全文获取类型
收费全文 | 1902篇 |
免费 | 149篇 |
国内免费 | 15篇 |
专业分类
电工技术 | 23篇 |
综合类 | 24篇 |
化学工业 | 381篇 |
金属工艺 | 62篇 |
机械仪表 | 75篇 |
建筑科学 | 32篇 |
能源动力 | 134篇 |
轻工业 | 211篇 |
水利工程 | 28篇 |
石油天然气 | 20篇 |
无线电 | 220篇 |
一般工业技术 | 425篇 |
冶金工业 | 126篇 |
原子能技术 | 34篇 |
自动化技术 | 271篇 |
出版年
2024年 | 5篇 |
2023年 | 54篇 |
2022年 | 88篇 |
2021年 | 158篇 |
2020年 | 109篇 |
2019年 | 109篇 |
2018年 | 145篇 |
2017年 | 123篇 |
2016年 | 102篇 |
2015年 | 73篇 |
2014年 | 105篇 |
2013年 | 167篇 |
2012年 | 103篇 |
2011年 | 109篇 |
2010年 | 74篇 |
2009年 | 57篇 |
2008年 | 39篇 |
2007年 | 35篇 |
2006年 | 30篇 |
2005年 | 17篇 |
2004年 | 30篇 |
2003年 | 16篇 |
2002年 | 24篇 |
2001年 | 17篇 |
2000年 | 8篇 |
1999年 | 15篇 |
1998年 | 39篇 |
1997年 | 30篇 |
1996年 | 21篇 |
1995年 | 16篇 |
1994年 | 16篇 |
1993年 | 17篇 |
1992年 | 12篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 13篇 |
1988年 | 16篇 |
1987年 | 8篇 |
1986年 | 8篇 |
1985年 | 8篇 |
1983年 | 2篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1979年 | 2篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1974年 | 4篇 |
1973年 | 2篇 |
排序方式: 共有2066条查询结果,搜索用时 15 毫秒
991.
Drops of a suspension of individual single‐walled carbon nanotubes in F68 Pluronic surfactant dry on glass substrates to form a “crust” at the free surface. The crust is extremely thin (~ 100 nm) and consists of an entangled mesh of nanotubes and Pluronic. Pasquali and co‐workers report on p. 29 that the convective flow associated with the drying preferentially assembles the micelles into a hexagonal arrangement, as revealed by the birefringent pattern shown on the cover. This technique is promising for developing thin, optically transparent, and electrically conductive coatings and films consisting of nanotubes. 相似文献
992.
S. Hussain S. Ahmad Mehboob Sadiq P. Lee M. Zakaullah A. Waheed 《Journal of Fusion Energy》2009,28(1):124-129
A study of X-ray emission from a Mather-type plasma focus device by simultaneously employing various X-ray detectors like
silicon pin diode, photoconducting detectors (PCDs)—CVD-diamond and gallium arsenide (GaAs), plastic scintillator coupled
with photomultiplier tube with and with out optical fiber is presented. The pin diode and PCDs are masked with 10 μm thick
cobalt filter. The device is energized by 9 μF capacitor bank charged at 18 kV (1.45 kJ), giving a peak discharge current
of about 175 kA, with hydrogen as the filling gas. The optical fiber coupling is found to be beneficial in minimizing the
electromagnetic noise generated during the system operation. 相似文献
993.
An Erratum has been published for this article in International Journal of Energy Research 2004; 28 (13): 1213. This paper deals with the simulation of thermal energy storage (TES) system for HVAC applications. TES is considered to be one of the most preferred demand side management technologies for shifting cooling electrical demand from peak daytime hours to off peak night hours. TES is incorporated into the conventional HVAC system to store cooling capacity by chilling ethylene glycol, which is used as a storage medium. The thermodynamic performance is assessed using exergy and energy analyses. The effects of various parameters such as ambient temperature, cooling load, and mass of storage are studied on the performance of the TES. A full storage cycle, with charging, storing and discharging stages, is considered. In addition, energy and exergy analysis of the TES is carried out for system design and optimization. The temperature in the storage is found to be as low as 6.4°C after 1 day of charging without load for a mass of 250 000 kg. It is found that COP of the HVAC system increases with the decrease of storage temperature. Energy efficiency of the TES is found to be 80% for all the mass flow rate of the discharging fluid, whereas exergy efficiency varies from 14 to 0.5%. This is in fact due to the irreversibilities in a TES process destroy a significant amount of the input exergy, and the TES exergy efficiencies therefore become always lower than the corresponding energy efficiencies. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
994.
