全文获取类型
收费全文 | 1782篇 |
免费 | 84篇 |
国内免费 | 1篇 |
专业分类
电工技术 | 79篇 |
综合类 | 1篇 |
化学工业 | 359篇 |
金属工艺 | 56篇 |
机械仪表 | 53篇 |
建筑科学 | 21篇 |
矿业工程 | 1篇 |
能源动力 | 37篇 |
轻工业 | 153篇 |
水利工程 | 2篇 |
石油天然气 | 1篇 |
无线电 | 253篇 |
一般工业技术 | 340篇 |
冶金工业 | 323篇 |
原子能技术 | 27篇 |
自动化技术 | 161篇 |
出版年
2023年 | 14篇 |
2022年 | 14篇 |
2021年 | 30篇 |
2020年 | 22篇 |
2019年 | 24篇 |
2018年 | 33篇 |
2017年 | 31篇 |
2016年 | 47篇 |
2015年 | 33篇 |
2014年 | 54篇 |
2013年 | 75篇 |
2012年 | 54篇 |
2011年 | 94篇 |
2010年 | 70篇 |
2009年 | 70篇 |
2008年 | 82篇 |
2007年 | 65篇 |
2006年 | 60篇 |
2005年 | 51篇 |
2004年 | 45篇 |
2003年 | 52篇 |
2002年 | 59篇 |
2001年 | 32篇 |
2000年 | 32篇 |
1999年 | 42篇 |
1998年 | 138篇 |
1997年 | 92篇 |
1996年 | 61篇 |
1995年 | 38篇 |
1994年 | 48篇 |
1993年 | 37篇 |
1992年 | 21篇 |
1991年 | 26篇 |
1990年 | 26篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 11篇 |
1986年 | 16篇 |
1985年 | 17篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 11篇 |
1979年 | 14篇 |
1978年 | 4篇 |
1977年 | 20篇 |
1976年 | 13篇 |
1974年 | 5篇 |
1973年 | 5篇 |
排序方式: 共有1867条查询结果,搜索用时 15 毫秒
101.
102.
Takashi Shimizu Yuji Usui Tomoyuki Nakagawa Hideyo Okushi 《Journal of Electroceramics》2000,4(2-3):299-303
Crystallographic orientation dependence of the Schottky properties of Au/Nb-doped SrTiO3 (STO:Nb) junctions has been investigated using single crystals of STO:Nb (1 0 0) and (1 1 1). It is found from electrical properties that the Schottky barrier height (SBH) of the Au/STO:Nb junctions estimated from current density (J)-voltage (V) characteristics shows crystallographic orientation dependence, while the flat band voltage estimated from capacitance (C)-voltage (V) characteristics is independent of the orientation. Displacement currents originated from the junction capacitance have been clearly observed at reverse bias voltage even in a condition of dV/dt 8.75 × 10–3 [V/s] because of large electrostatic permittivity of the STO, and the displacement currents also showed crystallographic orientation dependence. The different response in the electrical properties of the Schottky junctions suggests that electric properties of intrinsic low permittivity layers, which exist at Au/STO:Nb interfaces, have the crystallographic orientation dependence. 相似文献
103.
104.
M Nakase AM Alvarez T Adachi N Aoki R Nakamura T Matsuda 《Canadian Metallurgical Quarterly》1996,60(6):1031-1032
Previously isolated cDNA clone A3-12 that was expressed in E. coli as the fusion protein with Trp E showed immunoreactivity with the mouse antibody raised against isolated alpha-globulin from rice seed. The N-terminal amino acid sequences determined for the purified alpha-globulin and its tryptic peptides were identical with the deduced amino acid sequence reported, except for two residues at the protein N terminus. An error in the reported sequence was confirmed by re-sequencing the cDNA, the nucleotide sequence for the two N-terminal residues being shown to be CAGCTG and not CACGTG. Thus, the protein encoded by cDNA clone A3-12 was identified to be the major rice seed globulin, alpha-globulin, with an apparent molecular mass of 26kDa. 相似文献
105.
