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991.
Ramkumar Karuppiah Scott J. Bury Adriana Vazquez Gregg Poppe 《American Institute of Chemical Engineers》2012,58(9):2758-2769
We address the problem of optimal design of reverse osmosis (RO)‐based water treatment systems. A superstructure optimization method is proposed to solve the problem, where the superstructure for a RO system is structurally enhanced with additional features. We formulate the problem as mixed‐integer nonlinear program which is solved to yield optimal results. A case study on desalination is considered in this work, and the numerical results obtained using our approach are validated using a commercial simulation tool. We further extend the problem by considering the effects of degradation of membrane performance over time and solve it by representing the problem as a two‐stage stochastic program. This new approach is highly useful for identifying minimum cost robust designs for membrane‐based water purification systems, which are especially important in desalination applications. © 2012 American Institute of Chemical Engineers AIChE J, 2012 相似文献
992.
Pedro de Lima-Neto Adriana N. Correia Regilany P. Colares Paulo N.S. Casciano 《Electrochimica acta》2010,55(6):2078-2551
This study examines the corrosion of electrodeposited Cr and of two electrodeposited Ni-W coatings in 0.1 mol L−1 NaCl solution, as well as the influence of heat treatment on the crystallographic structure and microhardness properties of these coatings. Physical characterisation is carried out using scanning electron microscopy, X-ray diffraction, and energy dispersive X-ray analysis. Electrochemical characterisation is carried out using both the potentiodynamic linear polarization technique and open circuit measurements during long-term immersion tests. The corrosion products on the coating surfaces are characterised by ex situ Raman spectroscopy. As-electrodeposited Ni-W samples do not present defects, and the surface evolves from fine globular grains to rough polycrystalline morphology with decreasing electrodeposition current density. All the studied coatings corrode in the chloride medium and the corrosion is non-uniform for the Ni-W coatings. Raman analyses carried out after the immersion tests reveal Cr2O3 and Cr(OH)2 corrosion products on the Cr coating surface, and Ni(OH)2, NiO and WO3 corrosion products on the Ni-W coating surfaces. Ni, Ni4W and Ni-W phases are formed after heat treatment of the Ni86W14 coating at 600 °C. Although all the annealed Ni-W layers are cracked, their microhardness increases as the annealing temperature increases, suggesting that Ni-W coatings are potential substitutes for chromium in industrial applications in which good microhardness properties and stability at temperatures higher than 100 °C are required. 相似文献
993.
Adriana Lungu Madalina G. Albu Izabela Cristina Stancu Nicoleta M. Florea Eugeniu Vasile Horia Iovu 《应用聚合物科学杂志》2013,127(3):2269-2279
Superporous materials based on two proteins, collagen and sericin were synthesized by freeze‐drying considering various ratios between the two proteins. To evaluate the influence of sericin content on the structure/properties relationship, the obtained scaffolds were further characterized using spectroscopic analysis, thermal, and mechanical techniques. Scanning electron microscopy was used to investigate the morphological structure of the scaffolds and the swelling properties as well as the stability of the scaffolds were also assessed. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
994.
Tomasz Sledzinski Adriana Mika Piotr Stepnowski Monika Proczko-Markuszewska Lukasz Kaska Tomasz Stefaniak Julian Swierczynski 《Lipids》2013,48(8):839-848
Fatty acids containing a cyclopropane ring in their structure (cyclopropane FA) have been found in a wide variety of bacteria, a number of protozoa, and Myriapoda. Little is known about cyclopropane FA in mammal, especially in human tissues. The present study deals with the identification of cyclopropane FA in adipose tissue and serum of humans and rats. Fatty acids extracted from the adipose tissue and serum obtained from obese women during bariatric surgery were methylated and analyzed on GC–MS. We have identified: cyclopropaneoctanoic acid 2-hexyl, cyclopropaneoctanoic acid 2-octyl, cyclopropanenonanoic acid, and 2-[[2-[(2-ethylcyclopropyl)methyl]cyclopropyl]methyl] acid in human adipose tissue. We confirmed the presence of cyclopropaneoctanoic acid 2-hexyl by derivatization of FA extracted from human adipose tissue to picolinyl esters. Cyclopropaneoctanoic acid 2-hexyl was the main cyclopropane FA (approximately 0.4 % of total fatty acids in human adipose tissue, and about 0.2 % of total fatty acids in the serum). In adipose tissue cyclopropaneoctanoic acid 2-hexyl was found mainly in triacylglycerols, whereas in serum in phospholipids and triacylglycerols. The cyclopropaneoctanoic acid 2-hexyl has also been found in serum, and adipose tissue of rats in amounts comparable to humans. The content of cyclopropaneoctanoic acid 2-hexyl decreased in adipose tissue of rats maintained on a restricted diet for 1 month. In conclusion, we demonstrated that cyclopropaneoctanoic acid 2-hexyl is present in human adipose tissue and serum. Adipose tissue cyclopropaneoctanoic acid 2-hexyl is stored mainly in triacylglycerols and the storage of this cyclopropane FA is affected by food restriction. 相似文献
995.
