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101.
Indentation Determination of Fatigue Limits in Silicate Glasses 总被引:1,自引:0,他引:1
An experimental approach has been used to measure the threshold stress intensity factor ( K th ) for subcritical crack growth in brittle materials using indentation cracks. The data show that K th values existed in soda-lime-silica and soda-alumina-silica glasses that were tested in a neutral aqueous environment. For the former glass, tests also were performed in acidic and basic solutions. A threshold for subcritical crack growth was observed for acidic conditions but not for alkaline conditions. 相似文献
102.
Vincenzo M. Sglavo Paolo Bosetti Elena Trentini Michele Ceschini 《Journal of the American Ceramic Society》1999,82(8):2269-2272
A technique for precracking brittle materials is presented. This procedure, which is called the sandwiched-beam (SB) technique, allows the production of sharp through-thickness cracks with predetermined length in specimens with a rectangular section. A bar, in which an initial notch is produced by using a conventional saw, is inserted between two supporting beams and the sandwich assembly is loaded in three-point bending. Conditions can be defined that allow the stable propagation of a sharp flaw from the notch as the applied load is increased. Then, the cracked bar can be used to determine the fracture toughness. The SB technique is applied to different brittle materials, including soda-lime-silica glass, alumina, Si3 N4 , a SiC w -Si3 N4 composite, graphite, a Ti-Al intermetallic, and Carrara marble. 相似文献
103.
新村空间设计语汇模块化是村落景观设计较为普遍的现象,也是地域特征弱化和空间不契合空间行为等问题的主要原因之一。古村落宅间元素是村民日常生活与村落环境在相互影响下长期适应性发展的结果,宅间元素模式研究可促进丰富新村空间设计语汇。以徽州地区古村落为例,从宅间元素的分类、图示、与空间行为的关联3个方面论述了古村落宅间元素模式研究方法论。通过徽州茆田新村景观设计阐述了宅间元素模式的应用,论述了基于古村落宅间元素模式的村落景观设计优化策略,有益于形成并推广地方空间设计语汇,避免过度依赖和使用既有的、来自城市的广场、草坪、树池等元素造成的全国村落的无差别设计。 相似文献
104.
Martino Di Serio Riccardo Tesser Vincenzo Russo Rosa Turco Rosa Vitiello Yongqiang Sun Wiesław Hreczuch 《Journal of surfactants and detergents》2015,18(5):913-918
The intermediates for the production of nonionic surfactants can be derived from petrochemicals and/or from renewable raw materials. In both, the role of catalysis is fundamental. In this paper the main results reported in the literature related with the catalysis for ethoxylation of fatty esters will be reviewed. The main open challenges for these technologies will be outlined. 相似文献
105.
Vincenzo Petrozza Antonio Carbone Teresa Bellissimo Natale Porta Giovanni Palleschi Antonio Luigi Pastore Angelina Di Carlo Carlo Della Rocca Francesco Fazi 《International journal of molecular sciences》2015,16(12):29219-29225
A key challenge for the improvement of clear cell renal cell carcinoma (ccRCC) management could derive from a deeper characterization of the biology of these neoplasms that could greatly improve the diagnosis, prognosis and treatment choice. The aim of this study was to identify specific miRNAs that are deregulated in tumor vs. normal kidney tissues and that could impact on the biology of ccRCC. To this end we selected four miRNAs (miR-21-5p, miR-210-3p, miR-185-5p and miR-221-3p) and their expression has been evaluated in a retrospective cohort of formalin-fixed paraffin-embedded (FFPE) tissues from 20 ccRCC patients who underwent surgical nephrectomy resection. miR-21-5p and miR-210-3p resulted the most significantly up-regulated miRNAs in this patient cohort, highlighting these onco-miRNAs as possible relevant players involved in ccRCC tumorigenesis. Thus, this study reports the identification of specific oncogenic miRNAs that are altered in ccRCC tissues and suggests that they might be useful biomarkers in ccRCC management. 相似文献
106.
107.
The effect of small Al addition on pressureless-sintering and mechanical properties of B4C ceramic was analyzed. Different amounts of aluminium powder, from 0% to 5 wt%, were added to the base material and pressureless-sintering was conducted at 2050 and 2150 °C under argon atmosphere. Microstructure, crystalline phases, density evolution, fracture strength, elastic modulus, hardness and fracture toughness were analyzed and correlated to Al additions and firing temperature. Density and grain size of sintered samples increased significantly with Al load while the effect of sintering temperature was less evident; 94% dense material was obtained by adding 4 wt% Al. Bending strength, hardness and fracture toughness of sintered B4C samples were shown to increase for Al content up to 4 wt% while further additions resulted in a decrease of the mechanical resistance. Conversely, elastic modulus showed an increase with Al load especially between 1 and 3 wt%. 相似文献
108.
