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41.
Bharath Natarajan Ajay Krishnamurthy Xin Qin Caglar D. Emiroglu Amanda Forster E. Johan Foster Christoph Weder Douglas M. Fox Sinan Keten Jan Obrzut Jeffrey W. Gilman 《Advanced functional materials》2018,28(26)
Most attempts to emulate the mechanical properties of strong and tough natural composites using helicoidal films of wood‐derived cellulose nanocrystals (w‐CNCs) fall short in mechanical performance due to the limited shear transfer ability between the w‐CNCs. This shortcoming is ascribed to the small w‐CNC‐w‐CNC overlap lengths that lower the shear transfer efficiency. Herein, we present a simple strategy to fabricate superior helicoidal CNC films with mechanical properties that rival those of the best natural materials and are some of the best reported for photonic CNC materials thus far. Assembling the short w‐CNCs with a minority fraction of high aspect ratio CNCs derived from tunicates (t‐CNCs), we report remarkable simultaneous enhancement of all in‐plane mechanical properties and out‐of‐plane flexibility. The important role of t‐CNCs is revealed by coarse grained molecular dynamics simulations where the property enhancement are due to increased interaction lengths and the activation of additional toughening mechanisms. At t‐CNC contents greater than 5% by mass the mixed films also display UV reflecting behaviour. These damage tolerant optically active materials hold great promise for application as protective coatings. More broadly, we expect the strategy of using length‐bidispersity to be adaptable to mechanically enhancing other matrix‐free nanoparticle ensembles. 相似文献
42.
43.
Cebeli Özek Muhammet Bal 《The International Journal of Advanced Manufacturing Technology》2009,40(11-12):1077-1083
Deep-drawing is one of the most important methods used to form sheet metal. The radius of die/blank holder and punch is important for deep-drawing dies because of an effective way to promote deep drawability sheet metal. This paper presents an attempt to determine the effect of various radiuses of die and punch on the limit drawing ratio and was investigated using DIN EN 10130–91 sheet metal. The die/blank holder profile with angles of α?=?0°, α?=?2.5°, α?=?7.5°, α?=?12.5°, α?=?15° and die/punch profile with radiuses for R?=?10, R?=?8, R?=?6, R?=?4 and R?=?0 mm were analyzed to determine the influence of punch force on the limit drawing ratio. The aim of this study is to investigate the effect of radius and angle variables on drawability in the deep-drawing process and to obtain useful data from the industrial field. The experiments show that the limit drawing ratio increased with increasing radius of punch (R), die/blank holder angle (α). 相似文献
44.
İbrahim Kivrak Mehmet Emin Duru Mehmet Öztürk Nazime Mercan Mansur Harmandar Gülaçtı Topçu 《Food chemistry》2009
The essential oil of Salvia potentillifolia was analysed by GC and GC–MS. Totally, 123 components were detected in both hydrodistilled and steam-distilled oils, α- and β-pinenes being major compounds. The antioxidant activities were determined by using complementary tests, namely, DPPH radical-scavenging, β-carotene-linoleic acid and reducing power assays. The ethanol extract also showed better activity (IC50 = 69.4 ± 0.99 μg/ml) than that of BHT in the DPPH system, and showed great lipid peroxidation inhibition in the β-carotene-linoleic acid system (IC50 = 30.4 ± 0.50 μg/ml). The essential oil showed meaningful butyrylcholinesterase activity (65.7 ± 0.21%), and α-pinene showed high acetylcholinesterase inhibitory activity (IC50 = 86.2 ± 0.96 μM) while β-pinene was inactive. Antimicrobial activity was also investigated on several microorganisms, and the essential oil showed high activity against Bacillus subtilis and B. cereus. It also exhibited remarkable anticandidal activity against Candida albicans and C. tropicalis with MIC values of 18.5 and 15.5 μg/ml, respectively, while α- and β-pinenes showed moderate activity. 相似文献
45.