MM Hammami A al-Zahrani A Butt LJ Vencer SS Hussain 《Canadian Metallurgical Quarterly》1997,20(9):552-558
Several cases of sporadic primary hyperparathyroidism in association with fibrous dysplasia of the bone have been reported in the English literature. Since fibrous dysplasia is a major feature and hyperparathyroidism is occasionally found in the McCune-Albright syndrome, we hypothesized that such cases may represent a variant of this syndrome. A 28-year-old male had primary hyperparathyroidism associated with polyostotic fibrous dysplasia but no other manifestations of the McCune-Albright syndrome. Genomic DNA samples from his parathyroid adenoma, dysplastic bone sample, and peripheral leukocytes were analyzed for the presence of activating mutations of the stimulating G protein alpha subunit gene (gsp). Allele-specific hybridization revealed the presence of normal sequences only, coding for arginine and glutamine at codons 201 (exon 8) and 227 (exon 9), respectively. Further, single strand conformational analysis of a 224 base pair fragment of exon 8 revealed no conformational aberrations. Furthermore, the sequences of a 164 base pair fragment of exon 8 and a 170 base pair fragment of exon 9 were normal. The results strongly suggest that gsp mutation is absent in affected and normal tissues in this patient and that the association of hyperparathyroidism and fibrous dysplasia may not represent a variant of the McCune-Albright syndrome. 相似文献
995.
AK Rishi M Yu JJ Tsai-Wu CP Belani JA Fontana DL Baker M Periasamy A Hussain 《Canadian Metallurgical Quarterly》1998,26(19):4529-4537
996.
Kinetics of CO2 absorption by aqueous 3‐(methylamino)propylamine solutions: Experimental results and modeling 下载免费PDF全文
Juliana G. M.‐S. Monteiro Saddam Hussain Hammad Majeed Emmanuel O. Mba Ardi Hartono Hanna Knuutila Hallvard F. Svendsen 《American Institute of Chemical Engineers》2014,60(11):3792-3803
Experimental data and a model for the initial kinetics of CO2 into 3‐(methylamino)propylamine (MAPA) solutions are presented in work. MAPA has been tested as an activator for tertiary amines with encouraging results. The measurements were performed in a string of discs contactor and, as no initial kinetics data are available in literature, additional measurements were carried out and in a wetted wall column. The obtained overall mass‐transfer coefficients from both apparatuses are in reasonable agreement. To obtain values for the observed kinetic constant, , the experimental results were interpreted using a two‐film mass‐transfer model and invoking the pseudo‐first order assumption. Needed experimental values for density, viscosity, and Henry's law coefficient for CO2 were measured and are given. The results indicate that MAPA is almost twice as fast as piperazine, eight times faster than 2‐(2‐aminoethyl‐amino)ethanol (AEEA), and 15 times faster than monoethanolamine, when comparing unloaded 1 M solutions at 25°C. The observed kinetic constant was modeled using the direct mechanism. The final expression for can be applied for any concentration and temperature within the experimental data range, and, together with the presented physical data, comprises a complete model for calculating absorption fluxes. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3792–3803, 2014 相似文献
997.