Available options to upgrade LCO to diesel fuel are: i) aromatic saturation (ASAT) ii) mild hydrocracking and iii) aromatic saturation followed by selective ring opening (SRO) of naphthenic structures. Although the above mentioned routes lead to significant product quality enhancement, they suffer from several disadvantages. Hydrocracking leads to significant yields in gasoline-range products, ASAT is characterized by a relatively high consumption of hydrogen with only limited improvement of product quality in terms of density and cetane properties, ASAT + SRO route leads to higher improvements of product quality but it requires a very high hydrogen consumption which strongly affects the economics of the process.An alternative upgrading route consists in partial polyaromatic compound saturation and selective opening of both naphthenic and benzo-naphthenic structures to produce less condensed naphthenic structures and alkyl-benzenes respectively. In this case the hydrogen needed to improve product quality at the same level, of cetane properties and density, is lower in comparison with ASAT.This paper reports the results obtained during a research program aimed at upgrading LCO via selective ring opening. The hydroconversion of a low sulfur hydrotreated LCO has been studied over iridium and platinum loaded on different supports. The results of this study indicate that the properties of products heavily depend on the characteristics of the support and the metal used. The data obtained with the Ir/amorphous silica-alumina (MSA) show the possibility to get a clear increase of CN and decrease of density in comparison with the mere aromatic saturation. The practical consequence of this result is the possibility of producing products with CN and density similar to products obtained by complete dearomatization but still containing a significant percentage of aromatic structures so allowing a consistent saving of hydrogen. 相似文献
109.
Enrico Maccallini Theodoros Tsoufis Salvatore La Rosa Gennaro Chiarello Vincenzo Formoso Raffaele G. Agostino 《Carbon》2010,48(12):3434-3445
Fe-Co bimetallic catalysts supported on MgO were studied for the catalytic chemical vapor deposition growth of carbon nanotubes (CNTs). Different wt.% metal loadings were investigated at various deposition temperatures and times. Characterization of the products involved thermal analysis (DTA-TGA), X-ray diffraction, spectroscopy (Raman, UPS, EELS and STS) and microscopy (SEM, TEM and STM) techniques. It was found that the metal content is critical, not only to the yield and the structural quality of the synthesized carbon nanotubes, but it can be also used to tune the desired type of synthesized nanotubes. Lower (2 wt.%) loadings of Fe-Co catalysts favor the formation of single- and/or double-wall CNTs for deposition time and temperature 30 min and 800 °C, respectively. Thermal analysis and Raman measurements showed that these thin CNTs were synthesized at high amounts (CNT-per-catalyst wt.% of more than 100%), exhibiting high graphitization degree with only traces of by-products (mainly amorphous carbon) among them. Microscopy results revealed the formation of CNTs bundles, consisting of individual nanotubes with less than 2 nm outer diameter, while additional energy loss measurements pointed out that the deposited CNTs are mainly single wall. Higher (10 wt.%) Fe-Co loadings resulted to the formation of multi-wall CNTs. 相似文献
110.
Zicarelli F Calabrò S Cutrignelli MI Infascelli F Tudisco R Bovera F Piccolo V 《Journal of the science of food and agriculture》2011,91(7):1213-1221
BACKGROUND: The aim of this trial was to evaluate the replacement of rumen fluid with faeces as inoculum in studying the in vitro fermentation characteristics of diets for ruminants using the in vitro gas production technique. Six iso‐protein diets with different forage/concentrate ratios were incubated with rumen fluid (RI) or faeces (FI) collected from sheep. RESULTS: Most of the fermentation parameters were influenced by diet and inoculum (P < 0.01). With both inocula, organic matter degradability (dOM), cumulative gas production (OMCV) and maximum fermentation rate (Rmax) increased as the amount of concentrate in the diet increased. Rmax was lower with FI vs RI (P < 0.01); dOM was higher with FI vs RI and the diet × inoculum interaction was significant. As expected, with both inocula, Rmax increased as the neutral detergent fibre content of the diet decreased. Significant correlations were obtained using both inocula between OMCV/dOM and gas/volatile fatty acid (VFA), while the correlation VFA/dOM was significant only with FI. The microbial biomass yield calculated by stoichiometric analysis for all diets was higher with FI vs RI. With FI the organic matter used for microbial growth showed an overall decreasing trend as the amount of concentrate in the diet increased. CONCLUSION: The results indicate that both faeces and rumen fluid from sheep have the potential to be used as inoculum for the in vitro gas production technique. Copyright © 2011 Society of Chemical Industry 相似文献