全文获取类型
收费全文 | 84703篇 |
免费 | 10648篇 |
国内免费 | 6892篇 |
专业分类
电工技术 | 8879篇 |
技术理论 | 10篇 |
综合类 | 7567篇 |
化学工业 | 4164篇 |
金属工艺 | 1714篇 |
机械仪表 | 4152篇 |
建筑科学 | 3707篇 |
矿业工程 | 1856篇 |
能源动力 | 6129篇 |
轻工业 | 5605篇 |
水利工程 | 2289篇 |
石油天然气 | 3978篇 |
武器工业 | 963篇 |
无线电 | 10333篇 |
一般工业技术 | 5477篇 |
冶金工业 | 1563篇 |
原子能技术 | 894篇 |
自动化技术 | 32963篇 |
出版年
2024年 | 554篇 |
2023年 | 1725篇 |
2022年 | 3049篇 |
2021年 | 3607篇 |
2020年 | 3697篇 |
2019年 | 3152篇 |
2018年 | 2680篇 |
2017年 | 3134篇 |
2016年 | 3303篇 |
2015年 | 3626篇 |
2014年 | 5759篇 |
2013年 | 5185篇 |
2012年 | 6108篇 |
2011年 | 6581篇 |
2010年 | 4931篇 |
2009年 | 4786篇 |
2008年 | 5107篇 |
2007年 | 5827篇 |
2006年 | 5042篇 |
2005年 | 4405篇 |
2004年 | 3847篇 |
2003年 | 3199篇 |
2002年 | 2492篇 |
2001年 | 1924篇 |
2000年 | 1637篇 |
1999年 | 1234篇 |
1998年 | 959篇 |
1997年 | 786篇 |
1996年 | 664篇 |
1995年 | 575篇 |
1994年 | 487篇 |
1993年 | 353篇 |
1992年 | 274篇 |
1991年 | 242篇 |
1990年 | 180篇 |
1989年 | 151篇 |
1988年 | 130篇 |
1987年 | 106篇 |
1986年 | 90篇 |
1985年 | 130篇 |
1984年 | 84篇 |
1983年 | 91篇 |
1982年 | 78篇 |
1981年 | 50篇 |
1980年 | 29篇 |
1979年 | 41篇 |
1978年 | 15篇 |
1977年 | 27篇 |
1976年 | 20篇 |
1974年 | 14篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Basins with various mineral resources coexisting and enriching often occupy an important strategic position. The exploration of various mineral resources is repetitive at present due to unshared data and imperfect management mechanism. This situation greatly increases the cost of energy exploitation in the country. Traditional data-sharing mode has several disadvantages, such as high cost, difficulty in confirming the right of data, and lack of incentive mechanism, which make achieving real data sharing difficult. In this paper, we propose a data-sharing mechanism based on blockchain and provide implementation suggestions and technical key points. Compared with traditional data-sharing methods, the proposed data-sharing mechanism can realize data sharing, ensure data quality, and protect intellectual property. Moreover, key points in the construction are stated in the case study section to verify the feasibility of the data-sharing system based on blockchain proposed in this paper. 相似文献
62.
This study aimed to know the effect of adding pulp in rambutan fruit juice on the characteristics of rambutan juice during storage. Research using the CRD, the treatment were kind of pulp (mandarin and rambutan) and pulp concentration (5%, 7.5%, and 10%). The results showed that the addition of pulp significantly affect the characteristics of rambutan juice (pH, vitamin C, total acid) during storage. Pulpy juice with the most prefered was addition of rambutan pulp as much as 7.5% (w/v) and the addition of citrus pulp as much as 7.5% (w/v) with the score of 3-4 (moderate like - like). 相似文献
63.
Today’s information technologies involve increasingly intelligent systems, which come at the cost of increasingly complex equipment. Modern monitoring systems collect multi-measuring-point and long-term data which make equipment health prediction a “big data” problem. It is difficult to extract information from such condition monitoring data to accurately estimate or predict health statuses. Deep learning is a powerful tool for big data processing that is widely utilized in image and speech recognition applications, and can also provide effective predictions in industrial processes. This paper proposes the Long Short-term Memory Integrating Principal Component Analysis based on Human Experience (HEPCA-LSTM), which uses operational time-series data for equipment health prognostics. Principal component analysis based on human experience is first conducted to extract condition parameters from the condition monitoring system. The long short-term memory (LSTM) framework is then constructed to predict the target status. Finally, a dynamic update of the prediction model with incoming data is performed at a certain interval to prevent any model misalignment caused by the drifting of relevant variables. The proposed model is validated on a practical case and found to outperform other prediction methods. It utilizes a powerful deep learning analysis method, the LSTM, to fully process big condition monitoring series data; it effectively extracts the features involved with human experience and takes dynamic updates into consideration. 相似文献
64.
