperature of 600°C. The chemical composition of bio-oil obtained at optimum condition was analysed using Fourier-transformed infrared spectroscopy and Gas chromatography–mass spectrometry. The chemical analysis of the biofuel showed the presence of hydrocarbons in major, aldehydes, ketones, amides, nitriles, etc. The composition and fuel characteristics of the pyrolysis oil obtained in this work show that it may potentially be used as a renewable fuel and chemical feedstock. 相似文献
74.
Rey Alvaro Datta-Gupta Akhil Paulo Ballin 《Journal of Petroleum Science and Engineering》2011,78(2):415-430
In this paper we propose an efficient and novel technique that handles production discontinuities through a resampling of the production data, eliminating high frequency production details in a transformed domain. The technique also reduces non-monotonic behavior and results in a response more suitable for the GTTI based misfit calculations. Our proposed approach has been applied to an offshore turbidite reservoir with extensive well intervention resulting in highly detailed production responses. The static model contains more than three-hundred-thousand cells, complex sand depositional distribution combined with fault structures, four pairs of injector-producers, deviated producing wells and more than 8 years of production history. Previous history matching attempts using traditional approaches had difficulties matching production response at the individual well level. With our proposed modifications to the GTTI approach, a significant improvement was obtained on the well level match quality. Most importantly, by visualizing the streamlines and the dynamic adjustment of flow paths during history matching, we could easily identify the areas of inconsistency between the geologic model and the production data. The calibrated geologic model and streamline trajectories provided important insight about communication within sand channels, differences in flow paths and barriers that have not been included in the previous geologic and seismic interpretation. 相似文献
75.
Vijay K. Tomer Surender Duhan Ritu Malik Satya P. Nehra Sunita Devi 《Journal of the American Ceramic Society》2015,98(12):3719-3725
This work deals with the study of hydrothermally synthesized zinc oxide (ZnO) loaded mesoporous SBA‐15 hybrid nanocomposite for relative humidity sensing (RH) at room temperature. The sensor exhibits an excellent ~5 orders impedance change along with excellent linearity, quick response time (17 s), rapid recovery time (18 s), negligible hysteresis (1.2%), good repeatability, and stability (1.8%) in 11%–98% RH range. In addition, complex impedance spectra of the sensor at different RHs were analyzed to understand the humidity sensing mechanism. Our study can open a new way for realizing ZnO/SBA‐15 hybrid nanocomposite for fabrication of high‐performance RH sensors. 相似文献
76.
Amol B. Rahane Vijay Kumar Jennifer S. Dunn 《Journal of the American Ceramic Society》2015,98(7):2223-2233
The structural, electronic, and elastic properties of pristine and carbon‐doped boron suboxide (B6O) are calculated using density functional theory. The results indicate that it is energetically preferable for a single carbon atom to substitute into an oxygen site rather than a boron site. The lattice parameters and cell volume increase to relieve the residual stress created by the carbon substitution. The interstitial position is not favorable for a single atom substitution. However, if two carbon atoms substitute for two neighboring oxygen atoms, then it becomes energetically favorable to dope an interstitial oxygen, boron, or carbon atom along the C–C chain. If the interstitial dopant is either boron or carbon, a local B4C‐like structure with either a C–B–C or C–C–C chain is created within the boron suboxide unit cell. The resulting structure shows improvements in the bulk modulus at the expense of the shear and Young's moduli. The moduli further improve if an additional carbon is substituted within a polar or equatorial site of the neighboring B12 icosahedron. Based on these calculations, we conclude that carbon doping can either harden or soften B6O depending on the manner in which the substitutions are populated. Furthermore, as B6O samples are often oxygen deficient, C doping can occupy such sites and improve the elastic properties. 相似文献
77.
Niranjana Behera Vijay K. Agarwal Mark Jones Kenneth C. Williams 《Particulate Science and Technology》2015,33(5):510-516
In order to reveal the unsteady features of gas–solid flow, the pressure fluctuations were measured at different locations along the length of the pipeline while conveying powders through the pipeline. Power spectral density (PSD) functions were obtained for the analysis of the pressure fluctuation. Two types of powders (fly ash and alumina) were used in this analysis. The PSD analysis was conducted by taking into account different aspects such as flow conditions (dilute or dense), location of transmitter (top and bottom transmitters), location of transmitter along the length of the pipeline (three different locations), material property (fly ash or alumina), etc. Analysis of signals from top and bottom transmitters shows that it is not possible to identify the flow mode at upper and lower portions of pipeline. The magnitude of power is found to be higher for alumina as compared to fly ash. PSD parametric analysis reveals that frequency bandwidth and average power decreases exponentially with increase in solid loading ratio. 相似文献
78.
79.
Veer Pal Singh Ramasubbu Ramani Ajit Shankar Singh Preeti Mishra Vijay Pal Amit Saraiya 《应用聚合物科学杂志》2016,133(41)
Herein, we present the dielectric and electrical conductivity properties of the partially miscible polymer blend prepared using pyrene functionalized polyaniline (pf‐PANI) and poly(vinylidene fluoride‐co‐hexafluoro propylene) (PVDF‐co‐HFP). The blend mostly retains the fluorescent nature of pf‐PANI as well as can be moldable and possesses good damping property. The dielectric properties have been investigated as a function of temperature at three different frequencies and the plausible origin of polarization responsible for dielectric behavior in this blend has been identified. The experimental results of dielectric measurements are compared with theoretical models and discussed. The surface morphology of the samples has been examined with a scanning electron microscope. The electrical conductivity has also been studied as a function of temperature and explained in terms of hopping of charge carriers/interconnected networks. The combined dielectric and conductivity results together with scanning electron microscope micrographs, reveal that there is hindrance to achieve percolation threshold even after pf‐PANI addition of 57 vol % and subsequent thermal treatment. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44077. 相似文献
80.
Ponraj N. Vijay Azhagurajan A. Vettivel S. C. Sahaya Shajan X. Nabhiraj P. Y. Haiterlenin A. 《Metal Science and Heat Treatment》2019,60(9-10):611-615
Metal Science and Heat Treatment - Composites obtained by powder metallurgy from a mixture of copper powders and graphene nanosheets are studied. The response surface methodology is used to design... 相似文献