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91.
超疏水表面由于具有独特的微纳米粗糙结构和低表面能性质,能形成空气垫物理屏障层,减小材料表面与水或其他腐蚀介质之间的接触面积,因此被广泛应用于金属的腐蚀防护。首先简单介绍了超疏水表面的相关理论,主要包括Young氏方程、Wenzel模型和Cassie-Baxter模型。然后,归纳总结了三种制备超疏水表面的有效途径:在低表面能物质上构建微纳米级粗糙结构;先构建出具有微纳米级的粗糙结构,再对表面进行低表面能修饰;一步法完成低表面能修饰和微纳米级粗糙结构的构建。在此基础上,详细地综述了常见的超疏水表面(薄膜或涂层)在金属防护中的应用。进一步介绍了通过在超疏水体系中引入缓蚀剂的方式,构建具有主动防护功能的超疏水表面,并介绍了此种超疏水表面在金属防护中的应用。最后指出了目前的超疏水表面在制备工艺以及耐久性等方面存在的问题,并对其在金属防护领域的应用前景和发展方向作出了展望。 相似文献
92.
利用Thermo-Calc软件对镍基耐蚀Hastelloy G3合金进行了热力学计算,系统研究了成分对平衡相析出的影响规律,并通过SEM和TEM对合金时效处理后的析出相进行了观察。结果表明,合金析出的平衡相主要为σ相、μ相、M6C和M23C6;Cr、Mo含量主要影响σ相和μ相析出量及开始析出温度;而C元素显著影响碳化物M6C和M23C6的析出行为;进一步通过试验研究了时效过程中析出相的析出规律。 相似文献
93.
Huanhao Chen Yibing Mu Yan Shao Sarayute Chansai Huan Xiang Yilai Jiao Christopher Hardacre Xiaolei Fan 《American Institute of Chemical Engineers》2020,66(4):e16853
A systematic study of Ni supported on metal–organic frameworks (MOFs) catalyst (i.e., 15Ni/UiO-66) for catalytic CO2 hydrogenation under nonthermal plasma (NTP) conditions was presented. The catalyst outperformed other catalysts based on conventional supports such as ZrO2, representing highest CO2 conversion and CH4 selectivity at about 85 and 99%, respectively. We found that the turnover frequency of the NTP catalysis system (1.8 ± 0.02 s−1) has a nearly two-fold improvement compared with the thermal catalysis (1.0 ± 0.06 s−1). After 20 hr test, XPS and HRTEM characterizations confirmed the stability of the 15Ni/UiO-66 catalyst in the NTP-activated catalysis. The activation barrier for the NTP-activated catalysis was calculated as ~32 kJ mol−1, being lower than the activation energy of the thermal catalysis (~70 kJ mol−1). In situ DRIFTS characterization confirmed the formation of multiple carbonates and formates on catalyst surface activated by NTP, surpassing the control catalysts (e.g., 15Ni/α-Al2O3 and 15Ni/ZrO2). 相似文献
94.
Beilin Ye Che Fan Yangjie Han Mengdong Ma Yanhui Chu 《Journal of the American Ceramic Society》2020,103(9):4738-4741
Powder synthesis is critical for implementing the wide applications of high-entropy diborides (HEBs). However, the low-temperature synthesis of HEB powders was rarely reported. Herein, the low-temperature synthesis of the single-phase HEB nanopowders via molten salt-mediated magnesiothermic reduction (MMR) method was reported for the first time. The results showed that the as-synthesized nanopowders consisted of the single-phase HEBs and their average particle sizes are in the range of 28-56 nm. Meanwhile, they possessed the good compositional homogeneity and the low-content oxygen impurity in the range of 4.13-6.12 at%. In addition, their formation mechanism could be well interpreted by a classical MMR growth process. 相似文献
95.