Mauro D. Santos Ivonne Delgadillo Jorge A. Saraiva 《International Journal of Food Science & Technology》2020,55(3):1171-1179
Hyperbaric storage (HS) was evaluated as a new food preservation methodology at room temperature (RT) for beef and pork meat, both minced and in pieces, and compared to refrigeration (RF) storage. The meat samples were stored at 50, 75 and 100 MPa and variable RT up to 60 days. HS at 75 and 100 MPa could not only inhibit microbial growth but also inactivate microorganisms. Regarding physicochemical analyses, an overall equal to better pH maintenance in HS samples was achieved, and similar colour differences between HS and RF were observed. Generally, similarities in moisture content and drip loss between HS (mostly 75 and 100 MPa) and RF were detected (tendency for lower values in the former and higher values in the latter for the higher pressure level). Protein solubility revealed a decrease of sarcoplasmic protein values during storage with a pressure level dependency in some samples. 相似文献
65.
“Smart firefighting” construction as a part of the “smart city” has been a concern of the public security and fire agencies at all levels. In this study, the status, problems, and reflections of “smart firefighting” construction in China are discussed. A recent survey indicates that China has launched its smart firefighting construction and initially created a new perspective on its regional smart firefighting work based on three main aspects: intelligent disaster perception by Internet of Things (IoT) construction, intelligent disaster prevention by big data construction, and intelligent disaster disposal by emergency rescue platform construction. However, the current smart firefighting construction in China still has some prominent problems such as the data interconnectivity and normalized management of various platforms, the extensibility of smart firefighting platforms, and the intelligent level of smart firefighting researches, which need to be solved urgently. Therefore, we argue that smart firefighting construction in China should establish data interconnectivity, industrial normalized management, 2D/3D geographic information interaction and extension, high-integration fire protection theory, and many other aspects in the near future and truly realize firefighting visualization and efficient data applications for 4D time space. This study could provide valuable reference for smart firefighting and smart city construction. 相似文献
66.
带有传感器的可穿戴式医疗设备不断生成大量数据,由于数据的复杂性,难以通过处理和分析大数据来找到有价值的决策信息。为了解决这个问题,提出了一种新的物联网体系结构,用于存储和处理医疗应用的可扩展传感器数据(大数据)。所提出的架构主要由两个子架构组成:Meta Fog重定向(MF-R)架构和AWS密钥管理机制。MF-R架构使用Apache Pig和Apache HBase等大数据技术来收集和存储不同传感器设备生成的传感器数据,并利用卡尔曼滤波消除噪声。AWS密钥管理机制使用密钥管理方案,目的是保护云中的数据,防止未经授权的访问。当数据存储在云中时,所提出的系统能够使用随机梯度下降算法和逻辑回归来开发心脏病的预测模型。仿真实验表明,和其他几种算法相比,提出的算法具有更小的误差,且在吞吐量、准确度等方面具有一定的优越性。 相似文献
67.
An engineered variant of the yeast Pichia pastoris was used to produce the potential malaria vaccine D1M1. This paper describes the implementation of an expanded bed adsorption chromatography step into a sequential cultivation process of the yeast in order to link protein expression, cell release, and product capture of the secreted protein in a fully automated plant. The process is operated with a semi-continuous strategy for an integrated production. Process improvements have been achieved using design of experiments. Resulting purities of product achieved up to 87% with recoveries of 51% in a single downstream operation. Furthermore, a multivariate analysis of historical batch data was used to develop a golden batch model for process monitoring. 相似文献
68.
69.
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
70.
Katarzyna Samborska Elwira Langa Sławomir Bakier 《International Journal of Food Science & Technology》2015,50(6):1359-1365
Honey powders produced by spray drying with the addition of Arabic gum and sodium caseinate were characterised in terms of the influence of storage time on the following physical properties: particle size, moisture content, water activity, bulk density, flowability and hygroscopicity. The storage affected those properties; after 12 weeks of storage, particle size decreased (except Arabic gum powder treated as a control sample), moisture content and water activity increased, hygroscopicity decreased. Changes in bulk density, particle size and moisture content caused the rise of Hausner ratio value; however, the powders were still characterised by a very good flow properties and low cohesiveness. The colour of reconstituted powders was also affected by storage; in most of samples, the darkening, reduction in redness and yellowness were observed. Colour parameters were the most stable in powders obtained with the addition of 2% w/w of sodium caseinate. 相似文献