全文获取类型
收费全文 | 26939篇 |
免费 | 2126篇 |
国内免费 | 1198篇 |
专业分类
电工技术 | 496篇 |
技术理论 | 1篇 |
综合类 | 1923篇 |
化学工业 | 4171篇 |
金属工艺 | 1498篇 |
机械仪表 | 2370篇 |
建筑科学 | 954篇 |
矿业工程 | 629篇 |
能源动力 | 397篇 |
轻工业 | 6313篇 |
水利工程 | 233篇 |
石油天然气 | 1407篇 |
武器工业 | 265篇 |
无线电 | 1012篇 |
一般工业技术 | 3226篇 |
冶金工业 | 1596篇 |
原子能技术 | 237篇 |
自动化技术 | 3535篇 |
出版年
2024年 | 168篇 |
2023年 | 434篇 |
2022年 | 671篇 |
2021年 | 800篇 |
2020年 | 871篇 |
2019年 | 816篇 |
2018年 | 795篇 |
2017年 | 901篇 |
2016年 | 909篇 |
2015年 | 850篇 |
2014年 | 1315篇 |
2013年 | 1619篇 |
2012年 | 1731篇 |
2011年 | 1778篇 |
2010年 | 1543篇 |
2009年 | 1546篇 |
2008年 | 1356篇 |
2007年 | 1768篇 |
2006年 | 1584篇 |
2005年 | 1380篇 |
2004年 | 1215篇 |
2003年 | 1050篇 |
2002年 | 915篇 |
2001年 | 781篇 |
2000年 | 669篇 |
1999年 | 557篇 |
1998年 | 371篇 |
1997年 | 345篇 |
1996年 | 300篇 |
1995年 | 241篇 |
1994年 | 213篇 |
1993年 | 144篇 |
1992年 | 138篇 |
1991年 | 105篇 |
1990年 | 78篇 |
1989年 | 59篇 |
1988年 | 43篇 |
1987年 | 39篇 |
1986年 | 31篇 |
1985年 | 28篇 |
1984年 | 22篇 |
1983年 | 21篇 |
1982年 | 14篇 |
1981年 | 7篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1975年 | 3篇 |
1961年 | 4篇 |
1959年 | 3篇 |
1951年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
This research proposes ACARDS (Augmented-Context bAsed RecommenDation Service) framework that is able to utilize knowledge over the Linked Open Data (LOD) cloud to recommend context-based services to users. To improve the level of user satisfaction with the result of the recommendation, the ACARDS framework implements a novel recommendation algorithm that can utilize the knowledge over the LOD cloud. In addition, the noble algorithm is able to use new concepts like the enriched tags and the augmented tags that originate from the hashtags on the SNSs materials. These tags are utilized to recommend the most appropriate services in the user’s context, which can change dynamically. Last but not least, the ACARDS framework implements the context-based reshaping algorithm on the augmented tag cloud. In the reshaping process, the ACARDS framework can recommend the highly receptive services in the users’ context and their preferences. To evaluate the performance of the ACARDS framework, we conduct four kinds of experiments using the Instagram materials and the LOD cloud. As a result, we proved that the ACARDS framework contributes to increasing the query efficiency by reducing the search space and improving the user satisfaction on the recommended services. 相似文献
2.
The Chinese Remainder Theorem (CRT) explains how to estimate an integer-valued number from the knowledge of the remainders obtained by dividing such unknown integer by co-prime integers. As an algebraic theorem, CRT is the basis for several techniques concerning data processing. For instance, considering a single-tone signal whose frequency value is above the sampling rate, the respective peak in the DFT informs the impinging frequency value modulo the sampling rate. CRT is nevertheless sensitive to errors in the remainders, and many efforts have been developed in order to improve its robustness. In this paper, we propose a technique to estimate real-valued numbers by means of CRT, employing for this goal a Kroenecker based M-Estimation (ME), specially suitable for CRT systems with low number of remainders. Since ME schemes are in general computationally expensive, we propose a mapping vector obtained via Kroenecker products which considerably reduces the computational complexity. Furthermore, our proposed technique enhances the probability of estimating an unknown number accurately even when the errors in the remainders surpass 1/4 of the greatest common divisor of all moduli. We also provide a version of the mapping vectors based on tensorial n-mode products, delivering in the end the same information of the original method. Our approach outperforms the state-of-the-art CRT methods not only in terms of percentage of successful estimations but also in terms of smaller average error. 相似文献
3.
