全文获取类型
收费全文 | 951篇 |
免费 | 79篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 28篇 |
综合类 | 15篇 |
化学工业 | 230篇 |
金属工艺 | 41篇 |
机械仪表 | 37篇 |
建筑科学 | 66篇 |
矿业工程 | 10篇 |
能源动力 | 41篇 |
轻工业 | 120篇 |
水利工程 | 17篇 |
石油天然气 | 11篇 |
武器工业 | 1篇 |
无线电 | 92篇 |
一般工业技术 | 137篇 |
冶金工业 | 53篇 |
原子能技术 | 7篇 |
自动化技术 | 131篇 |
出版年
2024年 | 2篇 |
2023年 | 13篇 |
2022年 | 24篇 |
2021年 | 37篇 |
2020年 | 29篇 |
2019年 | 27篇 |
2018年 | 51篇 |
2017年 | 53篇 |
2016年 | 54篇 |
2015年 | 35篇 |
2014年 | 48篇 |
2013年 | 89篇 |
2012年 | 63篇 |
2011年 | 66篇 |
2010年 | 74篇 |
2009年 | 41篇 |
2008年 | 46篇 |
2007年 | 51篇 |
2006年 | 29篇 |
2005年 | 20篇 |
2004年 | 25篇 |
2003年 | 27篇 |
2002年 | 20篇 |
2001年 | 9篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1998年 | 14篇 |
1997年 | 20篇 |
1996年 | 8篇 |
1995年 | 9篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1986年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1977年 | 2篇 |
1976年 | 6篇 |
1975年 | 3篇 |
1917年 | 1篇 |
1909年 | 1篇 |
1907年 | 1篇 |
排序方式: 共有1037条查询结果,搜索用时 0 毫秒
91.
Khurram A. Khan Ramazan Kahraman Esam Z. Hamad Shaikh A. Ali Syed H. Hamid 《应用聚合物科学杂志》1997,64(4):645-652
A liquid crystalline polymer (LCP) was synthesized by an interfacial polycondensation reaction at room temperature from terephthaloyl chloride and p,p′-dihydroxydiphenyl sulfone. The LCP synthesized was so stable and molecularly rigid that it did not show any phase transition until it degraded at about 320°C. Composites of the LCP with polycarbonate (PC), polystyrene (PS), and sulfonated polystyrene (SPS) were formed by compression molding at a temperature at which the thermoplastic matrix was in the melt state. They were thermally analyzed by differential scanning calorimetry. Tensile specimens were cut from the compression-molded plates, and mechanical tests were performed. The morphology of the material systems was studied by performing scanning electron microscopy analysis on cryogenically fractured specimens. For LCP/PS and LCP/SPS systems, a sharp two-phase morphology was formed, which suggested poor interfacial adhesion. The tensile strength of both systems decreased with LCP addition. The LCP/PC system also revealed a two-phase morphology; however, the interfaces between the LCP domains and the PC matrix were not so well defined, showing better interfacial adhesion than the two previous systems studied. Stronger bonding between the LCP and PC resulted in a significant improvement in the mechanical behavior of PC by LCP addition. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 645–652, 1997 相似文献
92.
J Wuttke A Budwig M Drochner H Kämmerling FJ Kayser H Kleines V Ossovyi LC Pardo M Prager D Richter GJ Schneider H Schneider S Staringer 《The Review of scientific instruments》2012,83(7):075109
SPHERES is a third-generation neutron backscattering spectrometer, located at the 20 MW German neutron source FRM II and operated by the Ju?lich Centre for Neutron Science. It offers an energy resolution (fwhm) better than 0.65 μeV, a dynamic range of ±?31 μeV, and a signal-to-noise ratio of up to 1750:1. 相似文献
93.
94.
In this study, a reactive fibrous adsorbent was prepared by graft copolymerization of Acrylamide (AAm) onto poly(ethylene
terephthalate) (PET) fibers and the adsorption properties of Pb(II) ion from aqueous solution by the reactive fibers were
examined by batch equilibration technique. The effects of graft yield, pH, adsorption time, initial ion concentration and
adsorption temperature on the adsorption amount of Pb(II) ion was studied. The results show that the adsorption amounts of
Pb(II) ion increased with grafting yield, shaking time, initial ion concentration and adsorption temperature. Adsorption of
Pb(II) ion was strongly affected by pH. A Lagergren pseudo-second-order was the model that best described the adsorption mechanism.
