全文获取类型
收费全文 | 9536篇 |
免费 | 885篇 |
国内免费 | 34篇 |
专业分类
电工技术 | 137篇 |
综合类 | 15篇 |
化学工业 | 2168篇 |
金属工艺 | 283篇 |
机械仪表 | 399篇 |
建筑科学 | 241篇 |
矿业工程 | 4篇 |
能源动力 | 403篇 |
轻工业 | 786篇 |
水利工程 | 35篇 |
石油天然气 | 4篇 |
无线电 | 1785篇 |
一般工业技术 | 2038篇 |
冶金工业 | 820篇 |
原子能技术 | 125篇 |
自动化技术 | 1212篇 |
出版年
2024年 | 6篇 |
2023年 | 85篇 |
2022年 | 91篇 |
2021年 | 232篇 |
2020年 | 195篇 |
2019年 | 241篇 |
2018年 | 318篇 |
2017年 | 262篇 |
2016年 | 386篇 |
2015年 | 324篇 |
2014年 | 426篇 |
2013年 | 694篇 |
2012年 | 516篇 |
2011年 | 699篇 |
2010年 | 537篇 |
2009年 | 561篇 |
2008年 | 531篇 |
2007年 | 432篇 |
2006年 | 400篇 |
2005年 | 336篇 |
2004年 | 313篇 |
2003年 | 270篇 |
2002年 | 255篇 |
2001年 | 234篇 |
2000年 | 201篇 |
1999年 | 212篇 |
1998年 | 324篇 |
1997年 | 238篇 |
1996年 | 184篇 |
1995年 | 136篇 |
1994年 | 118篇 |
1993年 | 82篇 |
1992年 | 62篇 |
1991年 | 61篇 |
1990年 | 60篇 |
1989年 | 54篇 |
1988年 | 38篇 |
1987年 | 47篇 |
1986年 | 49篇 |
1985年 | 33篇 |
1984年 | 27篇 |
1983年 | 28篇 |
1982年 | 8篇 |
1981年 | 20篇 |
1980年 | 20篇 |
1979年 | 13篇 |
1978年 | 13篇 |
1977年 | 18篇 |
1976年 | 26篇 |
1975年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 968 毫秒
991.
992.
Ho Keun Song Soo Gil Kim Hyeong Joon Kim Suk Ki Kim Ki Wan Kang Jung Chul Leeand Kyung Hoon Yoon 《Solar Energy Materials & Solar Cells》2003,75(1-2):145-153
CuIn1−xGaxSe2 polycrystalline thin films were prepared by a two-step method. The metal precursors were deposited either sequentially or simultaneously using Cu–Ga (23 at%) alloy and In targets by DC magnetron sputtering. The Cu–In–Ga alloy precursor was deposited on glass or on Mo/glass substrates at either room temperature or 150°C. These metallic precursors were then selenized with Se pellets in a vacuum furnace. The CuIn1−xGaxSe2 films had a smooth surface morphology and a single chalcopyrite phase. 相似文献
993.
Man Gu Kang Nam-Gyu Park Yong Joon Park Kwang Sun Ryu Soon Ho Chang 《Solar Energy Materials & Solar Cells》2003,75(3-4):475-479
The transparent electric windows based on dye-sensitized nanocrystalline TiO2 solar cells have been prepared. The solar cell consists of dye-sensitized TiO2 electrode with a TiO2 layer of an about 8 μm thickness and of a 80×80 mm2 active area, Pt counter electrode and redox electrolyte. The solar cell shows a transmittance of approximately 60% in the visible range and an open-circuit voltage (Voc) of 0.64 V and a short-circuit photocurrent (Jsc) of 250 mA. A moderately transparent electric window composed of nine unit solar cells in series generates Voc of 5.7 V and Jsc of 220 mA at one sun light intensity. 相似文献
994.
