全文获取类型
收费全文 | 95116篇 |
免费 | 8525篇 |
国内免费 | 3665篇 |
专业分类
电工技术 | 6381篇 |
技术理论 | 3篇 |
综合类 | 10256篇 |
化学工业 | 6031篇 |
金属工艺 | 2567篇 |
机械仪表 | 3939篇 |
建筑科学 | 16202篇 |
矿业工程 | 3689篇 |
能源动力 | 2029篇 |
轻工业 | 17056篇 |
水利工程 | 6270篇 |
石油天然气 | 5892篇 |
武器工业 | 1042篇 |
无线电 | 5318篇 |
一般工业技术 | 5224篇 |
冶金工业 | 4361篇 |
原子能技术 | 481篇 |
自动化技术 | 10565篇 |
出版年
2024年 | 534篇 |
2023年 | 1385篇 |
2022年 | 2419篇 |
2021年 | 3050篇 |
2020年 | 3167篇 |
2019年 | 2581篇 |
2018年 | 2423篇 |
2017年 | 2828篇 |
2016年 | 3177篇 |
2015年 | 3460篇 |
2014年 | 6807篇 |
2013年 | 5625篇 |
2012年 | 7083篇 |
2011年 | 7421篇 |
2010年 | 5667篇 |
2009年 | 5987篇 |
2008年 | 5380篇 |
2007年 | 6379篇 |
2006年 | 5669篇 |
2005年 | 4786篇 |
2004年 | 4053篇 |
2003年 | 3537篇 |
2002年 | 2920篇 |
2001年 | 2271篇 |
2000年 | 1818篇 |
1999年 | 1491篇 |
1998年 | 1002篇 |
1997年 | 848篇 |
1996年 | 728篇 |
1995年 | 597篇 |
1994年 | 461篇 |
1993年 | 348篇 |
1992年 | 269篇 |
1991年 | 213篇 |
1990年 | 134篇 |
1989年 | 156篇 |
1988年 | 95篇 |
1987年 | 89篇 |
1986年 | 62篇 |
1985年 | 57篇 |
1984年 | 53篇 |
1983年 | 45篇 |
1982年 | 31篇 |
1981年 | 22篇 |
1980年 | 24篇 |
1979年 | 13篇 |
1978年 | 13篇 |
1977年 | 14篇 |
1975年 | 11篇 |
1959年 | 13篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
42.
Mohamed Abdellatif 《Color research and application》2015,40(6):564-576
The spectral overlap of color‐sampling filters increases errors when using a diagonal matrix transform, for color correction and reduces color distinction. Spectral sharpening is a transformation of colors that was introduced to reduce color‐constancy errors when the colors are collected through spectrally overlapping filters. The earlier color‐constancy methods improved color precision when the illuminant color is changed, but they overlooked the color distinction. In this article, we introduce a new spectral sharpening technique that has a good compromise of color precision and distinction, based on real physical constraints. The spectral overlap is measured through observing a gray reference chart with a set of real and spectrally disjoint filters selected by the user. The new sharpening method enables to sharpen colors obtained by a sensor without knowing the camera response functions. Experiments with real images showed that the colors sharpened by the new method have good levels of color precision and distinction as well. The color‐constancy performance is compared with the data‐based sharpening method in terms of both precision and distinction. © 2014 Wiley Periodicals, Inc. Col Res Appl, 40, 564–576, 2015 相似文献
43.
Suitability,efficiency and microbiological safety of novel physical technologies for the processing of ready‐to‐eat meals,meats and pumpable products
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)
Alexandros Ch. Stratakos Anastasios Koidis 《International Journal of Food Science & Technology》2015,50(6):1283-1302
Consumer studies and market reports show an increase in consumption of ready‐to‐eat (RTE) foods. Although conventional processing technologies can in most cases produce safe products, they can also lead to the degradation of nutritional compounds and negatively affect quality characteristics. Consumers strongly prefer food that is minimally processed with the maximum amount of health‐promoting substances. Novel processing technologies as pre‐ or post‐treatment decontamination methods or as substitutes of conventional technologies have the potential to produce foods that are safe, rich in nutrient content and with superior organoleptic properties. Combining novel with conventional processes can eliminate potential drawbacks of novel technologies. This review examines available scientific information and critically evaluates the suitability and efficiency of various novel thermal and nonthermal technologies in terms of microbial safety, quality as well as nutrient content on the production of RTE meals, meats and pumpable products. 相似文献
44.
