全文获取类型
收费全文 | 12702篇 |
免费 | 665篇 |
国内免费 | 58篇 |
专业分类
电工技术 | 278篇 |
综合类 | 22篇 |
化学工业 | 3097篇 |
金属工艺 | 243篇 |
机械仪表 | 323篇 |
建筑科学 | 466篇 |
矿业工程 | 14篇 |
能源动力 | 738篇 |
轻工业 | 1565篇 |
水利工程 | 151篇 |
石油天然气 | 209篇 |
武器工业 | 4篇 |
无线电 | 1264篇 |
一般工业技术 | 2077篇 |
冶金工业 | 639篇 |
原子能技术 | 99篇 |
自动化技术 | 2236篇 |
出版年
2024年 | 40篇 |
2023年 | 243篇 |
2022年 | 571篇 |
2021年 | 772篇 |
2020年 | 533篇 |
2019年 | 582篇 |
2018年 | 688篇 |
2017年 | 507篇 |
2016年 | 628篇 |
2015年 | 365篇 |
2014年 | 584篇 |
2013年 | 1026篇 |
2012年 | 720篇 |
2011年 | 847篇 |
2010年 | 605篇 |
2009年 | 584篇 |
2008年 | 496篇 |
2007年 | 438篇 |
2006年 | 333篇 |
2005年 | 269篇 |
2004年 | 249篇 |
2003年 | 201篇 |
2002年 | 219篇 |
2001年 | 119篇 |
2000年 | 111篇 |
1999年 | 126篇 |
1998年 | 179篇 |
1997年 | 166篇 |
1996年 | 109篇 |
1995年 | 118篇 |
1994年 | 83篇 |
1993年 | 73篇 |
1992年 | 73篇 |
1991年 | 38篇 |
1990年 | 46篇 |
1989年 | 60篇 |
1988年 | 65篇 |
1987年 | 39篇 |
1986年 | 33篇 |
1985年 | 53篇 |
1984年 | 62篇 |
1983年 | 51篇 |
1982年 | 29篇 |
1981年 | 28篇 |
1980年 | 35篇 |
1979年 | 28篇 |
1978年 | 23篇 |
1977年 | 28篇 |
1976年 | 37篇 |
1974年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Deborah Oliveira De Fusco Leonardo Lucas Madaleno Vanildo Luiz Del Bianchi Aline da Silva Bernardo Rafael Roberto Assis Gustavo Henrique de Almeida Teixeira 《International Journal of Food Science & Technology》2019,54(7):2416-2424
Alcohol-free beer with isotonic properties is getting more popular and its production can be carried out by different production strategies; however, interrupted fermentation is still a challenge. Therefore, the objective of this study was to develop a low-alcohol isotonic beer (<0.5% v/v) by interrupted fermentation. Moreover, the major objective is to compare the developed product to commercial beverages (sports drinks, ‘Pilsen' regular beer, alcohol-free beers and low-alcohol isotonic beer). The beverages were evaluated based on pH, alcohol content (% v/v), total titratable acidity (mEq L−1), osmolality (mOsmol kg−1), bitterness International Bitterness Units, colour European Brewery Convention, total phenolic compounds (mg L−1 gallic acid), reducing and total sugars (%) and Na and K contents (mg L−1). The developed low-alcohol isotonic beer presented characteristics similar to sports drinks, with the advantage of being richer in phenolic compounds and suitable osmolality. Despite salts were added in its formulation, the grades attributed to all beers employed in the sensory evaluation, as well as the purchase intention did not present significant differences. 相似文献
2.
3.
4.
5.
6.
This paper considers the state‐dependent interference relay channel (SIRC) in which one of the two users may operate as a secondary user and the relay has a noncausal access to the signals from both users. For discrete memoryless SIRC, we first establish the achievable rate region by carefully merging Han‐Kobayashi rate splitting encoding technique, superposition encoding, and Gelfand‐Pinsker encoding technique. Then, based on the achievable rate region that we derive, the capacity of the SIRC is established in many different scenarios including (a) the weak interference regime, (b) the strong interference regime, and (c) the very strong interference regime. This means that our capacity results contain all available known results in the literature. Next, the achievable rate region and the associated capacity results are also evaluated in the case of additive Gaussian noise. Additionally, many numerical examples are investigated to show the value of our theoretical derivations. 相似文献
7.
8.
Ahmed Obaid M. Alzahrani M. Sh. Abdel-wahab Meshari Alayash M. S. Aida 《Journal of Materials Science: Materials in Electronics》2018,29(19):16317-16324
In this work, p-NiO/n-ZnO heterostructures were successfully prepared at room temperature using RF sputtering technique. The influence of ZnO layer thickness on the performance of the heterojunction was investigated. The deposited ZnO layers have a hexagonal Wurtzite structure with preferable growth orientations along (002) and (103) for thinner films. Increasing the thickness results in more crystallographic orientation randomness. The current–voltage measurements of the realized heterojunctions showed a clear rectifying behavior. The measured ideality factor varies from 2.5 to 1.6 according to the thickness of ZnO layer. The series resistance of the device is enlarged with increasing ZnO thickness. The deduced parameters from the I–V characteristics suggest that 200 nm is the optimal thickness of the ZnO layer according to our experimental conditions. We attribute the relatively better performance of this thickness to achieving reasonable compensation between serial resistance and ideality factor. The best heterojunction was tested and successfully used as a UV detector. 相似文献
9.
In this work it is presented a study on the residence time distribution (RTD) of particles in a co-current pilot-plant spray dryer operated with a rotary atomization system. A nuclear technique is applied to investigate the RTD responses of spray dryers. The methodology is based on the injection of a radioisotope tracer in the feed stream followed by the monitoring of its concentration at the outlet stream. The experiments were performed during the drying of aqueous suspensions of gadolinium oxide. The RTD responses obtained experimentally presented good reproducibility, indicating that the technique applied is well suited to investigating fluid-dynamics of spray dryers. In addition to the experimental investigation, a mathematical model was used to describe the RTD experimental curves. 相似文献
10.
PURPOSE: To assess the role postoperative mydriatics play after extracapsular cataract extraction (ECCE) and posterior chamber intraocular lens (IOL) implantation in causing iris modifications and in controlling inflammation. SETTING: Outpatients Department, Ninewells Hospital, Dundee, Scotland. METHODS: The prospective study comprised 136 patients who had standardized ECCE. Half the patients used a mydriatic for 2 weeks postoperatively. Anterior chamber activity, pain, and eye redness were evaluated at 2 weeks postoperatively; pupil shape, peripheral anterior synechias, IOL position, and iris adhesions, at 6 weeks. RESULTS: Iris-lens adhesions were significantly more common in the group using a mydriatic. There was no difference between the two groups in postoperative inflammation. CONCLUSION: Mydriatics should not be used routinely after ECCE with posterior chamber IOL implantation. 相似文献