Antiscaling properties of novel maleic‐anhydride copolymers prepared via iron (II) – chloride mediated ATRP 下载免费PDF全文
A class of maleic anhydride copolymers (YMR‐A series) with a narrow molecular weight distribution between 500–1500 and a polydispersity of 1.0–1.11 was obtained from n‐alkylacrylamide and maleic anhydride monomers via atom transfer radical polymerization. The monomer conversion reached about 71% corresponding to 1:4 [FeCl2] to [SA] molar ratios for (AAH/MA) copolymer initiated by CPN whereas for the polymerization initiated by MCPN the conversion reached 51.9% under similar condition showing better performance of CPN initiator. Resultant polymers were characterized by means of 1H‐NMR and 13C‐NMR. The inhibition behavior of these YMR‐A polymers against CaCO3 and CaSO4 was evaluated using static scale inhibition method. The inhibition efficiency on the calcium carbonate scale is much higher and even with 5 ppm dosage level the efficiency is around 99.33 % at pH 10.45 and temperature 70°C, where as for calcium sulfate scales the inhibition efficiency, is lower and 99.9% inhibition is observed at 7–9 ppm level. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39827. 相似文献
998.
Biocompatibility and microscopic evaluation of polyurethane–poly(methyl methacrylate)–titnanium dioxide based composites for dental applications 下载免费PDF全文
Mohammad Zuber Shazia Tabasum Tahir Jamil Muhammad Shahid Rizwan Hussain Khalid Sajjad Feras Khalid Pervez Bhatti 《应用聚合物科学杂志》2014,131(3)
We prepared and then blended polyurethanes (PUs) with poly(methyl methacrylate)s (PMMAs) and TiO2 by varying the percentage compositions to form pellets. The chemistry of all of the blended samples was confirmed by Fourier transform infrared spectroscopy. The incorporation of TiO2 into the PU–PMMA matrix was confirmed with scanning electron microscopy analysis. Differential scanning calorimetry analysis and compression testing was performed, and the results are discussed. The cytotoxicity level of the prepared blends displayed dependence on the composition ratio of the PU–PMMA blends. The results reveal that the optimum PU contents in the PU–PMMA–TiO2 blend were responsible for its better biocompatibility. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39806. 相似文献
999.
V. Raghavendra Reddy Sanjay Kumar Upadhyay Ajay Gupta Anand M. Awasthi Shamima Hussain 《Ceramics International》2014
Structural, dielectric and ferroelectric properties of polycrystalline BaTiO3 (BTO) ceramics prepared with hybrid sintering i.e., microwave assisted radiant heating (MARH) are reported. It is observed that the permittivity (ε) and true switched ferroelectric charge density (QSW) of BTO ceramics can be enhanced by employing MARH. An enhancement of 58% in ε and 17% in QSW is observed for the BTO sample prepared with 30% microwave power applied during MARH as compared to the conventional radiant heating. The results are explained in terms of microstructure resulting from the microwave assisted sintering. 相似文献
1000.
Dielectric studies of composite paper reinforced with polypyrrole coated pulp fibers from wasted egg holders 下载免费PDF全文
Aamir Razaq Muhammad Idrees Adeel Malik Nafeesa Mushtaq Muhammad Nadeem Irshad Hussain Muhammad Yar 《应用聚合物科学杂志》2015,132(33)
Development of thin, flexible, light‐weight, renewable, low‐cost, and environmentally friendly electrode materials are highly feasible in era of modern disposable electronic technology. This article presents the synthesis and dielectric studies of polypyrrole (PPy) coated pulp fibers, directly collected from wasted egg holder's tray. PPy coated pulp fibers converted into compact sheet for the development of potential renewable and low‐cost electrode materials. The morphology, chemical structure, and thermal stability of naked and PPy coated pulp fibril sheets were investigated by scanning electron microscopy (SEM), Fourier transform infrared (FTIR) and thermogravimetric analysis (TGA), respectively. PPy coated pulp fibers revealed better thermal stability and compactness of sheet morphology. Impedance measurements showed a high value of dielectric constant of 1.15 × 106 at 0.5 Hz and conductivity of 7.45 × 10?4 S/cm at room temperature for PPy coated pulp fibril sheet. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42422. 相似文献