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61.
Tubular dentin sealer penetration after different final irrigation protocols: A confocal laser scanning microscopy study 下载免费PDF全文
Ricardo Machado Alessandra Timponi Goes Cruz Bianca Marques de Mattos de Araujo Adriane Antoniw Klemz Hellen Pontes Klug Ulisses Xavier da Silva Neto 《Microscopy research and technique》2018,81(6):649-654
The aim of this study was to evaluate tubular dentin sealer penetration, comparing different final irrigation protocols using a conventional needle (CONV), EndoActivator system (EAS), EndoVac system (EVS), and ultrasound (PUI). Initially, fifty‐two first maxillary molars with a single canal in the palatal root, without abrupt curvatures, resorptive processes, or previous endodontic treatment were selected for this study. Then, the crowns were sectioned to obtain palatal roots 15 mm in length. The root canals were prepared with the ProTaper Universal System and irrigated with 5% NaOCl. Afterwards, the specimens were divided into four groups (n. 13), according to the final irrigation protocol: CONV, EAS, EVS, and PUI. After filling, slices at 3 mm and 5 mm from the apex were obtained for analysis by confocal laser scanning microscopy. Two‐way comparisons between the groups and the levels were performed with Games Howell's test (p < .05). Tubular dentin sealer penetration was higher at 5 mm compared with 3 mm from the apex (p < .05). The EAS group showed a higher percentage of tubular dentin sealer penetration, compared with the CONV group, at both levels. At 3 mm, there was no statistically significant difference among EAS, EVS, and PUI; however, these groups showed better performance, compared with the CONV group. At 5 mm, there was no statistically significant difference between the EAS and EVS groups, but both showed higher sealer penetration than the PUI group (p < .05). The EAS and EVS groups achieved better degrees of tubular dentin sealer penetration, compared with the other groups. 相似文献
62.
Debora Salomon Marques Rachel Mika Dorin Ulrich Wiesner Detlef-M. Smilgies Ali R. Behzad Ulla Vainio Klaus-Viktor Peinemann Suzana P. Nunes 《Polymer》2014
Time-resolved grazing-incidence small-angle X-ray scattering (GISAXS) and cryo-microscopy were used for the first time to understand the pore evolution by copolymer assembly, leading to the formation of isoporous membranes with exceptional porosity and regularity. The formation of copolymer micelle strings in solution (in DMF/DOX/THF and DMF/DOX) was confirmed by cryo field emission scanning electron microscopy (cryo-FESEM) with a distance of 72 nm between centers of micelles placed in different strings. SAXS measurement of block copolymer solutions in DMF/DOX indicated hexagonal assembly with micelle-to-micelle distance of 84–87 nm for 14–20 wt% copolymer solutions. GISAXS in-plane peaks were detected, revealing order close to hexagonal. The d-spacing corresponding to the first peak in this case was 100–130 nm (lattice constant 115–150 nm) for 17 wt% copolymer solutions evaporating up to 100 s. Time-resolved cryo-FESEM showed the formation of incipient pores on the film surface after 4 s copolymer solution casting with distances between void centers of 125 nm. 相似文献
63.
Gerson Reginaldo Marques Soraia Vilela Borges Diego Alvarenga Botrel Joyce Maria Gomes da Costa Eric Keven Silva Jefferson Luiz Gomes Corrêa 《Drying Technology》2014,32(7):861-868
Maize (Zea mays) is a cereal grown in Brazil, and its availability is limited to the harvest season. An alternative processing route is based on the production of green corn powder, which has a longer shelf-life and increased versatility. This study aimed to evaluate the influence of drying conditions on the physical characteristics, size, and morphology of green corn powder. Drying experiments were performed on a spray dryer according to a central composite rotational design to evaluate inlet air temperature, feed flow rate, and pulp concentration. The yield of dried pulp corn had an average value of 36.19%. The following mean values for the physical properties of the powder were measured: solubility of 94.37 g/100 g, wettability of 128.05 seconds, moisture content of 1.97%, water activity of 0.13, density of 0.79 g/mL, and a particle diameter of 31.02 µm. The powder was also yellow with less intensity, and the particle surface was smooth at higher temperatures and had a tendency to form agglomerates. The estimated optimal conditions for spray drying were 48% (w/w) pulp concentration, 172°C inlet air temperature, and feed flow rate of 0.56 L/h. 相似文献
64.
This work presents useful composites for oil spill cleanup processes. These systems are composed of a polyester matrix loaded with coffee ground powder and maghemite. They were prepared by in situ polymerization. The aliphatic monomers proportion—castor oil and glycerin—was studied with the aim of understanding the effect of feed ratio on the product properties. The materials were studied using several techniques, including Fourier Transform Infrared Spectroscopy, Ultraviolet‐visible Spectrophotometry, and Wide Angle X‐ray Scattering, with magnetic force tests used for the characterization of materials. Density tests showed the presence of coffee grounds causes an important reduction in the density values of composites, improving their flotation. The interaction between composites and petroleum is more than twice that between composites and water. Moreover, for all magnetizable composites, the removal capability was (25.1 ± 1.2) g/g (petroleum/composite), allowing us to state that this is a promising material for use in oil spill cleanup processes. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43127. 相似文献
65.
Luís Filipe Sanches Fernandes Maria João Marques Paula Cristina Oliveira João Paulo Moura 《Water and Environment Journal》2014,28(3):350-357
This paper puts forward the importance of decision support systems (DSS) for the planning and management of water resources. A case study of the Pinhão river basin, in Portugal, is presented. Given the importance of vineyards in the Douro region, it is important to determine if water availability will be enough to meet present and future water demands. In order to answer this question, DSS tools were used to assess different scenarios. The MIKE BASIN software was used in the hydrographical basin of Pinhão river, assisted by a geographic information system, GIS, which allowed the modelling of the basin, both temporally and spatially, facilitating the visualisation and interpretation of results. According to the attained results, it was verified that, at present, the hydrographical basin meets the considered water needs. The DSS proved to be an important tool to assist the decision‐making process in the studied river basin. 相似文献
66.
