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991.
Synthesis and behaviour of two copolymers of poly[acrylamide-co-(N-(hydroxymethyl)acrylamide)] in ultrafiltration experiments 总被引:1,自引:0,他引:1
Summary
Water absorbing materials on the basis of acrylamide copolymers have been investigated. The cross-linking of polymer chains
strongly effects the degree of water absorption. The influence of starting composition of polyacrylamide : sodium hydroxide,
duration of hydrolysis and irradiation conditions on cross-linking have been determined and optimized technological parameters
have been derived. Water super absorbents with the ability to absorb up to 900g water by one gram material have been prepared.
Received: 20 December 1999/Revised version: 19 June 2000/Accepted: 17 July 2000 相似文献
992.
Eliseo Martinez-Espinosa William Vicente Martin Salinas-Vazquez Ignacio Carvajal-Mariscal 《传热工程》2017,38(1):47-62
A full finned tube bank is represented as a small finned tube bank in order to analyze numerically mean properties behavior in the streamwise direction. The main goal is to obtain criteria for implementing periodic boundary conditions in a single isolated finned tube module. The simulation is carried out with the Reynolds Averaged Navier–Stokes method and the turbulence effect is modeled with the Renormalization Group k-? model. The complex geometry of finned tube is represented by means of a cut-cell method. Numerical results are compared with experimental data, experimental visualizations, and semi-empirical correlations. Predictions show an adequate hydrodynamics and heat transfer representation. Additionally, mean properties in the streamwise direction show quasi-sinusoidal behavior, and the heat transfer presents approximately identical values in every finned tube in the fully developed flow zone. Therefore, periodic boundary conditions for turbulent kinetic energy and its dissipation rate and a constant wall heat flux condition in the fully developed flow are proposed in numerical simulations on a single isolated finned tube module. 相似文献
993.
Jos Ignacio Alonso‐Esteban María Jos Gonzlez‐Fernndez Dmitri Fabrikov Esperanza Torija‐Isasa María de Cortes Snchez‐Mata Jos Luis Guil‐Guerrero 《European Journal of Lipid Science and Technology》2020,122(7)
Hemp seeds (HS) constitute a rich nutrient source and contain γ‐linolenic acid (GLA, 18:3, n‐6), which is a healthy fatty acid (FA). The objectives of this research are i) to look for GLA‐rich varieties of unhusked hemp seeds (UHS) and commercial hulled hemp seeds (HHS); ii) to check the influence of different extracting systems on both oil yield and FA profiles; iii) to test a simultaneous oil extraction/GLA‐enrichment process looking to improve GLA content. Hop and European hackberry seeds (both from Cannabaceae family) are also analyzed for comparative purposes. GLA is the most discriminant FA among UHS varieties, ranging in both UHS and HHS seeds from 0.5% to 4.5% of total FA, while hop seeds are the richest GLA source from Cannabaceae (7.2% of total FA). The extraction system selected for hemp seeds processing has a clear influence on oil yields, although, the FA profiles are slightly modified. The use of n‐hexane and n‐hexane:acetone in extractions allows an improvement in oil yields at the same GLA percentage. A process comprising saponification and subsequent cooling allows the improvement of GLA percentage in both hemp and hop seeds extracts at values higher than 10% of total FA, at high yields (>70%). Practical Applications: The global HS market increases significantly year after year and the demand of hemp products is increasing rapidly. The natural GLA sources in nature are limited, and although hemp contains GLA, this reaches low percentages in the oil. Hemp is a well‐established crop with highly standardized agricultural technologies, thus, the development of any well‐designed processes feasible for application in oil extraction industries, would allow the development of new GLA‐based functional seed oils. This would boost the development of the agricultural and food industries dedicated to revaluing hemp products. 相似文献
994.
Dr. Maria Agustina Vila Dr. Viktoria Steck Prof. Dr. Sonia Rodriguez Giordano Prof. Dr. Ignacio Carrera Prof. Dr. Rudi Fasan 《Chembiochem : a European journal of chemical biology》2020,21(14):1981-1987
Expanding the reaction scope of natural metalloenzymes can provide new opportunities for biocatalysis. Mononuclear non-heme iron-dependent enzymes represent a large class of biological catalysts involved in the biosynthesis of natural products and catabolism of xenobiotics, among other processes. Here, we report that several members of this enzyme family, including Rieske dioxygenases as well as α-ketoglutarate-dependent dioxygenases and halogenases, are able to catalyze the intramolecular C−H amination of a sulfonyl azide substrate, thereby exhibiting a promiscuous nitrene transfer reactivity. One of these enzymes, naphthalene dioxygenase (NDO), was further engineered resulting in several active site variants that function as C−H aminases. Furthermore, this enzyme could be applied to execute this non-native transformation on a gram scale in a bioreactor, thus demonstrating its potential for synthetic applications. These studies highlight the functional versatility of non-heme iron-dependent enzymes and pave the way to their further investigation and development as promising biocatalysts for non-native metal-catalyzed transformations. 相似文献
995.
