全文获取类型
收费全文 | 976篇 |
免费 | 93篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 4篇 |
化学工业 | 302篇 |
金属工艺 | 6篇 |
机械仪表 | 18篇 |
建筑科学 | 28篇 |
矿业工程 | 3篇 |
能源动力 | 20篇 |
轻工业 | 402篇 |
水利工程 | 4篇 |
石油天然气 | 9篇 |
无线电 | 44篇 |
一般工业技术 | 115篇 |
冶金工业 | 41篇 |
原子能技术 | 3篇 |
自动化技术 | 71篇 |
出版年
2024年 | 1篇 |
2023年 | 12篇 |
2022年 | 23篇 |
2021年 | 45篇 |
2020年 | 21篇 |
2019年 | 48篇 |
2018年 | 44篇 |
2017年 | 40篇 |
2016年 | 40篇 |
2015年 | 36篇 |
2014年 | 55篇 |
2013年 | 65篇 |
2012年 | 83篇 |
2011年 | 91篇 |
2010年 | 55篇 |
2009年 | 56篇 |
2008年 | 56篇 |
2007年 | 56篇 |
2006年 | 53篇 |
2005年 | 31篇 |
2004年 | 19篇 |
2003年 | 24篇 |
2002年 | 22篇 |
2001年 | 15篇 |
2000年 | 4篇 |
1999年 | 5篇 |
1998年 | 16篇 |
1997年 | 13篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1993年 | 4篇 |
1991年 | 2篇 |
1988年 | 1篇 |
1986年 | 3篇 |
1984年 | 1篇 |
1983年 | 3篇 |
1976年 | 8篇 |
1973年 | 3篇 |
1971年 | 1篇 |
排序方式: 共有1070条查询结果,搜索用时 0 毫秒
951.
João Nogueira Lucas Guardalben Bernardo Cardoso Susana Sargento 《Multimedia Tools and Applications》2018,77(12):14527-14555
Due to recent developments in Over-The-Top (OTT) technologies, Pay-TV operators have begun a migration process of managed IP Television (IPTV) services to more appealing OTT approaches. In these scenarios, being able to predict when and what resources will be necessary at any given point is crucial to a high-quality, efficient, and cost-effective operation, especially when dealing with the dynamic and resource-intensive requirements of IPTV multimedia services. To evaluate the advantages of demand forecasting for efficient Catch-up TV delivery on OTT scenarios, this research work explores several classes of machine learning models regarding their accuracy, computational requirement trade-offs, and deployability. The training process relies on a dataset comprised of Catch-up TV usage logs acquired from an IPTV operator’s live production service containing over 1 million subscribers. A predictive and dynamic resource provisioning approach is proposed and evaluated in terms of bandwidth and storage savings. Results demonstrate that forecasting Catch-up TV demand is practical, suitable for integration in OTT solutions, and useful in improving efficiency, with benefits to operators and consumers. Significant savings in bandwidth and storage are shown to be achievable, enabling green and cost-effective resource usage. 相似文献
952.
953.
Concentration and temperature profiles were obtained for mass transfer in partially miscible binary systems under transient conditions by simultaneous solution of the diffusion and energy equations incorporating thermal effects due to heat of solution. The resulting profiles were linearised and previously established stability criterial were used for stability analysis of six partially miscible liquid pairs covering a wide range of physical properties. In general, good agreement was obtained with experimental observations. The characteristic equation was solved for four cases fo convective instability to give a relation between growth constant and wave number. 相似文献
954.
Schools are expected to prepare students for the future, providing them with methods for dealing with the emergent world. This article considers how teachers can work with digital productions at primary schools even when they are not acquainted with the new production genres. We propose a methodological framework to assist students and teachers in their exploration of unknown media genres based on a case study. We revive the ancient concept of imitatio and integrate it with contemporary design thinking to support production dynamics that lead to increased digital literacy. 相似文献
955.
The heavy and light chains of IgG monoclonal antibodies (mAbs) can be shown to be heterogeneous, with respect to isoelectric points, when analyzed by two-dimensional electrophoresis (2-DE). The molecular basis for this charge heterogeneity has not been clearly defined but it has been suggested that it could be due, in part, to differences in glycosylation. To investigate this possibility we have compared the 2-DE pattern of glycosylated and aglycosylated forms of the mouse IgG1 mAb (1B7-11), produced in vitro in the presence and absence of tunicamycin. Charge heterogeneity was shown not to be a consequence of glycosylation status. Intracellular and secreted IgG mAbs were also analyzed to investigate the time course of change in charge properties of the heavy and light chains. The charge heterogeneity was found to be generated intracellularly, and alterations in charge properties could be induced during incubation under physiological conditions. Semilogarithmic plots of the density of the principal heavy and light chain spots against incubation time showed linear relationships, suggesting that the charge shifts result from a first-order reaction. The semilogarithmic plot for the light chain correlated well with the time after IgG synthesis. These results suggest that the charge heterogeneity of an IgG mAb is due to intra- and extracellular modifications of the polypeptide chains which reflect "aging" of antibody molecules. 相似文献
956.
