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排序方式: 共有313条查询结果,搜索用时 9 毫秒
41.
Giorgos Papastergiou Ioannis Psaras Vassilis Tsaoussidis 《Computer Communications》2009,32(16):1757-1767
The Delay-/Disruption-Tolerant Networking Architecture calls for new design principles that will govern data transmission and retransmission scheduling over challenged environments. In that context, novel routing, transport and application layer algorithms have to be established in order to achieve efficient and reliable communication between DTN-nodes.In this study, we focus on the evolution of the terrestrial Internet into the Interplanetary or Space Internet and propose adoption of the Deep-Space Transport Protocol (DS-TP) as the transport layer scheme of choice for the space networking protocol stack. We present DS-TP’s basic design principles and we evaluate its performance both theoretically and experimentally. We verify that practice conforms with theory and observe great performance boost, in terms of file delivery time between DTN-nodes, in case of DS-TP. In particular, the gain of DS-TP against conventional proposals for deep-space communications increases with the link error rate; under conditions DS-TP can improve the performance of the transport layer protocol by a factor of two (i.e., DS-TP can become two times faster than conventional protocols). 相似文献
42.
L. Nalbandian A. Delimitis V.T. Zaspalis E.A. Deliyanni D.N. Bakoyannakis E.N. Peleka 《Microporous and mesoporous materials》2008,114(1-3):465-473
Nanocrystalline particles of MnxZn1−xFe2O4 were prepared by chemical precipitation of hydroxides, followed by hydrothermal processing and freeze–drying. The synthesis involves the hydrolysis of aqueous metal precursors by using ammonia as precipitating agent. The chlorine ion concentration in the solution and the pH of the precipitation, are shown to play a crucial role in retaining the initial stoichiometry of the solution to the nanoparticles. The obtained products exhibited some interesting and unique features: they consisted of nanoparticles with sizes ranging from 5 to 25 nm, they had surface areas between 60 and 110 m2 g−1 and pore sizes in the mesopore region (i.e. 8–20 nm). The produced materials were examined by powder X-ray diffraction for crystalline phase identification, scanning electron microscopy for grain morphology, high resolution transmission electron microscopy for particle size distribution and nitrogen sorption for surface area, pore volume and pore size distribution determination. The sintering of the ferrite powders was also studied by thermogravimetric analysis and dilatometry of the powders mixed with an organic binder to improve their compaction properties. 相似文献
43.
Single sampling plans for attributes satisfying an arbitrary set of constraints—A graphical approach
In this paper we present a solution to the problem of determining a single sampling plan, using Larson's Nomograph of the binomial distribution. The problem consists of deciding whether a lot of items will be accepted or rejected, by inspecting a sample of specified size n drawn from the lot. The lot is rejected if the number of bad iterms in the sample is greater than a specified threshold c, otherwise the lot is accepted. The classical procedure for determining a single sampling plan (n,c) is to specify the maximum acceptable probabilities of Type I and Type II errors. Next one expresses these errors in terms of n and c by using the binomial approximation to the hypergeometric distribution. Finally, the pair (n,c) is read at the intersection of the characteristic lines which correspond to the specified maximum error probabilities in the Nomograph. Here, we show that there is a region of plans in the Nomograph which satisfy the error constraints, rather than a single plan. Then we generalize the procedure to problems with an arbitrary number of constraints involving both error types. 相似文献
44.