Ultrastructural and immunohistochemical study of the effect of sodium alendronate in the progression of experimental periodontitis in rats 下载免费PDF全文
Mariana M. Moreira Vivian Bradaschia‐Correa Natasha D. M. Marques Lorraine Braga Ferreira Victor E. Arana‐Chavez 《Microscopy research and technique》2014,77(11):902-909
The aim of the present research was to investigate the ultrastructural aspects and the immunoexpression of receptor activator of NFκB ligand (RANKL) and osteoprotegerin (OPG) on experimental periodontal disease of alendronate (ALN)‐treated rats. Male Wistar rats received daily injections of 2.5 mg/kg body weight of ALN during 7 days previously and 7, 14, and 21 days after the insertion of a 4.0 silk suture into the gingival sulcus around the right upper second molar. Specimens were fixed in 0.1% glutaraldehyde + 4% formaldehyde under microwave irradiation, decalcified in 4.13% EDTA and paraffin embedded for TRAP histochemistry and immunohistochemistry for RANKL and OPG, or embedded in Spurr epoxy resin for TEM analysis. ALN reduced the activity of osteoclasts and significantly decreased the resorption of the alveolar crest. In the control group the alveolar crest appeared resorbed by TRAP‐positive osteoclasts, which presented ultrastructural features of activated cells. The immunoexpression of RANKL was not inhibited by the drug; however, the expression of OPG was increased in the treated animals. The alveolar crest of ALN‐treated specimens at 21 days showed signs of osteonecrosis, like empty osteocyte lacunae, the exposed bone regions and bacterial infection. The results showed that ALN treatment in individuals with periodontal disease represents a risk of osteonecrosis because of the reduced activity of osteoclasts resultant of the increased immunoexpression of OPG. Microsc. Res. Tech. 77:902–909, 2014. © 2014 Wiley Periodicals, Inc. 相似文献
67.
W. H. Cassinelli L. S. F. Feio J. C. S. Araújo C. E. Hori F. B. Noronha C. M. P. Marques J. M. C. Bueno 《Catalysis Letters》2008,120(1-2):86-94
The effect of the addition of CeO2 or La2O3 on the surface properties and catalytic behaviors of Al2O3-supported Pd catalysts was studied in the steam reforming of methane. The FTIR spectroscopy of adsorbed CO and the Pd dispersion
suggest the partial coverage of Pd0 by ceria or lanthana species. This could lead to the formation of an adduct MPd
x
O (M = Ce or La) at the surface of the metal crystallites. The addition of ceria or lanthana resulted in an increase of the
turnover rate and specific rate for steam reforming of methane. One possible explanation if that the Pd0*Pdδ+O–M interfacial species (M = Ce or La) are oxidized by H2O or CO2, promoting the O* transfer to the metal surface. This could facilitate the removal of C* species from the metal surface,
resulting in the increase of specific reaction rate and increase of the accessibility of CH4 to metal active sites. 相似文献
68.
E. A. S. Marques R. D. S. G. Campilho Lucas F. M. da Silva 《Journal of Adhesion Science and Technology》2016,30(7):691-707
The use of adhesives for high-performance structural applications has significantly increased in the last decades. However, the use of adhesive joints in adverse environmental conditions is still limited due to the reduced capability of adhesives to withstand large thermal gradients. Dual adhesive joints, which contain two adhesives with remarkably different mechanical behaviours, are a technique suitable for being used in extreme temperatures. The object of this study is a ceramic–metal joint, representative of the thermal protection systems of some aerospace vehicles. In this paper, several joint-mixed joint geometries are presented, studied with recourse to finite element analysis. In a first phase, the three-dimensional finite element models and the material properties are validated against experimental data. In a second phase, the model geometry is modified, with the aim of understanding the effect of several changes in the joints’ mechanical behaviour and comparing the merits of each geometry. The models’ presented good agreement was found between experimental and numerical data and the alternative geometries allowed the introduction of additional flexibility on the joint but at the cost of lower failure load. 相似文献
69.
Clément C. Campillo André P. Schroder Carlos M. Marques Brigitte Pépin-Donat 《Materials science & engineering. C, Materials for biological applications》2009,29(2):393-397
We further investigate the properties of composite Poly(NIPAM) (poly(N-isopropylacrylamide)) gel-filled giant vesicles, focusing here on i) the homogeneity of the membrane, ii) its coupling to the inner gel under strong suction pressures, and iii) the relation between the final elastic modulus of the vesicles and the amount of crosslinker in the pre-gel medium. We show that whereas the photo-polymerization process induces a decrease of the membrane homogeneity at the micrometer size range, the membrane still remains strongly coupled to the internal gel network. The vesicles studied here display average moduli in the range [0.5–25] kPa, confirming their potential as biomimetic mechanical systems. 相似文献
70.
Kristof De Witte Rui C. Marques 《International Transactions in Operational Research》2009,16(2):257-271
Environmental factors add complexity to the comparison between specific activities or entire entities. Decision making units with an inferior performance are tempted to invoke that their organization is "different" from the others in the data set. By reinterpreting and extending the metafrontier literature, we propose an all-embracing concept to fully capture the operational environment. We suggest the "Group Specific Technical Efficiency" as a new measure to assess the overall efficiency of a utility while allowing for environmental differences. A real-world example of drinking water utilities from five different countries illustrates the concept. 相似文献