Miguel Frau Susana Simal Antoni Femenia C. Rosselló 《Zeitschrift für Lebensmitteluntersuchung und -Forschung A》1998,207(2):164-169
Cluster analysis of cases (CAC) and variables (CAV) and stepwise discriminant analysis (SDA) were applied to estimate the
usefulness of various chemical determinations for the characterization and differentiation of the seven types of Mahon cheese,
four industrially manufactured (fresh, half-ripened, ripened and old-ripened cheeses) and three traditionally manufactured
(half-ripened, ripened and old-ripened cheeses). CAV showed that, on the one hand, moisture, non-proteic nitrogen (NPN) and
water activity measurements, and on the other ash, NaCl and fat measurements are very similar variables. Using SDA, it was
possible to differentiate between industrially and traditionally manufactured cheeses by measuring NaCl and fat contents,
and also between the four stages of ripening suggested by the "Mahon" cheese Appellation of Origin according to the moisture
and NPN variables. Using classification functions obtained by SDA, 94.1% of cheese samples were correctly classified into
traditional or industrial groups, and 89.7% of samples into fresh, half-ripened, ripened and old-ripened groups (jackknife
validation).
Received: 15 July 1997 / Revised version: 2 February 1998 相似文献
957.
958.
Susana Neto Jeff Camkin Andrew Fenemor Poh-Ling Tan Jaime Melo Baptista Marcia Ribeiro 《国际水》2018,43(1):60-89
ABSTRACTThrough the lens of the 12 OECD Principles on Water Governance, this article examines six water resources and water services frameworks in Europe, Asia-Pacific, Africa and South America to understand enhancing and constraining contextual factors. Qualitative and quantitative methods are used to analyze each framework against four criteria: alignment; implementation; on-ground results; and policy impact. Four main target areas are identified for improving water governance: policy coherence; financing; managing trade-offs; and ensuring integrity and transparency by all decision makers and stakeholders. Suggestions are presented to support practical implementation of the principles through better government action and stakeholder involvement. 相似文献
959.
Joana P. Neto Rui Moura Coelho Duarte Valério Susana Vinga Dominik Sierociuk Wiktor Malesza Michal Macias Andrzej Dzieliński 《Computers & Mathematics with Applications》2018,75(9):3147-3157
Bone is a living tissue that is constantly being renewed, where different cell types can induce a remodeling action to its structure. These mechanisms are typically represented through differential equations, accounting for the biochemical coupling between osteoclastic and osteoblastic cells. Remodeling models have also been extended to include the effects of tumorous disruptive pathologies in the bone dynamics.This article provides a novel approach to existing biochemical models, acting on two different stages. First, the models are said to physiologically better explain an osteolytic metastatic disease to the bone than the multiple myeloma previously considered. Second, and most importantly, variable order derivatives were introduced, for the first time in biochemical bone remodeling models. This resulted in a set of equations with less parameters that describe tumorous remodeling, and provide similar results to those of the original formulation. A more compact model, that promptly highlights tumorous bone interactions, is then achieved. Comparison of simulations and parameters is provided.Such results are a one-step-closer insight to, in a near future, easily provide clinical decision systems ensuring tailored personalized therapy schemes, for more efficient and targeted therapies. 相似文献
960.
Bentonite and concrete are considered as backfilling and sealing materials in a deep geologic repository of high-level radioactive waste (HLRW). The pH of the pore waters leached during concrete degradation is >11 for a long period of time. Under these alkaline conditions, bentonite is susceptible to dissolution–precipitation reactions. The aim of this work is to study mineralogical changes in bentonite in contact with synthetic pore waters of cements. The temperature effect has been taken into account in order to consider the thermal impact of radioactive decay.The bentonite used comes from “La Serrata de Níjar” (Almería, Spain) and is mainly composed of montmorillonite. Bentonite was submitted to alkaline solutions at 35, 60 and 90 °C up to 365 days. Alkaline solutions were similar to the pore waters leached in the first stage of cement degradation.The zeolite crystallization and the increase of magnesium in a non-exchangeable form in the smectitic clay fraction are the main mineralogical changes detected in the bentonite. Both processes are enhanced with the duration time and temperature of reaction. 相似文献