全文获取类型
收费全文 | 84913篇 |
免费 | 19544篇 |
国内免费 | 3155篇 |
专业分类
电工技术 | 3845篇 |
技术理论 | 1篇 |
综合类 | 3928篇 |
化学工业 | 24309篇 |
金属工艺 | 3142篇 |
机械仪表 | 3884篇 |
建筑科学 | 5103篇 |
矿业工程 | 1312篇 |
能源动力 | 1954篇 |
轻工业 | 12262篇 |
水利工程 | 1406篇 |
石油天然气 | 2054篇 |
武器工业 | 466篇 |
无线电 | 12235篇 |
一般工业技术 | 16429篇 |
冶金工业 | 2478篇 |
原子能技术 | 598篇 |
自动化技术 | 12206篇 |
出版年
2024年 | 279篇 |
2023年 | 819篇 |
2022年 | 1608篇 |
2021年 | 2251篇 |
2020年 | 2923篇 |
2019年 | 4368篇 |
2018年 | 4491篇 |
2017年 | 4922篇 |
2016年 | 5286篇 |
2015年 | 5960篇 |
2014年 | 6415篇 |
2013年 | 8082篇 |
2012年 | 6336篇 |
2011年 | 6436篇 |
2010年 | 6323篇 |
2009年 | 6116篇 |
2008年 | 5549篇 |
2007年 | 5180篇 |
2006年 | 4677篇 |
2005年 | 3873篇 |
2004年 | 3120篇 |
2003年 | 2673篇 |
2002年 | 2553篇 |
2001年 | 2183篇 |
2000年 | 1883篇 |
1999年 | 1073篇 |
1998年 | 418篇 |
1997年 | 355篇 |
1996年 | 286篇 |
1995年 | 213篇 |
1994年 | 190篇 |
1993年 | 161篇 |
1992年 | 118篇 |
1991年 | 107篇 |
1990年 | 71篇 |
1989年 | 57篇 |
1988年 | 41篇 |
1987年 | 39篇 |
1986年 | 32篇 |
1985年 | 16篇 |
1984年 | 12篇 |
1983年 | 15篇 |
1982年 | 18篇 |
1981年 | 4篇 |
1980年 | 8篇 |
1979年 | 11篇 |
1978年 | 10篇 |
1977年 | 12篇 |
1976年 | 13篇 |
1975年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Keran Su Kim Huey Ee Jingcan Sun Shao Quan Liu Benjamin Lassabliere Ulrich Feiter Yunle Huang Rui Min Vivian Goh Aileen Pua Bin Yu 《International Journal of Food Science & Technology》2022,57(3):1666-1678
The structural diversity of polyphenols and the inherent limitations of current extraction techniques pose a challenge to extract polyphenols using a simple and green method. Hence, in this study, a method was developed to simultaneously fractionate multiple classes of polyphenols by only varying ethanol-water solutions. Honeybush tea, which is rich in polyphenols, was selected as a model for this study. Solvent extraction followed by solid-phase extraction (SPE) was developed to obtain a polyphenol-rich fraction from six honeybush samples. Based on a gradient elution programme (10%, 30%, 50%, 70% and 90% (v/v) ethanol-water solution) of SPE, the Strata X cartridge showed a better recovery of most targeted polyphenols under 0.9 mL of the drying volume and 1 mL min−1 of the dispensing speed. The elution programme for fractionating most polyphenols was as follows: single elution with 50% ethanol, followed by twice elution with 70% ethanol. The antioxidant capacity was used to analyse the differences among the polyphenol-rich fractions from six honeybush samples. Principal component analysis (PCA) revealed that unfermented C. genistoides (GG) has the greatest antioxidant capacity among the honeybush species studied. Additionally, mangiferin, isomangiferin and vicenin-2 were the main contributors to the antioxidant capacity in six honeybush fractions according to the correlation study. 相似文献
12.
Amino acid modified polyaspartic acids were evaluated as calcium-scale inhibitors. Feasibility of scale inhibition experiments was analyzed by molecular dynamics simulation and Gaussian optimization, and the scale inhibition mechanism was theoretically analyzed. Scale inhibition performance was studied by scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, static scale inhibition experiments, and electrochemical performance testing, which provided an experimental basis for the molecular dynamics simulation. The experimental results showed that Arg-SA-PASP has better scale inhibition and corrosion inhibition performance than His-SA-PASP. The scale inhibition effect increased with increasing concentration. Electrochemical tests indicated that Arg-SA-PASP is an excellent scale and corrosion inhibitor. 相似文献
13.
Fluorescence‐Activated Cell Sorters: Standing Surface Acoustic Wave (SSAW)‐Based Fluorescence‐Activated Cell Sorter (Small 40/2018) 下载免费PDF全文
14.
15.
16.
SPEEK/cSMM membrane for simultaneous electricity generation and wastewater treatment in microbial fuel cell 下载免费PDF全文
17.
Efficacy of Crude and Purified Chitinases (SsChi50) Extracted from Offal Red Scorpion Fish in Biological Control of Chickpea Weevil (Callosobruchus maculatus L.) 下载免费PDF全文
18.
Quality enhancement of the abundant under‐valued crustacean,lobster krill (Munida spp.), during its chilled storage 下载免费PDF全文
Bibiana García‐Soto José M. Miranda Jorge Barros‐Velázquez Santiago P. Aubourg 《International Journal of Food Science & Technology》2015,50(3):708-716
Lobster krill (Munida genus) represents an under‐valued crustacean frequently caught on European fishing banks. In this work, its sensory, microbiological and biochemical qualities were evaluated during chilled storage. Additionally, the effects of a prestorage antimelanosic treatment consisting of soaking in sodium metabisulphite (SMB) solutions at two different concentrations (0.25% and 0.75%) were also studied. SMB prestorage treatment provided lobster specimens that still exhibited acceptable sensory quality after 10 days of storage, while control specimens were unacceptable at that time. SMB treatment also resulted in a significant (P < 0.05) inhibition of microbial growth, mainly of Enterobacteriaceae, psychrotrophes and proteolytic bacteria. Low lipid oxidation levels were observed for all batches; however, a significantly higher (P < 0.05) retention of polyunsaturated fatty acids was found in SMB‐treated lobster, especially in the 0.75% SMB batch. The results presented here open the way to the potential commercialisation of currently under‐utilised lobster krill as a chilled product. 相似文献
19.
红外偏振光治疗仪是一种将红外技术与电子技术应用到医学领域的康复理疗设备,主要用于软组织损伤和慢性疼痛的康复治疗,已在医院得到了推广使用。然而,现有医院使用的台式治疗仪由于体积大、售价高等特点,不方便居家使用。为了开发体积小、售价低、家庭可用的红外偏振光治疗仪,满足家用市场的潜在需求,本文提出了一种新的便携手持式红外偏振光治疗仪,并开发了该智能控制系统。本文首先介绍了一种新的家用手持式治疗仪应具备的特点和关键技术指标,在此基础上设计了手持式治疗仪的硬件总体方案和软件架构,简要介绍了该治疗仪的一些关键技术,最终实现了治疗仪样机的研制。为了验证该样机的性能,本文通过大量的测试,结果表明,研制的手持式红外偏振光治疗仪在关键参数指标上达到了医院同类产品的水平,能够很好地满足家用的需求,具有良好的市场前景。 相似文献