全文获取类型
收费全文 | 124349篇 |
免费 | 12134篇 |
国内免费 | 7405篇 |
专业分类
电工技术 | 8888篇 |
技术理论 | 7篇 |
综合类 | 10047篇 |
化学工业 | 18720篇 |
金属工艺 | 7276篇 |
机械仪表 | 8082篇 |
建筑科学 | 10030篇 |
矿业工程 | 4058篇 |
能源动力 | 3429篇 |
轻工业 | 11332篇 |
水利工程 | 3228篇 |
石油天然气 | 6632篇 |
武器工业 | 1280篇 |
无线电 | 13774篇 |
一般工业技术 | 13441篇 |
冶金工业 | 5539篇 |
原子能技术 | 1711篇 |
自动化技术 | 16414篇 |
出版年
2024年 | 606篇 |
2023年 | 2130篇 |
2022年 | 3973篇 |
2021年 | 5353篇 |
2020年 | 4121篇 |
2019年 | 3172篇 |
2018年 | 3478篇 |
2017年 | 3997篇 |
2016年 | 3589篇 |
2015年 | 4988篇 |
2014年 | 6637篇 |
2013年 | 7524篇 |
2012年 | 8833篇 |
2011年 | 9265篇 |
2010年 | 8701篇 |
2009年 | 8312篇 |
2008年 | 8233篇 |
2007年 | 7956篇 |
2006年 | 7432篇 |
2005年 | 6320篇 |
2004年 | 4511篇 |
2003年 | 3627篇 |
2002年 | 3438篇 |
2001年 | 3170篇 |
2000年 | 2864篇 |
1999年 | 2377篇 |
1998年 | 1676篇 |
1997年 | 1394篇 |
1996年 | 1244篇 |
1995年 | 1099篇 |
1994年 | 915篇 |
1993年 | 652篇 |
1992年 | 527篇 |
1991年 | 389篇 |
1990年 | 369篇 |
1989年 | 277篇 |
1988年 | 202篇 |
1987年 | 126篇 |
1986年 | 118篇 |
1985年 | 63篇 |
1984年 | 46篇 |
1983年 | 31篇 |
1982年 | 42篇 |
1981年 | 38篇 |
1980年 | 30篇 |
1979年 | 15篇 |
1977年 | 2篇 |
1975年 | 2篇 |
1959年 | 9篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Jialong Tian M. Babar Shahzad Wei Wang Lichang Yin Zhouhua Jiang Ke Yang 《材料科学技术学报》2018,34(9):1671-1675
The effect of Co addition on the formation of Ni-Ti clusters in maraging stainless steel was studied by three dimensional atom probe (3DAP) and first-principles calculation. The cluster analysis based on the maximum separation approach showed an increase in size but a decrease in density of Ni-Ti clusters with increasing the Co content. The first-principles calculation indicated weaker Co-Ni (Co-Ti) interactions than Co-Ti (Fe-Ti) interactions, which should be the essential reason for the change of distribution characteristics of Ni-Ti clusters in bcc Fe caused by Co addition. 相似文献
62.
63.
Amun Amri Ahmad Fadli Zhong-Tao Jiang Chun-Yang Yin M. Mahbubur Rahman Hantarto Widjaja Syamsu Herman Silvia Reni Yenti M. Miftahul Munir Gadang Priyotomo M. Iqbal Neni Frimayanti 《Ceramics International》2018,44(13):15274-15280
The copper and cobalt oxides composites coatings on aluminum substrates have been successfully synthesized via sol-gel method using nitrate-based sol precursors. The composites were characterized by X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field Emission Scanning Electron Microscopy (FESEM), Atomic Force Microscopy (AFM), and UV–Vis–NIR spectrophotometry. The sol-gel reactions were discussed and Molecular Dynamics (MD) simulation was integrated into the study to predict molecules assembly properties. The XRD analyses revealed that the CuO and the Co3O4 composites were formed after the annealing process with the average difference of the calculated lattice parameters compared to ICDDs was 1.17%. The surface electronic structure was mainly consisted of tetrahedral Cu(I), octahedral Cu(II), tetrahedral Co(II), octahedral Co(III) as well as surface, sub-surface and lattice oxygen O?. The XRD, XPS and MD simulation results showed that there was minimal (or possibly non-existing) indication of copper-cobalt mixed phase oxides formations. FESEM and AFM surveys revealed that the coating had a porous surface composed of interlinked nanoparticles in the range of ~?10 to ~?40?nm. UV–Vis–NIR reflectance spectra showed that the sol precursors concentration and the dip-drying cycle significantly influenced the absorptance value with optimum absorptance (α) of 88.7% exhibited by coating synthesized using sol concentration of 0.1?M and 10 dip-drying cycles. High absorptance value and simplicity in the synthesis process render the coatings to be very promising candidates for solar selective absorber (SSA) applications. 相似文献
64.