Katerina Alba Grant M Campbell Vassilis Kontogiorgos 《Journal of the science of food and agriculture》2019,99(9):4189-4199
The structure and function of by-products of berry-processing industries are reviewed, with particular attention to dietary fibre (DF) and its effects in food products. The complex chemical composition and physicochemical characteristics of DF have been investigated and strategies for extraction of specific fractions that provide tailored technological and physiological functionality have been reviewed. The aim of this review is to describe in detail the structural composition and isolation methods of dietary fibre derived from berry by-products, and to explore their potential functionality in foods. The goal is to introduce DF from berry waste streams into the food chain, for which bread is a major vehicle. However, the appeal of bread lies in its aerated structure, for which DF is generally detrimental. The technological influence of DF on the formation and stabilization of the aerated structure of bread is therefore reviewed, in order to understand how to incorporate DF into bread while maintaining palatability. The aerated structure of bread is stabilized by two mechanisms: the gluten matrix and the liquid film surrounding bubbles. Incorporating DF successfully into bread requires understanding its interactions with both of these mechanisms. DF fractions from berries offer superior nutritional value compared to cereal fibre, potentially with less damage to bread structure, due to the higher proportion of soluble fibre. By-products from berry-processing industries could be used as a source of technologically and nutritionally distinctive DF to fabricate foods with enhanced nutritional value. © 2019 Society of Chemical Industry 相似文献
45.
Evangelia A. Tsapou Fotini Drosou Elisabeth Koussissi Maria Dimopoulou Thalia Dourtoglou Vassilis Dourtoglou 《Journal of food science》2020,85(7):2069-2079
Triggered by the development of lactic acid bacteria (LAB) during the production of Scotch whisky, this study examined the influence of yeast and LAB inoculation on whisky flavor. Four new spirits were produced using the same process. LAB were added as a form of a Greek yogurt's live culture. In each category (barley and rye), one sample was fermented with Greek yogurt while the other was fermented without it. The spirits were matured and analyzed at five different points. Results from gas chromatography-mass spectrometry (GC-MS) analysis showed basic volatile compounds, along with some important extra compounds with yogurt culture. The most obvious differences were observed in the concentration of butanoic acid, a characteristic acid in spirits undergoing lactic acid fermentation: to identify esters such as ethyl butanoate, ethyl isobutanoate, isoamyl butanoate, and 2-phenylethyl butanoate, they are not typical compounds in whisky. 相似文献
46.
Elena Hadjimbei George Botsaris Vlasios Goulas Eleni Alexandri Vassilis Gekas Ioannis P Gerothanassis 《International Journal of Dairy Technology》2020,73(1):134-143
The present study describes the development of a functional goats' milk yoghurt, using Pistacia atlantica resin extracts and Saccharomyces boulardii, in an attempt to combine the beneficial effects of the milk, extract and probiotic microorganisms. Results demonstrated that Pistacia extracts promoted the survival of lactic acid bacteria and NMR spectra additionally revealed that the functional fatty acids can be retained during the shelf life of yoghurts, alongside with the other bioactive compounds. The organoleptic assessment revealed that there were no significant differences in flavour, body, texture and appearance between the different yoghurts. 相似文献
47.
Maria Dimopoulou Vassilis Kontogiorgos 《International Journal of Food Science & Technology》2020,55(5):1943-1949
Soluble dietary fibres from sugarcane bagasse were extracted under alkaline conditions and characterised. Precipitated fibres were dialysed, and the fibre composition was evaluated before and after the dialysis step. Compositional analysis indicated that the fibres both before and after dialysis consisted of 39% w/w total sugars, 16% w/w protein, 10% w/w Klason lignin and 30% w/w ash. Xylose was the main neutral sugar followed by arabinose with glucose, galactose and uronic acids also present in all samples. The structural properties were also spectroscopically examined, which confirmed the presence of arabinoxylans. Macromolecular characterisation revealed that molecular weight is reduced after dialysis, indicating that a range of dietary fibres with different macromolecular characteristics may be obtained depending on the specific processing steps. The present work shows that soluble arabinoxylans may be obtained from sugarcane agricultural wastes that may be used as a source of novel dietary fibres. 相似文献
48.
Physical and chemical quality characteristics and antioxidant properties of strawberry cultivars (Fragaria × ananassa Duch.) in Greece: assessment of their sensory impact 下载免费PDF全文
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