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排序方式: 共有265条查询结果,搜索用时 15 毫秒
51.
Christophe Chassenieux Taco Nicolai Dominique Durand Jean‐Franois Gohy Robert Jrme 《Polymer International》2000,49(6):561-566
The behaviour of monosulfonated telechelic polystyrene with various molar masses and different counterions has been investigated using static and dynamic light scattering. For concentrations above the critical micelle concentration, free unimers associate to form well‐defined star‐shaped micelles. The number of polystyrene chains per micelle (nag) is independent of the concentration and the type of counterion; nag decreases with decreasing molar mass of the polystyrene and increasing polarity of the solvent. The micelles behave like covalently bonded star polystyrene from a structural, dynamic and thermodynamic point of view. © 2000 Society of Chemical Industry 相似文献
52.
The macroscopic symptoms of the high crystallinity of solvent-spun cellulosic fibres appear as a specific tendency to fibrillation, if the swollen fibres are exposed to mechanical stress. The method of proving such fibrillations is the wet abrasion. An increase of the binding forces between the fibril structural elements of the solvent-spun cellulosic fibres results in a reduction of fibrillation. The reinforced bonds are also reflected in increased wet abrasion numbers. By reaction with solvent-spun cellulosic fibres, mono- as well as bi(poly)functional reactive dyestuffs can increase the wet abrasion number. This fact could indicate crosslinking processes between cellulosic chains. The effect of monofunctional reactive dyestuffs with two reactive centres in one reactive group is imaginable as a partial crosslinking realised by covalent and hydrogen bridge bonds. Essentially higher wet abrasion numbers can be achieved with bifunctional reactive dyestuffs. By means of the wet abrasion test it was found that there is a relation between the structural characteristics of the dyestuff and its ability to form crosslinking bridges. In this case the arrangement of the reactive groups on the chromophore and the constitution of the chromophore play an important role. Furthermore, the wet abrasion number is influenced by the concentration of the reactive dyestuff and by the dyeing conditions, for example electrolyte quantity, pH-value and dyeing temperature. 相似文献
53.
Axel Nechwatal Monika Nicolai Klaus-Peter Mieck Brigitte Heublein Gudrun Kühne Dieter Klemm 《大分子材料与工程》1999,271(1):84-92
The high wet fibrillation tendency of Lyocell fibres forms the background to this investigation. The wet abrasion behaviour can be improved by crosslinking reactions. Substances containing sulfato ethyl sulfonyl groups but different bridging groups were synthesised and optimised regarding to their application. The wet fibrillation tendency can be reduced clearly with these selected substances. If the concentration of the crosslinking agent on the fibre is the basis of comparisons the different structures have a similar effect on the fibrillation tendency. So the swollen Lyocell fibre permits a crosslinking reaction with curing agents of different size. 相似文献
54.
Axel Nechwatal Axel Blokesch Monika Nicolai Marcus Krieg Axel Kolbe Monika Wolf Matthias Gerhardt 《大分子材料与工程》2006,291(12):1486-1494
Summary: One strategy to solve the problem of unwanted PET oligomer deposits in textile production is their enzymatic cleavage. In this work a selection of different enzymes (esterases, lipases) were tested for this purpose. The capacity to hydrolyse PET oligomers of some of the tested enzymes has been previously described in the literature. In order to imitate practical conditions both dry and precipitated PET oligomers were used. The decrease in the amount of cyclic trimer, the main component of the PET oligomers, was monitored by HPLC. After treatment with the lipase from Triticum aestivum a decrease of 80 wt.‐% was found. However, the effect of this lipase seems to have less to do with catalysing hydrolytic cleavages of ester groups than with the absorption of the oligomer on the enzyme protein.
55.
Andrei Khodak Nicolai Martovetsky Alexandre Smirnov Peter Titus 《Fusion Engineering and Design》2013,88(9-10):1523-1527
The United States ITER Project Office (USIPO) is responsible for fabrication of the Central Solenoid (CS) for International Thermonuclear Experimental Reactor (ITER). The CS Insert (CSI) project should provide a verification of the conductor performance in relevant conditions of temperature, field, currents and mechanical strain. The US IPO will build the CSI that will be tested at the Central Solenoid Model Coil (CSMC) Test Facility at JAEA, Naka. One of the design goals of the CSI is to assure that the properties of the conductor near the median plane are measured accurately. Since Nb3Sn is strain sensitive and electromagnetic forces generate a significant strain that increases the current sharing temperature (Tcs), we need to design the Insert in such a way that the most strained conductor near the median plane would still have the lowest Tcs of all the rest of the conductor in the Insert. The difference between thermal contraction of the jacket and spacer material allows controlling axial distribution of the coil radial deformation. Numerical analysis of the CSI was performed using stainless steel, titanium and invar spacer material variants. Distribution of the Tcs was obtained from numerical results in the form similar to one proposed for ITER. 相似文献
56.