Mihaela Ciopec Corneliu M. Davidescu Adina Negrea Lavinia Lupa Adriana Popa Cornelia Muntean Radu Ardelean Gheorghe Ilia 《Polymer Engineering and Science》2013,53(5):1117-1124
In the present work, two novel aminophosphinic acid ligands grafted on poly(styrene‐1%divinylbenzene) (St‐1%DVB) have been synthesized by reacting polymer precursors bearing primary amino groups with benzaldehyde (or propionaldehyde) and phenylphosphinic acid by the “one‐pot” Kabatachnik‐Fields reaction. The resins functionalized with aminophosphinic pendant groups were characterized by means of Fourier transform infrared spectroscopy (FTIR), thermal analysis, energy dispersive X‐ray microanalysis (EDX), and Scanning electron microscopy (SEM) imaging. Its adsorption capacity for divalent metal ions such as Cu(II) and Ni(II) were investigated. The adsorption procedure of Cu(II) and Ni(II) ions on polymer‐grafted aminophosphinic acid ligands was carried out by batch experiments. The result also shows that the adsorption process was best described by a pseudo‐second‐order kinetic equation and by the Langmuir adsorption isotherm. The best maximum adsorption capacity was obtained for resin with aminobenzylphosphinic acid groups [1.46 mg Cu(II)/g and 1.36 mg Ni(II)/g]. POLYM. ENG. SCI., 2013. © 2012 Society of Plastics Engineers 相似文献
996.
Amanda de Oliveira Campos Cota Adriana de Fátima Caetano Silvana Coelho de Arruda Barbosa Nádia da Rocha Svizero Vinicius Di Hipólito Roberta Caroline Bruschi Alonso 《Journal of Adhesion Science and Technology》2013,27(15):1635-1646
This study aimed to evaluate the mechanical properties of self-adhesive resin cements mixed with hydroxyapatite, as a function of the polymerization activation mode among a variety of commercial self-adhesive cements. Four cements (MaxCem Elite, Bifix SE, G-Cem, and RelyX U200) were mixed, combined with hydroxyapatite, dispensed into molds, and distributed into three groups, according to polymerization protocols: IP (immediate photoactivation for 40 s); DP (delayed photoactivation, 10 min self-curing plus 40 s light-activated); and CA (chemical activation, no light exposure). After polymerization, the specimens were stored at 37 °C for 24 h. After storage, a three-point bending test was performed at 0.5 mm/min. Flexural strength (S) and flexural modulus (E) were calculated. The fractured surfaces were analyzed with scanning electron microscopy (SEM) technique. Data were analyzed by two-way ANOVA/Tukey’s test (5%). The tested parameters varied according with the resin cements and polymerization protocols. Regarding the S means, MaxCem Elite, G-Cem, and RelyX U200 demonstrated dependence on photoactivation (immediate or delayed), whereas Bifix SE exhibited no dependence on the polymerization protocol. The same was observed for Bifix SE for the E means, which presented the best balanced formulation, irrespective of the activation protocol. SEM analysis exhibited the presence of bubbles and porosities in all of the fractured surfaces. Chemical activation is not a guarantee of a complete polymerization for most of the cements tested. Only one of the cements maintained its mechanical properties when chemically activated, important characteristic in clinical situations in which the curing light penetrating the bulk material can be attenuated or scattered. 相似文献
997.
Adriana Mihaela Soaita 《Housing Studies》2012,27(7):1008-1030
Socio-economic and physical change have visibly affected post-socialist cities, yet the state of decay of their inherited large housing estates has only deepened throughout the 1990s, despite the change in tenure through policies of large-scale privatisation. Housing disrepair has now reached a critical stage that requires rapid private and public intervention. This paper examines the extent to which Romanian block residents have been able to improve in situ their housing conditions since 2000, the strategies they employed and the challenges they faced. It focuses on the often ignored private domain of housing, flats and blocks, where changes are also likely to be less visible. By analysing the process of individual utility metering and the practice of collective block management, I argue that besides economics, the unregulated housing context and a relaxed legal culture have challenged individual and collective action and have generated a framework of housing privatism. 相似文献
998.
