全文获取类型
收费全文 | 5805篇 |
免费 | 767篇 |
国内免费 | 465篇 |
专业分类
电工技术 | 211篇 |
综合类 | 784篇 |
化学工业 | 449篇 |
金属工艺 | 93篇 |
机械仪表 | 392篇 |
建筑科学 | 381篇 |
矿业工程 | 100篇 |
能源动力 | 63篇 |
轻工业 | 949篇 |
水利工程 | 152篇 |
石油天然气 | 52篇 |
武器工业 | 68篇 |
无线电 | 958篇 |
一般工业技术 | 549篇 |
冶金工业 | 102篇 |
原子能技术 | 37篇 |
自动化技术 | 1697篇 |
出版年
2024年 | 6篇 |
2023年 | 55篇 |
2022年 | 85篇 |
2021年 | 122篇 |
2020年 | 200篇 |
2019年 | 153篇 |
2018年 | 155篇 |
2017年 | 192篇 |
2016年 | 202篇 |
2015年 | 248篇 |
2014年 | 341篇 |
2013年 | 400篇 |
2012年 | 448篇 |
2011年 | 444篇 |
2010年 | 347篇 |
2009年 | 344篇 |
2008年 | 339篇 |
2007年 | 388篇 |
2006年 | 337篇 |
2005年 | 295篇 |
2004年 | 274篇 |
2003年 | 206篇 |
2002年 | 202篇 |
2001年 | 174篇 |
2000年 | 132篇 |
1999年 | 142篇 |
1998年 | 110篇 |
1997年 | 83篇 |
1996年 | 87篇 |
1995年 | 98篇 |
1994年 | 78篇 |
1993年 | 61篇 |
1992年 | 65篇 |
1991年 | 51篇 |
1990年 | 33篇 |
1989年 | 19篇 |
1988年 | 23篇 |
1987年 | 19篇 |
1986年 | 10篇 |
1985年 | 23篇 |
1984年 | 15篇 |
1983年 | 9篇 |
1982年 | 4篇 |
1980年 | 2篇 |
1963年 | 2篇 |
1962年 | 1篇 |
1959年 | 1篇 |
1957年 | 1篇 |
1956年 | 3篇 |
1955年 | 3篇 |
排序方式: 共有7037条查询结果,搜索用时 31 毫秒
1.
Ting Fang Jing Chen Qiong Lin Yaoguang Zhong Yuquan Duan Jinfeng Bi 《International Journal of Food Science & Technology》2022,57(4):2257-2266
Flesh colour, which is affected by cultivars and browning, can largely impact consumer acceptance in fresh-cut apples. The study profiled phenolic metabolites from apple flesh of twenty-three cultivars by widely targeted metabolomics. Comparison among white- and yellow-fleshed cultivars showed fifteen phenolics, mainly quercetin 3-O-glucoside, hyperoside, hesperetin 5-O-glucoside and cymaroside, in white-fleshed apples were significantly higher than those in yellow-fleshed apples. It may indicate a metabolite basis of yellow and white flesh colour, and better potential nutrition in white-fleshed apples. In addition, ten phenolic metabolites including five cyanidin glycosides showed significant differences between the highest and the lowest browning groups, indicating them may be crucial in browning of fresh-cut apple. This work elucidates the differences of phenolic profiles among apple cultivars with different flesh colour and provides useful data to evaluate the suitability of apple for fresh-cut processing. 相似文献
2.
3.
针对流程工业生产系统监测数据存在强噪声和混沌性的特点,提出了一种局部投影方法(Local Projection Method)与小波包方法相结合的信号降噪方法。该方法先利用局部投影方法从动力学系统嵌入流形的角度进行多次迭代降噪,并根据关联维数来判定迭代终止;再利用小波包方法从频率的角度进行降噪,抑制高频噪声的干扰,取得了较好的降噪效果。用Lorenz时间序列进行仿真验证,对仿真时间序列加入不同程度的噪声,对比分析小波包、局部投影与该方法降噪后的相空间、SNR值和最大Lyapunov指数,证明了该方法对于中高强度噪声具有更好的降噪效果。并将该方法用于某压缩机组的实际监测数据降噪,评估三种方法的降噪效果,进一步验证了该方法的优越性。 相似文献
4.