Mevlüt ?ahin Emin ?adirli 《Journal of Materials Science: Materials in Electronics》2012,23(2):484-492
The mechanical properties (microhardness, tensile strength) of alloys are controlled by their microstructure, which depends
strongly on temperature gradient (G) and growth rate (V). Thus, it is important to understand the relationships among G, V and microstructure (rod eutectic) of Sn–Ag solders. The Sn–3.5 wt% Ag eutectic alloy was directionally solidified upward
with a constant growth rate, V (16.5 μm/s) at different temperature gradients, G (1.43–4.28 K/mm) and with a constant temperature gradient, G (3.93 K/mm) at different growth rates, V (8.3–500 μm/s) in a Bridgman–type directional solidification furnace. The rod spacings (λ) have been measured from both longitudinal
section (parallel to the growth direction, λ
L
) and transverse section (perpendicular to the growth direction, λ
T
) of the samples. The undercooling values (ΔT) were calculated by using V, λ and system parameters (K
1 and K
2). It was found that the values of λ (λ
T
, λ
L
) decrease while V and G are increasing. The relationships between rod spacing and solidification parameters (G and V) were obtained by linear regression analysis. The dependences of eutectic spacings λ on undercooling (ΔT) are also analyzed. λ2
V, λΔT, ΔTV
−0.5 and ΔTG
−0.5 values were determined by using λ, ΔT, V and G values. The results obtained in this work are compared with the Jackson–Hunt eutectic theory and the similar experimental
works. The experimental
l\textT 2 \textV \lambda_{\text{T}}^{ 2} {\text{V}} value (159.3 μm3/s) is slightly lower than the result 174.6 μm3/s calculated from Jackson–Hunt eutectic theory. 相似文献
46.
Quality differences of hamburger patties incorporated with encapsulated β carotene both as an additive and edible coating 下载免费PDF全文
In this study, different formulations of chitosan (CS) and chitosan/sodium tripolyphosphate (CS/TPP) matrix solutions including β carotene were used as additives and edible coatings in hamburger patties, and the treatments were compared to control in terms of quality, oxidative and microbiological features of the patties. TBARS (2‐thiobarbituric acid reactive substances) values of almost all the treatments increased throughout storage at 4 °C for 8 days. (p < .05). On the last day of storage, the treatment including 5% CS/TPP with β carotene and all the coated treatments had lower TBARS values than the other treatments (p < .05). The comparison of different treatments including the solutions of chitosan or chitosan/TPP matrix containing β carotene showed that incorporation of solution as an edible coating was more effective in lipid oxidation and microbial growth than its utilization as an additive on quality of patties according to the results on last day of storage.
Practical applications
Using polymers loaded with antioxidant agents as additives or edible coatings in food products is one of the most popular scientific approaches in recent studies. In this study, hamburger patties were incorporated with chitosan/sodium tripolyphosphate (CS/TPP) matrix solution loaded with β carotene, CS/TPP matrix solution, pure chitosan solution and pure β carotene as additives and/or edible coatings. By this way, synergistic effects of β carotene with different formulations of chitosan (CS) and CS/TPP were also tested. The results showed that lipid oxidation and microbial growth in the coated patties were mostly lower than that of the other patties formulated with different additives on the last day of storage. 相似文献47.
Emine Acer Emin Çadırlı Harun Erol Hasan Kaya Mehmet Gündüz 《Metallurgical and Materials Transactions A》2017,48(12):5911-5923
Dendritic spacing can affect microsegregation profiles and also the formation of secondary phases within interdendritic regions, which influences the mechanical properties of cast structures. To understand dendritic spacings, it is important to understand the effects of growth rate and composition on primary dendrite arm spacing (λ 1) and secondary dendrite arm spacing (λ 2). In this study, aluminum alloys with concentrations of (1, 3, and 5 wt pct) Zn were directionally solidified upwards using a Bridgman-type directional solidification apparatus under a constant temperature gradient (10.3 K/mm), resulting in a wide range of growth rates (8.3–165.0 μm/s). Microstructural parameters, λ 1 and λ 2 were measured and expressed as functions of growth rate and composition using a linear regression analysis method. The values of λ 1 and λ 2 decreased with increasing growth rates. However, the values of λ 1 increased with increasing concentration of Zn in the Al-Zn alloy, but the values of λ 2 decreased systematically with an increased Zn concentration. In addition, a transition from a cellular to a dendritic structure was observed at a relatively low growth rate (16.5 μm/s) in this study of binary alloys. The experimental results were compared with predictive theoretical models as well as experimental works for dendritic spacing. 相似文献
48.
