全文获取类型
收费全文 | 2386篇 |
免费 | 71篇 |
国内免费 | 8篇 |
专业分类
电工技术 | 108篇 |
综合类 | 2篇 |
化学工业 | 752篇 |
金属工艺 | 89篇 |
机械仪表 | 58篇 |
建筑科学 | 44篇 |
矿业工程 | 3篇 |
能源动力 | 101篇 |
轻工业 | 236篇 |
水利工程 | 9篇 |
石油天然气 | 3篇 |
无线电 | 126篇 |
一般工业技术 | 542篇 |
冶金工业 | 111篇 |
原子能技术 | 75篇 |
自动化技术 | 206篇 |
出版年
2023年 | 11篇 |
2022年 | 34篇 |
2021年 | 48篇 |
2020年 | 27篇 |
2019年 | 41篇 |
2018年 | 49篇 |
2017年 | 35篇 |
2016年 | 58篇 |
2015年 | 46篇 |
2014年 | 72篇 |
2013年 | 130篇 |
2012年 | 120篇 |
2011年 | 150篇 |
2010年 | 126篇 |
2009年 | 132篇 |
2008年 | 140篇 |
2007年 | 127篇 |
2006年 | 98篇 |
2005年 | 78篇 |
2004年 | 87篇 |
2003年 | 72篇 |
2002年 | 59篇 |
2001年 | 45篇 |
2000年 | 44篇 |
1999年 | 48篇 |
1998年 | 75篇 |
1997年 | 51篇 |
1996年 | 54篇 |
1995年 | 28篇 |
1994年 | 37篇 |
1993年 | 22篇 |
1992年 | 26篇 |
1991年 | 26篇 |
1990年 | 17篇 |
1989年 | 17篇 |
1988年 | 10篇 |
1987年 | 24篇 |
1986年 | 19篇 |
1985年 | 19篇 |
1984年 | 14篇 |
1983年 | 12篇 |
1982年 | 23篇 |
1981年 | 17篇 |
1980年 | 19篇 |
1979年 | 21篇 |
1978年 | 12篇 |
1977年 | 11篇 |
1976年 | 15篇 |
1974年 | 4篇 |
1973年 | 4篇 |
排序方式: 共有2465条查询结果,搜索用时 0 毫秒
41.
Koji Fushimi Takatoshi Shimada Hiroki Habazaki Hidetaka Konno Masahiro Seo 《Electrochimica acta》2011,(4):1773
Depassivation–repassivation of iron surfaces in boric–borate solutions were investigated by using the micro-indentation test. A pair of current peaks due to repair of the passive film following rupture of the film were observed during a series of indenter drives, i.e., loading and unloading of the indenter. The shape of the current peak depended on environmental conditions (conductivity and pH of the solution) and substrate conditions (mechanical processing history, alloyed element) as well as indentation conditions (repetition, maximum depth, and maximum load). Plastic deformation of the surface was accompanied by surface depassivation, while no depassivation occurred during the elastic deformation, indicating that the passive film on iron has a ductile property. The solution conditions did not affect the scale of depassivation but affected the rate of repassivation. Dislocations in the substrate made surface depassivation difficult but enhanced reactivity during the repassivation. The test also revealed that type-312L stainless steel has high corrosion resistance in a concentrated NaCl solution. 相似文献
42.
Takafumi Motooka Atsushi Komatsu Takashi Tsukada Masahiro Yamamoto 《Journal of Nuclear Science and Technology》2014,51(7-8):987-995
In spent fuel pools at the Fukushima Daiichi Nuclear Power Station (1F), seawater was injected for cooling purposes after the tsunami disaster in March 2011. It is well known that the chloride in the seawater has the potential to cause localized corrosion (e.g., pitting corrosion) in metals. In this study, we evaluated the pitting potentials of zircaloy-2, the material used in the fuel cladding tubes in 1F, as a function of chloride concentration. To accomplish this, we used artificial seawater under gamma-ray irradiation and investigated the effect of radiolysis on pit initiation of zircaloy-2 in water containing sea salt. Changes in the composition of water containing sea salt were analyzed as well, both before and after gamma-ray irradiation. The characteristics of the resultant oxide films formed on zircaloy-2 were evaluated by X-ray photoelectron spectroscopy and electrochemical impedance spectroscopy. The experimental results showed that the pitting potential under irradiation was slightly higher than that under conditions in which no radiation was present, and that the pitting potential decreased with increasing chloride concentration in the presence as well as the absence of radiation. Solution analyses for water containing sea salt showed that hydrogen peroxide was generated by irradiation. The oxide film was composed of zirconium oxide and was made thicker during the irradiation. The higher pitting potential could thus be explained by the capacity of hydrogen peroxide to oxidize the surface and enhance oxide film formation. Under gamma-ray irradiation, the zircaloy-2 surface with an oxide film formed by radiolysis products was found to be resistant to pitting in the presence of chloride. 相似文献
43.
Takeo Hattori Atsushi Shigemori Jun-Ichi Mohri Masahiro Yoshimura Shigeyuki Somiya 《Journal of the American Ceramic Society》1982,65(9):c142-c142
Powder compacts of synthetic mica (fluorphlogopite) encapsulated in a boro–silicate glass tube were isostatically hot–pressed in a Roy–Tuttle–type pressure vessel. Synthetic mica was sintered to a density of 2.60 g/cm3 (91.2% of theoretical density) without additives under 98 MPa of water at 800°C for 45 min. 相似文献
44.