Ignacio Flor-Parra Susana Sabido-Bozo Atsuko Ikeda Kazuki Hanaoka Auxiliadora Aguilera-Romero Kouichi Funato Manuel Muiz Rafael Lucena 《International journal of molecular sciences》2022,23(1)
Cell division produces two viable cells of a defined size. Thus, all cells require mechanisms to measure growth and trigger cell division when sufficient growth has occurred. Previous data suggest a model in which growth rate and cell size are mechanistically linked by ceramide-dependent signals in budding yeast. However, the conservation of mechanisms that govern growth control is poorly understood. In fission yeast, ceramide synthase is encoded by two genes, Lac1 and Lag1. Here, we characterize them by using a combination of genetics, microscopy, and lipid analysis. We showed that Lac1 and Lag1 co-immunoprecipitate and co-localize at the endoplasmic reticulum. However, each protein generates different species of ceramides and complex sphingolipids. We further discovered that Lac1, but not Lag1, is specifically required for proper control of cell growth and size in Schizosaccharomyces pombe. We propose that specific ceramide and sphingolipid species produced by Lac1 are required for normal control of cell growth and size in fission yeast. 相似文献
996.
Neural Processing Letters - 相似文献
997.
Fátima Romero-Aguilera José Ignacio Alonso-Esteban María Esperanza Torija-Isasa Montaña Cámara María Cortes Sánchez-Mata 《Food Analytical Methods》2017,10(10):3285-3291
The analysis of phytates, as antinutrients that naturally occur in edible seeds, is important due to its interaction with certain minerals (Ca, Mg, Zn, Fe) essential for health, especially for children or other groups at risk of deficiency diseases. Although several analytical methods for phytates use complex techniques, complexometric methods are recently applied since they provide the knowledge of real mineral complexing activity of different phytates in foods, which is of great relevance for nutritional studies. A reliable method for phytate quantification in terms of cation binding activity has been optimized, based on previous complexometric methods, with the improvement of quantification through calibration with standards instead of estimation through equations. The methodology was optimized for different matrices of seeds and seed-derived food products, including infant foods, and it was validated according to AOAC standards to assess reliability. Due to the presence of different phytate forms in foods, and the different ability of complexation of each one, the expression of results of phytates as phytic acid equivalents (PAE) is proposed. With this methodology, phytates were found in all the samples analyzed, showing a higher amount in seeds (4029 mg PAE/100 g in dehulled hemp seed) than in infant foods (231 mg PAE/100 g in rice formula). From the validation protocol, the method showed good linearity, accuracy, and precision for food samples over 80 mg PAE/100 g, not requiring high-cost equipment, and providing high reliability and practical applicability for routine laboratories, with the purpose of monitoring of food quality. 相似文献
998.
Ignacio Montes Susana D��az Susana Montes 《Soft Computing - A Fusion of Foundations, Methodologies and Applications》2011,15(10):1999-2011
In the context of crisp or classical relations, one may find several alternative characterizations of the concept of a total
preorder. In this contribution, we first discuss the way of translating those characterizations to the framework of fuzzy
relations. Those new properties depend on t-norms. We focus on two important families of t-norms, namely those that do not
admit zero divisors and those that are rotation invariant. For these families, we study whether or not the properties shown
for fuzzy relations lead to characterizations of complete fuzzy preorders. Special attention is paid to the minimum operator,
which shows the best behaviour in preserving most of the characterizations known for crisp relations. 相似文献
999.
1000.
Alberto Lara-Guevara Ignacio Rojas-Rodríguez Ruben Velazquez-Hernandez David Jaramillo-Vigueras Karina del Ángel-Sánchez Mario E. Rodríguez-García 《Journal of Materials Engineering and Performance》2017,26(5):2040-2046
SAE4320H steel was characterized by photothermal radiometry spectroscopy, scanning electron microscopy, x-ray diffraction, and Vickers microhardness, to study metallurgical property changes as a result of the annealing heat treatment. Photothermal radiometry (PTR) images of hot forged and annealed SAE4320H steel were obtained to study the thermal changes, as a consequence of metallurgical microstructure changes that were produced by the heat treatment conditions. X-ray diffraction showed that the annealing process improves the crystalline quality of the SAE4320H steel and releases of any thermal stress. Widmanstatten microstructure was identified as a typical structure after the forging process. The Widmanstatten is a metallographic microstructure transformation to ferrite and pearlite which affected SAE4320H steel hardness and thermal properties. Vickers test showed that the hardness decreases as a result of the annealing process. A positive correlation between Vickers microhardness and PTR amplitude images was found, indicating that the annealing process increases the PTR signal. This methodology allows the determination of the changes in the Vickers microhardness from a non-contact and remote method as in PTR. 相似文献