全文获取类型
收费全文 | 2253篇 |
免费 | 6篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 49篇 |
综合类 | 1篇 |
化学工业 | 388篇 |
金属工艺 | 129篇 |
机械仪表 | 120篇 |
建筑科学 | 24篇 |
矿业工程 | 40篇 |
能源动力 | 6篇 |
轻工业 | 11篇 |
水利工程 | 34篇 |
石油天然气 | 125篇 |
武器工业 | 3篇 |
无线电 | 156篇 |
一般工业技术 | 536篇 |
冶金工业 | 361篇 |
原子能技术 | 217篇 |
自动化技术 | 62篇 |
出版年
2020年 | 34篇 |
2019年 | 37篇 |
2018年 | 68篇 |
2017年 | 68篇 |
2016年 | 86篇 |
2015年 | 40篇 |
2014年 | 59篇 |
2013年 | 63篇 |
2012年 | 57篇 |
2011年 | 58篇 |
2010年 | 81篇 |
2009年 | 67篇 |
2008年 | 67篇 |
2007年 | 72篇 |
2006年 | 62篇 |
2005年 | 40篇 |
2004年 | 50篇 |
2003年 | 48篇 |
2002年 | 38篇 |
2001年 | 30篇 |
2000年 | 33篇 |
1999年 | 30篇 |
1998年 | 38篇 |
1997年 | 33篇 |
1996年 | 39篇 |
1995年 | 25篇 |
1993年 | 25篇 |
1992年 | 26篇 |
1991年 | 31篇 |
1990年 | 27篇 |
1989年 | 29篇 |
1988年 | 28篇 |
1987年 | 27篇 |
1986年 | 26篇 |
1985年 | 34篇 |
1984年 | 32篇 |
1983年 | 24篇 |
1982年 | 33篇 |
1981年 | 31篇 |
1980年 | 31篇 |
1979年 | 29篇 |
1978年 | 25篇 |
1977年 | 34篇 |
1976年 | 39篇 |
1975年 | 28篇 |
1974年 | 25篇 |
1973年 | 40篇 |
1972年 | 31篇 |
1971年 | 33篇 |
1968年 | 26篇 |
排序方式: 共有2262条查询结果,搜索用时 15 毫秒
31.
Erkan Aydin Michele De Bastiani Xinbo Yang Muhammad Sajjad Faisal Aljamaan Yury Smirnov Mohamed Nejib Hedhili Wenzhu Liu Thomas G. Allen Lujia Xu Emmanuel Van Kerschaver Monica Morales‐Masis Udo Schwingenschlgl Stefaan De Wolf 《Advanced functional materials》2019,29(25)
Parasitic absorption in transparent electrodes is one of the main roadblocks to enabling power conversion efficiencies (PCEs) for perovskite‐based tandem solar cells beyond 30%. To reduce such losses and maximize light coupling, the broadband transparency of such electrodes should be improved, especially at the front of the device. Here, the excellent properties of Zr‐doped indium oxide (IZRO) transparent electrodes for such applications, with improved near‐infrared (NIR) response, compared to conventional tin‐doped indium oxide (ITO) electrodes, are shown. Optimized IZRO films feature a very high electron mobility (up to ≈77 cm2 V?1 s?1), enabling highly infrared transparent films with a very low sheet resistance (≈18 Ω □?1 for annealed 100 nm films). For devices, this translates in a parasitic absorption of only ≈5% for IZRO within the solar spectrum (250–2500 nm range), to be compared with ≈10% for commercial ITO. Fundamentally, it is found that the high conductivity of annealed IZRO films is directly linked to promoted crystallinity of the indium oxide (In2O3) films due to Zr‐doping. Overall, on a four‐terminal perovskite/silicon tandem device level, an absolute 3.5 mA cm?2 short‐circuit current improvement in silicon bottom cells is obtained by replacing commercial ITO electrodes with IZRO, resulting in improving the PCE from 23.3% to 26.2%. 相似文献
32.
Smirnov V. M. Smirnova E. V. Tynyankin S. I. 《Journal of Communications Technology and Electronics》2019,64(9):952-957
Journal of Communications Technology and Electronics - The paper considers the possibility of forecasting high-frequency (HF) radio communications based on GLONASS/GPS navigation satellite system... 相似文献
33.
