全文获取类型
收费全文 | 1745篇 |
免费 | 151篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 17篇 |
综合类 | 2篇 |
化学工业 | 482篇 |
金属工艺 | 29篇 |
机械仪表 | 53篇 |
建筑科学 | 57篇 |
矿业工程 | 2篇 |
能源动力 | 79篇 |
轻工业 | 290篇 |
水利工程 | 13篇 |
石油天然气 | 4篇 |
无线电 | 121篇 |
一般工业技术 | 290篇 |
冶金工业 | 121篇 |
原子能技术 | 4篇 |
自动化技术 | 335篇 |
出版年
2024年 | 2篇 |
2023年 | 25篇 |
2022年 | 71篇 |
2021年 | 115篇 |
2020年 | 50篇 |
2019年 | 89篇 |
2018年 | 77篇 |
2017年 | 79篇 |
2016年 | 88篇 |
2015年 | 68篇 |
2014年 | 74篇 |
2013年 | 131篇 |
2012年 | 133篇 |
2011年 | 139篇 |
2010年 | 105篇 |
2009年 | 109篇 |
2008年 | 90篇 |
2007年 | 92篇 |
2006年 | 50篇 |
2005年 | 39篇 |
2004年 | 42篇 |
2003年 | 28篇 |
2002年 | 28篇 |
2001年 | 19篇 |
2000年 | 8篇 |
1999年 | 17篇 |
1998年 | 22篇 |
1997年 | 24篇 |
1996年 | 18篇 |
1995年 | 10篇 |
1994年 | 8篇 |
1993年 | 5篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 7篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1976年 | 5篇 |
1975年 | 1篇 |
1972年 | 3篇 |
1957年 | 1篇 |
排序方式: 共有1899条查询结果,搜索用时 31 毫秒
1.
Deborah Oliveira De Fusco Leonardo Lucas Madaleno Vanildo Luiz Del Bianchi Aline da Silva Bernardo Rafael Roberto Assis Gustavo Henrique de Almeida Teixeira 《International Journal of Food Science & Technology》2019,54(7):2416-2424
Alcohol-free beer with isotonic properties is getting more popular and its production can be carried out by different production strategies; however, interrupted fermentation is still a challenge. Therefore, the objective of this study was to develop a low-alcohol isotonic beer (<0.5% v/v) by interrupted fermentation. Moreover, the major objective is to compare the developed product to commercial beverages (sports drinks, ‘Pilsen' regular beer, alcohol-free beers and low-alcohol isotonic beer). The beverages were evaluated based on pH, alcohol content (% v/v), total titratable acidity (mEq L−1), osmolality (mOsmol kg−1), bitterness International Bitterness Units, colour European Brewery Convention, total phenolic compounds (mg L−1 gallic acid), reducing and total sugars (%) and Na and K contents (mg L−1). The developed low-alcohol isotonic beer presented characteristics similar to sports drinks, with the advantage of being richer in phenolic compounds and suitable osmolality. Despite salts were added in its formulation, the grades attributed to all beers employed in the sensory evaluation, as well as the purchase intention did not present significant differences. 相似文献
2.
3.
4.
Désiré Lara; Veissier Isabelle; Després Gérard; Boissy Alain 《Canadian Metallurgical Quarterly》2004,118(4):363
Appraisal theories provide a framework that gives insight into emotions and could allow comparisons across species. According to these theories, events are first evaluated on their suddenness, novelty, and unpredictability. The authors examined the ability of lambs (Ovis aries) to evaluate an event according to these 3 criteria through 3 tests. The lambs responded to suddenness with a startle response coupled with an increase in heart rate and to novelty with an orientation response coupled with an increase of vagal activity. There was no clear evidence that lambs can detect the predictability of an event. Those results support the usefulness of appraisal theories to assess emotion in animals. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
Leonardo Candela Fuat Akal Henri Avancini Donatella Castelli Luigi Fusco Veronica Guidetti Christoph Langguth Andrea Manzi Pasquale Pagano Heiko Schuldt Manuele Simi Michael Springmann Laura Voicu 《International Journal on Digital Libraries》2007,7(1-2):59-80
This paper introduces DILIGENT, a digital library infrastructure built by integrating digital library and Grid technologies and resources. This infrastructure
allows different communities to dynamically build specialised digital libraries capable to support the entire e-Science knowledge
production and consumption life-cycle by using shared computing, storage, content, and application resources. The paper presents
some of the main software services that implement the DILIGENT system. Moreover, it exemplifies the provided features by presenting how the DILIGENT infrastructure is being exploited in supporting the activity of user communities working in the Earth Science Environmental
sector.