Dong Hwan Choi Jonathan A. Wickert Hong Hee Yoo 《Journal of Mechanical Science and Technology》2008,22(9):1747-1756
A general formulation is developed for the tolerance analysis of dynamic equilibria in a multibody system undergoing prescribed
rotational motion, with applications including robots, spacecraft, propulsion and power generation systems, and sensors and
actuators. In a state of dynamic equilibrium, a subset of the generalized coordinates assumes constant values while the remaining
coordinates vary and respond in time. Manufacturing tolerances can be mathematically represented by probabilistic distributions
or statistical variables through either an analytical approach or a Monte Carlo simulation. In the present tolerance work,
the tolerances of design parameters including lengths, stiffnesses, inertias, and attachment positions are examined. In order
to analytically calculate the statistical response of the dynamic equilibrium positions to such tolerances, the first-order
sensitivities of the equilibria with respect to parameters are calculated. To illustrate the method’s accuracy and computational
efficiency, two numerical examples are considered, and the statistical results obtained analytically for the equilibria are
compared with those calculated through Monte Carlo simulation. In some cases, an equilibrium configuration can have an operating
condition for which the response has zero standard deviation to perturbations of a design parameter. That condition can be
a useful design point to the extent that typical manufacturing tolerances or other sources of variation would have no effect
on the dynamic equilibrium configuration. 相似文献
57.
Nicolai Wörz Peter Claus Sebastian Lang Manfred J. Hampe 《American Institute of Chemical Engineers》2012,58(8):2557-2562
In this work, transport and thermodynamic properties of mixtures of n‐hexane with the aldehydes citral, citronellal and dihydrocitronellal, important to the fine chemicals industry, were determined experimentally and compared to theoretical predictions. Liquid binary diffusion coefficients were measured using the Taylor dispersion technique at various temperatures. The Wilke‐Chang correlation gave precise approximations. The second part of this work is concerned with the gas‐liquid phase equilibrium of citral/n‐hexane. The mixture is slightly nonideal and may be sufficiently described by applying the modified UNIFAC (Dortmund) group contribution method. © 2011 American Institute of Chemical Engineers AIChE J, 58: 2557–2562, 2012 相似文献
58.
Mingtao Lu Paul de Bruyn Herman T. Nicolai Gert-Jan A.H. Wetzelaer Paul W.M. Blom 《Organic Electronics》2012,13(9):1693-1699
Metal oxides as ZnO provide an interesting alternative for conventional low work function metals as electron injection layer in organic light-emitting diodes (OLEDs). However, for most state-of-the-art OLED materials the high work function of ZnO leads to a large injection barrier for electrons. As a result the electron current in the OLED is largely limited by the contact, leading to a strong reduction of the conversion efficiency. Here we demonstrate that by depositing an amorphous ZnO layer as cathode in an inverted polymer LED, the electron injection can be strongly enhanced by electrical conditioning. For suited polymers comparable conversion efficiencies of the conventional and inverted PLEDs can be achieved. 相似文献
59.
Sex determination in beef by melting curve analysis of PCR amplicons from the amelogenin locus 总被引:1,自引:0,他引:1
Sex determination of beef is important to meet the rules of the Commission Regulation (EC) 765/2002 that qualify for export refunds. A SYBR Green sex identification assay based on melting curve analysis of PCR amplicons from the amelogenin locus (AMELX and AMELY) was developed. The PCR amplicons of 130/130 and 130/67 base pairs produced from female and male beef, respectively, are easily distinguished by both melting curve analysis and gel electrophoresis. Results from the melting curve analysis of amplicons are ready in less than three minutes, and requires no additional work in addition to the PCR setup. Applicability of the sex determination assay was studied by analysis of 12 unknown beef samples and the results were compared to an accredited method based on gel electrophoresis. In addition, six different cattle breeds were examined. All test results were correct in respect to sex. 相似文献
60.
Alemayehu Ambaw Pieter Verboven Thijs Defraeye Engelbert Tijskens Ann Schenk Umezuruike Linus Opara Bart M. Nicolai 《Journal of food engineering》2013
1-Methylcyclopropene (1-MCP) is a synthetic plant growth regulator used commercially to delay ripening of fruits. The substance is applied in gas form (as a fumigant) in the storage room. In long term postharvest cold storage, fruit are placed in boxes (usually plastic or wooden bins) and stacked in a specific pattern. The top of the boxes are frequently covered with a thin plastic sheet for the purpose of reducing fruit moisture loss. Wooden boxes, card linings and other plant based porous materials used in bins have 1-MCP adsorption capacity. Plastic covers affect the airflow and with that the 1-MCP transport. In this paper, the influence of box materials and plastic cover on the distribution of 1-MCP in cold storage was studied using validated CFD models. Reynolds Average Navier–Stokes equations with the SST k–ω turbulence model were used to calculate the airflow. Diffusion, convection and adsorption of 1MCP were modeled to obtain 3D spatial and temporal distributions of 1-MCP inside a storage container, boxes and fruit. Time dependent profiles of calculated 1-MCP concentrations in the air in the container agreed well with measurement data. The plastic cover imposed no effect on the adsorption of 1-MCP. Wooden boxes notably adsorbed 1-MCP from the treatment atmosphere and may reduce the efficacy and uniformity of the treatment. 相似文献