Kultigin Turkmen Fatih Mehmet Erdur Fatih Ozcicek Adalet Ozcicek Emin Murat Akbas Aysu Ozbicer Levent Demirtas Suleyman Turk H. Zeki Tonbul 《Hemodialysis international. International Symposium on Home Hemodialysis》2013,17(3):391-396
Neutrophil‐to‐lymphocyte ratio (NLR) was introduced as a potential marker to determine inflammation in end‐stage renal disease (ESRD) patients. Recently, platelet‐to‐lymphocyte ratio (PLR) and NLR were found to positively correlated with inflammatory markers including tumor necrosis factor‐α (TNF‐α) and interleukin (IL)‐6 in cardiac and noncardiac patients. Data regarding PLR and its association with inflammation are lacking in hemodialysis (HD) and peritoneal dialysis (PD) patients. Hence, we aimed to determine the relationship between PLR, NLR, and inflammation in ESRD patients. This was a cross‐sectional study involving 62 ESRD patients (29 females, 33 males; mean age, 49.6 ± 14.6 years) receiving PD or HD for ≥6 months in the Dialysis Unit of Necmettin Erbakan University. PLR, NLR, C‐reactive protein, TNF‐α, IL‐6 levels were measured. PLR, NLR, serum high sensitive C‐reactive protein, IL‐6, and TNF‐α levels were significantly higher in PD patients when compared with HD patients. ESRD patients with PLR ≥ 140 had significantly higher NLR, IL‐6, and TNF‐α levels when compared to patients with PLR < 139. In the bivariate correlation analysis, PLR was positively correlated with NLR, IL‐6, and TNF‐α in this population. When we compared the association of PLR and NLR with IL‐6 (r = 0.371, P = 0.003 vs. r = 0.263, P = 0.04, respectively) and TNF‐α (r = 0.334, P = 0.008 vs. r = 0.273, P = 0.032, respectively), PLR was found to be superior to NLR in terms of inflammation in ESRD patients. Simple calculation of PLR can predict inflammation better than NLR in ESRD patients. 相似文献
49.
In this study, temperature distribution in a CCD coated piston used in an HCCI engine was investigated and was guided by existing experimental results. A model based on experimental observations obtained from the experiments at Shell research center was developed by using finite element technique to investigate 3D thermal analyses for both clean and deposited piston. Effect of the CCD thickness on the temperature distribution was analyzed by comparing the results from the clean piston and deposited one. It was observed that the deposited surface temperature increases with increasing the thickness in a decreasing rate. Both aluminum and steel piston compared with each other in respect to the maximum temperature for the same CCD thicknesses, which were tn = 9 and tm = 30 in micro meters. Compared to the clean piston, maximum temperature on the top surface of the aluminum and steel metals diminish 6 °C and 9 °C respectively, because of CCD's relatively low heat transfer coefficient. 相似文献
50.
Process management and innovation arguably remain among the concepts under focus of recent researches since there is no significantly outstanding method to measure and monitor the level of innovation in the manufacturing processes over a particular time period taking the fundamental activities of manufacturing processes into account. Although there are various studies relevant to process improvement, manufacturing processes are not focused on in the literature. This paper presents a novel performance indicator, called degree of process innovation, for monitoring and measuring innovation in manufacturing processes based on the four most important components among the fundamental activities of a manufacturing system. The components are namely Average Labour Utilisation, Cumulative Bottleneck Ratio, Unit Production Time and Unit Production Cost. The idea behind this approach has flourished on the basis of an indicator proposed in the literature to measure the general organisational improvements. The scope of that indicator has been narrowed down to manufacturing processes to accurately reflect the state of the manufacturing processes. The proposed approach has been verified with a case study in manufacturing industry, where each of the four sub-indicators was calculated based on the data provided and aggregated into the degree of process innovation. The innovation degree is successfully indicated. 相似文献