Impact of maceration time on colour‐related phenolics,sensory characteristics and volatile composition of mulberry wine 下载免费PDF全文
Shuxun Liu Enchao Liu Baoqing Zhu Bowen Chai Ruojin Liu Qiong Gao Bolin Zhang 《Journal of the Institute of Brewing》2018,124(1):45-56
This study investigated the effect of maceration treatment on colour‐related phenolics, sensory characteristics and volatile composition in mulberry wine. Pre‐fermentation maceration was performed for 2 days (‘short’), 6 days (‘medium’) and 8 days (‘long’), respectively, followed by the same fermentation process. Results showed that the long maceration (LM) caused higher level of anthocyanins in wine, especially cyaniding‐3‐O‐rutinoside, cyaniding‐3‐O‐glucoside and dephinidin‐3‐O‐glucoside, whereas the short maceration caused lower level of phenolic acids in wine. The medium maceration (MM) wine showed the highest level of flavonols but the lowest concentration of flavan‐3‐ol. The LM wine exhibited greater red tone and colour intensity accompanied by higher amounts of free and copigmented anthocyanins. The LM wine showed lower levels of alcohols, acids, terpenoids, benzenes and sulphur compounds, whereas the lowest level of esters was found in the MM wine. The LM wine had reduced fruity and floral aroma and overall flavour complexity compared with the other wines. Copyright © 2018 The Institute of Brewing & Distilling 相似文献
5.
Yana Jorge Polizer-Rocha José M. Lorenzo Daniel Pompeu Isabela Rodrigues Juliana Cristina Baldin Manoela A. Pires Maria Teresa A. Freire Francisco Jose Barba Marco Antonio Trindade 《International Journal of Food Science & Technology》2020,55(3):1018-1024
This study aimed to evaluate the physicochemical characteristics and sensory attributes of beef burgers with the addition of pea fibre as a partial substitute of meat or fat. Three formulations were prepared: control (CON) – similar to the commercial formulation; fibre/less meat (FLM)—5% meat reduction and addition of 1% pea fibre; fibre/less fat (FLF)—7% fat reduction and addition of 1% pea fibre. Non-significant differences were obtained for pH, colour parameters (L* and b*), texture profile, cooking loss and size reduction among formulations. Moreover, sensory analysis with consumers of beef burgers did not indicate differences among the formulations for all the analysed attributes. Therefore, pea fibre is a promising partial replacer for meat and fat in beef burgers due to the preservation of technological parameters and sensory acceptance. 相似文献
6.
7.
针对工作台扭摆会导致机械加工对接产生误差,提出基于三维投影矩阵构建生产流水线对接系统平台,以降低对接误差。三维运动平台采用脉冲信号控制的步进电机进行驱动,达到机床限位控制;通过控制激光器开关和控制激光器的输出功率实现系统的激光控制;通过多普勒频差测量位移技术,采用交流前置放大器替换常规直流放大器等,获取精准实时测量数据;根据三维立体视觉校对原理提取对接区域图像特征点,依据特征点校验机械加工平台三维对接图像时,采用Powell方法求解三维阶段投影矩阵对接目标函数最小值,实现机械加工的高精准度对接。结果表明:机械加工对接的最大相对误差为1.50%,精准度高,进行机械加工耗时18~23min,花费时间较短。 相似文献
8.
9.
Jun Dong Cho Luis Cavazos Quero Jorge Iranzo Bartolom Do Won Lee Uran Oh Inae Lee 《Color research and application》2021,46(1):103-116
A recent development in tactile technology enables an improvement in the appreciation of the visual arts for people with visual impairment (PVI). The tactile sense, in conjunction with, or a possibly as an alternative to, the auditory sense, would allow PVIs to approach artwork in a more self‐driven and engaging way that would be difficult to achieve with just an auditory stimulus. Tactile colour pictograms (TCPs), which are raised geometric patterns, are ideographic characters that are designed to enable PVIs to identify colours and interpret information by touch. In this article, three TCPs are introduced to code colours in the Munsell colour system. Each colour pattern consists of a basic cell size of 10 mm × 10 mm to represent the patterns consistently in terms of regular shape. Each TCP consists of basic geometric patterns that are combined to create primary, secondary, and tertiary colour pictograms of shapes indicating colour hue, intensity and lightness. Each TCP represents 29 colours including six hues; they were then further expanded to represent 53 colours. Two of them did not increase the cell size, the other increased the cell size 1.5 times for some colours, such as yellow‐orange, yellow, blue, and blue‐purple. Our proposed TCPs use a slightly larger cell size compared to most tactile patterns currently used to indicate colour, but code for more colours. With user experience and identification tests, conducted with 23 visually impaired adults, the effectiveness of the TCPs suggests that they were helpful for the participants. 相似文献
10.