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171.
Jukka Viheriälä Juha Tommila Tomi Leinonen Mihail Dumitrescu Lauri Toikkanen Tapio Niemi Markus Pessa 《Microelectronic Engineering》2009,86(3):321-324
We show how to use a modified poly-dimethyl-siloxane (PDMS) soft stamp to reduce pattern deformation and residual layer thickness in soft UV-nanoimprint lithography. A soft stamp thinned with toluene reduces the residual layer of a resist by as much as 50% compared to an unthinned stamp. We apply the soft UV-nanoimprint to prepare nanopatterned waveguides for a single-frequency diode laser. This laser operates with a side-mode suppression ratio of 50 dB, which indicates that the patterns are precise and uniform over the whole imprint field. To the best of our knowledge, this is the first single-frequency laser fabricated by soft UV-nanoimprint technology. 相似文献
172.
Dense sialon ceramics along the tie line between Si3 N4 and Nd2 O3 ·9AlN were prepared by hot-pressing at 1800°C. The materials were subsequently heat-treated in the temperature range 1300–1750°C and cooled either by turning off the furnace (yielding a cooling rate (Tcool ) of ∼50°C/min) or quenching (Tcool ≥ 400°C/min). It was found necessary to use the quenching technique to reveal the true phase relationships at high temperature, and it was established that single-phase α-sialon forms for 0.30 x 0. 51 in the formula Ndx Si12–4S x Al4.5 x O1. 5 x , N16–1.5 x . The α-sialon is stable only at temperatures above 1650°C, and it transforms at lower temperatures by two slightly different diffusion-controlled processes. Firstly, an α-sialon phase with lower Nd content is formed together with an Al-containing Nd-melilite phase, and upon prolonged heat treatment thus-formed α-sialon decomposes to the more stable β-sialon and either the melilite phase or a new phase of the composition NdAl(Si6-z Alz )N10-z Oz . Nd-doped α-sialon ceramics containing no crystalline intergranular phase show very high hardness (HV10 = 22. 5 GPa) and a fracture toughness ( K lc = 4.4 MPa·m1/2 ) at room temperature. The presence of the melilite phase, which easily formed when slow cooling rates were applied or by post-heat-treatment, reduced both the fracture toughness and hardness of the materials. 相似文献
173.
The melting behaviour of the metallized, porous wustite pellets immersed in liquid slag, as well as the influences of the metallization ratio, pre-heating temperature of the pellet and slag temperature were examined in this work by means of an X-ray imaging system. The internal structure of the pellets after having been immersed in slag was checked by optical microscope and EPMA. The adoption of digital image processing improved the image analysis dramatically and, as a result, some important phenomena, such as solid slag shell forming and melting, slag penetration, wustite component dissolution as well as the influence of experimental conditions, were quantified. 相似文献
174.
This study set out to identify the most important needs of hospital patients on surgical and medical wards and to assess the ability of nurses to identify these needs. The population consisted of 92 Finnish patients and 69 Finnish nurses. The study was carried out using a questionnaire designed on the basis of the need theory presented by Yura and Walsh. The results of the statistical analyses were presented in the form of frequencies, cross-tabulations and chi-square tests. The patients' most common needs were related to vital functions (44%), followed by those related to functional health status (38%) and environmental needs (36%). The last item on the list of expressed needs concerned reactions to functional health status (31%). Over 70% of the surgical patients suffered from problems related to sleep and rest. Less than 60% of them suffered from acute pain. Medical patients, in turn, had more frequent needs related to vital functions than did surgical patients. Three out of four medical patients suffered from acute pain. Sleep and rest disturbances, stress, bad mood and listlessness were also common problems. The nurses underestimated all patient needs, apart from environmental needs, which they regarded as the main concern of patients. There was a statistically significant difference between patients' and nurses' assessments for 38% of all needs. Moreover, there were differences in assessments between the surgical and medical wards included in the study. 相似文献
175.
Neugebauer Alyson; Katz Patricia P.; Pasch Lauri A. 《Canadian Metallurgical Quarterly》2003,22(3):253
This longitudinal study identified a model through which function affects the psychological well-being of individuals with rheumatoid arthritis (RA). Results of hierarchical linear regression analyses (N = 436) demonstrated that greater physical impairment resulted in greater disability in valued activities and engagement in unfavorable social comparisons. All 3 factors--greater physical impairment, greater disability in valued activities, and unfavorable comparison evaluations--predicted low satisfaction with abilities. Low satisfaction with abilities was the most important predictor of higher depressive symptoms and mediated the impact of physical impairment, valued activity disability, and unfavorable comparisons on depressive symptoms. Results highlight the role of personal meaning attached to changes in functional status in predicting the long-term psychological well-being of individuals with chronic illnesses such as RA. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
176.
