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71.
In Swedish district heating systems several large (25 MW) turbo-compressor driven heat pumps using R22 are installed. The only commercially available alternative is R134a, but its use could decrease the heating capacity by 35%. In this paper a method for finding the best working fluid for a specific heat pump plant is presented, and applied to a district heating plant. First, a screening is made among almost 2000 mixtures, using criteria such as condenser pressure, Mach number and temperature glide. Simulations of the plant are then made to investigate the change in heating capacity and COP when using a mixture instead of R134a. The results show that there are mixtures that can offer a substantially higher heating capacity than R134a, but there is a decrease in COP. The importance of considering the limiting parameters of the heat pump, such as maximum volume flow to each compressor stage and minimum evaporator pressure, is shown. 相似文献
72.
Riccioli C Pérez-Marín D Guerrero-Ginel JE Saeys W Garrido-Varo A 《Applied spectroscopy》2011,65(7):771-781
This paper proposes a method based on near-infrared hyperspectral imaging for discriminating between terrestrial and fish species in animal protein by-products used in livestock feed. Four algorithms (Mahalanobis distance, Kennard-Stone, spatial interpolation, and binning) were compared in order to select an appropriate subset of pixels for further partial least squares discriminant analysis (PLS-DA). The method was applied to a set of 50 terrestrial and 40 fish meals analyzed in the 1000-1700 nm range. Models were then tested using an external validation set comprising 45 samples (25 fish and 20 terrestrial). The PLS-DA models obtained using the four subset-selection algorithms yielded a classification accuracy of 99.80%, 99.79%, 99.85%, and 99.61%, respectively. The results represent a first step for the analysis of mixtures of species and suggest that NIR-CI, providing valuable information on the origin of animal components in processed animal proteins, is a promising method that could be used as part of the EU feed control program aimed at eradicating and preventing bovine spongiform encephalopathy (BSE) and related diseases. 相似文献
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74.
Industrial product development requires continuous improvements in work procedures as a result of constantly changing demands.
Support tools have proven to be an oft chosen way to meet new demands; however, few research efforts have been made in how to implement new tools. This article is a contribution to knowledge on carrying out the implementation of support tools. The basis consists
of four field studies performed during 1994–1999, containing 78 qualitative research interviews and focusing on the implementation
and use of different support tools. A re-analysis has been performed of selected interviews from the field studies, in total
30 interviews. This resulted in recommendations for an implementation framework, consisting of an Implementation Cycle, Organizational Change Field and Managerial Consistence, and five implementation keys: Goal setting, Kowledge Development, Anchoring at All Levels, Suitable Resources and Focus on the Individual. 相似文献
75.
Stefania Vichi Cecilia Santini Nadia Natali Claudio Riponi Elvira López-Tamames Susana Buxaderas 《Food chemistry》2007,102(4):1260-1269
Volatile and semi-volatile compounds of French and American oak wood used in wine and spirits ageing were extracted by an Accelerated Solvent Extractor (ASE) and analysed by gas chromatography–mass spectrometry. More than 90 compounds were isolated, characterised and quantified after being separated on two chromatographic columns with distinct polarity. The main oak wood components were quantitatively determined by using standard reference compounds. In addition, a number of compounds, mainly guaiacol and syringol derivatives, were detected and characterised. In particular, 10 compounds were tentatively identified as lignin dimers derivatives, whose presence in oak wood chips or barrels for wine and spirits ageing had not been previously described. Several of the characterised compounds enabled a distinction to be drawn between medium and high toasted wood chips, independently of their geographical origin. 相似文献
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78.
In Machiavelli's theory of power, the concept of ‘divide and rule’ forms the main theme: the ruler has absolute power and to maintain and increase such power all means are justified. When viewed against the background of this theory, the current debate in the Netherlands on the unbundling of energy (electricity, gas) companies can be observed as an example of ‘divide and rule’, in which the Dutch Minister of Economic Affairs plays a central role. Yet, contrary to Machiavelli in his time, the Dutch government does, in fact, aim principally at the greater welfare of the Dutch people. It is therefore noteworthy that, while important steps in the decision to unbundled have been taken, there is no evidence that the Dutch people will indeed benefit from the envisaged unbundling. 相似文献
79.
Honsell G De Bortoli M Boscolo S Dell'Aversano C Battocchi C Fontanive G Penna A Berti F Sosa S Yasumoto T Ciminiello P Poli M Tubaro A 《Environmental science & technology》2011,45(16):7051-7059
Ostreopsis cf. ovata, a benthic dinoflagellate often blooming along the Mediterranean coasts, has been associated with toxic events ranging from dyspnea to mild dermatitis. In late September 2009, an Ostreopsis cf. ovata bloom occurred in the Gulf of Trieste (Northern Adriatic Sea; Italy), causing pruritus and mild dermatitis in beachgoers. An integrated study was initiated to characterize Ostreopsis cells by light and confocal microscopy, PCR techniques, immunocytochemistry, and high resolution liquid chromatography-mass spectrometry (HR LC-MS). The presence of Ostreopsis cf. ovata of the Atlantic/Mediterranean clade was unambiguously established by morphological and genetic analyses in field samples. Several palytoxin-like compounds (ovatoxin-a,-b,-c,-d,-e) were identified by HR LC-MS, ovatoxin-a being the most abundant (45-64 pg/cell). Surprisingly, no palytoxin was detected. For the first time, monoclonal and polyclonal antipalytoxin antibodies revealed the intracellular cytoplasmic localization of ovatoxins, suggesting their cross-reactivity with these antibodies. Since harmful dinoflagellates do not always produce toxins, the immunocytochemical localization of ovatoxins, although qualitative, can provide an early warning for toxic Ostreopsis cells before their massive diffusion and/or concentration in seafood. 相似文献
80.
Native cassava starch was modified by dry heating treatment, and sodic montmorillonite was modified using an alkylpolyglucoside biosurfactant to produce a novel montmorillonite-filled starch bionanocomposites with improved performance. The bionanocomposites were produced in two extrusion steps using a co-rotating twin-screw extruder. The structural properties of the bionanocomposites were studied by X-ray diffraction. The reinforcement effect and material performance were evaluated by hydrophobicity, solubility, opacity, barrier, thermal and mechanical properties. In general, the dispersion of the nanofillers resulted in bionanocomposites with intercalated structures and improved properties compared with unfilled bioplastics. The main results exhibited that modified montmorillonite showed better compatibility with starch, improving nanofiller dispersion and interaction than the native one. As a result, it increased the hydrophobicity and reduced solubility, water, and oxygen permeabilities in comparison with bionanocomposites based on native starch by 36%, 48%, and 68%, respectively. Also, the tensile strength and Young modulus increased from 0.60 to 2.56 MPa and from 2.99 to 15.68 MPa, respectively. In conclusion, modification of MMT by the biosurfactant is a good approach to enhance dispersion/interaction with the starch matrix. 相似文献