全文获取类型
收费全文 | 611篇 |
免费 | 23篇 |
国内免费 | 11篇 |
专业分类
电工技术 | 44篇 |
综合类 | 5篇 |
化学工业 | 215篇 |
金属工艺 | 15篇 |
机械仪表 | 7篇 |
建筑科学 | 36篇 |
能源动力 | 11篇 |
轻工业 | 46篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 29篇 |
一般工业技术 | 138篇 |
冶金工业 | 7篇 |
原子能技术 | 15篇 |
自动化技术 | 74篇 |
出版年
2023年 | 2篇 |
2022年 | 2篇 |
2021年 | 11篇 |
2020年 | 3篇 |
2019年 | 12篇 |
2018年 | 7篇 |
2017年 | 9篇 |
2016年 | 14篇 |
2015年 | 10篇 |
2014年 | 19篇 |
2013年 | 25篇 |
2012年 | 23篇 |
2011年 | 32篇 |
2010年 | 24篇 |
2009年 | 29篇 |
2008年 | 36篇 |
2007年 | 18篇 |
2006年 | 33篇 |
2005年 | 31篇 |
2004年 | 27篇 |
2003年 | 22篇 |
2002年 | 19篇 |
2001年 | 14篇 |
2000年 | 10篇 |
1999年 | 16篇 |
1998年 | 6篇 |
1997年 | 11篇 |
1996年 | 14篇 |
1995年 | 6篇 |
1994年 | 12篇 |
1993年 | 9篇 |
1992年 | 3篇 |
1991年 | 7篇 |
1990年 | 8篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 9篇 |
1986年 | 14篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 10篇 |
1982年 | 11篇 |
1981年 | 5篇 |
1980年 | 10篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 5篇 |
1975年 | 3篇 |
1973年 | 3篇 |
1971年 | 2篇 |
排序方式: 共有645条查询结果,搜索用时 31 毫秒
101.
Takeshi Kikutani J. Radhakrishnan Sadaaki Arikawa Akira Takaku Norimasa Okui Xia Jin Fumio Niwa Yosuke Kudo 《应用聚合物科学杂志》1996,62(11):1913-1924
High-speed bicomponent spinning of poly(ethylene terephthalate)(PET)(core) and poly-propylene (PP) (sheath) was carried out and the structure development in the individual components, PET and PP, was investigated. The orientation and crystallinity development in the PET component was enhanced as compared to that of the single-component spinning while the PP component remained in a low orientation state and had a pseudohexagonal crystal structure even at high take-up speeds. To clarify the mutual interaction between the two components in bicomponent spinning, a semiquantitative numerical simulation was performed. The simulation results obtained using the Newtonian fluid model showed that the solidification stress in the PET component was enhanced while that of the PP component was decreased in comparison with the corresponding single-component spinning. This is due to the difference in the temperature dependence of their elongational viscosity. Simulation with an upper-convected Maxwell model as the constitutive equation suggested that significant stress relaxation of the PP component can occur in the spinline if the PET component solidifies earlier than does PP. Based on the structural characterization results, and the simulation results, it was concluded that the difference in the activation energy of the elongational viscosity and solidification temperature between the two polymers are the main factors influencing the mutual interaction in the bicomponent spinning process. © 1996 John Wiley & Sons, Inc. 相似文献
102.
A series of liquid crystalline aromatic polyesters containing 3,3′-dimethylbiphenyl-4,4′-dicarboxylic acid and 3,4′-dimethyl-biphenyl-4,3′-dicarboxylic acid was prepared by a melt polycondensation procedure and characterized by elemental analysis, DSC and TMA measurements, and optical polarizing microscopy. An optimal composition of the copolymer having a melting temperature around 300°C is proposed and the rheological behavior is discussed. Most of the mechanical properties of this copolymer were found to be close to those of Vectra A950® used as a reference sample. © 1996 John Wiley & Sons, Inc. 相似文献
103.
Lili Jiang Xiong Lu Yang Leng Shuxin Qu Bo Feng Jie Weng Fumio Watari 《Materials science & engineering. C, Materials for biological applications》2012,32(4):742-748
This study focused on the effects of microgrooved TiO2 surfaces on osteoblast behavior. Microgrooved TiO2 surfaces with different widths (12 μm and 40 μm) and flat surfaces were fabricated on glass substrates based on the combination of a sol–gel technique and soft-lithography. Osteoblasts (MC3T3-E1) were cultured on the as-prepared microgrooved and flat TiO2 surfaces. Optical microscopy and scanning electron microscopy were used to analyze the adherent cell behavior by examining the cell morphology. Orientation angle analysis indicated that the cells tended to align along the microgrooves. This tendency was stronger on the microgrooves with smaller widths and became weak with increasing width. Alamar Blue assay indicated that the microgrooves restricted cell proliferation and the alkaline phosphatase assay revealed that the microgrooves limited the differentiation rate. This restriction increased with decreasing microgroove width. The surface energy of the TiO2 surfaces was size-dependent and followed the order γ 12 μm < γ 40 μm < γ flat surfaces. Osteoblast proliferation and differentiation on the surface with high surface energy exhibited high proliferation and differentiation rates. These results indicated that surface energy appeared to be a dominant factor for cell activity. Thus, surface energy would be a valuable index for the cell compatibility of a micropatterned surface. 相似文献
104.
105.
We discuss the mode I energy release rate of a rectangular piezoelectric material with a crack under electromechanical loading at cryogenic temperatures. A crack was created normal or parallel to the poling direction, and electric fields were applied parallel or normal to the poling. A plane strain finite element analysis was carried out, and the effects of electric field and localized polarization switching on the energy release rate were discussed for the piezoelectric ceramics at cryogenic temperatures. 相似文献
106.