I. L. Drichko A. M. D’yakonov I. Yu. Smirnov Yu. M. Gal’perin V. V. Preobrazhenskii A. I. Toropov 《Semiconductors》2004,38(6):702-711
The complex high-frequency conductivity of GaAs/Al0.3Ga0.7As heterostructures that are δ-doped and modulation-doped with silicon was investigated by acoustic methods under conditions of the integer quantum Hall effect. Both the real (σ1) and imaginary (σ2) parts of the complex conductivity σ(ω, H)=σi?iσ2 were determined from the dependences of the absorption and velocity of surface acoustic waves on magnetic field. It is shown that, in the heterostructures with electron density ns=(1.3–7)×1011 cm?2 and mobility μ=(1–2)×105 cm2/(V s), the high-frequency conductivity near the centers of the Hall plateau is due to electron hopping between localized states. It is established that, with filling numbers 2 and 4, the conductivity of the Al0.3Ga0.7As:Si layer efficiently shunts the high-frequency hopping conductivity of the two-dimensional interface layer. A method of separating the contributions of the interface and Al0.3Ga0.7As:Si layers to the hopping conductivity σ(ω, H) is developed. The localization length of electrons in the interface layer is determined on the basis of the nearest neighbor hopping model. It is shown that, near the centers of the Hall plateau, both σ(ω, H) and ns depend on the cooling rate of a GaAs/Al0.3Ga0.7As sample. As a result, the sample “remembers” the cooling conditions. Infrared light and static strain also change both σ(ω, H) and ns. We attribute this behavior to the presence of two-electron defects (so-called DX? centers) in the Al0.3Ga0.7As:Si layer. 相似文献
34.
P. V. Seredin A. V. Glotov E. P. Domashevskaya A. S. Lenshin M. S. Smirnov I. N. Arsentyev D. A. Vinokurov A. L. Stankevich I. S. Tarasov 《Semiconductors》2012,46(6):719-729
The study is concerned with MOCVD epitaxial heterostructures grown on the basis of Al x Ga y In1 ? x ? y As z P1 ? z quinary alloys in the region of alloy compositions isoperiodic to GaAs. By the X-ray diffraction technique and atomic force microscopy, it is shown that, on the surface of the heterostructures, there are nanometric objects capable of lining up along a certain direction. From calculations of the crystal lattice parameters with consideration for internal strains, it can be inferred that the new compound is a phase based on the Al x Ga y In1 ? x ? y As z P1 ? z alloy. 相似文献
35.
36.
V. M. Ievlev S. B. Kushev O. V. Ovchinnikov M. P. Sumez A. N. Latyshev M. N. Bezryadin L. Yu. Leonova S. V. Kannykin A. M. Vozgorkov M. S. Smirnov 《Semiconductors》2014,48(2):251-256
The structure and electrical and optical properties of heterostructures formed on the surface of single-crystal silicon wafers as a result of the heat treatment and pulsed photon treatment of Ti films in oxygen, air, and nitrogen are investigated. It is shown that a TiO2/Ti5Si3/p-Si heterostructure is formed upon heat treatment in air, whereas a TiO2/TiSi2/p-Si heterostructure is formed upon photon treatment. It is established that rutile films with pronounced n-type conductivity are formed as a result of the heat treatment of Ni-doped Ti films in oxygen. Rutile films with p-type conductivity are formed upon the thermal annealing of Ti films in air with subsequent photon treatment in nitrogen. 相似文献
37.
Ongoing control of the transverse thickness fluctuation of cold-rolled high-strength strip 总被引:1,自引:0,他引:1
Minimization of the transverse thickness fluctuation is considered, in the production of cold-rolled strip from a blank of
multiple-strip width on a five-cell 630 mill. The forces and torques in the multipass rolling of strip produced from intermediate
strip with an asymmetric cross section are determined. 相似文献
38.
Pyshmintsev L. Yu. Uskov D. P. Mal’tseva A. N. Smirnov M. A. Goikhenberg Yu. N. 《Metallurgist》2019,63(1-2):41-50
Metallurgist - The effect of alloying on the properties of highly tempered steels used for production of a range of petroleum pipes is studied. It is shown that an increase in molybdenum content... 相似文献
39.
40.
Budinovskii S. A. Matveev P. V. Smirnov A. A. 《Metal Science and Heat Treatment》2017,59(1-2):110-116
Metal Science and Heat Treatment - Multilayer heat-resistant ion-plasma coatings for protecting the parts of the hot duct of gas-turbine engines produced from refractory nickel alloys based on VKNA... 相似文献