The influence of surface morphology of TiO2 coating on the performance of dye-sensitized solar cells
Kun-Mu Lee Vembu Suryanarayanan Kuo-Chuan Ho 《Solar Energy Materials & Solar Cells》2006,90(15):2398-2404
The optimization of solar energy conversion efficiency of dye-sensitized solar cells (DSSCs) was investigated by the tuning of TiO2 photoelectrode's surface morphology. Double-layered TiO2 photoelectrodes with four different structures were designed by the coating of TiO2 suspension, incorporated with low and high molecular weight poly(ethylene glycol) as a binder. Among these four systems, P2P1, where P1 and P2 correspond to the molecular weight of 20,000 and 200,000, respectively, showed the highest efficiency under the conditions of identical film thickness and constant irradiation. This can be explained by the larger pore size and higher surface area of P2P1 TiO2 electrode than the other materials as revealed by scanning electron microscopic (SEM) and Brunauer–Emmett–Teller (BET) analyses. Electrochemical Impedance Spectroscopy (EIS) analysis shows that P2P1 formulation displayed a smaller resistance than the others at the TiO2/electrolyte interface. The best efficiency (η) of 9.04% with the short-circuit photocurrent density (Jsc) and open-circuit voltage (Voc) of 18.9 mA/cm2 and 0.74 V, respectively, was obtained for a solar cell by introducing the light-scattering particles to the TiO2 nanoparticles matrix coated on FTO electrode having the sheet resistivity of 8 Ω/sq. 相似文献
995.
In the present paper, critical heat flux (CHF) experiments for flow boiling of R-134a were performed to investigate the CHF characteristics of four-head and six-head rifled tubes in comparison with a smooth tube. Both of rifled tubes having different head geometry have the maximum inner diameter of 17.04 mm while the smooth tube has the average inner diameter of 17.04 mm. The experiments were conducted for the vertical orientation under outlet pressures of 13, 16.5, and 23.9 bar, mass fluxes of 285-1300 kg/m2s and inlet subcooling temperatures of 5-40 °C in the R-134a CHF test loop. The parametric trends of CHF for the tubes show a good agreement with previous understanding. In particular, CHF data of the smooth tube for R-134a were compared with well-known CHF correlations such as Bowring and Katto correlations. The CHF in the rifled tube was enhanced to 40-60% for the CHF in the smooth tube with depending on the rifled geometry and flow parameters such as pressure and mass flux. In relation to the enhancement mechanism, the relative vapor velocity is used to explain the characteristics of the CHF performance in the rifled tube. 相似文献
996.
Yunpeng Zhang Siu-Lau Ho Huihuan Wu 《Numerical Heat Transfer, Part A: Applications》2019,75(8):523-532
An adaptive degrees-of-freedom finite element method (FEM) for 3-dimensional nonlinear magneto-thermal fields is proposed in this article. Both magnetic field and thermal field are discretized using a single FEM mesh, and their degrees of freedom (DoFs) are individually controlled based on the field characteristics. Before solving the algebraic equations, the constrained DoFs are removed using the slave-master technique. The computing time and the storage resources of the second set of FEM mesh are saved while meeting the different requirements on discretization. Data transfer between the thermal and magnetic fields are easily implemented, and mapping errors between different meshes are avoided. To showcase the feasibility and the effectiveness of this method, several numerical examples are tested. 相似文献
997.
Xizu Wang Jian Wei Ho Qingyi Yang Hoi Lam Tam Gui Xin Li Kok Wai Cheah Furong Zhu 《Organic Electronics》2011,12(11):1943-1947
In this work, Ag nanoparticles were modified by an ultra-thin plasma-polymerized fluorocarbon film (CFX) to form a composite CFX-modified Ag nanoparticles/indium tin oxide (ITO) anode for application in organic photovoltaic (OPV) devices. A CFX-modified Ag nanoparticles/ITO anode exhibited a superior surface work function of 5.4 eV suited for application in OPV devices. The performance of zinc phthalocyanine:fullerene-based OPV devices showed a significant improvement when the structural identical cells are made with the CFX-modified Ag nanoparticles/ITO. This work yielded a promising power conversion efficiency of 3.5 ± 0.1%, notably higher than that with a bare ITO anode (2.7 ± 0.1%). 相似文献
998.
