全文获取类型
收费全文 | 6862篇 |
免费 | 791篇 |
国内免费 | 508篇 |
专业分类
电工技术 | 885篇 |
综合类 | 777篇 |
化学工业 | 891篇 |
金属工艺 | 409篇 |
机械仪表 | 489篇 |
建筑科学 | 538篇 |
矿业工程 | 216篇 |
能源动力 | 218篇 |
轻工业 | 713篇 |
水利工程 | 246篇 |
石油天然气 | 249篇 |
武器工业 | 65篇 |
无线电 | 648篇 |
一般工业技术 | 537篇 |
冶金工业 | 218篇 |
原子能技术 | 75篇 |
自动化技术 | 987篇 |
出版年
2024年 | 41篇 |
2023年 | 120篇 |
2022年 | 253篇 |
2021年 | 325篇 |
2020年 | 256篇 |
2019年 | 168篇 |
2018年 | 199篇 |
2017年 | 224篇 |
2016年 | 203篇 |
2015年 | 258篇 |
2014年 | 328篇 |
2013年 | 437篇 |
2012年 | 569篇 |
2011年 | 563篇 |
2010年 | 540篇 |
2009年 | 506篇 |
2008年 | 563篇 |
2007年 | 571篇 |
2006年 | 525篇 |
2005年 | 371篇 |
2004年 | 264篇 |
2003年 | 229篇 |
2002年 | 178篇 |
2001年 | 151篇 |
2000年 | 126篇 |
1999年 | 47篇 |
1998年 | 22篇 |
1997年 | 13篇 |
1996年 | 21篇 |
1995年 | 15篇 |
1994年 | 16篇 |
1993年 | 10篇 |
1992年 | 4篇 |
1991年 | 11篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1983年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有8161条查询结果,搜索用时 15 毫秒
1.
3.
预处理工艺对硬质合金与金刚石膜间粘结力的影响 总被引:1,自引:0,他引:1
在两种经不同预处理的硬质合金YG8基底上,采用微波等离子体化学气相沉积法,在微波功率2kW,压强4.0kPa和6.5kPa,CH4和H2流量分别为1.6cm/s和100.0cm/s的条件下生长金刚石薄膜。利用X射线衍射检测了金刚石薄膜是否存在,用拉曼光谱分析了薄膜的质量,用金相显微镜观察了薄膜的洛氏硬度压痕,标定并比较了不同预处理工艺膜与基底的结合力。实验结果表明,不同的预处理方法对于粘结力的影响不大,最主要的因素是钴含量的多少。 相似文献
4.
The sorghum distillery residue (SDR) has been an underutilized by‐product with estimated production of 150 ton/day in Kinmen, Taiwan. The objective of this study was to test for any physiological effects of SDR, thus to utilize it as a nutraceutical feed ingredient in diets for cultured fish. Hot air‐dried, wet, and dehulled‐wet sorghum distillery residue showed 63%, 90% and 97% inhibition of the hemoglobin‐catalyzed oxidation of linoleic acid compared to soybean (13%) and rice bran (78%). The feed formulated with 20% wet or dehulled‐wet sorghum distillery residue both showed an antioxidant activity of 68% being higher than the control diet (53%). Feeding these diets to cultured grey mullet for 60 days in summer (temperature ranged 24–30C), resulted in a lower hydroperoxide content in gill tissue, as shown by a chemiluminesence intensity of 1806 or 1409 mV as opposed to 2666 mV for fish fed a control diet. In winter, when the water temperature decreased to 14C, grey mullet fed a diet consisting of 10% dehulled wet sorghum distillery residue had a blood viscosity of 1.9 mPas and a hematocrit value of 33%, in contrast to 3.6 mPas and 41% for control. The blood of the control group started to aggregate in 6 h and showed hemolysis, while the mullet fed dehulled, wet sorghum distillery residue did not show blood aggregation, maintained normal fluidity and erythrocyte membrane integrity. It seems that cultured fish may have the potential as an animal model for prescreening antioxidant and blood thinning effects of food ingredients. 相似文献
5.
6.
梅水燕 《武汉工程大学学报》2006,28(6)
文学艺术教育在人格修养方面具有内涵的丰富性,层次的兼容性,方式的独特性.因此,文学艺术教育对人格修养方面起着可贵的辅助作用,它是思想道德课所代替不了的人格修养课程. 相似文献
7.
The Gd substituting effects for La in La0.67Ca0.33MnO3 has been studied .With increasing the substituting amount of Gd,the phase transition temperature of metal-isolator for the samples decreases,the corresponding peak resistivity increases,the Curie temperature decreases monotonically.The substitution of La-Ca-Mn-O with 11% Gd for La improved the magnetoresistance ratio by an order of magnitude.The effects of substituting Gd can be explained in terms of the lattice effects.An irreversible MR behaviour was observed in Gd-substituting compounds.This effect became marked when the substituting amount of Gd was greater than 7%.A maximum irreversible increment of MR ratio as large as 91% was obtained when Gd substituting amount was 11%. 相似文献
8.
9.
Huiping Hu Qiyuan Chen Zhoulan Yin Pingmin Zhang Lusheng Ye 《Metallurgical and Materials Transactions A》2003,34(13):793-797
The thermal decompositions of mechanically activated and nonactivated galenas were studied by thermogravimetry analysis (TGA)
at the heating rate of 10 K min−1 in argon. Results indicate that the initial temperature of thermal decomposition (abbreviated as T
di) in the TGA curves for different galenas decreases gradually with increased grinding time. The specific granulometric surface
area (S
G), the structural disorder, and the content of elemental sulfur of mechanically activated galenas were analyzed by an X-ray
diffraction (XRD) laser particle-size analyzer, XRD analysis, and the gravimetric method, respectively, which shows that the
specific granulometric surface area of mechanically activated galenas remains almost constant after a certain grinding time,
but the lattice distortions (ε) rise, the crystallite sizes (D) decrease, and the elemental sulfur contents of mechanically activated galenas increase with increased grinding time. The
results imply that the decrease of the initial temperature of thermal decomposition in the TGA curves for mechanically activated
galenas is mainly caused by the increase of lattice distortions, and the formation of new dangling bonds resulted from the
production of elemental sulfur of mechanically activated galenas with increased grinding time. Finally, the differences in
the thermal-decomposition reactivity between nonactivated and mechanically activated galenas were also discussed. 相似文献
10.
Different material-doped Raman fiber lasers with very high efficiency operating in continuous-wave are presented.With 1 W Nd∶YVO 4 laser pumping at wavelength of 1 342 nm, single mode output power of above 500 mW (optical-to-optical conversion efficiency of 50%) is simulated in the range of 1 400-1 500 nm.Using high-germanium,high-phosphate and high-borate silicate fibers as the gain medium,laser output at wavelengths of 1 420,1 450,1 480 and 1 495 nm can be achieved with different geometries,which are just as pumping C-band and L-band distributed Raman fiber amplifiers. 相似文献