全文获取类型
收费全文 | 366738篇 |
免费 | 29415篇 |
国内免费 | 16061篇 |
专业分类
电工技术 | 21527篇 |
技术理论 | 48篇 |
综合类 | 26252篇 |
化学工业 | 61282篇 |
金属工艺 | 21303篇 |
机械仪表 | 23221篇 |
建筑科学 | 28545篇 |
矿业工程 | 11891篇 |
能源动力 | 10083篇 |
轻工业 | 24397篇 |
水利工程 | 6942篇 |
石油天然气 | 23973篇 |
武器工业 | 2890篇 |
无线电 | 40045篇 |
一般工业技术 | 40780篇 |
冶金工业 | 18625篇 |
原子能技术 | 3767篇 |
自动化技术 | 46643篇 |
出版年
2024年 | 1206篇 |
2023年 | 5374篇 |
2022年 | 9383篇 |
2021年 | 14022篇 |
2020年 | 10471篇 |
2019年 | 8611篇 |
2018年 | 9979篇 |
2017年 | 11134篇 |
2016年 | 10188篇 |
2015年 | 14146篇 |
2014年 | 17903篇 |
2013年 | 21458篇 |
2012年 | 23501篇 |
2011年 | 26041篇 |
2010年 | 23041篇 |
2009年 | 21860篇 |
2008年 | 21420篇 |
2007年 | 20417篇 |
2006年 | 20864篇 |
2005年 | 18334篇 |
2004年 | 12422篇 |
2003年 | 11129篇 |
2002年 | 10296篇 |
2001年 | 9157篇 |
2000年 | 9146篇 |
1999年 | 9765篇 |
1998年 | 7506篇 |
1997年 | 6447篇 |
1996年 | 6093篇 |
1995年 | 5020篇 |
1994年 | 4045篇 |
1993年 | 2768篇 |
1992年 | 2178篇 |
1991年 | 1630篇 |
1990年 | 1304篇 |
1989年 | 1073篇 |
1988年 | 866篇 |
1987年 | 509篇 |
1986年 | 410篇 |
1985年 | 253篇 |
1984年 | 196篇 |
1983年 | 145篇 |
1982年 | 134篇 |
1981年 | 75篇 |
1980年 | 102篇 |
1979年 | 44篇 |
1978年 | 18篇 |
1977年 | 23篇 |
1976年 | 30篇 |
1973年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
241.
在国家政策和市场需求的双重推动下,BIM技术在国内建筑领域迎来快速发展阶段,从最初的概念普及,到能够局部应用,再到现在能够全过程应用,其趋势是十分明确的,但是在其发展的过程中仍然存在着不少问题,如传统技术与BIM技术深入融合问题,BIM技术如何解决工程施工现场实际问题等.本文主要研究BIM技术在连云港民用机场迁建工程旅客过夜用房酒店项目中的综合应用,从协同建模、碰撞检查、管线综合、施工图深化出图及漫游展示等方面着手,着重解决BIM技术在施工过程中应用的落地问题,从而达到提高效率,缩短工期,降低成本,提升质量的目标. 相似文献
242.
Elucidation of colour development and microstructural characteristics of Allium sativum fumigated with acetic acid
下载免费PDF全文
![点击此处可从《International Journal of Food Science & Technology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Li Li Dan Wang Xihong Li Yu Wang Xiaofeng Ju 《International Journal of Food Science & Technology》2015,50(5):1083-1088
It has been well known that the greening of Allium sativum cloves could be formed after immersed in acetic acid solution. Nonetheless, no investigation was reported on colour development of A. sativum in response to acetic acid vapour until now. In this study, the brief exposure of A. sativum to acetic acid vapour (200–400 ppm) was combined with controlled atmosphere (5%, 20% and 80% CO2) packaging storage to break cell membrane and green garlic. The garlic bulbs were fumigated with acetic acid before controlled CO2 atmosphere packaging for 25 days at 4 °C. Fumigation with 200 ppm acetic acid followed by high CO2 atmosphere packaging (80% CO2) facilitated the garlic greening. It was also verified that γ‐glutamyl transpeptidase was involved in garlic greening in present study, and the compromise of glacial acetic acid vapour fumigation and CO2 gas atmosphere in package stored at low temperature could result in garlic greening as well. 相似文献
243.
244.
245.
246.
制备了一种厚膜型双组分丙烯酸聚氨酯面漆。介绍了该面漆的配方和制备工艺。讨论了羟基丙烯酸树脂、分散剂、触变剂对面漆性能及施工性能的影响。 相似文献
247.
太阳能热采暖是节能减排、减少雾霾污染的有效途径之一,我国太阳能热采暖技术已经非常成熟,大范围市场推广真正需要的是政策环境、经济环境和物理环境的改善.太阳能采暖不但节约能源,还能让很多家庭感受到太阳能带来的舒适和温暖.利用太阳能采暖,改变了几千年来我们房屋从耗能变成产能业结构. 相似文献
248.
Sumeng Wei Yuling Yang Xiao Feng Shanshan Li Lei Zhou Jingyu Wang Xiaozhi Tang 《International Journal of Food Science & Technology》2020,55(7):2691-2699
Structures and properties of myofibrillar protein gel prepared at different power (300–800 W) were evaluated. Amino acid analysis demonstrated that changes in microwave power did not alter primary structure of gel. However, an increase in microwave power could change higher structures of gel. As microwave power increased, α-helix content decreased and β-sheet content increased. Increased microwave power probably facilitated protein to unfold and expose the internal groups, causing surface hydrophobicity and the formation of disulphide bonds were enhanced, which indicated changes in tertiary and quaternary structures of protein. At 500 W, gel had the best ultrastructure where surface morphology, springiness and water holding capacity reached the optimum. Our findings suggested that microwave at an appropriate power (500 W) could change higher structures of myofibrillar protein gel to achieve desired processing and quality protein gel characteristics. 相似文献
249.
Chunliang Li Theo Veldhuis Bart Reuvers Rafaël J Sablong Cor E Koning 《Polymer International》2020,69(1):24-30
Limonene‐derived polycarbonate‐based alkyd resins (ARs) have been prepared by copolymerization of limonene dioxide with CO2, catalysed by a β‐diiminate zinc–bis(trimethylsilyl)amido complex, and subsequent chemical modification with soybean oil fatty acids using triphenylethylphosphonium bromide as the catalyst. This quantitative partial modification was realized via epoxy–carboxylic acid chemistry, affording ARs with higher oil lengths, lower polydispersities and higher glass transition temperatures (Tg) in comparison to a conventional polyester AR based on phthalic acid, multifunctional polyol pentaerythritol and soybean fatty acid. The novel limonene polycarbonate AR and the conventional polyester AR were evaluated as coatings and both the physical drying (without the presence of the oxidative drying accelerator Borchi® Oxy Coat) and chemical curing (with Borchi® Oxy Coat) processes of these coatings were monitored by measuring the König hardness and complex modulus development with time. A better performance was obtained for the alkyd paint containing polycarbonates modified with fatty acids (FA‐PCs), which showed a faster chemical drying, a higher König hardness and a higher Tg in coating evaluation, demonstrating that the fully renewable FA‐PCs are promising resins for alkyd paint applications. © 2019 Society of Chemical Industry 相似文献
250.
To improve the electrochemical properties of rare-earth–Mg–Ni-based hydrogen storage alloys, the effects of stoichiometry and Cu-substitution on the phase structure and thermodynamic properties of the ... 相似文献