全文获取类型
收费全文 | 132540篇 |
免费 | 6784篇 |
国内免费 | 3080篇 |
专业分类
电工技术 | 4902篇 |
技术理论 | 1篇 |
综合类 | 5534篇 |
化学工业 | 18807篇 |
金属工艺 | 7777篇 |
机械仪表 | 6571篇 |
建筑科学 | 5748篇 |
矿业工程 | 2254篇 |
能源动力 | 2741篇 |
轻工业 | 6926篇 |
水利工程 | 2279篇 |
石油天然气 | 2367篇 |
武器工业 | 519篇 |
无线电 | 15627篇 |
一般工业技术 | 22662篇 |
冶金工业 | 4866篇 |
原子能技术 | 807篇 |
自动化技术 | 32016篇 |
出版年
2024年 | 318篇 |
2023年 | 1066篇 |
2022年 | 2082篇 |
2021年 | 3000篇 |
2020年 | 2134篇 |
2019年 | 1640篇 |
2018年 | 16143篇 |
2017年 | 15100篇 |
2016年 | 11698篇 |
2015年 | 3147篇 |
2014年 | 3134篇 |
2013年 | 3684篇 |
2012年 | 6852篇 |
2011年 | 13223篇 |
2010年 | 11563篇 |
2009年 | 8701篇 |
2008年 | 9617篇 |
2007年 | 10298篇 |
2006年 | 2456篇 |
2005年 | 3116篇 |
2004年 | 2498篇 |
2003年 | 2382篇 |
2002年 | 1694篇 |
2001年 | 1047篇 |
2000年 | 1005篇 |
1999年 | 783篇 |
1998年 | 686篇 |
1997年 | 523篇 |
1996年 | 487篇 |
1995年 | 378篇 |
1994年 | 279篇 |
1993年 | 196篇 |
1992年 | 171篇 |
1991年 | 121篇 |
1990年 | 96篇 |
1989年 | 102篇 |
1988年 | 68篇 |
1987年 | 48篇 |
1986年 | 55篇 |
1985年 | 40篇 |
1968年 | 43篇 |
1967年 | 35篇 |
1966年 | 43篇 |
1965年 | 45篇 |
1959年 | 44篇 |
1958年 | 37篇 |
1957年 | 37篇 |
1956年 | 34篇 |
1955年 | 63篇 |
1954年 | 68篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
A polymer electrolyte based on microporous poly(vinylidene fluoride-co-hexafluoropropane) (PVdF-HFP) film was studied for use in lithium ion batteries. The microporous PVdF-HFP (Kynar 2801) matrix was prepared from a cast of homogeneous mixture of PVdF-HFP and solvents such as ethylene carbonate (EC), dimethyl carbonate (DMC), and ethyl methyl carbonate (EMC). After evaporation of DMC and EMC, a sold film of the PVdF-HFP and the EC mixture was obtained. EC-rich phase started its formation in the PVdF-HFP/EC film at EC content of about 60 wt.% based on the total weight of PVdF-HFP and EC. The formation of the new phase resulted in the abrupt increase of the porosity of the PVdF-HFP matrix from 32 to 62%. The ionic conductivity of the film soaked in 1 M LiPF6-EC/DMC=1/1 was significantly increased from order of 10−4 S/cm to order of 10−3 S/cm at the EC content of 60 wt.%. Thermal and spectroscopic investigations showed that most of the EC interact with PVdF-HFP with the EC content being below 60 wt.%. MCMB/polymer electrolyte/LiCoO2 cells employing the microporous PVdF-HFP polymer film showed stable charging/discharging characteristics at 1C rate and good rate capability. 相似文献
992.
Hongcang Zhou Baosheng Jin Zhaoping Zhong Yaji Huang Rui Xiao Youfei Zheng 《Korean Journal of Chemical Engineering》2007,24(3):489-494
The coal partial gasification catalyzed by limestone, sodium carbonate and dolomite was studied using a bench-scale atmospheric
fluidized bed in the presence of air and steam at 900 °C. The effects of limestone, sodium carbonate and dolomite on composition,
heating value, gas yield of product gas and carbon conversion in the catalytic coal partial gasification have been examined.
