全文获取类型
收费全文 | 57439篇 |
免费 | 3356篇 |
国内免费 | 77篇 |
专业分类
电工技术 | 404篇 |
综合类 | 134篇 |
化学工业 | 12584篇 |
金属工艺 | 1078篇 |
机械仪表 | 1179篇 |
建筑科学 | 1712篇 |
矿业工程 | 137篇 |
能源动力 | 1307篇 |
轻工业 | 10209篇 |
水利工程 | 566篇 |
石油天然气 | 295篇 |
武器工业 | 7篇 |
无线电 | 2315篇 |
一般工业技术 | 9210篇 |
冶金工业 | 11645篇 |
原子能技术 | 248篇 |
自动化技术 | 7842篇 |
出版年
2024年 | 119篇 |
2023年 | 529篇 |
2022年 | 1030篇 |
2021年 | 1697篇 |
2020年 | 1235篇 |
2019年 | 1391篇 |
2018年 | 2214篇 |
2017年 | 2193篇 |
2016年 | 2311篇 |
2015年 | 1695篇 |
2014年 | 2179篇 |
2013年 | 4508篇 |
2012年 | 3490篇 |
2011年 | 3365篇 |
2010年 | 2726篇 |
2009年 | 2480篇 |
2008年 | 2356篇 |
2007年 | 2112篇 |
2006年 | 1557篇 |
2005年 | 1305篇 |
2004年 | 1161篇 |
2003年 | 1148篇 |
2002年 | 988篇 |
2001年 | 770篇 |
2000年 | 700篇 |
1999年 | 762篇 |
1998年 | 3692篇 |
1997年 | 2455篇 |
1996年 | 1612篇 |
1995年 | 954篇 |
1994年 | 740篇 |
1993年 | 790篇 |
1992年 | 305篇 |
1991年 | 281篇 |
1990年 | 217篇 |
1989年 | 232篇 |
1988年 | 242篇 |
1987年 | 213篇 |
1986年 | 176篇 |
1985年 | 210篇 |
1984年 | 188篇 |
1983年 | 134篇 |
1982年 | 170篇 |
1981年 | 196篇 |
1980年 | 216篇 |
1979年 | 103篇 |
1978年 | 103篇 |
1977年 | 351篇 |
1976年 | 747篇 |
1973年 | 94篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
23.
24.
High‐intensity sweeteners in espresso coffee: ideal and equivalent sweetness and time–intensity analysis 下载免费PDF全文
Bruna M. Azevedo Flávio L. Schmidt Helena M. A. Bolini 《International Journal of Food Science & Technology》2015,50(6):1374-1381
The efficient substitution of sucrose by a sweetener in beverages requires the application of some sensory techniques. First, one must determine the concentrations of the sweeteners under study, equivalent in sweetness to the ideal sucrose concentration. In addition, it is fundamental to determine which is most similar to sucrose. The objectives of this study were to determine the ideal sweetness for espresso coffee and the equivalent concentrations in sweetness of different sweeteners, as well as characterise the time–intensity profile of each sweetener in relation to sweetness. The sweeteners evaluated were sucralose, aspartame, neotame, a cyclamate/saccharin mixture (2:1) and stevia. The sucrose concentration considered ideal by consumers was 12.5% (w/v), and the equivalent concentrations of the sweeteners were 0.0159% for sucralose, 0.0549% for aspartame, 0.0016% for neotame, 0.0359% for the cyclamate/saccharin mixture and 0.0998% for stevia. The time–intensity analysis indicated that possibly the sweeteners neotame, aspartame and sucralose would be the best substitutes for sucrose. 相似文献
25.
26.
Zdeněk Slanina Filip Uhlík Lipiao Bao Takeshi Akasaka Xing Lu Ludwik Adamowicz 《Fullerenes, Nanotubes and Carbon Nanostructures》2020,28(7):565-570
AbstractRelative populations of four energy-lowest IPR (isolated-pentagon-rule) isomers of Eu@C86 are computed using the Gibbs energy based on characteristics from density functional theory calculations (M06-2X/3-21G?~?SDD entropy term, M06-2X/6-31G*~SDD or B2PLYP(D)/6-31G*~SDD energetics). The calculations confirm that the recently isolated Eu@C1(7)-C86 species is a major isomer in a relevant temperature region. Relationship to the empty C86 cages is discussed, too. 相似文献
27.
Alfredo M. Gravagnuolo Eden Morales‐Narváez Charlene Regina Santos Matos Sara Longobardi Paola Giardina Arben Merkoçi 《Advanced functional materials》2015,25(38):6084-6092
Class I hydrophobin Vmh2, a peculiar surface active and versatile fungal protein, is known to self‐assemble into chemically stable amphiphilic films, to be able to change wettability of surfaces, and to strongly adsorb other proteins. Herein, a fast, highly homogeneous and efficient glass functionalization by spontaneous self‐assembling of Vmh2 at liquid–solid interfaces is achieved (in 2 min). The Vmh2‐coated glass slides are proven to immobilize not only proteins but also nanomaterials such as graphene oxide (GO) and quantum dots (QDs). As models, bovine serum albumin labeled with Alexa 555 fluorophore, anti‐immunoglobulin G antibodies, and cadmium telluride QDs are patterned in a microarray fashion in order to demonstrate functionality, reproducibility, and versatility of the proposed substrate. Additionally, a GO layer is effectively and homogeneously self‐assembled onto the studied functionalized surface. This approach offers a quick and simple alternative to immobilize nanomaterials and proteins, which is appealing for new bioanalytical and nanobioenabled applications. 相似文献
28.
29.
30.