Eduardo Ramírez‐Vargas Saúl Sánchez‐Valdes Octavio Parra‐Tabla Sergio Castañeda‐Gutiérrez Juan Méndez‐Nonell Luis Francisco Ramos‐deValle Adriana López‐León Roberto Lujan‐Acosta 《应用聚合物科学杂志》2012,123(2):1125-1136
The combination of different types of organo‐modified montmorillonite (MMT) with aluminum hydroxide (aluminum trihydrate—ATH), as a flame retardant system for polyethylene‐ethylene vinyl acetate (LDPE/EVA), blends were studied. Five different types of organically modified montmorillonite clays, each with different modifier, were used. The structural characterization was carried out by X‐ray diffraction (XRD) and scanning electron microscopy in transmission mode (STEM). The mechanical and rheological properties were also evaluated. The XRD analysis showed a clear displacement of the d001 signal, which indicates a good degree of intercalation, especially for the MMT‐I28 and MMT‐20, from Nanocor and Southern Clay Products, respectively. The presence of ATH and the compatibilizer did not have any effect on the exfoliation of the studied samples. The thermal stability and flame retardant properties were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI—ASTM D2863), and flammability tests (Underwriters Laboratory—UL‐94). The effect of different compatibilizers on the clay dispersion and exfoliation was studied. The results indicated that the addition of montmorillonite makes it possible to substitute part of the ATH filler content while maintaining the flame retardant requirements. The thermal stability of MMT/ATH‐filled LDPE/EVA blends presented a slight increase over the reference ATH‐filled LDPE/EVA blend. Compositions with higher clay content (10 wt %) showed better physicochemical properties. The increased stability of the higher clay content compositions results from the greater inorganic residual formation; this material has been reported to impart better performance in flammability tests. The mechanical properties and flame retardancy remained similar to those of the reference compound. The reduced ATH content resulted in lower viscosities and densities, facilitating the processing of the polymer/ATH/clay compounds. Extrusion of these compounds produced a lower pressure in the extrusion head and required reduced electrical power consumption. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
999.
Polyphenols from flesh and peels of red pitaya (Hylocereus polyrhizus) fruit were quantified by employing an extract sub-fractionation procedure applied for the first time to this fruit. Higher polyphenolic contents than those from the literature were measured by using analogous spectroscopic techniques to those reported in previous works. Betacyanin fractions exhibited the highest reducing and radical-scavenging capacities among the extracts and fractions tested by FRAP and DPPH assays, respectively. Finally, polyphenolic fractions showed a broad antimicrobial spectrum by inhibiting the growth of all of food-borne pathogens tested, while the non-fractionated extracts revealed a very low or no activity. Results indicated flesh as a good source of antioxidants with healthy benefits for human diet and peels as a valuable manufacture by-product to be exploited for the formulation of nutraceuticals and food applications. 相似文献
1000.
Mónico Pifarré A Martín O de Portela ML Langini SH Weisstaub AR Greco C de Ferrer PR 《Archivos latinoamericanos de nutrición》2006,56(4):356-360
Orange juice may be a nutrient vehicle that helps to improve diet quality. The addition of whey allows the incorporation of high quality proteins. However, a good acceptability is necessary. The aims of the present study were: a) to assess the acceptability of a beverage prepared with orange juice (J) and whey powder (WP) at 7 g/100 g (J+WP7) or at 13 g/100 g (J+WP13); b) to measure available lysine content and ascorbic acid retention of the more accepted formulation, comparing the effect of HIPEF treatment (29 kV/cm, t(acum): 59 micros) with a conventional heat treatment at 75 degrees C, for 15 minutes (HT). The beverages were subjected to sensory evaluation (Friedman test). Available lysine was assessed by the Carpenter method, modified by Booth, and vitamin C by HPLC; minerals Na and K, by flame photometry; Ca, Mg and Zn by atomic absorption spectrometry. There were no significant differences between the acceptance of J and J+WP7. J+WP13 was significantly less accepted (p < 0.01), so it was discarded. Available lysine (mg/g protein) in untreated J+WP7 was 60.2 +/- 0.15; after treatments: 50.0 +/- 2.8 (HT) and 51.0 +/- 3.4 (HIPEF). The HIPEF treated J and (J+WP7) retained 100% and 98% of their vitamin C initial content and the HT treated, 91% and 88%, respectively. The amount of whey powder added to the orange juice conditioned the acceptability. The juice containing 7% of whey powder was well accepted, and after treatment by HIPEF, it retained a good nutritional quality, regarding available lysine, vitamin C retention and provision of mineral nutrients. 相似文献