全文获取类型
收费全文 | 2885篇 |
免费 | 192篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 18篇 |
综合类 | 4篇 |
化学工业 | 1005篇 |
金属工艺 | 22篇 |
机械仪表 | 52篇 |
建筑科学 | 79篇 |
矿业工程 | 5篇 |
能源动力 | 59篇 |
轻工业 | 439篇 |
水利工程 | 16篇 |
石油天然气 | 12篇 |
无线电 | 208篇 |
一般工业技术 | 512篇 |
冶金工业 | 247篇 |
原子能技术 | 9篇 |
自动化技术 | 391篇 |
出版年
2024年 | 9篇 |
2023年 | 32篇 |
2022年 | 208篇 |
2021年 | 226篇 |
2020年 | 70篇 |
2019年 | 91篇 |
2018年 | 82篇 |
2017年 | 94篇 |
2016年 | 119篇 |
2015年 | 96篇 |
2014年 | 127篇 |
2013年 | 187篇 |
2012年 | 167篇 |
2011年 | 210篇 |
2010年 | 142篇 |
2009年 | 131篇 |
2008年 | 159篇 |
2007年 | 116篇 |
2006年 | 106篇 |
2005年 | 98篇 |
2004年 | 69篇 |
2003年 | 52篇 |
2002年 | 39篇 |
2001年 | 40篇 |
2000年 | 29篇 |
1999年 | 26篇 |
1998年 | 89篇 |
1997年 | 61篇 |
1996年 | 42篇 |
1995年 | 21篇 |
1994年 | 18篇 |
1993年 | 16篇 |
1992年 | 2篇 |
1991年 | 6篇 |
1990年 | 11篇 |
1989年 | 10篇 |
1988年 | 6篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 9篇 |
1983年 | 6篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1976年 | 10篇 |
1975年 | 2篇 |
1968年 | 2篇 |
排序方式: 共有3078条查询结果,搜索用时 8 毫秒
1.
2.
Daniela M. Nevskaia Maria Luisa Rojas Cervantes Antonio Guerrero Ruíz Juan de Dios Lpez Gonzlez 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,63(3):249-256
Adsorption of Triton X-100 on various silica substrates has been investigated. A number of solids, including a natural quartz, this quartz washed with HCl acid and subsequently heated at 1273 K; two aerosils and one Kieselgel silicas were studied. These solids exhibit surface areas in the range of 5 to 430 m2 g?1. All the Triton adsorption isotherms display an S-shape at the adsorption temperatures studied (298 and 308 K). It has been found that the pretreatments of natural quartz (by water washing, impurities removed by acid and/or high temperature calcination) affect considerably the amounts of TX-100 adsorbed. Measurements of surface composition have been made by X-ray photoelectron spectroscopy (XPS) with particular emphasis on the presence of impurities and on the number of OH groups at the surface of the samples. The nature of the surface hydroxyl has also been studied by infrared spectroscopy. Furthermore, the specific number of hydroxyl groups on the surface of the silica samples has been determined by thermogravimetric analysis. Finally an attempt to correlate solid surface characteristics with adsorption isotherms has been developed. 相似文献
3.
Corazza G.E. Ferrari G. 《IEEE transactions on information theory / Professional Technical Group on Information Theory》2002,48(11):3003-3008
New bounds are proposed for the Marcum Q-function, which is defined by an integral expression where the 0th-order modified Bessel function appears. The proposed bounds are derived by suitable approximations of the 0th-order modified Bessel function in the integration region of the Marcum Q-function. They prove to be very tight and outperform bounds previously proposed in the literature. In particular, the proposed bounds are noticeably good for large values of the parameters of the Marcum Q-function, where previously introduced bounds fail and where exact computation of the function becomes critical due to numerical problems 相似文献
4.
Thermal conductivity of apple and potato samples was measured by means of a specifically designed apparatus based on Fitch's method. The thermal conductivity was determined at various moisture contents at the sample mean temperature of 30 °C. As expected the conductivity decreases with the decrease in moisture content. Thermal conductivity data were correlated with moisture content using a straight line. 相似文献
5.
6.
F. Ferrari M. Bertoni S. Rossi M. C. Bonferoni C. Caramella M. J. Waring M. E. Aulton 《Drug development and industrial pharmacy》1996,22(12):1223-1230
Hydration is believed to modify the mechanical properties (resistance to stress) and the rheological (viscoelastic) properties of hydrocolloid dressings. Rheomechanical properties in turn influence adhesional properties. In this work the relationships between the degree of hydration and the rheomechanical and the adhesive properties of two different commercial dressings (regular and nondispersive) were investigated. The two dressings showed different hydration characteristics. The regular dressing takes up water rapidly and tends to reach saturation after 12 hr. As the dressing swells and loses its integrity there is an accompanying reduction of both rheomechanical and adhesive properties. The nondispersive dressing exhibits a linear water uptake profile over extended periods of hydration up to 4 days. It does not swell and its rheomechanical and adhesive properties remain unchanged after hydration, The comparative evaluation of the results obtained with the various methods points to the relevance of mechanical and viscoelastic properties to the functionality assessment of dressings. 相似文献
7.
R Pérez Ferrari L Lambra?o R Aranda L Ferrabone 《Canadian Metallurgical Quarterly》1993,18(3):229-232
We studied the incidence of infection with Helicobacter pylori in Panamanians with chronic dyspepsia, gastric or duodenal ulcer, gastritis or gastric cancer. The histopathology was positive in 54 (81%) of 66 patients; the urea test was positive in 52 (82.5%) of 63 cases; the impromptu was positive in 51 (79.6) of 64 patients; the endoscopic examination was positive in 64 (82.9%) of 77 examinations. 相似文献
8.
Karin Metz Stephanie Fl?ter Christoph Kr?ger Carolin Donath Daniela Piontek Sabine Gradl 《Nicotine & tobacco research》2007,9(8):853-863
Smokers with smoking-related diseases who are hospitalized in rehabilitation centers should be offered smoking cessation. This is the first study evaluating whether telephone booster sessions after intensive inpatient treatment are an effective strategy. The present study was conducted in 13 rehabilitation centers for somatic disorders as a prospective multicenter study with a randomized treatment-control group design. We compared abstinence rates after hospital discharge from treatment that included a group smoking cessation program with (treatment group) and without telephone booster sessions (control group). Data from 290 smokers were analyzed. After 6 and 12 months the treatment group achieved abstinence rates twice as high as those of the control group. Men profited more from telephone booster sessions than did women. Results indicated that telephone booster sessions were highly effective (even) after an inherently intensive group program during a hospital stay. Further research should focus on the special needs of women receiving telephone counseling. 相似文献
9.
Ferrari A. Ghislotti G. Balsamo S. Spano V. Trezzi F. 《Lightwave Technology, Journal of》2002,20(3):515-518
The behavior of fiber Bragg grating (FBG)-stabilized 980-nm pump lasers is experimentally and theoretically investigated. The subkilohertz noise in the emitted power is related to the coexistence and oscillation between coherence collapsed state and narrow linewidth single-mode (SM) operation. These findings are theoretically discussed by using a multimode time-domain model that accounts for spatial harmonics and includes nonlinear gain. One additional result is an indication that kinks in the L-I curve can be explained by nonlinear mode competition 相似文献