Toshiyuki Iguchi Sakae Takenaka Keizo Nakagawa Yoshiki Orita Hideki Matsune Masahiro Kishida 《Topics in Catalysis》2009,52(6-7):563-570
Formation of carbon nanofibers (CNFs) and carbon nanotubes (CNTs) through the decomposition of ethylene at 973 K was achieved using various metal catalysts covered with silica layers. CNFs of various diameters were formed by ethylene decomposition over a Co metal catalyst supported on the outer surface of the silica. In contrast, silica-coated Co catalysts formed CNTs with uniform diameters by ethylene decomposition. Silica-coated Ni/SiO2 and Pt/carbon black also formed CNTs with uniform diameters, while CNFs and CNTs with various diameters were formed over Ni/SiO2 and Pt/carbon black without a silica coating. These results indicate that silica layers that envelop metal particles prevent sintering of the metal particles during ethylene decomposition. This results in the preferential formation of CNTs with a uniform diameter. 相似文献
45.
Measurement of particle concentration in powder coating process using capacitance computed tomography and wavelet analysis 总被引:1,自引:0,他引:1
Capacitance computed tomography techniques were used to visualize particles movement in the draft tube of a spouted fluidized bed for the coating process of drug production. A total of 512 frames images of the particle concentration distribution were obtained at 10-millisecond intervals over a coating time of 5 min using a capacitance computed tomography system. The three-dimensional capacitance CT images (time and two-dimensional space images) were decomposed to wavelet time and space levels to extract the dominant particle distribution feature using three-dimensional discrete wavelet multiresolution at different coating times. As a result, the time and space dominant particle distribution with a specific frequency level can be visualized. 相似文献
46.
Transparent Nano-Composites Ceramics by Annealing of Amorphous Phase in the HfO2 -Al2 O3 -GdAlO3 System
Shunji Araki Masahiro Yoshimura 《International Journal of Applied Ceramic Technology》2004,1(2):155-160
We have succeeded in fabricating transparent nano-structured ceramics by annealing of the amorphous phase obtained by the solidification of the eutectic melt in the ternary system HfO2 − Al2 O3 − GdAlO3 . The ceramics annealed at 1273 K for 6 hr contained 5-10-nm cubic hafnia grains, and those annealed at 1273 K for 72 hr contained both cubic hafnia and gadolinium aluminum garnet grains 5-10 nm in size. They showed high transparency. Annealing at 1473 K, however, resulted in grain growths that brought about non-transparency. 相似文献
47.
48.
By adsorbing bovine serum albumin (BSA) on gold nanoparticles (Aunps) with diameters 30 nm and 80 nm, different degrees of protein unfolding were obtained. Adsorption and adlayer conformation were characterized by UV-vis spectroscopy, ζ-potential measurements, steady-state and time-resolved fluorescence. The unfolding was also studied using 1-anilino-8-naphthalene sulfonate (ANS) as an extrinsic probe, showing that BSA unfolds more on 80 nm Aunp than on 30 nm Aunp. Langmuir monolayer studies using two distinct methods of introducing the BSA and BSA-Aunp constructs accompanied with Brewster Angle Microscopy (BAM) and Digital Video Microscope (DVM) imaging demonstrated that BSA-Aunp constructs induce film miscibility with L-α-phosphatidylethanolamine not seen for BSA or Aunp alone. The changes induced by partial unfolding clearly give better film-penetration ability, as well as disruption of liquid crystalline domains in the film, thereby inducing film miscibility. Gold or protein only does not possess the nanoscale film-affecting properties of the protein-gold constructs, and as such the surface-active and miscibility-affecting characteristics of the BSA-Aunp represent emergent qualities. 相似文献
49.
50.
Yoriko Tanaka Masahiro Furuta Koichi Kuriyama Ryosuke Kuwabara Yukiko Katsuki Takeshi Kondo Akira Fujishima Kensuke Honda 《Electrochimica acta》2011,(3):1172
Nitrogen-doped hydrogenated amorphous carbon thin films (a-C:N:H, N-doped DLC) were synthesized with microwave-assisted plasma-enhanced chemical vapor deposition widely used for DLC coating such as the inner surface of PET bottles. The electrochemical properties of N-doped DLC surfaces that can be useful in the application as an electrochemical sensor were investigated. N-doped DLC was easily fabricated using the vapor of nitrogen contained hydrocarbon as carbon and nitrogen source. A N/C ratio of resulting N-doped DLC films was 0.08 and atomic ratio of sp3/sp2-bonded carbons was 25/75. The electrical resistivity and optical gap were 0.695 Ω cm and 0.38 eV, respectively. N-doped DLC thin film was found to be an ideal polarizable electrode material with physical stability and chemical inertness. The film has a wide working potential range over 3 V, low double-layer capacitance, and high resistance to electrochemically induced corrosion in strong acid media, which were the same level as those for boron-doped diamond (BDD). The charge transfer rates for the inorganic redox species, Fe2+/3+ and Fe(CN)64−/3− at N-doped DLC were sufficiently high. The redox reaction of Ce2+/3+ with standard potential higher than H2O/O2 were observed due to the wider potential window. At N-doped DLC, the change of the kinetics of Fe(CN)63−/4− by surface oxidation is different from that at BDD. The rate of Fe(CN)63−/4− was not varied before and after oxidative treatment on N-doped DLC includes sp2 carbons, which indicates high durability of the electrochemical activity against surface oxidation. 相似文献