Correlation between instrumental texture and colour quality attributes with sensory analysis of selected cheeses as affected by fat contents 下载免费PDF全文
A. Półtorak J. Wyrwisz M. Moczkowska M. Marcinkowska‐Lesiak A. Stelmasiak U. Ulanicka M. Zalewska A. Wierzbicka Da‐Wen Sun 《International Journal of Food Science & Technology》2015,50(4):999-1008
This study evaluated several physical and sensory parameters of different types of cheese available in the Polish market. The measurements of textural properties were conducted in an Instron universal testing machine, while the colour properties of cheeses were measured using a Minolta chromameter. The chemical composition was determined by means of the near‐infrared spectroscopy (NIRs). Moreover, a trained sensory panel was invited to assess the cheese texture‐related properties. Generally, cheeses with reduced fat content were characterised by higher hardness, adhesiveness, cohesiveness and elasticity. Texture‐related parameters of cheese with canola oil were comparable to that of most of full‐fat cheeses. The correlation analysis between physical and sensory attributes related to cheese textural properties indicated the potential applications of TPA, shear and penetration tests (r = 0.766, r = 0.75 and r = 0.765, respectively) for the evaluation of sensory properties related to the hardness. Meanwhile, the elasticity of cheese obtained from sensory evaluation was strongly correlated with the elasticity determined from the shear test (r = 0.722) and moderately correlated with the elasticity from penetration test (r = 0.588), indicating a need to refine the method of penetration test. In addition, cheeses exhibited higher meltability during convection heating at 230 °C than microwave heating. The values of meltability for cheese with reduced fat content were lower than those of full‐fat cheese. 相似文献
4.
5.
6.
陆东凹陷油气藏烃类组成非均质性及其意义 总被引:1,自引:1,他引:0
陆东凹陷原油和油砂抽提物中烃类的宏观组成存在着明显的非均质性。在高孔隙度(>15%)储层单元中,饱和烃的含量高,占总组成的含量均大于40%,而极性化合物则相对较低,一般不足40%;相反,在低孔隙度(<15%)储层单元中,饱和烃的含量明显降低,而极性化合物则显著增加。此外,陆东凹陷原油和油砂抽提物中烃类成熟度亦存在着非均质性:在高孔隙度储层中,原油和油砂烃类的成熟度参数高,而在低孔隙度储层中原油和油砂烃类的成熟度参数低。根据原油和油砂抽提物中烃类的宏观组成特征和成熟度参数的变化规律,提出了陆东凹陷油气聚集模式。 相似文献
7.
加快塑料技术中心建设提高新产品开发水平 总被引:2,自引:2,他引:0
对中国石油化工集团公司(简称中国石化)合成树脂生产及加工应用技术的现状进行了分析,指出中国石化应加快建设塑料加工应用技术中心,为塑料产品的加工用户提供高技术水平和快捷周到的技术服务,在合成树脂新产品开发和产品结构调整中发挥积极作用,以提高合成树脂产品的市场竞争力。 相似文献
8.
9.
新产品研发是建陶企业可持续发展的核心 总被引:2,自引:0,他引:2
新世纪我国建陶企业在整个国民经济的带动下将进一步发展,入世后经济全球化的市场竞争格局,建陶企业只有走新产口研发之路,严格企业管理,才会在日趋激烈的市场竞争中得以生存和可持续发展。 相似文献
10.