Kang Du Jun Fan Zheng-Yu Zou Xiao-Qiang Song Wen-Zhong Lu Wen Lei 《Journal of the American Ceramic Society》2020,103(11):6369-6377
Low-permittivity Ca1−xSrxSnSiO5 (0 ≤ x ≤ 0.45) microwave dielectric ceramics were prepared via traditional state-reaction at 1400°C-1450°C for 5 hours. Moreover the microwave dielectric properties of SnO2 ceramic were obtained for the first time. SnO2 ceramic was difficult to densify, and SnO2 ceramic (ρrel = 65.1%) that was sintered at 1525°C exhibited the optimal microwave dielectric properties of εr = 5.27, Q × f = 89 300 GHz (at 14.5 GHz), and τf = −26.7 ppm/°C. For Ca1−xSrxSnSiO5 (0 ≤ x ≤ 0.15) ceramics, Sr2+ could be dissolved in the Ca2+ site of Ca1−xSrxSnSiO5 to form a single phase, and the partial substitution of Ca2+ by Sr2+ could improve the microwave dielectric properties of CaSnSiO5 ceramic. Secondary phases (SnO2 and SrSiO3) appeared at 0.2 ≤ x ≤ 0.45 and could adjust the abnormally positive τf value of CaSnSiO5 ceramic. The highest Q × f value (60 100 GHz at 10.4 GHz) and optimal microwave dielectric properties (εr = 9.42, Q × f = 47 500 GHz at 12.4 GHz, and τf = −1.2 ppm/°C) of Ca1−xSrxSnSiO5 ceramics were obtained at x = 0.05 and 0.45, respectively. 相似文献
96.
Emilio Pradal-Velázquez Fan Yang Derek C. Sinclair 《Journal of the American Ceramic Society》2020,103(12):6801-6810
The compositional limits of a previously reported (J. Am. Ceram. Soc., 61, 5-8. (1978)) but relatively unstudied sodium-bismuth titanate pyrochlore solid solution are revised and their electrical properties presented. The pyrochlore solid solution we report forms via a different mechanism to that originally reported and occurs in a different location within the Na2O-Bi2O3-TiO2 ternary system. In both cases, relatively large amounts of vacancies are required on the A-sites and on the oxygen sites, similar to that reported for undoped ‘Bi2Ti2O7’ pyrochlore. In contrast to ‘Bi2Ti2O7’, this ternary pyrochlore solid solution can be prepared and ceramics sintered using conventional solid-state methods; however, the processing requires several challenges to be overcome to obtain dense ceramics. This cubic pyrochlore series has low electrical conductivity (and does not exhibit any evidence of oxide-ion conduction) and exhibits relaxor ferroelectric behavior with a broad permittivity maximum of ~100 near room temperature. Variable temperature neutron diffraction data do not provide any conclusive evidence for a phase transition in the pyrochlore solid solution between ~4 and 873 K. 相似文献
97.
Kuzenkov Yu. A. Anufriev N. G. Oleinik S. V. Ty Fan Ba Filichev N. L. Karpov V. A. 《Protection of Metals and Physical Chemistry of Surfaces》2020,56(7):1315-1320
Protection of Metals and Physical Chemistry of Surfaces - Abstract—In this paper, chromate-free conversion coatings on aluminum alloys D16 and AMg3 are studied in a tropical marine climate.... 相似文献
98.
西部油田某油井油管发生严重腐蚀甚至穿孔。通过宏观形貌和显微组织观察、化学成分分析、硬度测试、拉伸和冲击性能测试、腐蚀产物检测等方法对油管失效原因进行了分析。结果表明:油管在含Cl^-、H2S、CO2酸性环境下发生了均匀腐蚀和局部腐蚀。均匀腐蚀由H2S-CO2-H2O(Cl^-)体系引起的析氢腐蚀所致;而CaCO3沉积造成的微电偶效应以及Fe^2+与地层水中Cl^-的水合作用导致了油管的局部腐蚀穿孔。建议油井管材采用具有一定抗硫性的P110-3Cr钢或耐蚀性能更优的钢,并添加缓蚀阻垢剂进行防护。 相似文献
99.
100.
Fan Zhang Chuan Zhang Duchao Lv Jun Zhu Weisheng Cao Shuanglin Chen Rainer Schmid-Fetzer 《Journal of Phase Equilibria and Diffusion》2018,39(5):562-570
In this work, high throughput calculation (HTC) is used to identify composition regions with good glass forming ability (GFA) in the Al-Cu-Zr, Cu-Ni-Zr, Cu-Ti-Zr, Cu-Ni-Ti-Zr, Al-Cu-Ni-Ti-Zr, Mg-Ca-Cu, and Mg-Ca-Ni systems. The predicted composition regions agree well with those observed by experiments in the ternary systems, while less satisfactory agreement is found in the Cu-Ni-Ti-Zr quaternary and the Al-Cu-Ni-Ti-Zr quinary systems. The possible causes that lead to the deviation in the higher order systems are discussed. The major advantage of the HTC method used in this study is that it is simple and can be easily applied to multicomponent systems. The color maps of liquidus temperature and solidification range obtained by HTC provide a valuable guidance to the experimentalists, thus they can focus on the composition regions with high potential of forming bulk metallic glasses, avoid unnecessary trial-and-error test and save time and cost. This approach can also be combined with other criteria to filter compositions with better GFA. 相似文献