全文获取类型
收费全文 | 9285篇 |
免费 | 472篇 |
国内免费 | 75篇 |
专业分类
电工技术 | 120篇 |
综合类 | 208篇 |
化学工业 | 707篇 |
金属工艺 | 93篇 |
机械仪表 | 385篇 |
建筑科学 | 477篇 |
矿业工程 | 475篇 |
能源动力 | 342篇 |
轻工业 | 3287篇 |
水利工程 | 133篇 |
石油天然气 | 801篇 |
武器工业 | 54篇 |
无线电 | 150篇 |
一般工业技术 | 1163篇 |
冶金工业 | 224篇 |
原子能技术 | 316篇 |
自动化技术 | 897篇 |
出版年
2024年 | 15篇 |
2023年 | 82篇 |
2022年 | 253篇 |
2021年 | 264篇 |
2020年 | 243篇 |
2019年 | 162篇 |
2018年 | 168篇 |
2017年 | 281篇 |
2016年 | 352篇 |
2015年 | 368篇 |
2014年 | 533篇 |
2013年 | 584篇 |
2012年 | 581篇 |
2011年 | 689篇 |
2010年 | 600篇 |
2009年 | 593篇 |
2008年 | 489篇 |
2007年 | 520篇 |
2006年 | 522篇 |
2005年 | 418篇 |
2004年 | 399篇 |
2003年 | 344篇 |
2002年 | 279篇 |
2001年 | 197篇 |
2000年 | 186篇 |
1999年 | 174篇 |
1998年 | 101篇 |
1997年 | 89篇 |
1996年 | 79篇 |
1995年 | 48篇 |
1994年 | 50篇 |
1993年 | 31篇 |
1992年 | 21篇 |
1991年 | 15篇 |
1990年 | 25篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 4篇 |
1985年 | 16篇 |
1984年 | 7篇 |
1983年 | 7篇 |
1981年 | 1篇 |
1980年 | 4篇 |
排序方式: 共有9832条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
In this study, sea bream, sea bass, anchovy and trout were captured and recorded using a digital camera during refrigerated storage for 7 days. In addition, their total viable counts (TVC) were determined on a daily basis. Based on the TVC, each fish was classified as ‘fresh’ when it was <5 log cfu per g, and as ‘not fresh’ when it was >7 log cfu per g. They were uploaded on a web-based machine learning software called Teachable Machine (TM), which was trained about the pupils and heads of the fish. In addition, images of each species from different angles were uploaded to the software in order to ensure the recognition of fish species by TM. The data of the study indicated that the TM was able to distinguish fish species with high accuracy rates and achieved over 86% success in estimating the freshness of the fish species tested. 相似文献
5.
6.
7.
《Journal of Great Lakes research》2022,48(5):1288-1297
Beginning in 2013, sites at the 128-m bottom depth contour were added to the sampling design of the annual Lake Michigan bottom trawl survey for prey fish, which has been conducted by the U.S. Geological Survey Great Lakes Science Center (GLSC) each fall since 1973, to better assess fish depth distributions in a changing ecosystem. The standard sampling design included bottom depths from 9 to 110 m, although the GLSC also sporadically conducted bottom trawl tows at the 128-m bottom depth contour during 1973–1988. Enactment of this new sampling design in 2013 revealed that mean biomass density of deepwater sculpins (Myoxocephalus thompsonii) at the 128-m depth exceeded the sum of mean biomass densities at shallower depths, indicating that the bulk of the deepwater sculpin population is residing in waters deeper than 110 m. Thus, our findings supported the hypothesis that the depth distribution of the deepwater sculpin population had shifted to deeper waters beginning in 2007, thereby explaining, at least in part, the marked decline in deepwater sculpin abundance since 2006 based on the standard sampling design. In contrast, our results did not support the hypothesis that the slimy sculpin (Cottus cognatus) population had shifted to deeper waters sometime after 2000. A portion of the burbot (Lota lota) population may have also shifted in depth distribution to waters deeper than 110 m after 2007, based on our results. Our findings have served as an impetus to further expand the range of depths sampled in our bottom trawl survey. 相似文献
8.
Marcus Reppich Zdeněk Jegla Jakob Grondinger Yaovi Ouézou Azouma Vojtěch Turek 《化学,工程师,技术》2021,93(10):1581-1589
This study investigates the behavior of fruit and vegetable samples during drying. The experimental data are fitted to several different thin-layer drying models. Regression analysis is used to determine model parameters, while statistical indicators serve to evaluate the goodness of fit. The power function model gives the best fit for all examined samples. Based on this model, different drying and heat storage technologies can be combined to ensure that the required residual moisture content of an agricultural product is reached. It is demonstrated on the case of a specific Togolese processing plant that under favorable conditions, fossil fuel consumption can be decreased by 33 %. 相似文献
9.
Grace Lara Chieko Takahashi Miku Nagaya Kunihiko Uemura 《International Journal of Food Science & Technology》2022,57(6):3251-3262
The present study aimed to investigate the influence of radio frequency (RF) heating at 70 and 80 °C, in comparison with the traditional conventional heating. The RF heating technology was applied for maintaining the colour and textural quality as well as inactivating the enzymatic activity of polyphenol oxidase (PPO) and reducing the Escherichia coli growth in packaged fresh-cut peach samples. To evaluate this, 120 g of freshly cut peach fruit was placed in heat-resistant plastic bags, and 50 mL of sugar solution (12°Brix) was added to each bag and vacuum-packed for conventional heating and radio frequency (RF) heating. Our results demonstrated that the RF heating process could reduce the heating time by up to 83% at 70 and 80 °C as compared to conventional heating. Moreover, RF heating at 70 and 80 °C reduced the PPO enzymatic activity, which caused enzymatic browning, up to 85.46% and 93.5%, respectively, as compared to 40.86% reduction only for conventional heating. Furthermore, RF heating completely inhibited E. coli growth. Collectively, we demonstrated that RF heating is an emerging and promising technology for improving the quality of fresh-cut fruits such as peach during various storage conditions. The present study provides relatively novel information on the effectiveness of RF heating in maintaining the quality of fresh-cut peaches. In the future, we would like to investigate the effectiveness of RF heating on other agricultural products. 相似文献
10.
Mohammad Shafiur Rahman Kutaila Al-Farsi Salha Saleh Al-Maskari 《International Journal of Food Properties》2018,21(1):849-856
Variability and sensitivity of a portable electronic nose (32 sensors) was assessed by considering different variables for measurement (i.e., reference, standard, first and second purges, sample draw time, waiting time for the volatiles released in the headspace, and mass of sample or headspace volume of the jar containing sample). In this study, dried date-pits were used a model sample. The highest stability was achieved when both reference and standard (i.e., dried date-pits, no heating treatment) were used before test sample measurement. Higher sample draw time more than 10 s significantly decreased the stability, whereas optimum second purge was observed at 50 s. Optimum time to generate volatile was observed as 24 h. A sample of 100 g increased the signal intensity compared to the 50 g sample for the 60°C and 100°C treated samples, while an opposite trend was observed for the 150°C treated sample. Finally, the responses of volatile components in date-pits heated at different temperatures (60°C, 100°C, and 150°C) were measured using the optimum operating conditions. Principal component analysis explored the relationships between the volatile features and classified date-pits heated at different temperatures. The results showed that an electronic nose was able to classify date-pits based on their volatile components generated by different degrees of heating (93.3% accuracy). 相似文献