Yoshiyuki Mizushina Yoshihiro Takahashi Yoshihiro Sato Yasuhiro Yamaguchi Toshifumi Takeuchi Isoko Kuriyama Fumio Sugawara Hiromi Yoshida 《Food chemistry》2012
During the screening of selective DNA polymerase (pol) inhibitors, we isolated two glucosyl compounds, a cerebroside (glucosyl ceramide, AS-1-4, compound 1) and a steroidal glycoside (eleutheroside A, compound 2) from soybean (Glycine max L.). Compounds 1 and 2 selectively inhibited the activity of eukaryotic pol λ in vitro, with IC50 values of 12.2 and 9.1 μM, respectively. These compounds did not influence the activities of other eukaryotic pols including those from the A-family (pol γ), B-family (pols α, δ and ε), and Y-family (pols η, ι and κ), and also showed no effect on the activity of pol β which is of the same family (X) as pol λ. The tendency for in vitro pol λ inhibition by these compounds showed a positive correlation with the in vivo suppression of TPA (12-O-tetradecanoylphorbol-13-acetate)-induced inflammation in mouse ear. These results suggest that these glucosyl compounds from soybean may be useful for their anti-inflammatory properties. 相似文献
107.
Poly(vinyl chloride) (PVC) was ground in air with CaO in the presence of quartz powder as a grinding aid by a small-scale planetary ball mill to investigate the relation of the dechlorination rate of PVC with the impact energy of the balls calculated from a computer simulation based on the Discrete Element Method under various conditions. Mechanochemical dechlorination proceeds as the grinding progresses and is improved with an increase in both the mill speed and the amount of balls introduced into the mill. The same trend can be seen in the relation between the specific normal impact energy of the balls and the rotational speed. The relationship between the observed dechlorination rate and the computed normal impact energy of the balls is linear, with a correlation coefficient of 0.965. This relationship can be used to estimate the dechlorination rate of PVC in a large-scale planetary ball mill. 相似文献
108.
Yuji Wada Hideo Yabashi Masamitsu Tamura Tadao Yoshida Toshio Matsuzawa Fumio Hosoya 《Journal of Energetic Materials》2013,31(1-2):105-132
Abstract The undersand variable gap–initiator test was applied to most Japanese blasting explosive cartridges and found useful as the sensitivity test for the cartridges. The recent Japanese watergel and emulsion explosives were shown to be more shock–sensitive than previous ones. The blast noise in the undersand explosion was shown to decrease when the depth of sand cover the cartridge was increased. For 100g of explosive, a sand layer 20cm deep was effective in reducing the blast noise, when the depth of the sand layer was increased, there was no additional effect. All blasting explosives excluding Kuro Carlit were not ignited by a small gas flame. A cartridge of 100g Kuro Carlit was ignited undersand but did not show the phenomenon of deflagration to detonation 相似文献
109.
Christopher S. Dandeneau Tyler W. Bodick Rajendra K. Bordia Fumio S. Ohuchi 《Journal of the American Ceramic Society》2013,96(7):2230-2237
The thermoelectric properties of bulk polycrystalline Sr0.5Ba0.5Nb2O6 (SBN50) fabricated via solution combustion synthesis (SCS) and reduced at temperatures of 900°C–1150°C were explored. The Seebeck coefficient (S) of all samples increased over the entire range of testing temperatures; a peak S value of ?281 μV/K was obtained at 930 K for the sample reduced at 900°C. A metal‐insulator transition was observed in the electrical conductivity (σ) of samples reduced at 1000°C–1150°C, whereas only semiconducting electrical behavior was observed for the sample reduced at 900°C. An optimal balance between S and σ was achieved for the pellet reduced at 1000°C, which exhibited a maximum power factor of 1.78 μW/cm·K2 at 930 K. Over a temperature range of 300–930 K, the thermal conductivity (κ) of as‐processed and reduced (1000°C) SBN50 was found to be 1.03–1.4 and 1.46–1.84 W/m·K, respectively. A maximum figure of merit (ZT) of 0.09 was obtained at 930 K for the 1000°C‐reduced sample. X‐ray photoelectron spectroscopy revealed that the Nb2+ peak intensity increased at higher reduction temperatures, which could possibly lead to a distortion of NbO6 octahedra and a decrease in the Seebeck coefficient. 相似文献
110.
Prediction of cutting forces and machining error in ball end milling of curved surfaces -I theoretical analysis 总被引:1,自引:0,他引:1
Bernard W. Ikua Hisataka Tanaka Fumio Obata Satoshi Sakamoto 《Precision Engineering》2001,25(4):266-273
This paper presents a theoretical model by which cutting forces and machining error in ball end milling of curved surfaces can be predicted. The actual trochoidal paths of the cutting edges are considered in the evaluation of the chip geometry. The cutting forces are evaluated based on the theory of oblique cutting. The machining errors resulting from force induced tool deflections are calculated at various parts of the machined surface. The influences of various cutting conditions, cutting styles and cutting modes on cutting forces and machining error are investigated. The results of this study show that in contouring, the cutting force component which influences the machining error decreases with increase in milling position angle; while in ramping, the two force components which influence machining error are hardly affected by the milling position angle. It is further seen that in contouring, down cross-feed yields higher accuracy than up cross-feed, while in ramping, right cross-feed yields higher accuracy than left cross-feed. The machining error generally decreases with increase in milling position angle. 相似文献