含动力学抑制剂的天然气水合物相平衡研究对新型低剂量抑制剂的开发具有指导作用。在283.6 ~ 290.9 K和7.51 MPa ~ 15.97 MPa的温压范围内研究了抑制剂Inhibex501及其溶剂2-乙二醇单丁醚对甲烷水合物相平衡条件的影响。实验结果显示,0.5wt%和2.0wt%浓度的Inhibex501对甲烷水合物形成的热力学条件具有促进作用,能使甲烷水合物形成移向更高的温度或者更低的压力,而2-乙二醇单丁醚在浓度0.2wt% ~ 1.0wt%范围几乎不改变甲烷水合物形成的热力学条件,N-乙烯基己内酰胺与N-乙烯基吡咯烷酮的共聚物对水合物形成热力学条件的改变起主要作用。 相似文献
65.
Xu Zhi-Zheng Jiang Feng Zhong Chong-Quan Gou Yong-Jie Teng Hong-Fei 《Structural and Multidisciplinary Optimization》2020,61(1):207-223
Structural and Multidisciplinary Optimization - The overall layout optimization design of an orbital propellant depot involves the optimization of shape, size, and positions of propellant tanks in... 相似文献
66.
Single image super resolution (SISR) is an important research content in the
field of computer vision and image processing. With the rapid development of deep
neural networks, different image super-resolution models have emerged. Compared to
some traditional SISR methods, deep learning-based methods can complete the superresolution tasks through a single image. In addition, compared with the SISR methods
using traditional convolutional neural networks, SISR based on generative adversarial
networks (GAN) has achieved the most advanced visual performance. In this review, we
first explore the challenges faced by SISR and introduce some common datasets and
evaluation metrics. Then, we review the improved network structures and loss functions
of GAN-based perceptual SISR. Subsequently, the advantages and disadvantages of
different networks are analyzed by multiple comparative experiments. Finally, we
summarize the paper and look forward to the future development trends of GAN-based
perceptual SISR. 相似文献
67.
The corrosion behavior of synthetic Cu–Sn bronze alloys with six different Sn contents was examined through an electrochemical test and a synthetic test in a simulated corrosive medium. The mechanism of corrosion and the morphology of the corroded surfaces were characterized through field emission scanning electron microscopy equipped with energy-dispersive spectroscopy. At the corrosion potential, the corrosion behavior appears to be determined by the charge transfer step and the diffusion process. It was found that the bronze-IV (Cu–26.8Sn) specimen exhibited the best corrosion resistance, as evidenced by a low corrosion current density and a high impedance. This improvement resulted from an increase in the content of the Cu–Sn solid solution in the alloy, which was conducive to forming a relatively more protective passive film on the surface of the bronze alloy. This finding would be valuable in the anticorrosion protection of archeological artefacts after their excavation. 相似文献
68.
Ziqian Wang Yalan Chen Yating He Weidong Jiang Yan Long Guangyin Fan 《International Journal of Hydrogen Energy》2021,46(21):11587-11596
Developing high-efficiency and low-cost catalysts for hydrogen evolution from hydrolysis of ammonia borane (AB) is significant and critical for the exploitation and utilization of hydrogen energy. Herein, the in-situ fabrication of well-dispersed and small bimetallic RuNi alloy nanoparticles (NPs) with tuned compositions and concomitant hydrolysis of AB are successfully achieved by using graphitic carbon nitride (g-C3N4) as a NP support without additional stabilizing ligands. The optimized Ru1Ni7.5/g-C3N4 catalyst exhibits an excellent catalytic activity with a high turnover frequency of 901 min?1 and an activation energy of 28.46 kJ mol?1 without any base additives, overtaking the activities of many previously reported catalysts for AB hydrolysis. The kinetic studies indicate that the AB hydrolysis over Ru1Ni7.5/g-C3N4 is first-order and zero-order reactions with respect to the catalyst and AB concentrations, respectively. Ru1Ni7.5/g-C3N4 has a good recyclability with 46% of the initial catalytic activity retained even after five runs. The high performance of Ru1Ni7.5/g-C3N4 should be assigned to the small-sized alloy NPs with abundant accessible active sites and the synergistic effect between the composition-tuned Ru–Ni bimetals. This work highlights a potentially powerful and simple strategy for preparing highly active bimetallic alloy catalysts for AB hydrolysis to generate hydrogen. 相似文献
69.
热电厂煤泥掺烧机组利用吸收式热泵耦合带式干化技术,不仅可对污泥进行无害化处置,同时回收利用污泥干化及电厂焚烧余热废热,减少环境热污染,提高能源利用率. 相似文献
70.
宁东供水工程供水水泵共有卧式和立式离心泵2种方案可供选择,也是工程论证时争论的焦点,经综合比较及主机设备的国际招标,最终确定了奥地利安德里兹公司的卧式双吸中开式离心泵为宁东供水工程的供水水泵。 相似文献