全文获取类型
收费全文 | 1117篇 |
免费 | 51篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 15篇 |
化学工业 | 305篇 |
金属工艺 | 15篇 |
机械仪表 | 22篇 |
建筑科学 | 39篇 |
矿业工程 | 2篇 |
能源动力 | 21篇 |
轻工业 | 144篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 121篇 |
一般工业技术 | 173篇 |
冶金工业 | 208篇 |
原子能技术 | 8篇 |
自动化技术 | 94篇 |
出版年
2023年 | 13篇 |
2022年 | 38篇 |
2021年 | 54篇 |
2020年 | 22篇 |
2019年 | 18篇 |
2018年 | 43篇 |
2017年 | 27篇 |
2016年 | 21篇 |
2015年 | 24篇 |
2014年 | 33篇 |
2013年 | 80篇 |
2012年 | 47篇 |
2011年 | 55篇 |
2010年 | 48篇 |
2009年 | 49篇 |
2008年 | 49篇 |
2007年 | 41篇 |
2006年 | 31篇 |
2005年 | 27篇 |
2004年 | 28篇 |
2003年 | 27篇 |
2002年 | 21篇 |
2001年 | 17篇 |
2000年 | 10篇 |
1999年 | 21篇 |
1998年 | 52篇 |
1997年 | 27篇 |
1996年 | 20篇 |
1995年 | 16篇 |
1994年 | 20篇 |
1993年 | 13篇 |
1992年 | 9篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 16篇 |
1988年 | 13篇 |
1987年 | 10篇 |
1984年 | 7篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1979年 | 9篇 |
1978年 | 8篇 |
1977年 | 6篇 |
1976年 | 13篇 |
1975年 | 5篇 |
1974年 | 8篇 |
1973年 | 5篇 |
1972年 | 5篇 |
1970年 | 4篇 |
1969年 | 4篇 |
排序方式: 共有1174条查询结果,搜索用时 15 毫秒
1.
S. B. Hanna F. F. Abdel-Mohsen 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1985,35(6):285-290
A beta-silicon carbide powder with a surface area of 30m2g?l and a mean particle size of < 1μm was produced from the thermal conversion of silicon resin in an atmosphere of hydrogen. The amount of product increased with increasing iron content (0–2.1 wt%) and firing temperature (1200–1500°C). Chemical analysis, X-ray diffraction and i.r. absorption spectrometry were used to follow the conversion reaction. 相似文献
2.
Hanna Pietil inen Tarja Saesmaa Veli-Pekka Tanninen 《Drug development and industrial pharmacy》1996,22(11):1063-1073
In order to investigate the formation of organic salts of drugs, two salts of pindolol were prepared using salt-forming agents which were crystalline and suitable for physical studies in the solid state. The stoichiometry of the products, pindolol benzoate and pindolol 2-methoxyphenylacetate, was established by elemental analysis. The precipitates formed were assessed by differential scanning calorimetry (DSC), thermogravimetry (TG), x-ray powder diffractometry (XRPD) and Fourier transform-infrared spectrometry (FT-IR). According to the TG and DSC curves, there was no water of crystallization in the precipitates, and the products were thermally stable. Both precipitates gave one sharp melting endotherm which differed from the endotherms of the starting compounds. The x-ray dipaction pattern of the precipitates direred clearly from those of the starting materials, acid and base. The products showed absorption by FT-IR typical of carboxylic acid salts at about 1640-1540 cm-1. The carbonyl absorption indicative of the carboxylic acid group of benzoic acid or 2-methonyphenylacetic acid was not detectable in the spectra of the precipitates. All this indicates that two new crystalline organic salts (1:1) were formed during the syntheses. 相似文献
3.
Electrical conductivity of concrete containing silica fume 总被引:15,自引:0,他引:15
S. A. Abo El-Enein M. F. Kotkata G. B. Hanna M. Saad M. M. Abd El Razek 《Cement and Concrete Research》1995,25(8):1615-1620
The influence of silica fume on concrete properties represents an important technical research. In general, silica fume tends to improve both mechanical characteristics and durability of concrete. Thus the electrical properties of concrete containing silica fume can be studied to clarify its physical performance during hydration. The electrical conductivity of neat cement, mortar and concrete pastes was measured during setting and hardening. The ordinary Portland cement was partially replaced by different amounts of silica fume by weight. The changes in the electrical conductivity were reported during setting and hardening after gauging with water. The results of this study showed that the electrical conductivity can be used as an indication for the setting characteristics as well as the structural changes of the hardened pastes made with and without silica fume. 相似文献
4.