This work is partially funded by the European Commission in the context of the DILIGENT project, under the 2nd call of FP6 IST priority. 相似文献
6.
LA Pérula de Torres J Martínez de la Iglesia J Espejo Espejo MV Rubio Cuadrado I Enciso Berge FJ Fonseca del Pozo JM Aranda Lara 《Canadian Metallurgical Quarterly》1997,20(8):425-434
OBJECTIVE: To describe the health status of a population over 60 years and to study their relationship with several socio-demographic variables. DESIGN: A cross-sectional study, population based. SETTINGS: A community. PARTICIPANTS: A randomized sample of 1,103 non institutionalized people over 60 years living in the city of Cordoba (Spain). MEASUREMENTS AND MAIN RESULTS: By mean of a personal interview at home we used the OARS-MFAQ-VE questionnaire. Low self-rated health was associated with the age, to be female sex, a low cultural background, and a low income. Only 5.2% of the study people do not suffered any illness and 56% state that their health problems are major problems for doing their current activities. 4.9% declared to have some degree of physical incapacity. 3.7% of elderly population has an important cognitive deficit. CONCLUSIONS: The majority of elderly people has good health. Age is related with a poor health. Women have more health problems than men. 相似文献
7.
Paulo S. André António L. Teixeira Armando N. Pinto Lara P. Pellegrino Berta B. Neto José F. Rocha Joäo L. Pinto Paulo N. Monteiro 《ETRI Journal》2006,28(2):257-259
In this letter, we will evaluate the performance degradation of a 40 km high‐speed (40 Gb/s) optical system, induced by optical fiber variations of the chromatic dispersion induced by temperature changes. The chromatic dispersion temperature sensitivity will be estimated based on the signal quality parameters. 相似文献
8.
Leonardo Badia Andrea Baiocchi Alfredo Todini Simone Merlin Silvano Pupolin Andrea Zanella Michele Zorzi 《Wireless Communications, IEEE》2007,14(1):36-43
Multicellular networks based on the IEEE 802.16 standard appear to be very promising candidates to provide end users with broadband wireless access. However, they also pose interesting challenges in terms of radio resource management, where several design choices are not specified in the standard, intentionally left open to implementors. For this reason, we focus in this article on scheduling and resource allocation, and investigate how they could operate in a cross-layer fashion. In particular, we describe the principles of joint scheduling and resource allocation for IEEE 802.16 operating in AMC mode, and discuss the critical role played by physical layer considerations, especially intercell interference estimation and channel state awareness, in the obtained performance. This leads to identifying key open issues and possible general solutions 相似文献
9.
Anna Grazia Mignani Peter R. Smith Leonardo Ciaccheri Antonio Cimato Graziano Sani 《Sensors and actuators. B, Chemical》2003,90(1-3):157-162
In spectral nephelometry, absorption spectroscopy and nephelometry are innovatively combined to provide simultaneous online monitoring of color and turbidity of edible oils. Spectral nephelometry instrumentation consists of an optoelectronic device that measures the absorption spectrum of the oil sample at different angles. Data processing, carried out by principal component analysis (PCA), allows identification of the oil sample and creates a two-dimensional map as a fingerprint of oil types. 相似文献
10.