Film-type electrodes of hydrogen absorbing intermetallic compound and alloys, LaNi5, Ni0.11 Ti0.89, Ni0.50 Ti0.50 and Ni0.76 Ti0.24 were prepared by a flash evaporation method. The hydrogen electrode reaction characteristics of the LaNi5 and NiTi alloy films in 1 M NaOH are very similar to each other. The reaction proceeds via the Volmer-Tafel reaction route with mixed rate-determining characteristics. The exchange current densities of the constituent steps, as well as the overall reaction, are in the range of 10?6 A cm?2 (true). Surface analysis by an XPS technique has shown that La or Ti on the electrode surface exists as an electrocatalytically innert oxide of La2O3 or TiO2. Close similarities of these electrodes with pure Ni electrodes indicate that Ni is responsible for the electrocatalytic activity. No synergistic effect is thus noticeable. 相似文献
106.
M Adachi A Hayashi N Ohkoshi H Nagata H Mizusawa S Shoji F Tabei A Matsumura 《Canadian Metallurgical Quarterly》1995,34(8):806-810
A 67-year-old woman with a one-year history of tinnitus and headache had multiple cranial nerve palsies of V, VII, VIII, IX, X, XI and spastic paraparesis. She also had a secretory otitis media. Gd-DTPA-enhanced magnetic resonance imaging (MRI) revealed hypertrophy of the dura of the posterior fossa and spinal epidural mass which extended from C7 to T10. A biopsy of the epidural mass showed chronic granulomatous change. These lesions were completely cured with administration of antibiotics. We believe this case of double-lesion of hypertrophic cranial pachymeningitis and spinal epidural granulomatous lesion originated from a bacterial infection secondary to the secretory otitis media. 相似文献
107.
A new K2Cr2O7-H2SO4-HCl system has been developed that is particularly suitable for use in etching solutions of GaAs and InP. This system provides high quality etched surfaces without any undesirable roughness or etch pits. It has been found that the etching rate can be controlled by changing the etchant component proportions. This is especially the case with HCl. This leads to no change of surface quality. Vertical walls, and mesa-shaped structures have been formed on etching profiles of (001) GaAs by stripes parallel to the [110], and [¯110] directions, respectively. The mesa-shaped profiles have been formed for (001) InP in both the [110] and [¯110] directions. The solution does not erode photoresist masks and is thereby attractive for a variety of device applications. 相似文献
108.
Evaporation of SiO was carried out in the pressure range 10-5–10-1 Torr for several gas compositions. It is observed that the film structure varies from uniform to crystalline. The composition of the crystalline films seems to be close to SiO2, as confirmed by the structural features seen with a high resolution scanning electron microscope. In the uniform films conduction is considered to occur by Poole-Frenkel emission. In the crystalline films the conduction properties can be explained in terms of a space-charge-limited current. 相似文献
109.
T. Shin-ike T. Sakai Tetsuo Sakai G. Adachi J. Shiokawa 《Materials Research Bulletin》1977,12(7):685-688
The nature of the V/1bO/1bV interaction of the perovskite type rare-earth vanadites were studied by spectroscopic methods. Infrared and ultraviolet analyses revealed that the V/1bO bond length became shorter and that the V/1bO bond strength increased, as a function of the atomic number of lanthanide elements in LnVO3. Judging from the x-ray fluorescent spectra of oxygen-Kα, the energy level of O2? (pπ) orbitals of the heavier rare-earth vanadites was lower than that of the lighter rare-earth vanadites. 相似文献
110.
Nonstoichiometric , which exhibits a metallic behavior, was obtained by heating an insulating Gd2S3 at various temperatures under a vacuum. Electrical and magnetic properties of the samples obtained have been investigated from 4.2 K to 300 K. A maximum in resistivity was observed in the curve of resistivity vs. temperature. The temperature TP, at which the maximum emerged, was very close to the Curie temperature TC for the sample. An increase in resistivity at TP, Δ?, is proportional to ?P exp (), where ?P is the resistivity obtained by the extrapolation from the linear portion to TP in the ? vs. T curve. Using the relationship obtained, a model based on the formation of magnetic polaron was proposed for this system. 相似文献