Yingli Li Shaoying Zhang Yu Dong 《International Journal of Food Science & Technology》2021,56(1):115-125
Ethylene continues to be a major factor influencing quality of European pears during storage. Although research has been done on the effect of pre-harvest 1-methylcyclopropene (1-MCP) on physiological characteristics in pears, a full understanding of cultivar response and antioxidant metabolism remains elusive. Spraying 1-MCP on ‘Bartlett’ and ‘d’Anjou’ pears was studied with respect to physiology, storage and eating quality, disorders, and antioxidant properties at two harvest date (H1 and H2) during storage and ripening. Treatment with 1-MCP extended the harvest window of ‘Bartlett’ and ‘d’Anjou’ pears 3 and 4 days, respectively, without reducing storage or eating quality. Treatment with 1-MCP reduced ethylene production (EPR) and respiration rates (RR), maintained fruit firmness and green colour during storage and retarded development of desirable melting texture in both cultivars. Additionally, 1-MCP lowered the incidence of disorders by alleviating membrane lipid peroxidation, retaining high total flavonoids (TF) and antioxidant capacity, and enhancing superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) activity in both cultivars. Overall, pre-harvest 1-MCP applications could extend storage time of ‘Bartlett’ and ‘d’Anjou’ pears to 5 and 6 months, respectively, at −1.1 ± 0.5 °C, by reducing ethylene synthesis and enhancing antioxidant metabolism. 相似文献
45.
46.
In recent years, the Industry 4.0 concept brings new demands and trends in different areas; one of them is distributing computational power to the cloud. This concept also introduced the Reference Architectural Model for Industry 4.0 (RAMI 4.0). The efficiency of data communications within the RAMI 4.0 model is a critical issue. Aiming to evaluate the efficiency of data communication in the Cloud Based Cyber-Physical Systems (CB-CPS), this study analyzes the periods and data amount required to communicate with individual hierarchy levels of the RAMI 4.0 model. The evaluation of the network properties of the communication protocols eligible for CB-CPS is presented. The network properties to different cloud providers and data centers’ locations have been measured and interpreted. To test the findings, an architecture for cloud control of laboratory model was proposed. It was found that the time of the day; the day of the week; and data center utilization have a negligible impact on latency. The most significant impact lies in the data center distance and the speed of the communication channel. Moreover, the communication protocol also has impact on the latency. The feasibility of controlling each level of RAMI 4.0 through cloud services was investigated. Experimental results showed that control is possible in many solutions, but these solutions mostly cannot depend just on cloud services. The intelligence on the edge of the network will play a significant role. The main contribution is a thorough evaluation of different cloud providers, locations, and communication protocols to provide recommendations sufficient for different levels of the RAMI 4.0 architecture. 相似文献
47.
Galin Ivanov Ertugrul Bilgucu Ivelina Ivanova Milena Dimitrova 《International Journal of Dairy Technology》2020,73(3):563-569
The present study aimed to investigate the effect of somatic cell count (SCC) of raw cow's milk on the volatile organic compound (VOC) profiles of yoghurt. Test yoghurt samples were produced from three batches of cow's milk with low, medium and high SCC, respectively. The VOCs were determined by gas chromatography–mass spectrometry (GC–MS) analysis. A lower diacetyl and acetoin content and a higher content of 2‐heptanone, and butanoic and hexanoic acids were established in the yoghurt samples from batches with high SCC of above 1 000 000 cells/cm3. The increased SCC of cow's milk had a negative effect on the volatile organic compound profiles of yoghurt. 相似文献
48.
49.
50.
硫化物预处理方法研究及测定中的质量保证 总被引:1,自引:0,他引:1
针对水和废水中硫离子的特点,设计制作了测定硫化物的酸化—吹气—吸收预处理装置,并验证了该装置对硫化物的回收效果,简化了原来的预处理方法。总结分光测定过程中注意的若干事项,确定了最佳实验条件,使该方法具有更准确、简便、快速的特点。 相似文献