Iron droplets can be ejected into the surrounding atmosphere or entrained into the slag phase when gas bubbles pass through
the metal surface or the metal/slag interface. The phenomena occurring during passage of single bubbles through the free surface
and the interface were investigated by using the in-situ X-ray transmission technique. The mass of droplets ejected into the atmosphere attained a maximum value at a certain bubble
size, which depended on the surface tension of the iron melt. Bubble bursting on the free surface of iron melt ejected numerous
fine iron droplets called “film droplets” and a few much larger jet droplets. Two different groups of iron droplets were also
observed as entrained in the slag due to bubble passage through the iron/slag interface, although the physical phenomena are
to some extent different from bubble bursting to the gas phase.
This article is based on a presentation given in the Mills Symposium entitled “Metals, Slags, Glasses: High Temperature Properties
& Phenomena,” which took place at The Institute of Materials in London, England, on August 22–23, 2002. 相似文献
177.
This study looks at the influence of alumina powder processing on the preparation of transparent alumina by Spark Plasma Sintering (SPS). Zeta potential measurements were carried out on alumina suspensions in order to determine the best dispersion conditions. Stable slurries were submitted to a spray freeze drying process and their sintering behavior was compared with the corresponding non spray freeze dried powders. Transparent alumina samples were successfully prepared from alumina powders by Spark Plasma Sintering. An optical model considering pore and grain size distributions has been developed to obtain information about porosity in dense materials. It was found that the final density and, accordingly, the optical properties were improved when spray freeze dried starting powder was used. 相似文献
178.
Victor Zamora Angel L. Ortiz Fernando Guiberteau Mats Nygren 《Ceramics International》2013,39(4):4191-4204
The spark-plasma sintering (SPS) kinetics of ZrB2–SiC powder mixtures was investigated as a function of the degree of high-energy co-ball-milling and of the SiC content (5, 17.5, or 30 vol%). As in ZrB2 without SiC, it was found that the crystal size refinement induced by the continued milling progressively enhances the SPS kinetics of ZrB2–SiC, again only moderately if the refinement is to the ultra-fine range, but very marked if the refinement is to the nanoscale. It was also found that the SiC addition further enhances the SPS kinetics of ZrB2, although the improvement did not scale directly with the SiC content, and became less relevant with the refinement of the ZrB2 crystal sizes to the nanoscale. The improved kinetics induced by the SiC addition was identified as being due to the formation of amorphous borosilicate from the oxide passivating layers on the ZrB2 and SiC particles. This not only speeds up the interparticle diffusion, but also it is segregated under the application of pressure into the multi-grain joints, filling pores. The enhanced kinetics induced by the progressive milling is due to the continuous reduction of the diffusion distances and to the development of a greater density of grain boundaries available as faster diffusion paths, together with the greater formation of amorphous borosilicate. Implications of interest for the ultra-high-temperature ceramics community are discussed. 相似文献
179.
Laura Silvestroni Mats Nygren Diletta Sciti 《Journal of the European Ceramic Society》2013,33(15-16):2879-2888
This work aims at studying the interactions between Hi-Nicalon SiC fiber and HfB2 in presence of various sintering additive, such as Si3N4 or ZrSi2. Spark plasma sintering was used as suitable technique to interrupt the sintering at intermediate temperatures and thus analyze the microstructure evolution at the various densification stages. SEM investigations enabled to disclose the interaction mechanisms not only among fiber and matrix, but also revealed the curious mechanisms of formation of core–shell structures in HfB2 grains when ZrSi2 was employed. 相似文献
180.
Sergey A. Grinshpun Atin Adhikari Chunlei Li Michael Yermakov Lauri Reponen Elisabet Johansson 《Aerosol science and technology》2013,47(11):1042-1048
Thermal inactivation of viruses has been studied in relevance to food sterilization, water purification, and other “non-aerosol” applications, in which heat treatment is applied for a relatively long time. No data are available on the inactivation of airborne viruses exposed to dry heat for a short time, although this is relevant to bio-defense and indoor air quality control. In this study, we investigated inactivation of aerosolized MS2 viruses in a continuous air flow chamber with axial heating resulted from exposures during ~ 0.1–1 s. For an airborne virion, the characteristic exposure temperature, T e , was defined utilizing the air temperature profiles in the chamber. The tests were conducted at two air flow rates, Q, which allowed for establishing different thermal flow regimes and exposure time intervals. The experimentally determined inactivation factor, IF, was subjected to correction to account for the temperature profiles. At T e up to ~ 90°C (Q = 18 L/min) and up to ~ 140°C (Q = 36 L/min), the loss of viral infectivity was relatively modest (≤ 10). However, IF increased exponentially as T e rose from ~ 90°C to ~ 160°C (for 18 L/min) or from ~ 140°C to ~ 230°C (for 36 L/min). Under specific thermal exposure conditions (~ 170°C and ~ 250°C, respectively), IF exceeded ~ 2.4 × 104 (~ 99.996% infectivity loss)—the maximum quantifiable in this study. The airborne MS2 virions exposed to hot air for < 1 s were found to have survived much higher temperatures than those subjected to thermal treatment in liquid for minutes or hours. The findings are significant for establishing limitations of the heat-based bioaerosol control methods. 相似文献