The experimental results show that the catalysts can effectively improve the gas quality, the heating value and the gas yield
of product gas and carbon conversion. The catalytic effect of sodium carbonate is better than that of limestone and dolomite.
The increase of limestone loading can enhance the quality of product gas, such as the content of combustible gas, the high
heating value and the gas yield, during coal partial gasification.
This work was presented at the 6
th
Korea-China Workshop on Clean Energy Technology held at Busan, Korea, July 4–7, 2006. 相似文献
993.
Yeong-Koo?YeoEmail author Ki-Seok?Hwang Sung?Chul?Yi Hong?Kang 《Korean Journal of Chemical Engineering》2004,21(4):761-766
In this study a model for the drying process in paper production plants was developed based on the mass and heat balances
around drying cycles. Relationships for the heat transfer coefficients between the web and the air as well as between the
drying cylinder and the web were extracted from the closed-loop plant operation data. It was found that the heat transfer
coefficients could be represented effectively in terms of moisture content, basis weight and reel velocity. The effectiveness
of the proposed model was illustrated through numerical simulations. From the comparison with the operation data, the proposed
model represents the paper plant being considered with sufficient accuracy. 相似文献
994.
Bin Li Chang-Rui Zhang Si-Qing Wang Feng Cao Yong-Gang Jiang 《Refractories and Industrial Ceramics》2007,48(4):280-283
A new wave-transparent composite reinforced by silica fibers with a hybrid matrix comprising BN and Si3N4 was prepared by precursor infiltration and pyrolysis, and it was heat-treated at elevated temperatures. The variations of
the composite during heat treatments were characterized and investigated by Fourier transform infrared spectroscopy (FT-IR),
X-ray diffraction (XRD) and scanning electron microscopy (SEM). The as-received composite exhibits good mechanical properties,
and it is almost amorphous. When treated at 1600°C, it turned brittle, and silica fibers in it were fused; the composite showed
a good crystalline form. When treated at 2100°C, the composite broke into pieces, and the composition showed only BN. Si3N4 was decomposed, and silica fibers were volatilized. The presence of BN probably affected the phase transitions of silica
fibers.
__________
Translated from Novye Ogneupory, No. 8, pp. 49–52, August 2007. 相似文献
995.
996.
The hydrodynamic and gas mixing characteristics have been determined in a FCC regenerator (0.48 m I.D.x3.4 m high) with FCC
particles. Solids holdup in the dense bed decreases with increasing gas velocity, but it increases in the freeboard region.
The bubble/void fraction increases with an increase along the bed height at a given gas velocity and increases with increasing
gas velocity at a constant bed height. Backmixed tracer gas at the wall region is higher than that at the center region of
the bed. The gas backmixing coefficient decreases with increasing gas velocity. 相似文献
997.
A water‐developable negative photoresist based on the photocrosslinking of N‐phenylamide groups was prepared by the copolymerization of 4‐styrenesulfonic acid sodium salts (SSS) with N‐phenylmethacrylamide (copolymer A) or p‐hydroxy‐N‐phenylmethacrylamide (copolymer B), and its properties such as solubility changes, photochemical reaction, and photoresist characteristics were studied. The copolymer containing a relatively higher amount of SSS units was soluble in water. Solubility changes of the copolymers in the various buffer solutions of pH 4 ~ 11 and in water upon irradiation were observed by the measurement of insoluble fraction. The copolymers were soluble in water before irradiation, whereas they became insoluble upon irradiation with the UV light of 254 nm. The photochemical reaction of the copolymer studied by the UV and IR absorption spectroscopies indicated that a photo‐Fries rearrangement was favored for copolymer A, whereas a photocrosslinking reaction was predominate for copolymer B. Resist properties of the copolymers were studied by measurement of the normalized thickness and by development of the micropattern. Negative tone images with a resolution of 1 μm were obtained with these materials that have a sensitivity (D) of ~ 1100 mJ/cm2 with an aqueous developing process.© 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1172–1180, 2002 相似文献
998.
999.
1000.