It was found that the adsorption isotherm of the Pb(II) ion fit Langmuir-type isotherms. From the Langmuir equation the adsorption
capacity was found as 39.57 mg/g fiber for Pb(II) ion for the copolymer with a graft yield of 15.7%. Quantitative desorption
of Pb(II) from reactive fibers were found to be 96% by 5 M HNO3. Five adsorption–desorption cycles demonstrated that the reactive fibers were suitable for repeated use without considerable
change in adsorption capacity. The results of the thermodynamic study indicated that the adsorption processes was endothermic
and spontaneous. 相似文献
95.
The mechanical properties and thermal conductivity of concretes including pumice aggregate (PA) exposed to elevated temperature were analyzed by thermal conductivity, compressive strength, flexure strength, dynamic elasticity modulus (DEM) and dry unit weight tests. PA concrete specimens were cast by replacing a varying part of the normal aggregate (0–2 mm) with the PA. All concrete samples were prepared and cured at 23 ± 10C lime saturated water for 28 days. Compressive strength of concretes including PA decreased that reductions were 14, 19, 25 and 34% for 25, 50, 75 and 100% PA, respectively. The maximum thermal conductivity of 1.9382 W/mK was observed with the control samples containing normal aggregate. The tests were carried out by subjecting the samples to a temperature of 0, 100, 200, 300, 400 500, 600 and 700 °C for 3 h, then cooling by air cooling or in water method. The results indicated that all concretes exposed to a temperature of 500 and 700 °C occurred a significant decrease in thermal conductivity, compressive strength, flexure strength and DEM. An artificial neural network (ANN) approach was used to model the thermal and mechanical properties of PA concretes. The predicted values of the ANN were in accordance with the experimental data. The results indicate that the model can predict the concrete properties after elevated temperatures with adequate accuracy. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
96.
Respiratory bioaerosol deposition from a cough and recovery of viable viruses on nearby seats in a cabin environment 总被引:1,自引:0,他引:1
Cunteng Wang Jingcui Xu Sau Chung Fu Ka Chung Chan Christopher Y. H. Chao 《Indoor air》2021,31(6):1913-1925
Respiratory bioaerosol deposition in public transport cabins is critical for risk analysis and control of contact transmission. In this work, we built a two-row four-seat setup and an air duct system to simulate a cabin environment. A thermal manikin on the rear left-hand seat was taken as the infected passenger (IP) and “coughed” three times through a cough generator. The deposited viruses and droplets on nearby seats were measured by a cultivation method and microscope, respectively. The effects of seat backrest and overhead gasper jet were studied. Results showed that the number of deposited virus on the front seat was one order of magnitude higher than that on other seats which only contained droplets smaller than 10 µm in diameter. When the backrest was 15 cm higher than the cough, the deposited number of viruses was reduced to 5% of that with the backrest at the same height with the cough. The gasper jet above the IP with a velocity of 1.5 m/s can reduce the deposited viruses to 4% of that with gasper off. It indicates that both the gasper jet and backrest can work as mitigation measures to block the cough jet and protect the nearby passengers. 相似文献
97.
98.
99.
100.
Hyun‐Ju Yang Ji‐Hyeon Lee Ka‐Yeon Lee Kyung Bin Song 《International Journal of Food Science & Technology》2017,52(2):398-403
To develop a value‐added product, we used the under‐utilised seaweed Undaria pinnatifida as a source material for the fabrication of a biodegradable film by extracting U. pinnatifida protein (UPP). UPP/gelatine composite films with different constituent ratios were prepared. In addition, the UPP/gelatine composite films containing vanillin (0.05%, 0.1% and 0.5%) were prepared as antimicrobial packaging material. To evaluate the utility of the UPP composite film containing 0.5% vanillin as food packaging material, smoked chicken breast samples inoculated with Escherichia coli were packed with the film and stored at 4 °C for 10 days. It was observed that packaging of smoked chicken breast with the UPP composite film containing vanillin decreased the population of the inoculated E. coli by 1.12 log CFU g?1 compared with that in the control sample. Thus, the UPP/gelatine composite film with added vanillin can be utilised as a packaging material for smoked chicken breast. 相似文献