5.
Khalid Quertite Hanna Enriquez Nicolas Trcera Yongfeng Tong Azzedine Bendounan Andrew J. Mayne Gérald Dujardin Pierre Lagarde Abdallah El kenz Abdelilah Benyoussef Yannick J. Dappe Abdelkader Kara Hamid Oughaddou 《Advanced functional materials》2021,31(7):2007013
Silicene, a new 2D material has attracted intense research because of the ubiquitous use of silicon in modern technology. However, producing free-standing silicene has proved to be a huge challenge. Until now, silicene could be synthesized only on metal surfaces where it naturally forms strong interactions with the metal substrate that modify its electronic properties. Here, the authors report the first experimental evidence of silicene nanoribbons on an insulating NaCl thin film. This work represents a major breakthrough, for the study of the intrinsic properties of silicene, and by extension to other 2D materials that have so far only been grown on metal surfaces. 相似文献
6.
Raphael J. Gübeli Désirée Hövermann Hanna Seitz Balder Rebmann Ronald G. Schoenmakers Martin Ehrbar Ghislaine Charpin‐El Hamri Marie Daoud‐El Baba Martin Werner Martin Müller Wilfried Weber 《Advanced functional materials》2013,23(43):5355-5362
Remote‐controlled drug depots represent a highly valuable tool for the timely controlled administration of pharmaceuticals in a patient compliant manner. Here, the first pharmacologically controlled material that allows for the scheduled induction of a medical response in mice is described. To this aim, a novel, humanized biohybrid material that releases its cargo in response to a small‐molecule stimulus licensed for human use is developed. The functionality of the material in mice is demonstrated by the remote‐controlled delivery of a vaccine against the oncogenic human papillomavirus type 16. It is shown that the biohybrid depot‐mediated immunoprotection is equivalent to the classical multi‐injection‐based vaccination. These results indicate that this material can be used as a universal remote‐controlled vehicle for the patient‐compliant delivery of vaccines and pharmaceuticals. 相似文献
7.
Fardi H.Z. Winston D.W. Hayes R.E. Hanna M.C. 《Electron Devices, IEEE Transactions on》2000,47(5):915-921
The energy balance equations coupled with drift diffusion transport equations in heterojunction semiconductor devices are solved modeling hot electron effects in single quantum well p-i-n photodiodes. The transports across the heterojunction boundary and through quantum wells are modeled by thermionic emission theory. The simulation and experimental current-voltage characteristics of a single p-i-n GaAs/Al xGa1-xAs quantum well agree over a wide range of current and voltage, The GaAs/AlxGa1-xAs p-i-n structures with multi quantum wells are simulated and the dark current voltage characteristics, short circuit current, and open circuit voltage results are compared with the available experimental data, In agreement with the experimental data, simulated results show that by adding GaAs quantum wells to the conventional cell made of wider bandgap Alx Ga1-xAs, short circuit current is improved, but there is a loss of the voltage of the host cell, In the limit of radiative recombination, the maximum power point of an Al0.35Ga0.65As/GaAs p-i-n photodiode with 30-quantum-well periods is higher than the maximum power point of similar conventional bulk p-i-n cells made out of either host Al0.35Ga0.65As or bulk GaAs material 相似文献
8.
K.?AllakhverdievEmail author S.?Hanna A.?Kulibekov S.??zbek E.?Gunay D.?Huseinova 《Journal of Infrared, Millimeter and Terahertz Waves》2005,26(12):1741-1755
We report room-temperature measurements of the mid- and far-IR absorption throughout the 400 – 4000 cm?1 and 10 – 700 cm?1 spectral ranges and the resistivity of layered p-GaSe and p-TlInS2 intercalated with Li+. Intercalation was performed by immersing Bridgman grown crystals in 0.5 M solutions of LiCl in distilled water at ambient conditions. The crystal structure and the stoichiometry of the grown crystals were determined by X-ray diffraction and XRF methods. It is shown that intercalation does not change the frequency of the IR-, and Raman active low-frequency“rigid layer” mode (GaSe), the space symmetry group or the lattice parameters of the crystals. It was found that for both crystals, the resistivity versus time dependencies are nearly the same. Three ranges in the resistivity-intercalation time dependencies were explained qualitatively. The resistivity increase due to intercalation was explained by assuming that the intercalated lithium ions act as ionized donors and compensate the host p-type crystal. The highest degree of compensation for GaSe and TlInS2 crystals was achieved after intercalation during 12 and 10 days, respectively. 相似文献
9.
10.