Seul‐Ki Park So‐Eun Kim Dae‐Yoon Kim Shin‐Woong Kang Seunghan Shin Shiao‐Wei Kuo Seok‐Ho Hwang Seung Hee Lee Myong‐Hoon Lee Kwang‐Un Jeong 《Advanced functional materials》2011,21(11):2129-2139
Robust coatable polarizer is fabricated by the self‐assembly of lyotropic chromonic liquid crystals and subsequent photo‐polymerizing processes. Their molecular packing structures and optical behaviors are investigated by the combined techniques of microscopy, scattering and spectroscopy. To stabilize the oriented Sunset Yellow FCF (H‐SY) films and to minimize the possible defects generated during and after the coating, acrylic acid (AA) is added to the H‐SY/H2O solution and photo‐polymerized. Utilizing cross‐polarized optical microscopy, phase behaviors of the H‐SY/H2O/AA solution are monitored by varying the compositions and temperatures of the solution. Based on the experimental results of two‐dimensional wide angle X‐ray diffraction and selected area electron diffraction, the H‐SY crystalline unit cell is determined to be a monoclinic structure with the dimensions of a = 1.70 nm, b = 1.78 nm, c = 0.68 nm, α = β = 90.0° and γ = 84.5°. The molecular arrangements in the oriented H‐SY films were further confirmed by polarized Fourier‐transform infrared spectroscopy. The polymer‐stabilized H‐SY films show good mechanical and chemical stabilities with a high polarizability. Additionally, patterned polarizers are fabricated by applying a photo‐mask during the photo‐polymerization of AA, which may open new doors for practical applications in electro‐optic devices. 相似文献
999.
Sub‐Nanometer Level Size Tuning of a Monodisperse Nanoparticle Array Via Block Copolymer Lithography
Dong Ok Shin Duck Hyun Lee Hyoung‐Seok Moon Seong‐Jun Jeong Ju Young Kim Jeong Ho Mun Heesook Cho Soojin Park Sang Ouk Kim 《Advanced functional materials》2011,21(2):250-254
The fabrication and catalytic application of a size‐tunable monodisperse nanoparticle array enabled by block copolymer lithography is demonstrated. Highly uniform vertical cylinder nanodomains are achieved in poly(styrene‐block‐4‐vinylpyridine) (PS‐b‐P4VP) diblock copolymer thin‐films by solvent annealing. The prominent diffusion of the anionic metal complexes into the protonated P4VP cylinder nanodomains occurs through specific electrostatic interactions in a weakly acidic aqueous solution. This well‐defined diffusion with nanoscale confinement enables preparation of the laterally ordered monodisperse nanoparticle array with sub‐nanometer level precise size tuning. The controlled growth of monodisperse nanoparticle arrays is proven by their catalytic use for vertical carbon nanotube (CNT) growth via plasma enhanced chemical vapor deposition (PECVD). Since the size of the catalyst particles is the decisive parameter for the diameters and wall‐numbers of CNTs, the highly selective growth of double‐walled or triple‐walled CNTs could be accomplished using monodisperse nanoparticle arrays. 相似文献
1000.
Hee Jin Jeong Hae Deuk Jeong Ho Young Kim Jun Suk Kim Seung Yol Jeong Joong Tark Han Dae Suk Bang Geon‐Woong Lee 《Advanced functional materials》2011,21(8):1526-1532
The fabrication of a flexible field‐emission device (FED) using single‐walled carbon nanotube (SWNT) network films as the conducting electrodes (anode and cathode) and thin multi‐walled CNT/TEOS hybrid films as the emitters is reported. P‐type doping with gold ions and passivation with tetraethylorthosilicate (TEOS) made the SWNT network film highly conductive and environmentally stable, and hence a good alternative to conventional indium tin oxide electrodes. CNT/TEOS hybrid emitters showed high current density, low turn‐on field, and long‐term emission stability, compared with CNT emitters; these characteristics can be attributed to the TEOS sol, acting both as a protective layer surrounding the nanotube tip, and as an adhesive layer enhancing the nanotube adhesion to the substrate. All‐CNT‐based flexible FEDs fabricated by this approach showed high flexibility in field emission characteristics and extremely bright electron emission patterns. 相似文献