全文获取类型
收费全文 | 72856篇 |
免费 | 15638篇 |
国内免费 | 57篇 |
专业分类
电工技术 | 956篇 |
综合类 | 40篇 |
化学工业 | 24514篇 |
金属工艺 | 1048篇 |
机械仪表 | 1386篇 |
建筑科学 | 2777篇 |
矿业工程 | 76篇 |
能源动力 | 2036篇 |
轻工业 | 12753篇 |
水利工程 | 630篇 |
石油天然气 | 221篇 |
武器工业 | 2篇 |
无线电 | 8240篇 |
一般工业技术 | 16556篇 |
冶金工业 | 7881篇 |
原子能技术 | 257篇 |
自动化技术 | 9178篇 |
出版年
2024年 | 77篇 |
2023年 | 299篇 |
2022年 | 785篇 |
2021年 | 1270篇 |
2020年 | 2123篇 |
2019年 | 3959篇 |
2018年 | 4049篇 |
2017年 | 4340篇 |
2016年 | 4882篇 |
2015年 | 4697篇 |
2014年 | 4974篇 |
2013年 | 7326篇 |
2012年 | 4648篇 |
2011年 | 4551篇 |
2010年 | 4294篇 |
2009年 | 4163篇 |
2008年 | 3550篇 |
2007年 | 3236篇 |
2006年 | 2718篇 |
2005年 | 2257篇 |
2004年 | 2219篇 |
2003年 | 2081篇 |
2002年 | 1954篇 |
2001年 | 1586篇 |
2000年 | 1560篇 |
1999年 | 1023篇 |
1998年 | 2476篇 |
1997年 | 1629篇 |
1996年 | 1131篇 |
1995年 | 622篇 |
1994年 | 537篇 |
1993年 | 564篇 |
1992年 | 220篇 |
1991年 | 209篇 |
1990年 | 177篇 |
1989年 | 194篇 |
1988年 | 171篇 |
1987年 | 155篇 |
1986年 | 131篇 |
1985年 | 178篇 |
1984年 | 115篇 |
1983年 | 103篇 |
1982年 | 112篇 |
1981年 | 125篇 |
1980年 | 114篇 |
1979年 | 58篇 |
1978年 | 62篇 |
1977年 | 190篇 |
1976年 | 346篇 |
1973年 | 49篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
51.
Jincy Joy Jessica Pereira Rachida Aid‐Launais Graciela Pavon‐Djavid Alok R Ray Didier Letourneur Anne Meddahi‐Pell Bhuvanesh Gupta 《Polymer International》2019,68(7):1367-1377
The work reported involved the fabrication of an electrospun tubular conduit of a gelatin and polycaprolactone (PCL) blend as an adventitia‐equivalent construct. Gelatin was included as the matrix for increased biocompatibility with the addition of PCL for durability. This is contrary to most of the literature available for biomaterials based on blends of gelatin and PCL where PCL is the major matrix. The work includes the assiduous selection of key electrospinning parameters to obtain smooth bead‐free fibres with a narrow distribution of pore size and fibre diameter. Few reports elucidate the optimization of all electrospinning parameters to fabricate tubular conduits with a focus on obtaining homogeneous pores and fibres. This stepwise investigation would be unique for the fabrication of gelatin–PCL electrospun tubular constructs. The fabricated microfibrous gelatin–PCL constructs had pores of size ca 50–100 μm reportedly conducive for cell infiltration. The measured value of surface roughness of 57.99 ± 17.4 nm is reported to be favourable for protein adhesion and cell adhesion. The elastic modulus was observed to be similar to that of the tunica adventitia of the native artery. Preliminary in vitro and in vivo biocompatibility tests suggest safe applicability as a biomaterial. Minimal cytotoxicity was observed using MTT assay. Subcutaneous implantation of the scaffold demonstrated acute inflammation which decreased by day 15. The findings of this study could enable the fabrication of smooth bead‐free microfibrous gelatin–PCL tubular construct as viable biomaterial which can be included in a bilayer or a trilayer scaffold for vascular tissue engineering. © 2019 Society of Chemical Industry 相似文献
52.
53.
Joon‐Young Jun Sosuke Nakajima Koji Yamazaki Yuji Kawai Hajime Yasui Yasuyuki Konishi 《International Journal of Food Science & Technology》2015,50(4):871-877
Cystoseira hakodatensis is an unutilised brown algae belonging to family Sargassaceae. A crude methanol extract from the algae showed inhibitory effects on the growths of Bacillus cereus and Bacillus licheniformis. To isolate the major antimicrobial agent, a sequential active‐guided isolation procedure was applied: liquid–liquid extraction, column chromatography and bio‐autography. A marked antimicrobial agent (active α) was isolated in hydrophobic fraction and was determined to phenolics without carbohydrates and proteins by phytochemical test. Regarding the antimicrobial potential, the isolated active α showed better inhibitory effects against B. cereus and B. licheniformis at 2 and 4 times of lower concentrations (62.5 and 31.3 μg mL?1) in comparison with epigallocatechin gallate. These results showed that C. hakodatensis is a potential source of antimicrobial agent capable of preventing the growth of the two bacteria. 相似文献
54.
55.
56.
57.
Machine Learning - We propose a data-driven approach to quantify the uncertainty of models constructed by kernel methods. Our approach minimizes the needed distributional assumptions, hence,... 相似文献
58.
59.
Zhang Xi Wang Xianhai Zhao Hongke Ordóñez de Pablos Patricia Sun Yongqiang Xiong Hui 《Scientometrics》2019,119(3):1311-1344
Scientometrics - Altmetrics indices are increasingly applied to measure scholarly influence in recent years because they can reflect the influence of research outputs more timely comparing with... 相似文献
60.
Indium separation using ion exchange resins from acidic polymetallic and very diluted solutions are investigated. Since the selectivity of commercial ion exchange resins have proven to be too low for an effective separation from solutions with high content of other metals, Lewatit® TP 208 was impregnated with common extractants to enhance its properties. By resin impregnation with D2EHPA and Cyanex 272, not only the selective indium recovery was reached but also the resin capacity was increased approx. two times. The best loading and elution performance were shown by Cyanex 272-impregnated Lewatit® TP 208, increasing the indium purity in the eluate from 0.75 % to 85 %. 相似文献